New Zealand Plant Protection <p>ISSN 1175-9003 (print), ISSN 1179-352X (online)</p> <p><strong>2018 CiteScore</strong>: 0.68</p> <p><strong>Scope:</strong> Research on all aspects of biology, ecology and control of weeds, vertebrate and invertebrate pests, and pathogens and beneficial micro-organisms in agriculture, horticulture, forestry and natural ecosystems.</p> en-US (Dr Ruth Falshaw) (Ruth Falshaw) Sun, 28 Jul 2019 06:01:35 -0500 OJS 60 Title Pages <p>-</p> Copyright (c) 2019 New Zealand Plant Protection Fri, 26 Jul 2019 00:00:00 -0500 Table of Contents <p>&nbsp; &nbsp;</p> Copyright (c) Fri, 26 Jul 2019 00:00:00 -0500 Author Index <p>&nbsp; &nbsp; &nbsp;</p> Copyright (c) Fri, 26 Jul 2019 00:00:00 -0500 Foreword <p>&nbsp; &nbsp; &nbsp; &nbsp;&nbsp;</p> Eirian Jones Copyright (c) Fri, 26 Jul 2019 00:00:00 -0500 Pathogenicity of <i>Ilyonectria pseudodestructans </i>propagules to grapevine rootstocks <p>Black foot disease of grapevines is a major economic issue for the viticulture industry, with several <em>Dactylonectria</em> and <em>Ilyonectria</em> species identified as causal agents worldwide. This study aimed to confirm the pathogenicity of an <em>Ilyonectria pseudodestructans</em> isolate recovered from a symptomatic grapevine in a nationwide survey. An initial pot experiment inoculated callused and root-wounded grapevine propagation material of varieties ‘101- 14’ and ‘5C’ with <em>I. pseudodestructans</em> conidia. The second pot experiment compared the pathogenicity of <em>I. pseudodestructans</em> conidial, chlamydospore and mycelial inocula. Disease incidence, severity and root and shoot dry weights were determined after 4–5 months of growth. <em>Ilyonectria pseudodestructans</em> was recovered from inoculated plants resulting in higher disease incidence and severity compared with the uninoculated control. Disease severity and incidence was higher for callused compared to rooted propagation material, but did not differ between grapevine varieties. Conidial inoculum caused greater disease incidence and severity compared with chlamydospore and mycelial inocula. <em>Ilyonectria pseudodestructans</em> propagules infected grapevine plant material via the callused basal ends or wounded roots, indicating this species is a potentially important pathogen of grapevines both in nurseries and vineyards.</p> Chantal M. Probst, Hayley J. Ridgway, Marlene V. Jaspers, E. Eirian Jones Copyright (c) 2019 New Zealand Plant Protection Fri, 26 Jul 2019 01:31:31 -0500 The current outbreak of stemphylium leaf blight of onion in New Zealand – identification of cause and review of possible risk factors associated with the disease <p>During the 2017–18 growing season, significant outbreaks of leaf blight occurred in Pukekohe, Hawke’s Bay and Canterbury commercial onion fields. It was unknown if the causal agent was <em>Stemphylium vesicarium</em>, a pathogen already present in New Zealand that causes stemphylium leaf blight (SLB), or a new introduction of another <em>Stemphylium</em> species. Morphological and molecular characterisation methods were used to identify the pathogen present on diseased onion leaves. The possibility that climate may have been a contributor to the outbreak was evaluated using hourly temperature and relative humidity data, and comparing the 2017–18 growing season with the previous four seasons in these regions when no disease was observed. Our research indicates that the recent leaf blight outbreak in New Zealand was caused by <em>S. vesicarium</em>, and not the introduction of a novel species of <em>Stemphylium</em>. The warm, and wet summer of 2017–18 possibly contributed to the SLB outbreak.</p> Peter J. Wright, Bruce Searle, Joy L. Tyson, Kieran D. Mellow Copyright (c) 2019 New Zealand Plant Protection Mon, 22 Jul 2019 05:59:42 -0500 Pathogenicity of <i>Phoma betae </i>isolates from red beet (<i>Beta vulgaris</i>) at seed farms in Canterbury, New Zealand <p><em>Phoma betae</em> is an economically important pathogen of red beet causing preemergence seedling damping, leaf spot and root rot. However, the pathogenicity of <em>P. betae</em> is unknown in New Zealand despite the economic importance of this pathogen. Twenty-five isolates were collected from a survey of red beet seed farms in Canterbury, New Zealand during 2016/2017 and three of these PB101 (from seeds), PB103 (from roots) and PB106 (from leaves) were used for pathogenicity testing of two red-beet cultivars. Isolate PB106 was further used to investigate its effects on spinach and fodder beet as well as red beet under greenhouse conditions. All three <em>P. betae</em> isolates were pathogenic on both red-beet cultivars tested, causing leaf-spot symptoms. Isolates PB101 and PB106 produced significantly larger leaf-spot lesions (P&lt;0.001) compared with PB103. <em>Phoma betae</em> isolate PB106 was pathogenic to both red-beet cultivars, spinach and fodder beet but fodder beet was less susceptible than the other species tested. Regardless of cultivar, &lt;i&gt;<em>P. betae</em> &lt;/i&gt;is an important pathogen of beets and is capable of causing leaf spots.</p> Nitesh Chand, E. Eirian Jones, Seona Casonato Copyright (c) 2019 New Zealand Plant Protection Fri, 26 Jul 2019 00:00:00 -0500 Fate of mycelial and conidial propagules of Ilyonectria and Dactylonectria species in soil <p>Black foot disease of grapevines causes significant economic loss to the viticulture industry worldwide. A novel method was developed to investigate the fate of propagules of three species associated with black foot disease in New Zealand, <em>Dactylonectria macrodidyma</em>, <em>Ilyonectria europaea</em> and <em>I. liriodendri</em>, in soil. Conidia or mycelium of one isolate each of the three species were buried in soil in nylon mesh bags, and conidia/chlamydospore numbers were determined microscopically after 2 and 3 weeks. Conidia and chlamydospores were produced by mycelial inocula of all isolates, with greater numbers of chlamydospores after 3 weeks. Conidial inocula of all isolates also produced chlamydospores. Chlamydospores were formed at either the terminus or side of a hypha, and single and multiple conidia formed chlamydospores by combining their cellular protoplasm. Chlamydospores were produced from conidia, and conidia from mycelium faster for the <em>I. europaea</em> isolate than the <em>D. macrodidyma</em> and <em>I. liriodendri</em> isolates. The rapid formation of chlamydospores as survival propagules will facilitate the ability of these pathogens to persist in soil in the absence of a host.</p> Chantal Probst, Dudley Crabbe, Hayley Ridgway, Marlene V. Jaspers, E. Eirian Jones Copyright (c) 2019 New Zealand Plant Protection Fri, 26 Jul 2019 01:51:23 -0500 Trapping for early detection of the brown marmorated stink bug, <i>Halyomorpha halys</i>, in New Zealand <p>The brown marmorated stink bug (BMSB) would have wide-ranging and likely devastating effects on New Zealand’s horticultural industries if it were to establish here. This insect has spread rapidly around the world, becoming pestiferous only a few years after detection; therefore, there will be limited time to develop management strategies to prevent damage if viable BMSB populations were to establish in New Zealand. Lures containing BMSB pheromone paired with 92 sticky panels were deployed near transitional facilities and other potentially high-risk entry points in the Auckland, Hawke’s Bay and Nelson regions. Traps were monitored fortnightly from November 2018 to April 2019 and all pentatomid species identified and enumerated. No BMSB were captured, but seven other pentatomid species were caught. Numbers and species varied among site, region and date. The phenology of the pentatomids captured supports reports of one to two generations occurring in pipfruitproduction regions depending on growing-degree days. The phenologies of the pentatomid species caught suggest that any control measures for prevention of fruit damage by BMSB would be limited to late summer. A number of recommendations for a BMSB monitoring programme are provided.</p> Timothy F. Vandervoet, David E. Bellamy, Diane Anderson, Rory MacLellan Copyright (c) 2019 New Zealand Plant Protection Fri, 26 Jul 2019 01:59:24 -0500 Establishing a base for understanding the threat of the brown marmorated stink bug to plants of value to Māori / E whakarite ana he tūāpapa e mārama ai i ngā kino o te ngārara pīhau parauri ki ngā tipu e whai hua ki te Māori <p>The brown marmorated stink bug (BMSB) <em>Halyomorpha halys </em>(Heteroptera: Pentatomidae) is an invasive pest in North America and Europe that damages many plant species and invades human dwellings. It is regularly intercepted at Aotearoa/New Zealand’s borders but is not yet known to have established. Māori are partners in New Zealand’s biosecurity community and an understanding of the potential impact of any invasive alien species to their interests is essential. The known impacts of BMSB in published literature were reviewed with a focus on Māori plant taonga (valued or treasured plant species) in: (1) Māori commercial enterprises; (2) mara kai (food gardens); and (3) the natural estate. Many fruit and some vegetable species are likely to be affected by BMSB in commercial and non-commercial Māori horticulture but the impact of BMSB on indigenous/native and other taonga plant species in mara kai and the native estate is difficult to evaluate. BMSB poses a serious economic threat to some crop species of commercial value to Māori, as well as threat to some native taonga species. A kaupapa Māori approach examining unpublished mātauranga (knowledge) would considerably broaden this understanding.