New Zealand Plant Protection 2020-06-03T21:42:31+12:00 Dr Ruth Falshaw Open Journal Systems <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> Pathogenicity of Ceratocystis fimbriata from New Zealand kūmara on kiwifruit cultivars 2020-06-03T21:42:31+12:00 Joy L. Tyson Michael A. Manning Peter J. Wright <p><strong>Abstract</strong> <em>Ceratocystis fimbriata</em> was reported in 2010 causing wilt and death of kiwifruit (<em>Actinidia</em> spp.) vines in Brazil, with losses of up to 50% of vines on some orchards. New Zealand is one of the largest producers of kiwifruit in the world, but <em>C. fimbriata</em> has been recorded only on kūmara (<em>Ipomoea batatas</em>) in this country. In this study the pathogenicity of New Zealand isolates of <em>C. fimbriata</em> from kūmara was examined using potted vines of four kiwifruit cultivars. During the trial, none of the vines became visibly diseased, growth rates were not restricted, and discolouration at the inoculation sites on the stem was minimal. In comparison, tests by researchers in Brazil using <em>C. fimbriata</em> isolated from symptomatic kiwifruit resulted in lengthy lesions and death of susceptible kiwifruit seedlings. Sequences of the internal transcribed spacer (ITS) region of rRNA from the New Zealand <em>C. fimbriata</em> isolates were 100% identical to those sequences from <em>C. fimbriata</em> isolates from Ipomoea batatas in GenBank. This study has shown that the New Zealand isolates of <em>C. fimbriata</em> from kūmara are not pathogenic to the kiwifruit cultivars tested, and are a different pathotype to those found on kiwifruit in Brazil.</p> 2020-07-27T00:00:00+12:00 Copyright (c) 2020 New Zealand Plant Protection Symptom expression of Phytophthora colocasiae in inoculated taro corms 2020-01-27T06:00:51+13:00 Amy Maslen-Miller Robert A. Fullerton Angelika Tugaga Faalelei Tunupopo Seeseei Molimau-Samasoni Joanna K. Bowen Robin M. MacDiarmid Joy L. Tyson <p>Taro leaf blight (TLB), caused by <em>Phytophthora colocasiae</em>, is normally characterised by leaf lesions. There are isolated reports of <em>P. colocasiae</em> causing a corm rot but the symptoms are not well defined and have not been recorded in Samoa. Here we report on an inoculation method and describe the symptoms of corm rot caused by <em>P. colocasiae</em>. In this study, a corm inoculation method was developed in physical containment laboratories in New Zealand and subsequent symptom development studies were undertaken on TLB-tolerant taro cultivars in Apia, Samoa. The Samoan TLB-tolerant taro cultivars were able to be wound-infected with <em>P. colocasiae</em> and the results confirm previous descriptions of <em>P. colocasiae</em> infection giving rise to light brown firm rots in corms. This work has allowed the pictorial record of corm rots to be updated, potentially providing for better distinction between corm rots caused by <em>P. colocasiae</em> and those caused by other pathogens, such as <em>Fusarium</em> spp.</p> 2020-01-27T00:00:00+13:00 Copyright (c) 2020 New Zealand Plant Protection