Laboratory and Field Evaluations of Silwet L-77 and Kinetic Alone and in Combination with Imidacloprid and Abamectin for the Management of the Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Psyllidae)

Rajagopalbabu Srinivasan, Marjorie A. Hoy, Raghuwinder Singh, Michael E. Rogers


Silwet L-77, an organosilicone adjuvant, was used to enhance coverage of an entomopathogenic fungus in field trials conducted in a central Florida citrus research grove. The results indicated that Silwet L-77, by itself, was toxic to nymphs of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae). Laboratory bioassays were conducted to confirm the toxicity of the adjuvant to eggs, nymphs, and adults of D. citri. Silwet L-77 at 0.05% (500 ppm) killed all nymphs, but was not as effective against eggs and adults. However, Silwet L-77, when combined with a reduced rate (one-tenth the lowest label rate = LLR) of imidacloprid, killed >90% of eggs and adults in laboratory tests. In a subsequent field trial, the combination of Silwet L-77 and one-tenth the LLR of imidacloprid gave good control of nymphs, but exhibited weak residual toxicity to adults when compared to imidacloprid at the LLR. Additional trials were then conducted with Silwet L-77 and Kinetic, another organosilicone adjuvant, alone and in combination with different rates of imidacloprid or abamectin using potted citrus trees in the greenhouse. Combining Silwet L-77 or Kinetic with one-fourth or one-half the LLR of imidacloprid killed as many eggs, nymphs, or adults as the LLR of imidacloprid. The combination of Silwet L-77 or Kinetic with one-fourth or one-half the LLR of abamectin killed as many eggs and nymphs as the LLR, but did not control adults as well. The results are discussed in terms of managing the Asian citrus psyllid in Florida now that citrus greening disease is endemic.

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