</p> <p><span class="s2">He ngārara raupatu kaha nei i te tini o ngā tipu, te urutomo noa i te hunga tangata te ngārara nei. Ka kaha haukotingia te ngārara nei e te mana ārai o Aotearoa heoi anō, kāore anō kia whakawhenua i a ia. E mahi tahi ana a Māori rāua ko te hapori marukoiora, anō hoki e mārama ana i te mōrearea o ngā tipu tauiwi - e whai pānga kia rātou.</span><span class="s1">&nbsp;Te Tukanga.&nbsp;</span><span class="s2">I arotake i ngā tuhinga e hāngai ana ki ngā kopuratanga e mōhio nei&nbsp; - e Māori ai te titiro o roto: (1) ngā pākihi Māori (2) ngā māra kai (3) te taiao anō hoki.&nbsp;</span><span class="s1">Te Whakautu.&nbsp;</span><span class="s2">He maha hoki ngā huawhenua me ngā huarākau ka pāngia e te BMSB o roto i ngā pākihi, i ngā ahuone Māori heoi anō, te taea te whakatau i ngā pānga o te BMSB ki te iwi taketake me ōna taonga o roto i ngā māra kai.</span><span class="s1">&nbsp;Te Whakakapinga.</span><span class="s2">&nbsp;Kei tino raru ētahi tipu e whai pānga ki te Māori, ngā tipu taketake anō hoki i te BMSB. Mā te tirohanga Māori e whakawhānui i ngā mōhiotanga.&nbsp;</span></p> David A.J. Teulon, Aleise Puketapu, Hone T. Ropata, Ross Bicknell Copyright (c) 2019 New Zealand Plant Protection Fri, 26 Jul 2019 02:11:05 -0500 Development of heat treatments for two species of Samoan fruit flies (<i>Bactrocera </i>spp., Diptera: Tephritidae) <p>Of the seven species of <em>Bactrocera</em> fruit flies found in Samoa, only two (<em>B. kirki</em> (Froggatt) and <em>B. xanthodes</em> (Broun)) are of economic importance. These species attack a range of fruit, including papaya (<em>Carica papaya</em>), breadfruit (<em>Artocarpus altilis</em>), eggplants (<em>Solanum melongena</em>) and citrus. The presence of these two species limits export market access for Samoan produce. Eggplants and breadfruit infested with the eggs of <em>B. kirki</em> and <em>B. xanthodes</em>, respectively, were treated using a high-temperature forced-air (HTFA) protocol to heat the fruits to core temperatures of 40<sup>o</sup>C, 42<sup>o</sup>C, 44<sup>o</sup>C or 46<sup>o</sup>C. No <em>B. xanthodes </em>pupae emerged from fruit treated at 42<sup>o</sup>C or greater. Pupae of <em>B. kirki</em> were found from fruit treated at temperatures up to 44<sup>o</sup>C, but failed to survive treatments at 46oC. The HTFA protocol previously approved for treatment of other Pacific fruit flies (fruit core temperature to 47.2<sup>o</sup>C for 20 min) works without modification for treatment of the two combinations of fruit flies and commodities tested. However, less intense HTFA treatments are worth investigating, if required to enhance fruit quality.</p> Fa'alelei Tunupopo, Fai'ilagi Sa'ili, Lisa E. Jamieson, Samuel D.J. Brown Copyright (c) 2019 New Zealand Plant Protection Fri, 26 Jul 2019 02:42:41 -0500 A comparison of postharvest quality of breadfruit (<i>Artocarpus altilis</i>) after disinfestation with hot air or hot water treatments <p>Breadfruit from Samoa potentially host the Pacific fruit fly (<em>Bactrocera xanthodes</em>) and so their export to New Zealand requires a disinfestation treatment. Heat treatments by air (HAT) or water (HWT) are common fruit-fly disinfestation treatments for tropical crops. Two breadfruit cultivars – Puou and Ma’afala – were subjected to three heat treatments, HAT-1 (minimum 47.2<sup>o</sup>C for 20 min at core), HAT-2 (49.0<sup>o</sup>C for 100 min at core) and HWT (47.2<sup>o</sup>C for 20 min at core), and an untreated control was also included. Fruit were stored for one week at 15oC followed by three days at 25<sup>o</sup>C. Disorders observed were heat damage to the skin (blackening) and increased decay on the body and stem-end. Heat damage was at an acceptably low level following HAT-1 but was unacceptable following HAT-2 or HWT. Initial results suggest that a HAT can be tolerated, but the effect of ramp rate and the potential of using a two-step HWT system should be examined.</p> Seeseei Molimau-Samasoni, Veronica Vaaiva, Semi Seruvakula, Angelika Tugaga, Guinevere Ortiz, Stephen Wallace, Mark Seelye, Barbara C. Waddell, Samuel D.J. Brown, Lisa E. Jamieson, Allan Woolf Copyright (c) 2019 New Zealand Plant Protection Fri, 26 Jul 2019 02:47:31 -0500 <i>Neofabraea actinidiae </i>in New Zealand kiwifruit orchards: current status and knowledge gaps <p><em>Neofabraea actinidiae</em> (syn. <em>Cryptosporiopsis actinidiae</em>) is a member of a suite of fungi associated with ‘ripe rots’ of kiwifruit. Although it has been recorded regularly from kiwifruit in New Zealand over the past 30-40 years, initially as ‘<em>Cryptosporiopsis</em> sp.’, there is a general lack of knowledge of this fungus. This paper provides a review of the current records and available literature on the taxonomy and biology of the organism, and assesses the knowledge gaps in the disease cycle and epidemiology of <em>N. actinidiae</em> in kiwifruit orchards. The conidia of the fungus are likely to be water borne, infect fruit during or near to flowering and remain latent until harvest and subsequent ripening. The source of inoculum remains unknown. This review may stimulate new research into this pathogen and give insights into potential control strategies.</p> Joy L. Tyson, Michael A. Manning, Kerry R. Everett, Robert A. Fullerton Copyright (c) 2019 New Zealand Plant Protection Fri, 26 Jul 2019 06:16:26 -0500 Understanding flower-bud rot development caused by <i>Pseudomonas syringae </i>pv. <i>actinidiae </i>in green-fleshed kiwifruit <p>A greater understanding of the epidemiology of flower bud rot caused by <em>Pseudomonas syringae</em> pv. <em>actinidiae</em> (Psa) in New Zealand green-fleshed kiwifruit cultivars is required to develop successful disease-management strategies. This study sought evidence as to whether the source of Psa bacteria that causes flower bud infection is internal or external to the flower buds as they emerge in spring. Psa was detected using qPCR in asymptomatic flower buds of two green-fleshed cultivars during spring 2016 and 2017, between bud emergence and immediately before flower opening. Bacterial isolations were made from surface sterilised and non-sterilised buds. Asymptomatic and symptomatic buds were dissected and isolations made from each of the dissected flower parts over time. Significantly more Psa was detected from non-sterilised flower buds during the early stages of bud development compared with later stages. Bud dissections showed that Psa colonisation began in the outer flower parts and moved inwards and this coincided with the development of bud rot symptoms. This study supports a hypothesis that bud rot arises when buds are externally contaminated by Psa early in their development and subsequent infection moves into the inner parts of developing flowers, destroying tissue and causing bud death. Effective control must aim to prevent initial Psa contamination.</p> M. Shahjahan Kabir, Bethan E. Parry, Joy L. Tyson, Robert M. Beresford Copyright (c) 2019 New Zealand Plant Protection Fri, 26 Jul 2019 06:19:29 -0500 Preliminary pathogenicity screening of <i>Verticillium</i> spp. on kiwifruit in New Zealand <p>Plant-pathogenic <em>Verticillium </em>species have been present in New Zealand for many years, and have been considered minor wilt pathogens of kiwifruit. However, an outbreak of <em>Verticillium nonalfalfae </em>(previously identified as <em>Verticillium alboatrum</em>) causing wilt and death of the kiwifruit cultivar <em>Actinidia chinensis </em>var. <em>chinensis </em>‘Hort16A’ in Chile has raised questions around the pathogenicity and significance of New Zealand <em>Verticillium </em>species. This study investigated the pathogenicity of New Zealand isolates of <em>Verticillium </em>spp. to ‘Hort16A’. Three isolates of <em>Verticillium dahliae </em>and one of <em>V. alboatrum sensu stricto</em>, previously recovered from kiwifruit in New Zealand, were tested for pathogenicity against ‘Hort16A’ by artificial inoculation of young vines. Disease assessments were carried out monthly. Symptoms observed ranged from minor wilt to vine death. The <em>V. alboatrum </em>isolate appeared the most aggressive. Although there is evidence of some pathogenicity on kiwifruit within this group of isolates from <em>Verticillium </em>species in New Zealand, they appear less aggressive than those recorded in Chile. However, this cannot be confirmed without testing isolates from both countries concurrently under the same conditions.