Bactericera cockerelli (the tomatopotato psyllid; TPP) and associated insects were monitored weekly in unsprayed potatoes at Pukekohe by using yellow sticky traps and sampling plants from late July 2009 until mid March 2010 TPP adult catches and egg and nymphal infestations were absent or low until mid December Other exotic and native psyllid species dominated trap catches until TPP populations increased markedly in mid January and peaked at 120 adults per trap in late February with egg numbers reaching 520 per plant a week later TPP nymphs peaked at 260 per plant in early February Micromus tasmaniae (brown lacewing) was common in spring and summer but Melanostoma fasciatum (small hover fly) became the dominant predator peaking at 162 eggs and 35 larvae per plant in mid January Naturally occurring predators appear to be important biological control agents of aphids small caterpillars and probably TPP on potatoes at Pukekohe
Bactericera cockerelli (tomato potato psyllid, TPP) is a serious pest of potato crops, causing feeding damage and also vectoring Candidatus Liberibacter solanacearum, the causal agent of the Zebra Chip (ZC) disease in potatoes. The results of 6 years of early and main crop potato trials at Pukekohe, New Zealand, are summarised and damage caused by TPP is reported. Results show that spring-sown (early) potato crops do not require insecticides. In main crop summer trials we tested action thresholds based on 10 and 20 TPP nymphs per 100 middle leaves but the incidence of ZC damage was commercially unacceptable, ranging from 4 to 9 %. Subsequently we tested an action threshold of >3 TPP adults per yellow sticky trap per week that led to ZC damage ranging from 0.9 to 1.6 %. We also compared monitoring of TPP using sticky trap catches with a degree day model started in mid winter (1 July) for forecasting generation times of TPP. On the basis of the field trial results, we recommend that from early summer onwards, the timing of the first foliar application of insecticide needs to be applied early enough to protect main crop potatoes from the first generation of TPP that occurs after potato tubers have emerged (at Pukekohe, this is the third TPP generation from 1 July when using degree day modelling). Three years of main crop trials indicate that an action threshold of >3 TPP per trap per week provides effective TPP/ZC management in the Pukekohe region when used in conjunction with natural enemies and an insecticide programme that features the use of selective insecticides.Resumen Bactericera cockerelli, (el psílido del tomate y de la papa, TPP), es una plaga seria en los cultivos de papa, causando daño al alimentarse y también como vector de Candidatus Liberibacter solanacearum, el agente causal de la enfermedad de la Zebra Chip (ZC) de papa. Se resumen los resultados de seis años de ensayos en cultivos tempranos y de principales fechas de siembra de papa en Pukekohe, Nueva Zelandia, y se reporta el daño causado por TPP. Los resultados muestran que los cultivos de fechas tempranas de siembra en primavera no requieren de insecticidas. En los ensayos de las fechas principales del verano probamos niveles críticos de acción basados en 10 y 20 ninfas de TPP por 100 hojas intermedias, pero la incidencia del daño por ZC fue inaceptable comercialmente, variando de 4 al 9 %. Subsecuentemente, probamos el límite crítico de acción de> 3 adultos de TPP por trampa adherente amarilla por semana que condujera a niveles de daño con variación de 0.9 a 1.6 %. También comparamos el monitoreo de TPP utilizando trampas de captura adhesivas con un modelo de un grado por día empezando a la mitad del invierno (1°de julio) para predecir los tiempos de generación de TPP. Con base a los resultados de los ensayos de campo, recomendamos que, a partir del principio del verano en adelante, el tiempo para la primera aplicación foliar de insecticida necesita hacerse lo suficientemente temprano para proteger al cultivo de papa de la fecha principal, de ...
The use of pheromone traps was investigated as a monitoring tool to forewarn crop scouts of risk periods when diamondback moth (DBM; Plutella xylostella) larval numbers in crops are likely to increase to damaging levels. We monitored traps at five brassica planting sites for 8 months and also counted numbers of DBM larvae on 50-100 plants at each site. Crops were scouted weekly and insecticide application decisions were made using the Crop & Food Research IPM programme. Results showed that increases in moth trap catches predicted increases in larval infestations in three of four commercial crops in spring by 2-3 weeks and gave 2 weeks warning in four of five summer crops. An epizootic of Zoophthora radicans caused a rapid decline in larval populations in mid to late January at all sites. In these trials, use of the IPM action thresholds led to a 75% reduction in insecticide use on vegetable brassica crops. Overall, pheromone traps were of limited value, except in early spring, because crops needed to be scouted regularly for other pests.
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