Tag: fungicides
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Reminders about Managing Cucurbit Downy Mildew with Fungicides
From Clemson Plant Pathologist Tony Keinath Cucurbit Downy Mildew This Fall Warm days and cool nights help create long dew periods in the fall, weather is ideal for cucurbit downy mildew (CDM) to start and spread, as reported in the Weekly Field Update – 9/15/25. We have not yet seen CDM in our fall sentinel…
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2025 Recommendations to Manage Powdery Mildew on Cucurbits
From Clemson Plant Pathologist Tony Keinath Results from a June 2025 bioassay with powdery mildew on susceptible yellow summer squash ‘Early Prolific’ showed that, although all 8 fungicides reduced powdery mildew, 4 worked better than the rest. The Best Fungicides To Manage Powdery Mildew on Cucurbits Torino, Quintec, Gatten, and Vivando completely suppressed powdery mildew…
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Biologicals and Their General Performance Against Strawberry Diseases
Johanna Wesche and Guido Schnabel, Clemson University “Do biologicals work?” That is a frequently asked question coming not only from strawberry growers, especially in light of increasing resistance issues with many of the conventional fungicides and the fungicide insensitivity of Neopestalotiopis sp. In our recent article, “Biologicals Made Easy: Grouping and Understanding Biological Fungicides,” we…
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Cucurbit Disease Update for Mid-May 2025 (Downy Mildew Found in SC)
From Clemson Plant Pathologist Tony Keinath Despite relatively dry conditions this spring, two foliar diseases have shown up on cucurbits in different parts of South Carolina. Gummy stem blight was found on watermelon in the Central Savannah River Area, and downy mildew was found on cucumbers at Coastal REC. Five of 23 watermelon samples (that’s…
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Cucurbit Downy Mildew Fungicide Trial Report for Fall 2024: Part 1, Pickling Cucumber
From Clemson Plant Pathologist Tony Keinath In fall 2024, fungicide programs were tested on ‘Gershwin’ pickling cucumber to find out which programs worked best. Eight fungicide programs (plus a non-sprayed control) were used with various combinations of chlorothalonil (Bravo), Ranman, and Orondis Opti (Orondis + Bravo pre-mix). Cucurbit downy mildew (CDM) symptoms were noticed on…
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Biologicals Made Easy: Grouping and Understanding Biological Fungicides
Johanna Wesche and Guido Schnabel, Clemson University Biologicals are gaining interest in modern agriculture for several reasons. They are used in organic farming to suppress pests and diseases and may have a place in spray programs used in conventional farming when disease pressure is low, when fungicide efficacy is threatened by resistance development, or when…
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Fungus-Based Biological Control Agents: How Useful Are They for Strawberry Disease Management?
From Guido Schnabel, Jeffrey A. Hopkins, Jim Faust, and William Gura Biological control agents (BCAs) are being promoted for disease management in fruits, nuts, and vegetables but very little data is available about their efficacy especially when it comes to preharvest field performance. The Schnabel lab has investigated yeast-like fungi and true yeast BCAs, namely…
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More Evidence that Choosing Grafting or the Right Cultivar is More Important than Using Fungicides to Manage Fusarium Wilt of Watermelon
By Clemson Plant Pathologist Tony Keinath My 2024 Fusarium wilt experiment at Coastal REC, Charleston, SC, was a streamlined version of the 2023 experiment with 2 fungicides, 2 cultivars, and grafting, except we tested 1 different fungicide and 1 different cultivar. The 2024 results, however, matched the results from 2023 (see title). Already at 3…
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Cucurbit Downy Mildew Found in SC
Prepared by Rob Last, Justin Ballew, and Tony Keinath. Cucurbit downy mildew was identified in South Carolina on 5/12/23. The identification came from butternut squash grown in a sentinel plot at the Coastal REC in Charleston. The same strain that affects butternut squash also affects watermelon and summer squash. Now that downy mildew has been…
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2023 Gummy Stem Blight Control for Watermelon Growers: Early is on Time
From Tony Keinath, Extension Vegetable Pathologist. The recent freeze in the lower part of South Carolina more than ended the 2022 watermelon season. It’s not too early to plan for gummy stem blight control in 2023 to allow time to buy the right fungicides in case of shortages. As the saying goes, early is on…
The South Carolina Grower 