</p> Kieran D. Mellow, Joy L. Tyson, Michael A. Manning, Peter J. Wright Copyright (c) 2019 New Zealand Plant Protection Fri, 26 Jul 2019 06:45:30 -0500 How much captan is required for wound protection of <i>Neonectria ditissima </i>conidial infection in apple? <p>Captan (a trichloromethyl sulfenyl fungicide) is commonly used for control of <em>Neonectria ditissima</em> in apple. In New Zealand, picking and leaf scars are the main source of new infections. The captan concentrations required for wound protection of leaf scars, picking and rasp wounds was determined <em>in planta</em>. Fresh wounds, inoculated with <em>N. ditissima</em>, were sprayed with captan using a motorised knapsack (leaf scars) or hand-held spray bottles targeting the wound area (picking and rasp wounds). Captan concentrations ranged from 0 to 400% field rate (100% = 2 kg captan/ha). Wounds were sampled pre- and post-captan application for residue analyses and the remainder assessed regularly in the field for disease expression. Disease development decreased as captan concentrations increased. Approximately 2 μg captan/scar (100% field rate) was required to protect leaf scars. Four times the field rate of captan was needed for a 55 and 70% disease reduction on picking and rasp wounds, respectively. Label-rate applications of captan controlled low incidence of <em>N. ditissima</em> leaf-scar infections in the field in autumn, but disease control of picking scars and other large wounds might be difficult to achieve.</p> Monika Walter, David W.L. Manktelow, Fanny Le Berre, Rebecca E. Campbell, Lauren Turner, Lizelle Vorster, Emma Patrick, Ruth C. Butler, Grant L. Northcott Copyright (c) 2019 New Zealand Plant Protection Fri, 26 Jul 2019 07:12:49 -0500 Successive passaging through an apple host of six low-virulent <i>Neonectria ditissima </i>isolates increased virulence in one of them <p><em>Neonectria ditissima</em> is a serious pathogen of apple. Low-virulent cultures of this fungus have been isolated from cankers, but how and why low-virulent isolates can infect apple is unknown. Rasp wounds on ‘Royal Gala’ trees were inoculated with agar plugs from six low-virulent <em>N. ditissima</em> isolates in a glasshouse. <em>Neonectria ditissima</em> was re-isolated 10 weeks after inoculation. Agar plugs from the re-isolated cultures were used to inoculate ‘Royal Gala’ trees again. After the second re-isolation, conidial suspensions of the original cultures and the 2 x 6 re-isolates were used to determine the virulence on ‘Royal Gala’ compared with field-collected conidia. Three cultures did not cause any lesions; neither did their re-isolates. The re-isolates of two cultures did not differ in virulence compared with the originals. However, the virulence of one isolate increased with each re-isolation, with the second re-isolation causing significantly more lesions, lesion development occurring faster and the lesions being larger than those caused by the original isolate. Therefore, the virulence of <em>N. ditissima</em> isolates can change over time, with loss or gain possibly being attributed to epigenetic and/or genetic changes in the genome.</p> Reiny W.A. Scheper, Brent M. Fisher, Joanna K. Bowen, Nicholas T. Amponsah, Duncan I. Hedderley Copyright (c) 2019 New Zealand Plant Protection Fri, 26 Jul 2019 07:16:58 -0500 Can phosphorous acid be used to control <i>Neonectria </i><i>ditissima </i>in New Zealand grown apples? <p>European canker, <em>Neonectria ditissima</em>, is a worldwide apple tree disease killing shoots, branches and trees, and treatment with phosphorous acid is a possible control option. The effect of six postharvest phosphorous acid (PA) treatments on fruit residues the following season was studied in Tasman on two trial sites growing ‘Scifresh’ or ‘Scilate’ apple trees. Spray treatments consisted of number (0–3) and timing (early, mid and/or late) of PA applications. Additionally, leaf-scar wounds were artificially inoculated with <em>N. ditissima</em> spores at the ‘Scilate’ site on 1 and 8 June 2017 to determine disease control. Symptom expression was checked regularly between October 2017 and February 2018. None of the treatments caused a statistically significant reduction in the incidence of canker development compared with the control. Two or more PA applications resulted in PA residues in fruit, at harvest, the following season. Higher PA residues were found in fruit following early applications than with late applications. More applications of PA resulted in higher residues. This finding has important implications for exporting fruit to markets that have no tolerance for PA residues.</p> Jason Smith, Monika Walter, Rebecca E. Campbell, Lauren Turner Copyright (c) 2019 New Zealand Plant Protection Fri, 26 Jul 2019 07:19:29 -0500 Lesion development and conidial production of <i>Neonectria ditissima </i>on apple trees in four New Zealand regions <p>This study examined incubation period, lesion length and conidial release in <em>Neonectria ditissima</em> (European canker) in four New Zealand regions in relation to climatic factors. Incubation period was studied on potted ‘Royal Gala’ trees inoculated with <em>N. ditissima</em>. One week after inoculation, symptomless trees were dispatched to Waikato, Hawke’s Bay, Tasman, Otago and positive controls remained in a glasshouse. Conidial release was studied in trees with lesions that were dispatched to the same regions. Rain traps were placed under each lesion and conidia quantified after each rain event. Disease progress and conidial production were examined in relation to weather. Lesions developed significantly slower in Otago and faster in Waikato and the glasshouse, compared with Tasman and Hawke’s Bay. Symptom development accelerated with increasing daily hours of 11–16°C and humidity (74.6–87.2% RH). The highest conidium counts occurred in Waikato and the lowest in Otago, while conidial production started earlier in Tasman than elsewhere. Temperature is the main driver for symptom development during the incubation period and rainfall is not required. Rainfall frequency drives conidial production.</p> Reiny W.A. Scheper, Lizelle Vorster, Lauren Turner, Rebecca E. Campbell, Kate Colhoun, Danielle McArley, Rosalind Murti, Andrew Hodson, Robert Beresford, Maryam Stock, Brent M. Fisher, Duncan I. Hedderley, Monika Walter Copyright (c) 2019 New Zealand Plant Protection Fri, 26 Jul 2019 07:23:23 -0500 Effects of various ecological factors on the germination of two crop and pasture weed species, Vulpia bromoides and Vulpia myuros <p><em>Vulpia</em> species (silver grasses), including <em>V. bromoides</em> and <em>V. myuros</em>, are native to the Mediterranean, Middle East and Eurasia, but have become dispersed worldwide. These two species reduce the grazing quality of pastures, frequently co-occur and are often associated with poor-quality acidic soils. This study investigated two species, <em>Vulpia </em><em>bromoides </em>and<em> V. myuros</em>. Germination trials tested the effects of seasonal temperature, light,<br>pH, moisture, salinity, pre-germination heat shock and smoke, and seed burial depth. <em>Vulpia </em><em>bromoides</em> germinated well regardless of temperature or light (&gt;80%, all conditions), whereas <em>V. myuros</em> preferred lower temperatures and absence of light (97%, 7/17<sup>o</sup>C in 24-h dark). Under different culture conditions, the two species germinated well across the pH range 4 to 10 (&gt;85%). Reduced moisture, pre-germination heat shock and smoke, and increased burial depth reduced germination and emergence of both species. Preventing germination of these species in pastures must begin before or during winter. Fire may be useful for control, but<br>sufficiently high temperatures must be achieved to kill seeds. Tillage to bury seeds, prior to pasture renovation, may prevent germination of seeds.</p> Sandra Weller, Singarayer Florentine, Bhagirath S. Chauhan, Ako Mahmood, Arunthathy Florentine Copyright (c) 2019 New Zealand Plant Protection Fri, 26 Jul 2019 07:26:17 -0500 Factors affecting germination of great bindweed (Calystegia silvatica) seeds <p>Great bindweed (<em>Calystegia silvatica</em>) invades riparian plantings in New Zealand but little is known about the factors influencing seed germination of this species, the number of seeds produced per flower or whether seed banks build up in the soil below infested sites. Dormancy-breaking treatments involving scarification and/or pre-chilling of seeds were evaluated. The effect of temperature on germination was also studied. The presence of viable seeds in capsules on vines and in the soil beneath established stands was quantified. Great bindweed seeds needed scarification but not a period of cold temperature to germinate. Germination occurred from 5<sup>o</sup>C to 25<sup>o</sup>C but germination was greater and more rapid at higher temperatures. Seed capsules contained an average of only 2.3 seeds, and the soil beneath plants had, on average, only 21.9 seeds/m<sup>2</sup>. Seeds were large with one thousand seeds weighing 43.4 g. Once the hard seed coat is broken, seeds will germinate readily at warmer times of the year, but seed production is not prolific so seeds might not be that important for spread of the species.