Foliar sprays of delegate WG and closer 240 SC with adjuvants for control of asian citrus psyllid and citrus leafminer

Jawwad A. Qureshi, Barry C. Kostyk, Philip A. Stansly

Abstract


The Asian citrus psyllid (ACP) Diaphorina citri and citrus leafminer (CLM) Phyllocnistis citrella are key insect pests of citrus. ACP vectors Ca. Liberibacter asiaticus, causal pathogen of the Asian form of “huanglongbing” (HLB) or citrus greening disease and CLM facilitates spread of citrus canker. ACP and CLM need young shoots for egg laying and development and are often managed with insecticides simultaneously. Many insecticides require adjuvants to improve spread and penetration. Spinetoram (Delegate WG) is recommended for both ACP and CLM control and sulfoxaflor (Closer 240 SC) against ACP. Both were evaluated at 292 ml/ha (4 oz/ac) of product with adjuvants 435 Oil, Activator 90, Citru-Film, Citrus Wrap, Diamond R, and Dyne-Amic at 2% of the application volume. Foliar sprays were applied using an air blast speed sprayer to 12-year-old Citrus sinensis (L.) Osbeck ʻHamlinʼ orange trees in a commercial grove near LaBelle, FL (Hendry County). Significantly more dead ACP nymphs compared to untreated control at 4 days after treatment (DAT) were observed in all treatments except Closer 240 SC + Activator 90. All treatments reduced ACP nymphs through 28 DAT and adults through 41 DAT, except for Closer 240 SC + Diamond R or Activator 90 at 34 DAT. Overall ACP reduction with Delegate WG and Closer 240 SC averaged 96% and 84%, respectively. Closer 240 SC treatments reduced CLM larvae by 49% through 8 DAT. Larval reduction with Delegate WG treatments averaged 91% through 8 DAT and 69% through 28 DAT. Effects of most treatments with 435 Oil or other adjuvants against ACP or CLM were comparable suggesting that all were compatible with Delegate WG and Closer 240 SC and that alternatives to 435 Oil are available.


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