Effects of kaolin clay sulphur and fosetylaluminium on tomatopotato psyllid and zebra chip in fried potato crisps

Abstract

Zebra chip (ZC) is mottled browning discolouration of cooked potato crisps caused by the bacterium Candidatus Liberibacter solanacearum (CLso) ZC has caused significant problems in the New Zealand potato industry Tomatopotato psyllid (Bactericera cockerelli) (TPP) is a vector for CLso Surround WP formulated from nontoxic kaolin clay and a spreadersticker is effective in protecting fruit trees from various insect pests Sulphur has been widely used to control arthropod pests especially mites Fosetylaluminium has no bactericide properties as such but can change the host susceptibility to some bacteria such as fire blight (Erwinia amylovora) A field trial conducted at Pukekohe to determine the effects of kaolin clay sulphur and fosetylaluminium applied as foliar sprays on TPP potato yields tuber dry matter content and incidence of ZC found that while not reducing ZC sulphur demonstrated potential for reducing TPP nymph numbers in the crop Kaolin and fosetylaluminium were not effective in controlling either TPP or ZC