</p> Kerry C. Harrington, Tracey L. Gawn, Cory Matthew, Hossein Ghanizadeh Copyright (c) 2019 New Zealand Plant Protection Mon, 22 Jul 2019 05:53:04 -0500 Roadside mowing spreads yellow bristle grass (Setaria pumila) seeds further than by natural dispersal <p>Yellow bristle grass is a highly invasive annual C<sub>4</sub> pasture weed that has spread rapidly through many New Zealand dairying regions via seed dispersal. Seven trials were conducted on roadsides infested with yellow bristle grass to evaluate natural and mower-assisted dispersal. To trap seeds, yellow sticky traps were laid out at various intervals both perpendicular to and parallel to the road. Traps were in place for 24 h in the four natural dispersal trials but only for the event in the mowing trials. Seeds on the retrieved traps were counted and the seeds caught in the mower estimated. For natural dispersal, 90% of seeds fell within 0.5 m. When mown, 90% of the seeds fell within 2 metres in the direction of mowing and 80% within 20 cm in the perpendicular direction. More importantly, a small percentage of dispersed seeds were caught in the mower and presumably could subsequently fall off anywhere. Mowing mature yellow bristle grass on the roadside will result in accelerating seed dispersal along the roadside for many metres and potentially many kilometres.</p> Trevor K. James, Michael R. Trolove, Claire A. Dowsett Copyright (c) 2019 New Zealand Plant Protection Mon, 22 Jul 2019 05:37:11 -0500 The impact of cutting prior to goat grazing on variegated thistle (<i>Silybum marianum</i>) <p>Variegated thistle (<em>Silybum marianum</em>) is a prevalent weed on the East Coast of the North Island of New Zealand. Goats may provide a novel management tool to control thistles, but little is known about how cutting thistles prior to grazing affects thistle consumption by goats. This study investigated the extent to which goats consume either uncut entire variegated thistle plants or cut thistles. Eight groups of three goats were presented with thistle vegetation in each of two replicate 1-hour feeding sessions on 2 consecutive days. Averaged over both days, in the cut treatment, goats consumed 99% of the leaves that had been removed from the thistles and reduced the ground cover of the thistle plants by 68%. In the uncut treatment, ground cover of the thistles was reduced by 46%. A combination of cutting and goat grazing is likely to be a useful tool for stopping variegated thistle debris from smothering pasture and for inhibiting seed setting. Further work is required to test this at paddock scale.</p> Rose Greenfield, Katherine Tozer, Gosia Zobel, Catherine Cameron, Elizabeth North Copyright (c) 2019 New Zealand Plant Protection Fri, 26 Jul 2019 07:30:03 -0500 Investigating time and economic costs of botrytis bunch rot sampling using interpolated data <p><em>Botrytis cinerea</em> causes botrytis bunch rot (BBR) disease in wine grapes. Small-scale labour-intensive visual disease assessments may not adequately represent an entire vineyard but larger assessments add cost without necessarily improving accuracy or financial returns. BBR-severity data were collected on three dates from two sites and spatially interpolated. Balanced acceptance sampling (BAS) and simple random sampling (SRS) were compared using sample sizes of 2 to 200 vines. Assessment times were calculated for both walking (rows ignored) and driving (rows impassable) and costs compared with assessment error and effects on crop value. Overall, BAS performed better than SRS. Driving was faster than walking except when sample distribution necessitated travelling down every row regardless of sample size. Annual crop losses of up to NZ$2578 per hectare could result from short assessment times and subsequent inaccurate estimates of BBR severity. Spatial interpolation was shown to be a useful and promising technique for studying BBR sampling strategies in vineyard blocks. Travel was not a substantial component of assessment time. An 80-minute-long assessment could substantially reduce economic losses because of errors in BBR assessments.</p> Gareth N. Hill, Peter Jaksons, Joanna M. Sharp, Adrian G. Hunt, Kai S.J. Lewis Copyright (c) 2019 New Zealand Plant Protection Sat, 27 Jul 2019 00:10:38 -0500 Mapping European canker spatial pattern and disease progression in apples using GIS, Tasman, New Zealand <p>European canker (EC), caused by <em>Neonectria ditissima</em>, is an important disease in apple-producing regions in New Zealand. In order to improve plant protection, Geographic Information Systems (GIS) can be used to map plant disease location and severity in agricultural settings. Data were compiled from apple growers in Tasman, New Zealand, to investigate EC distribution over 4 years, for the period 2015–2018. ArcGIS software, including the Spatial Analyst, Interpolation and Geospatial statistics toolboxes, was used to map EC incidence at the spatial scale of orchard blocks, which allowed the identification of disease hot-spots. A clustered spatial pattern of disease was detected every year and areas with higher risk of EC were identified within the region. The spatial patterns detected were related to disease pressure over time for different apple cultivars. The use of GIS provides a platform for analysing and visually communicating disease patterns over time. Investigating disease spatial pattern allows the inference of spatial processes and further hypothesis generation to understand the pathogen.</p> Diletta Di Iorio, Monika Walter, Egbert Lantinga, Huub Kerckhoffs, Rebecca E. Campbell Copyright (c) 2019 New Zealand Plant Protection Sat, 27 Jul 2019 00:25:07 -0500 Comparison of four off-the-shelf unmanned aerial vehicles (UAVs) and two photogrammetry programmes for monitoring pasture and cropping field trials <p>Rapid advancements in UAVs, computing power and photogrammetry techniques now permit low cost biological-monitoring applications using off-the-shelf hardware and software. The utility of four UAV models costing $1,200 - $11, 000 and two photogrammetry programmes were assessed in separate experiments to evaluate their ability to detect standardised plant targets and to generate useable orthomoasic images. The colour and contrast of standardised targets influenced detection by UAVs more than their size as height increased. A large green rosette (50.8 cm2) could be detected by all UAVs from 28–90 m, while a yellow target 13 times smaller could be detected at 36–100 m, with the more expensive UAVs being effective at the higher altitudes. Monitoring vegetation cover or flowering plants is possible at the minimum allowable height altitude of 20 m by all four UAVs. However, identification of species in their vegetative state would require the UAVs with the better camera optics. The two photogrammetry programmes produced suitable orthomosaic images under the pasture, maize and hill country scenarios tested.</p> Michael R. Trolove, Paul Shorten Copyright (c) 2019 New Zealand Plant Protection Sat, 27 Jul 2019 00:27:00 -0500 Paper-based inoculum of <i>Bacillus megaterium </i>and its practical application for simple culture preparation <p>The bacterium <em>Bacillus megaterium</em> can be used to biologically control sheath blight and grain discoloration in rice. Large-scale inoculations using liquid cultures are cumbersome so the efficacy of an alternative, paper-based system was examined. Bacterial endospores were embedded on filter papers and multiplied using a simple culture technique. The resulting suspension was used to pre-soak yardlong bean and cucumber seeds before sowing to assess its effect on seed germination and weight. The efficacy of the bacterium in protecting cucumber seeds from pre-emergent damping-off was also examined. The population of bacteria embedded in paper declined initially but remained stable for 150 days at room temperature. Bacterial culture reduced seed germination of cucumber and seedling weight of yardlong beans. Dilution with water either increased or reduced germination of cucumber seeds depending on concentration. A 1:10 v/v dilution increased cucumber-seed germination in a pre-emergent damping-off pot test but all seedlings later died, irrespective of treatment. Paper-based inoculum has the potential to replace liquid inoculum but further work is required to optimise the concentrations of the bacterial culture to achieve disease control without adversely affecting the host plant.