The application of 980 degree days as a trigger for rapid increases in <i>Bactericera cockerelli</i> in Hawkes Bay solanaceae crops

Abstract

During 200708 the tomato potato psyllid (TPP Bactericera cockerelli) was observed in outdoor tomato and potato crops in Hawkes Bay Many crops were heavily infested resulting in severe yield losses and in some cases crop abandonment Since then growers have been proactive in plant monitoring and sticky trap use but these methods are expensive and quite often a calendar spray programme is begun once the first adult TPP have been observed in traps It has been proposed that 980 degreedays (DDs) from 1 July is used as an indicator of when TPP numbers are about to increase rapidly in North Island crops This study describes the application of 980 DDs to recent sticky trap data from Hawkes Bay For most sites 980 DDs occurred just before rapid increases in adult TPP numbers However there were a small number of sites where this was not so The presence of noncrop TPP host plants bordering these sites may explain rapid increases in TPP trap catches well before reaching 980 DDs