Can WashGard (carnauba wax adjuvant) applications deter phloem feeding insects on woody plants?

Mahmut Mahmut Doğramaci1, Craig Campbell, Lance Osborne, Jan Narciso


Ficus whitefly, Singhiella simplex (Singh), is a significant pest of ficus plants, especially weeping fig, Ficus benjamina L. Ficus whitefly is a relatively new exotic pest established in several counties in Florida since 2007. The pest can cause complete ficus plant defoliation when left uncontrolled. WashGard is a plant based wax product. The main ingredient in WashGard, carnauba wax, has been widely applied as a polish, food preservative, and to reduce sunburn in apples. But in recent years it has been used as an adjuvant to increase the adherence of copper sprays to citrus tree leaves. The adjuvant prolongs the time that copper residue remains on the leaves thereby improving the management of citrus canker disease which is caused by the bacterium Xanthomonas axonopodis. Studies have shown that WashGard application could reduce piercing-sucking insect feeding such as the Asian citrus psyllid, Diaphorina citri Kuwayama, the vector of citrus greening disease. In this study, we applied WashGard to potted ficus plants for management of ficus whitefly. The plants were treated with 3% and 10% WashGard. Both the WashGard treatments significantly reduced whitefly populations and plant foliar damage. Preliminary results indicate that WashGard application forms a wax layer on plant leaves that works as a physical barrier to phloem-feeding insects. Tank mixes of WashGard with insecticides that may enhance woody plant pest management such as reducing citrus canker disease and citrus psyllid feeding thus reducing citrus greening disease. Further studies are needed to quantify the effects of WashGard in controlling insect pests.


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Proc. Fla. State Hort. Soc.     ISSN 0886-7283