</p> Mana Kanjanamaneesathian, Wasunan Nimanong Copyright (c) 2019 New Zealand Plant Protection Sat, 27 Jul 2019 00:00:00 -0500 Comparison of aqueous seasoning cube solution and nutrient broth as culture media for production of the biocontrol agent <i>Bacillus megaterium </i>in the laboratory, and for suppression of rice grain discolouration in the field <p><em>Bacillus megaterium</em> is a beneficial bacterium that is used as a biological control agent (BCA) against the fungi <em>Rhizoctonia solani, Fusarium sacchari</em> and <em>Curvularia lunata</em>, which attack rice plants. However, the cost of preparing the bacterium using standard nutrient broth is prohibitively expensive on a large scale. Therefore, a low-cost product (seasoning cube, a common ingredient for cooking) was examined as an alternative nutrient medium. <em>Bacillus megaterium</em> was cultured in either nutrient broth or in dissolved seasoning cube. These cultures were evaluated for their effect on the growth of rice seedlings in the laboratory and to suppress grain discoloration of rice in small-scale field trials. <em>Bacillus megaterium</em> cultured with a seasoning cube was as effective as standard nutrient broth for the growth of rice seedlings in the laboratory. It also suppressed grain discoloration disease of rice in small-scale field trials. Use of a seasoning cube is suitable for culturing <em>B. megaterium</em> and should be recommended to farmers.</p> Mana Kanjanamaneesathian, Pimjai Meetum Copyright (c) 2019 New Zealand Plant Protection Sat, 27 Jul 2019 03:32:41 -0500 Potential biological control of take-all disease in perennial ryegrass <p>Perennial ryegrass (<em>Lolium perenne</em>) is the major pasture grass in New Zealand but is highly susceptible to take-all disease, caused by the root-rot pathogen <em>Gaeumannomyces graminis</em> (Gg). Isolates of the fungus <em>Trichoderma atroviride</em> are known to control <em>Gg</em> but it is not known if a mixture of isolates would be more effective than individual ones. Soil from a field naturally infested with <em>Gg </em>was placed in containers in a glasshouse and sown with ryegrass seeds then treated with one of three <em>Trichoderma atroviride</em> isolates or a mixture of all three isolates. All <em>T. atroviride</em> treatments significantly increased shoot dry matter by 46–73% and root dry matter by 42–62% compared with the control but a mixture of isolates was no more effective than individual isolates. Application of <em>T. atroviride </em>also significantly decreased root disease severity, which was negatively correlated with root dry matter. Takeall in pastures could possibly be controlled by overdrilling grass with a single isolate of <em>T. atroviride</em>.</p> Abdullah Umar, Diwakar R.W. Kandula, John G. Hampton, M. Phil Rolston, Soonie F. Chng Copyright (c) 2019 New Zealand Plant Protection Sat, 27 Jul 2019 03:38:38 -0500 The potential management of the drone fly (<i>Eristalis tenax</i>) as a crop pollinator in New Zealand <p>The drone fly (<em>Eristalis tenax</em>) pollinates many crops and is found almost worldwide. Its successful management as a field-crop pollinator would provide an additional option to augment bee pollination. We reviewed literature to assess their management potential. A literature search was conducted for information on drone-fly abundance across New Zealand crops, pollinator effectiveness, lifecycle-requirements and potential for mass rearing. Relevant literature was then evaluated to assess the feasibility, benefits and limitations of their management. <em>Eristalis tenax</em> is a proven pollinator of pak choi (<em>Brassica rapa</em> spp. <em>chinensis</em>), kiwifruit (<em>Actinidia deliciosa</em>) and onion (<em>Allium cepa</em>), and visits the flowers of several more crops in New Zealand. It readily completes its lifecycle under laboratory conditions when reared on various organic materials. No reviewed studies were identified that showed successful management of populations for the purpose of field-crop pollination. Key challenges for their management as field-crop pollinators include: being able to mass rear them at an appropriate scale; retaining numbers within targeted areas in the field; and ensuring their use does not significantly impact on non-target species and land-user interests.</p> Brad G. Howlett, Megan Gee Copyright (c) 2019 New Zealand Plant Protection Sat, 27 Jul 2019 03:42:07 -0500 The effectiveness of two types of adhesive for catching insects in traps <p>Sticky traps for monitoring insects use polybutene adhesive (PBA) to entangle insects. This glue is effective but messy to use and an alternative, hot-melt pressure-sensitive adhesive (HMPSA) is available. The effectiveness of these two adhesives was compared for catching pest and beneficial insects, primarily in apples. Various types of trap with either PBA or HMSPA were placed in orchards and vineyards in Hawke’s Bay and Nelson. Eight pests from six families, six parasitoids, five predators and one pollinator were commonly recorded. Traps with HMPSA generally caught similar numbers or more of both insect pests and beneficial insects than traps with PBA. Traps with HMPSA performed better for larger insects (&gt;1.5 mm), whereas those with PBA tended to be more effective for smaller insects. Both types of adhesive were effective for up to 4 weeks. HMPSA was effective for monitoring a range of insect pests and beneficial insects. Compared with PBA, HMPSA was more consistent and much cleaner and easier to use. It is recommended that HMPSA replaces PBA in traps for monitoring moth pests in the pipfruit industry.</p> Peter L. Lo, Roger Wallis, David E. Bellamy Copyright (c) 2019 New Zealand Plant Protection Sat, 27 Jul 2019 03:49:34 -0500 Preferences of the wheat bug (<i>Nysius huttoni</i>) for particular growth stages of the potential trap crop, alyssum (<i>Lobularia maritima</i>) <p>The New Zealand endemic wheat bug, <em>Nysius huttoni</em> (Hemiptera: Lygaeidae), is a pest of brassica seedlings. However, it has a wide host range comprising almost all cultivated brassicas, cereals and many other cultivated crops, as well as weeds. The brassica alyssum (<em>Lobularia maritima</em>) is a potential trap crop of <em>N. huttoni</em>, having the potential to keep the bugs away from seedlings. Laboratory no-choice and choice tests evaluated the relative preference of <em>N. huttoni</em> for two major growth stages of alyssum – vegetative and flowering. In both bioassays, <em>N. huttoni</em> adults settled significantly more promptly on the flowering than on the vegetative stage. The same preference was evident for adult numbers settling. Survival was higher on the flowering (38%) than on the vegetative stage (28%), although this was not significant. The implications of these findings are important in the design of trap cropping protocols for <em>N. huttoni</em> management. Flowering alyssum in brassica fields can also potentially improve pest biological control and provide other ecosystem services that can contribute to mitigating diminished ecosystem functions in agriculture.</p> Sundar Tiwari, David J. Saville, Stephen D. Wratten Copyright (c) 2019 New Zealand Plant Protection Mon, 22 Jul 2019 00:00:00 -0500 A comparison of two methods to determine the susceptibility of sawtoothed grain beetle (<i>Oryzaephilus surinamensis</i>) populations to pirimiphos-methyl from Canterbury, New Zealand <p>Resistance of sawtoothed grain beetle (<em>Oryzaephilus surinamensis</em>) to organophosphate insecticides is documented internationally. There are anecdotal reports of reduced efficacy in New Zealand but to date no empirical assessments have been made. Two-laboratory-based test methods using either a dust (Actellic® Dust) or liquid (Actellic® 50EC) formulations of pirimiphos-methyl, were compared to determine the response of five Canterbury sawtoothed grain beetle populations. A mini-silo method employed grain treated with the recommended application rate (200 g a.i./tonne seed) of pirimiphos-methyl dust. A Petri-dish method treated internal surfaces of 50-mm diameter Petri dishes with liquid pirimiphos-methyl at concentrations from 0–0.1 g a.i./L to determine an estimated LC<sub>50</sub> (lethal concentration for 50% mortality) for each population. The rank order of mortality (highest to lowest) in the mini-silo test was similar to the Petri-dish LC<sub>50</sub> rankings for the five populations tested. The results illustrate variation in responses to pirimiphosmethyl concentrations by sawtoothed grain beetle populations, indicating both methods are potential options for future resistance testing and will aid the development of management strategies for control of stored insect pests.