![]() ![]() Efficacy overall being lower than in previous years may be due to the impact of two storms (hurricane remnants) on application timing, product residues, and/or disease development. In 2021, fluoxapiprolin (new fungicide not registered yet) was most effective (64% control), Revus was least effective (43%), and 56% control was achieved with the grower recommended program (Ranman + K-Phite alt. Ranman applied in alternation with Revus + K-Phite was not quite as effective (89% vs 99% control). Many of these fungicides in different combinations in another experiment provided poor control at least partly due to an unintended lapse in the spray schedule with 13 days between applications and rainfall 9 days after the previous application ( 2015b report). Excellent control was obtained with 4 fungicide programs with Orondis, Revus, and Prophyt indicating this combination of chemistry was more important than specific timing for each fungicide ( 2016 report). K-Phite was applied at lowest label rate with all applications of the other fungicides based on the current opinion that this is the best use pattern for phosphorous acid fungicides. The programs included Ridomil, Quadris, Ranman, Revus, and K-Phite or Quadris, Ranman, Revus, and Orondis. Best control (90-100%) was obtained with combination programs that were applied on a preventive, weekly schedule using a boom with drop nozzles in 2014 and also 2015 (2015a report). ![]() ![]() Limited efficacy detected in these experiments is at least partly due to the stringent assessment used: when assessing percent leaves affected, the severity of disease on the leaves is not taken into considered in the assessment. Revus was ineffective in 20 when a single-nozzle boom was used. Only Orondis and Zampro were effective in the 2012 experiment. ProPhyt was effective in 2013 but not 2012 when another phosphorous acid fungicide, K-Phite, also was ineffective. When tested singly, the most effective fungicides in the 2013 experiment were Zampro*, Revus, Orondis (pka Zorvec)*, and Ranman (*not registered yet). Fungicide Evaluations – Conventional Products Percent affected leaves (with sporulation of the pathogen visible on the underside) was assessed rather than severity (except in 2010) because any amount of symptoms renders a leaf unmarketable. Most fungicide treatments were applied on a weekly schedule. This boom was used to improve coverage achieved with a single nozzle directed to the top of plants. Starting in 2012, this boom was used for the first applications until basil plants were large enough to use a boom with two drop nozzles directed to the side of plants as well as a nozzle delivering spray over the top of the plant. A boom with a single (TJ60-4004EVS) nozzle delivering spray to the top of plants was used in 20. Where in the USA is basil downy mildew?įungicides were applied with a backpack sprayer beginning before or after symptoms were found in the field, which included basil planted before the experiments to serve as a spreader row.First observations of basil and cucumber downy mildews at LIHREC.Plant Resistance Evaluations – Commercial Varieties, Experimental Varieties, and Breeding Lines.Fungicide Evaluations – Organic Products.Fungicide Evaluations – Conventional Products.Severity on affected leaves was usually lower for fungicide-treated plants and resistant varieties compared to controls. Incidence of affected leaves (percent leaves with sporulation of the pathogen visible on the underside) was assessed rather than severity because any amount of symptoms renders a leaf unmarketable. Naturally-occurring inoculum was relied on. Plots were single beds with one or two staggered rows of basil at 9-inch plant spacing. Replicated experiments have been conducted since 2010 under field conditions at the Cornell University research facility on Long Island. ![]()
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