![]() If more sprays are needed after the eighth spray, repeat sprays 5-8 again until one week before the last harvest. Apply Orondis if downy mildew has been reported on watermelon in your state. Tank mix Orondis products with mancozeb to protect against gummy stem blight and anthracnose. If harvest has started, use Miravis Prime (1-day PHI). Use this program if gummy stem blight is present. Gavel protects against anthracnose, gummy stem blight, and downy mildew. Starting week 5, use mancozeb to avoid injury to fruit on hot, sunny days. Quadris Top protects against anthracnose and gummy stem blight. If fruit blotch or bacterial leaf spots are a concern, substitute mancozeb + fixed copper. If fruit blotch is a concern, add fixed copper.Īpply Gatten if weather is unusually dry to prevent powdery mildew.Īdd Flint if anthracnose fruit rot was found on your farm the previous year.Īpply Ranman if downy mildew has been reported on watermelon in your state. Do not tank mix copper with chlorothalonil. If fruit blotch or bacterial leaf spot is a concern, use mancozeb + fixed copper instead. To prevent bacterial leaf spot and fruit blotch. Excess rates could lead to unlawful residues on fruit, phytotoxicity, and will shift the population to highly resistant. Continued use of tebuconazole will shift the resistance to highly resistant, which means percent control is reduced to approximately 45%.ĭo not increase the rate of tebuconazole as a way to continue using this inexpensive fungicide. Widespread resistance is why the number of tebuconazole sprays is limited to one at the beginning of the season in the 2022 update. This means when tebuconazole is sprayed, 30% of the treated foliage will likely develop gummy stem blight. Moderately resistant isolates were only 70% controlled by tebuconazole in greenhouse tests. The frequency of moderately resistant isolates on the seven farms sampled ranged from 69% to 100%. Only 3% of the samples were sensitive, and 4% were highly resistant. Most (93%) samples of the gummy stem blight fungus collected in 20 from watermelon crops in South Carolina are moderately resistant to tebuconazole, the active ingredient in Monsoon, Folicur, and other products. Important Update for 2022: Resistance to Tebuconazole Vegetable Crop Handbook for more information. See the current edition of the Southeastern U.S.When harvest begins early, skip ahead to spray number 6a or 6b listed in table 1. These fungicides should not be sprayed during the harvest period (weeks 6-8 in the spray programs). Tebuconazole and Inspire Super have a 7-day pre-harvest interval (PHI) on watermelon.Week-by-week rotation is built into the spray programs for systemic fungicides, like tebuconazole, to reduce the risk of fungicide resistance.The fall program is designed to manage gummy stem blight, downy mildew, anthracnose, and powdery mildew.The spring program is designed to manage bacterial fruit blotch, bacterial leaf spot, gummy stem blight, powdery mildew, anthracnose, and downy mildew on watermelon.Chlorothalonil and mancozeb protect against gummy stem blight, downy mildew, and anthracnose chlorothalonil also protects against powdery mildew.Do not stop spraying until one week before the final picking.For best control after disease starts, use systemic fungicides (see option “b” in the first column of table 1).Apply fungicides, allowing time to dry, before a predicted rain rather than after.Downy or powdery mildew can attack any time a crop goes more than a week without a fungicide. ![]() After mid-May, spray every week through harvest regardless of the weather.From vine run until mid-May, spray every ten days.Start spraying when vines start to run, no later than when the first (male) flowers open.Rotate fields to crops other than cucurbits for two years in between watermelon and cantaloupe to help control gummy stem blight and anthracnose.Follow these steps to get the most out of your fungicide program. Table 1 provides details for fungicide spray programs for spring and fall crops. Anthracnose also shows up as tan, narrow, sunken spots on vines. Brown spots are usually gummy stem blight or anthracnose.Call your local Extension office if you can’t identify the disease. Look for spores on the underside of leaves in the early morning. Yellow spots on leaves are symptoms of powdery mildew or downy mildew.Walk fields weekly and the day before spraying.
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