</p> Joanne B. Drummond, R. Bruce Chapman Copyright (c) 2019 New Zealand Plant Protection Sat, 27 Jul 2019 04:03:27 -0500 Virulence of the plant-associated endophytic fungus <i>Lecanicillium muscarium </i>to diamondback moth larvae <p><em>Plutella xylostella</em> (diamondback moth) is a prominent pest of brassicas which is now resistant to most insecticides. Despite years of research, the range of available products used in biological control of diamondback moth is still somewhat limited. We isolated putative endophytic fungi from New Zealand cabbage plants to search for unique biological control agents of diamondback moth larvae. The larvae were fed leaf discs from commercially grown cabbage covered in spores from endophytic fungal isolates to test the insecticidal properties of these fungi. Twenty of the 52 fungal isolates tested failed to kill any diamondback moth larvae. However, three isolates of <em>Lecanicillium muscarium</em> induced mortality greater than 80%. While these isolates have potential for use in biological control applications, further research into propagation, formulation, and method, rate and timing of application is needed.</p> Michal Kuchár, Travis R. Glare, John G. Hampton, Ian A. Dickie, Mary C. Christey Copyright (c) 2019 New Zealand Plant Protection Sat, 27 Jul 2019 05:50:40 -0500 Impact of generalist predation on two weed biocontrol agents in New Zealand <p>The broom leaf beetle (<em>Gonioctena olivacea</em>) and the Honshu white admiral butterfly (<em>Limenitis glorifica</em>) have been introduced into New Zealand as biocontrol agents of the weeds Scotch broom (<em>Cytisus scoparius</em>) and Japanese honeysuckle (<em>Lonicera japonica</em>) respectively. However, neither agent has been successful yet. Larval predation of these species could be a factor affecting their success, and this hypothesis was tested using various predator-exclusion treatments. Survival of broom leaf beetle larvae increased c. five-fold by sleeving Scotch broom seedlings in fine mesh. In contrast, survival was unaffected by excluding either crawling predators using sticky barriers or larger predators using chicken wire. Survival of Honshu white admiral butterfly larvae increased c. ten-fold by excluding either crawling predators using sticky barriers or flying predators using a fine-mesh sleeve. Simultaneously excluding both crawling and flying predators resulted in a c. 23-fold increase in survival. These results suggest that larval predation could be limiting the populations of both broom leaf beetle and Honshu white admiral. Future biocontrol programmes could prioritise candidate agents accordingly.</p> Quentin Paynter, Paul Peterson, Samantha Cranwell, Chris J. Winks, Zane McGrath Copyright (c) 2019 New Zealand Plant Protection Sat, 27 Jul 2019 05:55:24 -0500 Distribution of <i>Puccinia punctiformis </i>in above-ground tissue of <i>Cirsium arvense </i>(Californian thistle) <p><em>Cirsium arvense</em> (Californian thistle) is a problematic weed in agricultural systems throughout New Zealand and the rust fungus <em>Puccinia punctiformis</em> is a potential biological control agent for this weed. <em>Puccinia punctiformis </em>can systemically infect thistles but the movement of the pathogen <em>in planta</em> is not fully understood. This research determined the level of infection <em>in planta </em>caused by <em>P. punctiformis </em>at a single time point. The concentration of <em>P. punctiformis </em>DNA <em>in planta </em>was determined to ascertain the location of the fungus within naturally field-infected <em>C. arvense</em>. Quantitative polymerase chain reaction was undertaken on above-ground symptomatic and asymptomatic <em>C. arvense </em>tissue at various locations within leaves (top, middle and bottom) and the main stem. All <em>C. arvense </em>shoots had detectable amounts of <em>P. punctiformis </em>but the concentration was 100× greater in symptomatic compared with asymptomatic shoots. In general, the concentration of fungus progressed up the leaves with a significant effect between locations (P&lt;0.001). <em>Puccinia punctiformis </em>was found <em>in planta </em>but broadscale disease of <em>C. arvense </em>does not occur and the reason for this is unknown.</p> Caitlin Henderson, Michael Cripps, Seona Casonato Copyright (c) 2019 New Zealand Plant Protection Sat, 27 Jul 2019 06:00:39 -0500 Fruit drop in two kiwifruit varieties and the use of two <i>Bacillus</i>-based biofungicides <p>Recently, fruit drop in two green varieties of kiwifruit (<em>Actinidia deliciosa</em>; VarA and VarB) has increased towards the harvest date. The efficacy of two biofungicides, applied post-flowering, to ameliorate the effects of early fruit drop in VarA and VarB during the 2017–18 growing season was tested. Treatments were applied to a single bay, with buffer bays and rows adjacent. Treatments were two different <em>Bacillus</em>-based biofungicide products; Serenade® Max (a.i. <em>B. subtilis </em>QST713 strain) and Triple-X® (a.i. <em>B. amyloliquefaciens </em>BS 1b). There was an untreated control. All fruits in the canopy, within the treated bay, were counted and recorded at 4-weekly intervals, over 5 months until harvest. At the VarA site, there was no statistical difference (P&gt;0.1) in the percentage of fruit drop between the control (7%), Triple-X® (5%) and Serenade® Max (10%) treated vines. At the VarB site, fruit drop differed statistically (P&lt;0.1) between Triple-X® treated vines (5%) and the control (10.5%), with Serenade® Max treated vines (6.5%) having intermediate fruit drop. The use of Triple-X® may be an option to assist with reducing fruit drop in kiwifruit.</p> Seona Casonato Copyright (c) 2019 New Zealand Plant Protection Sat, 27 Jul 2019 06:03:48 -0500 Next-generation DNA sequencing shows a microbiota shift after an incursion of <i>Pseudomonas syringae </i>pv. <i>actinidiae </i>(Psa) on a single kiwifruit orchard <p>A virulent strain of <em>Pseudomonas syringae </em>pv. <em>actinidiae </em>(Psa) is a major pathogen for New Zealand’s $3B kiwifruit (<em>Actinidia </em>spp.) industry, and was first identified from a Te Puke orchard on 5 November 2010. Psa was first found on the Kerikeri research orchard (KRO) of Plant &amp; Food Research on 19 September 2014. The samples for this study were collected from the same orchard on 7 December 2012 and 25 November 2014, i.e. before and after the Psa incursion. Polymerase chain reaction (PCR) was conducted on total genomic DNA from four leaf discs of 15 individual vines sampled from two kiwifruit cv. ‘Hort16A’ orchard blocks at KRO, using modified PCR primers complementary to bacterial 16S ribosomal DNA and the fungal inter-transcribed spacer (ITS) region. The microbiota present before and after the Psa incursion were investigated by Illumina MiSeq™ next-generation sequencing to produce 2 × 300 bp pair end reads, followed by metabarcoding analysis using QIIME2 software. Populations of fungi from the Basidiomycete orders Filobasidiales, Sporidiobolales, Tremellales and Leucosporidiales, and genera of bacteria with known biological control activity, such as <em>Erwinia, Pantoea, Methylobacterium, Sphingomonas </em>and <em>Paenibacillus</em>, increased in the presence of Psa.</p> I.P. Shamini Pushparajah, Daniel F. Jones, Kerry R. Everett Copyright (c) 2019 New Zealand Plant Protection Sun, 28 Jul 2019 06:18:10 -0500 Testing new PCR primers and a TaqMan™ probe for detection of <i>Phlyctema vagabunda </i>syn. <i>Neofabraea alba </i> <p><em>Phlyctema vagabunda </em>syn. <em>Neofabraea alba </em>is a fungal pathogen that causes bull’s eye rot (BER) of apples. Polymerase chain reaction (PCR) primers complementary to the inter-transcribed spacer region of ribosomal DNA (ITS) and the <em>β</em>-tubulin gene region, and a TaqMan™ probe assay were developed to detect this pathogen. These assays were compared in quantitative PCR (qPCR) reactions for amplification of DNA extracted from several fungal species and from apple tissue. Although the ITS and the <em>β</em>-tubulin primers amplified all <em>N. alba </em>isolates, both primers also amplified a few other fungal species. The TaqMan™ probe used with published primers for <em>N. alba </em>only amplified <em>N. alba </em>isolates. The TaqMan™ assay resulted in the lowest crossing threshold (Ct) values for DNA extracted from apple fruit, leaves, and spores collected on cellophane from eight apple orchards. The TaqMan™ results were correlated with percentage BER (%BER) in a 400-apple sample harvested from the same orchards. The TaqMan™ probe assay was the most sensitive and specific qPCR protocol tested, and Ct values showed the best correlation with %BER.</p> Michelle J. Vergara, I.P. Shamini Pushparajah, John F. Mackay, Kerry R. Everett Copyright (c) 2019 New Zealand Plant Protection Sun, 28 Jul 2019 00:00:00 -0500 Current and planned research for managing the fruit fly threat to New Zealand <p>Fruit flies (Family Tephritidae), in particular the Queensland fruit fly (<em>Bactrocera tryoni</em>; QFF), are one of the biggest biosecurity risks for New Zealand horticulture. New Zealand has one of the best science-based biosecurity systems in the world, based on years of experience and sound research. The introduction of fruit flies to New Zealand is now well managed in commercial fruit imports, but the risk is rising from growing trade and travel and, in the case of QFF, climatic adaptation and spread to more southern localities. Smarter solutions are continually needed to manage this increasing risk, and to deal with such pests when they arrive. We present a brief summary of current and anticipated research aimed at reducing the likelihood of entry into New Zealand and/or minimising the impact for the fruit fly species of greatest threat to New Zealand. Research spans risk assessment, pathway risk management, diagnostics, surveillance and eradication.