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Evaluating insecticide coverage and determining its effect on the duration of control for navel orangeworm ( Amyelois transitella Walker ) (Lepidoptera: Pyralidae) in California almonds
Author(s) -
Siegel Joel P,
Strmiska Mathew M,
Walse Spenser S
Publication year - 2019
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.5413
Subject(s) - imidacloprid , pyralidae , biology , toxicology , pesticide , sprayer , bifenthrin , horticulture , pest control , agronomy , pest analysis
BACKGROUND Insecticide application is essential to control navel orangeworm ( Amyelois transitella ) in California almonds ( Prunus dulcis ), but coverage is challenging. Laboratory and field trials were conducted from 2014 to 2017 to quantify insecticide deposition and duration of control. RESULTS In the laboratory for filter paper, photolysis reduced the contact toxicity of bifenthrin, and its half‐life was 6.2 days. For chlorantraniliprole applied in the field, there was 87–94% less insecticide deposited in the almond suture, the most vulnerable part of the nut, than on the hull. For chlorantraniliprole, adjuvant choice (alcohol ethoxylate versus mineral oil) affected both initial insecticide deposition and half‐life. Chlorantraniliprole degradation was greater at 6.1 m than at 3 m for both adjuvants assessed, whereas contact mortality was similar at both heights for the alcohol ethoxylate adjuvant. CONCLUSION The combination of photolysis and differential distribution of insecticide on the nut can account for the variable control observed in the field. This was particularly problematic in the upper canopy and adjuvant choice affected deposition and insecticide degradation. Less than 1% of the insecticide in the tank was deposited on the almond suture. These results demonstrating the fraction of the insecticide in the sprayer tank deposited on the nut target, combined with reduced coverage in the upper canopy are also applicable to the control of A. transitella in pistachio ( Pistacia vera ) and walnut ( Juglans regia ) orchards. © 2019 Society of Chemical Industry