Management of Asian citrus psyllid (Diaphorina citri) in organic and conventional citrus

The Asian citrus psyllid (ACP) vectors huanglongbing (HLB) or citrus greening disease. This vector disease complex is established in Florida. Management of ACP in all habitats is critical to reduce spread of HLB. Mature citrus trees go through dormancy in winter without producing new growth required for ACP to develop and reproduce. However, adults can survive on mature leaves. Thus, winter is good to target overwintering adults of ACP and spare beneficial insects which are common during the growing season. Insecticides allowed for organic citrus may not be as effective as some conventional insecticides with extended residual effects. We evaluated dormant winter sprays of an organic insecticide, Pyganic (pyrethrins) applied in November, December and January compared to a single spray of the conventional insecticide Danitol (fenpropathrin) in January against ACP in Valencia and Hamlin oranges. Pyganic was applied either alone, with 435 oil or with CitruSoy 2% volume by volume. Significant effects of Pyganic plus 435 oil or CitruSoy lasted for 1-2 weeks after November and December applications. Pyganic + 435 oil and Danitol held ACP to 0.1 adults per tap sample for 4-5 weeks after the January application. Monthly applications of Pyganic with 435 oil appear to be a reasonable option for organic growers to suppress overwintering populations of ACP. Organic programs evaluating promising insecticides alone or altered with 435 oil or CitruSoy are being evaluated parallel to a conventional program.