</p> David A.J. Teulon, John M. Kean, Karen F. Armstrong Copyright (c) 2019 New Zealand Plant Protection Sun, 28 Jul 2019 06:52:39 -0500 <i>Ustilago maydis </i>yeast stage found on imported sweet corn <p>During the inspection of imported sweet corn (<em>Zea mays</em>), a specimen with dry rot symptoms was detected by Ministry for Primary Industries quarantine officers. A sample was sent to the MPI Plant Health and Environment Laboratory for diagnostics, and initial examination found a layer of yeast cells on the surface of the symptomatic tissue. The fungus was cultured and identified based on DNA sequences as <em>Ustilago maydis</em>. While the corn-smut pathogen <em>U. maydis </em>is well known to cause tumour like galls on corn kernels, it is a less recognised fact that this fungus can also grow as a yeast. To determine if the yeast stage could have been associated with the dry-rot symptoms observed on the specimen, healthy material was inoculated with the isolated <em>U. maydis </em>strain. No symptoms developed on inoculated material, indicating that the yeast cells were likely multiplying on the surface of the cut corn ear as saprobes. To our knowledge, this is the first report of <em>U. maydis </em>yeast stage on corn ears and indicates a previously unconsidered pathway for the organism. For the yeast stage to cause disease, mating with a compatible mating type on the surface of a living host plant would be required.</p> Merje Toome-Heller, Brett J.R. Alexander Copyright (c) 2019 New Zealand Plant Protection Sun, 28 Jul 2019 06:54:39 -0500 Enhancing plant disease diagnostics in the Pacific <p>A project aiming to enhance biosecurity and market access in the Pacific was launched by NZ Aid in 2016. The project intends to benefit the economies of New Zealand’s Pacific neighbours by improving their biosecurity systems which, in turn, would help to protect New Zealand’s borders. Under the current project, the MPI’s Plant Health and Environment Laboratory (PHEL) is accountable for delivering insect pest and disease diagnostic training in the Pacific and developing diagnostic tools. The PHEL Mycology and Bacteriology team has delivered a number of plant pathology training sessions in New Zealand, Cook Islands and Fiji. The main focus of the pathology module was to provide the Biosecurity Authority of Fiji (BAF) Plant Health Laboratory staff with skills and tools to conduct plant disease diagnostics at their facility. This included a full laboratory refurbishment and new molecular setup. As a result, the BAF team has become efficient with isolating and identifying plant pathogens using a combination of morphology and DNA-based approaches. They are now able to provide fast and sensitive testing for high impact diseases at the border or in future incursions. In addition to laboratory staff training, a number of quarantine officers were trained to enable them to recognise diseased plant material during import and export fresh produce inspections.</p> Katharina M. Hofer, Merje Toome-Heller, Brett J.R. Alexander Copyright (c) 2019 New Zealand Plant Protection Sun, 28 Jul 2019 06:56:40 -0500 Better biological control in glasshouses: synergies between biological control agents from different guilds and floral resources <p>The tomato/potato psyllid (TPP), <em>Bactericera cockerelli </em>(Hemiptera, Triozidae), is an adventive psyllid in New Zealand that is a major pest of solanaceous crops and a serious threat to growers in the glasshouse industry. Worldwide, evaluation of potential biological control (BC) agents is normally conducted using single species and this is the case with some potential BC agents for TPP. However, the idea that multiple species can act synergistically remains largely untested so that is the aim of the current work, which is funded by Tomatoes New Zealand. The introduced parasitoid <em>Tamarixia triozae </em>is a BC agent of TPP that attacks mainly late instars. It lives for just 1 day when provided with water but can live up to 11 days (and consume more pests) when nectar in the flowers of buckwheat (<em>Fagopyrum esculentum</em>) is provided. In addition, another potential BC agent, the mirid bug <em>Engytatus nicotianae, </em>prefers young nymphal instars, while the ladybird <em>Cleobora mellyi </em>is voracious and consumes all instars. We are testing combinations of these species to understand the potential for synergies between and within trophic levels for better biological control.</p> Emiliano R. Veronesi, Oluwashola Olaniyan, Stephen D. Wratten, Melanie Davidson, Chris Thompson Copyright (c) 2019 New Zealand Plant Protection Sun, 28 Jul 2019 06:59:11 -0500 Arthropod pests of kiwifruit identified from Chinese language literature <p>References to many other kiwifruit arthropod pests (and diseases) were found as part of a process of searching Chinese language literature to understand the impact of brown marmorated stink bug (<em>Halyomorpha halys</em>; BMSB) and spotted lantern fly (<em>Lycorma delicatula</em>; SLF) on kiwifruit (<em>Actinidia chinensis</em>) and <em>A. deliciosa </em>in China. Information on other kiwifruit pests was collated from over 20 Chinese language publications found in searches of the Chinese National Knowledge Infrastructure platform using standard Chinese characters for BMSB, SLF and kiwifruit, and was ranked according to: (1) the number of publications they were mentioned in; and (2) the type of words used to describe their impact. In addition to BMSB and SLF, approximately 50 kiwifruit pests were identified from this process, including a number of species that were unknown to the New Zealand kiwifruit biosecurity community and which may pose a threat to kiwifruit production if they established in New Zealand. This work reinforces the need for searching Chinese databases with Chinese characters in combination with searches in international databases, to ensure comprehensive coverage for biosecurity risk assessment.</p> Bingqin Xu, David A.J. Teulon Copyright (c) 2019 New Zealand Plant Protection Sun, 28 Jul 2019 07:02:08 -0500 An insight into biosecurity plant-disease diagnostics at MPI <p>The Mycology and Bacteriology team of the Ministry for Primary Industries’ Plant Health and Environment Laboratory is responsible for the identification and verification of all suspected exotic, new, and emerging pathogens affecting plants and the environment in New Zealand. We work in an applied diagnostic environment where results can have significant implications for biosecurity. Sample submissions often result in detection of new to New Zealand fungi and bacteria on plants for which information on fungal and bacterial associations is generally sparse. The complexity of testing required is quite varied with samples being submitted from post entry quarantine (looking for a known pathogen using specific tests), border or surveillance (unknown pathogens requiring multiple tests), or a biosecurity response (scaling up to test large numbers, identification resolution required to strain level). Applied test methods depend largely on the sample type and consist of morphological identification, biochemical testing, pathogenicity testing, serological and molecular techniques, including high throughput sequencing. A profile of our diagnostic work and the most commonly detected taxa and host associations are presented.</p> Robert K. Taylor, Merje Toome-Heller, Wellcome W.H. Ho, Brett J.R. Alexander Copyright (c) 2019 New Zealand Plant Protection Sun, 28 Jul 2019 07:04:30 -0500 Validation of qPCR assays for the detection of citrus canker <p>Citrus canker, a serious bacterial disease affecting the citrus industry worldwide, is caused by <em>Xanthomonas citri </em>subsp. <em>citri </em>(<em>Xcc</em>) pathotypes A, A* and Aw, and to a lesser extent by <em>X. fuscans </em>subsp. <em>aurantifolii </em>(<em>Xfa</em>). The recent citrus canker outbreak in Australia has emphasised the need to re-evaluate the efficiency of molecular assays used for detecting citrus canker bacteria. Two published probe-based qPCR assays targeting the <em>pth </em>and <em>lrp </em>genes were tested for <em>Xcc</em>, whereas a SYBR Greenbased qPCR assay was tested for <em>Xfa</em>. The <em>Xcc pth </em>gene and <em>Xfa </em>qPCR assays were shown to be specific towards all pathotypes of <em>Xcc </em>and <em>Xfa</em>, respectively. The detection limit for both assays were 1 pg of genomic DNA or 103 CFU in bacteria-spiked leaf sample. The <em>Xcc lrp </em>gene qPCR assay was able to discriminate <em>Xcc </em>pathotypes with a detection limit of 1 ng of genomic DNA or 106 CFU in bacteriaspiked leaf sample, but this assay showed cross-reaction with <em>Xfa</em>. To allow rapid high-throughput detection of all <em>Xcc </em>pathotypes, a duplex probe-based qPCR assay was developed by incorporating COX primers as an internal control for plant DNA into the <em>pth </em>gene qPCR assay.