Published 2009-12-01
Abstract
The Asian citrus psyllid (ACP) Diaphorina citri damages new growth in citrus by feeding and vectors Candidatus Liberibacter asiaticus, a bacterium that causes “huanglongbing” or citrus greening disease. Therefore, reduction in psyllid populations is key to reducing spread of the disease. Several insecticides were evaluated for psyllid suppression in young and mature ‘Valencia’ orange trees. Drench applications of imidacloprid (Admire Pro and MANA AG 8412- 094B at 14 and 16 oz per acre, respectively) and thiamethoxam (Platinum at 13.7 or 18.8 oz per acre) to 4-year-old trees in June significantly reduced psyllid population density for 3 months. Thiamethoxam tended to act more quickly compared with imidacloprid and the higher rate was more effective. Effects of foliar sprays with or without adjuvants targeted at new growth in mature trees were variable with products and rates and lasted from 2 to 4 weeks. The nonionic surfactant Induce or “435 horticultural oil” were more effective adjuvants for spirotetramat (Movento) than methylated seed oil or the organo-silicone surfactant Kinetic. When present, more ladybeetles were seen on untreated trees compared to treated trees. Soil applied systemic insecticides provided much longer term ACP suppression than foliar applied materials during the growing season.