</p> Hui Wen Lee, Wellcome W.H. Ho, Raja Thangavel, Jeyaseelan Baskarathevan, Brett J.R. Alexander Copyright (c) 2019 New Zealand Plant Protection Sun, 28 Jul 2019 07:06:19 -0500 Heat treatments of dormant scion wood killed the European canker pathogen <i>in planta</i>, while chemical treatments did not <p><em>Neonectria ditissima</em>, the causal agent of European canker, can be present in symptomless scion wood. Sanitation treatments could minimise this risk to nursery trees. In this trial, six heat treatments and five chemical treatments were tested for their effectiveness in removing this pathogen from dormant ‘Royal Gala’ wood. In July 2018, 120 symptomless inoculated shoots (three inoculations/shoot) were harvested and stored at 1<sup>o</sup>C for 3 months. Bundles of five inoculated shoots (45 cm) were placed in the centre of 24 bundles, each consisting of 25 wood pieces. Heat-treated bundles were submerged in water (45<sup>o</sup>C for 45 min or 50<sup>o</sup>C for 15 min), or wrapped in moist cloth, vacuum sealed inside plastic then submerged for 3–6 h at the same temperatures. Chemical-treated bundles were submerged for 16 h at room temperature. Treatments were compared with untreated wood. After surface sterilising, isolation of <em>N. ditissima </em>from inoculated wounds was attempted on apple-sap amended water agar. All wounds from the untreated wood and from the chemical-treated wood yielded the pathogen. However, <em>N. ditissima </em>was not isolated from wounds that had been heat treated. Therefore, heat treatments that do not affect scion wood viability may prove an effective tool to remove European canker from nursery material.</p> Brent M. Fisher, Reiny W.A. Scheper Copyright (c) 2019 New Zealand Plant Protection Sun, 28 Jul 2019 07:07:10 -0500 Galling in <i>Actinidia </i>spp. seedlings <p>Several <em>Actinidia </em>spp. genotypes exhibit crown gall-like symptoms in both roots and canes. Galls form on roots and pruning wounds of canes. Investigations were undertaken to determine if an <em>Agrobacterium </em>species was responsible for gall formation in the <em>Actinidia </em>spp. material. Macerated galls were plated onto King’s B and various selective <em>Agrobacterium </em>agars, e.g. 1A and Roy &amp; Sasser media. Bacterial isolates were tested by PCR for the presence of tumour-inducing (Ti) plasmids. Isolates that tested positive for the Ti plasmid were subsequently tested for pathogenicity by inoculation onto cut carrot discs, <em>Nicotiana glutinosa </em>and <em>Solanum lycopersicum</em>, and assessed for gall formation. Bacterial isolates that tested positive by PCR for the Ti plasmid were an orange tan colour on selective medium 1A, and clear with a red centre on the Roy &amp; Sasser medium. Galls formed on cut carrots, <em>S. lycopersicum </em>and <em>N. glutinosa </em>after inoculation of Ti-positive bacterial isolates. Initial results indicate that an <em>Agrobacterium </em>species is associated with the formation of galls in <em>Actinidia </em>seedlings. However, biochemical characterisation and confirmation of Koch’s postulates using <em>Actinidia </em>species are needed for verification of this result.</p> Mary B. Horner, Ellena Carroll, Jayne Wilton, Will Barrett Copyright (c) 2019 New Zealand Plant Protection Sun, 28 Jul 2019 07:11:30 -0500 Parasitism of diamondback moth <i>Plutella xylostella</i> by the solitary parasitoid wasp <i>Cotesia vestalis</i> in Samoa <p><em>Plutella xylostella </em>is a major pest of crucifier crops in Samoa and other Pacific islands. This pest has developed resistance to most insecticides available in the island nations so the objective of this study was to examine potential biological control options for <em>P. xylostella </em>in Samoa. Existing parasitism of <em>P. xylostella </em>on Chinese cabbage (<em>Brassica rapa </em>subspp.) was investigated at a farm in Alesia and at the USP farm in Alafua, and established populations of <em>Cotesia vestalis </em>were found at both locations. <em>Plutella xylostella </em>larvae turn light yellow and show sluggish behaviour after parasitism, and they could be easily differentiated from unparasitised ones. Developing <em>C. vestalis </em>larvae emerge from their hosts and spin white cocoon around their body. After 5–6 days, a single adult emerges from the <em>C. vestalis </em>cocoon. The average parasitism rate between April 2015 and March 2016 was 10–18% but was significantly higher at the USP farm than the Alesia farm. This result could be because no insecticides were applied to the crops at USP. Parasitism was highest between June and August when the lowest average daily temperatures occur.</p> Hau’ofa Siasau, Rashmi Kant Copyright (c) 2019 New Zealand Plant Protection Sun, 28 Jul 2019 07:13:23 -0500 Current and planned research for managing the risk of <i>Xylella fastidiosa </i>to New Zealand <p><em>Xylella fastidiosa </em>(<em>Xf</em>), a xylem-limited bacterium native to the Americas, has a devastating impact on many crops internationally. In California, <em>Xf </em>causes over USD 100 million in yearly losses to the grape industry and infects an estimated 200 million citrus trees in Brazil. More recently, <em>Xf </em>killed around one million olive trees on the Italian peninsula of Salento. <em>Xylella fastidiosa </em>is not known to be present in New Zealand. The glassy-winged sharpshooter (<em>Homalodisca vitripennis</em>), an important vector of <em>Xf </em>in California, is also not present in New Zealand. However, the meadow spittle bug (<em>Philaenus spumarius</em>), an important vector of <em>Xf </em>in Italy, is present. Many economically important horticultural, viticultural, agricultural, amenity and indigenous/native plant species, including taonga, are likely to be susceptible to <em>Xf</em>. Aspects of our research on <em>Xf </em>to understand the impact, reduce the likelihood of entry into New Zealand and/or minimising its impact in New Zealand will be presented. The research listed on the poster spans risk assessment, diagnostics, surveillance and biological control but could certainly be increased across the biosecurity continuum given the magnitude of the threat from <em>Xf </em>to New Zealand’s valuable plant systems.</p> Sandra B. Visnovsky, Robert K. Taylor, David A.J. Teulon Copyright (c) 2019 New Zealand Plant Protection Sun, 28 Jul 2019 00:00:00 -0500 Semi-commercial hot water treatments for control of bull’s eye rot of apples <p>Bull’s eye rot (BER) of apples is caused by a postharvest fungal pathogen (<em>Phlyctema vagabunda </em>syn. <em>Neofabraea alba</em>). Previous laboratory experiments found hot water treatments (HWT) resulted in a significant reduction of BER incidence for artificially inoculated fruit so the feasibility of HWT to control naturally infected fruit in a semi-commercial trial was tested. One bin (1934 fruit) of naturally infected ‘Scired’ apples was harvested from a Hawke’s Bay orchard with a known high incidence of BER, then placed in a coolstore for 1 week until treated. All fruit were passed through a high-pressure water blaster then air dried. Approximately half the contents of the bin (1034 fruit) were packed into Friday trays in apple boxes with a plastic polyliner. The other half (900 fruit) were treated for 2 min with hot water at 51°C in a semi-commercial hot water bath before packing. All fruit were then coolstored for 20 weeks before assessment for BER. This HWT resulted in a 6-fold reduction of BER incidence so was an effective treatment for BER in a semi-commercial test.</p> Luna Hasna, Kerry R. Everett, Michelle J. Vergara, I.P. Shamini Pushparajah, Peter N. Wood, Brent M. Fisher, Lucia R. Ramos, Carol Middleditch, Shane Olsson, Agam Nangul, Jung Ook Cho, Allan B. Woolf Copyright (c) 2019 New Zealand Plant Protection Sun, 28 Jul 2019 07:16:49 -0500 New Zealand Plant Protection Medal 2018 <p>&nbsp; &nbsp;&nbsp;</p> Barbara Barratt Copyright (c) Fri, 26 Jul 2019 00:00:00 -0500 Dan Watkins Scholarship in Weed Science <p>&nbsp; &nbsp; &nbsp;</p> Thomas Carlin Copyright (c) Sat, 27 Jul 2019 00:00:00 -0500 New Zealand Plant Protection Society Research Scholarship <p>&nbsp; &nbsp; &nbsp;&nbsp;</p> Tom Saunders Copyright (c) Sat, 27 Jul 2019 00:00:00 -0500 Obituary - Dr Ronald Close <p>&nbsp; &nbsp; &nbsp;&nbsp;</p> Ian Harvey Copyright (c) Sat, 27 Jul 2019 00:00:00 -0500 Executive Committee and Life Members <p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;</p> NZPP Editor Copyright (c) Sat, 27 Jul 2019 00:00:00 -0500 Rules of the Society <p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;</p> NZPP Editor Copyright (c) Sat, 27 Jul 2019 00:00:00 -0500 NZPPS List of Publications <p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;</p> NZPP Editor Copyright (c) Sat, 27 Jul 2019 00:00:00 -0500