Category: Disease
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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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Weekly Field Update – 7/7/25
After some rain and wind in the Pee Dee from Tropical Storm Chantal on Sunday, the week is off to a hot start. Watermelons, peaches, tomatoes, peppers, etc. are being harvested. Disease and insect pressures are climbing. See details below. Keep an eye on the Upcoming Events tab periodically so you don’t miss any of…
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Weekly Field Update – 6/30/25
Keep an eye on the Upcoming Events tab periodically so you don’t miss any of our winter/spring meetings. Also, check out the latest episode of the SC Grower Exchange Podcast below. Don’t forget to look at our Resources tab for links to crop handbooks, helpful websites, and related blogs. Be sure to scroll all the…
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Gray Leaf Spot on Heirloom Tomatoes
From Clemson Plant Pathologist Tony Keinath Gray leaf spot has been found in a home garden in Greenville County and on a farm in Charleston County, South Carolina. This disease is the most common foliar problem on heirloom tomatoes. ‘Cherokee Purple’ is particularly susceptible. The recent hot, humid, rainy weather is ideal for the gray…
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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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Sudden Wilt or Pythium Root Rot On Mature Cantaloupe
From Clemson Plant Pathologist Tony Keinath After a very dry April, the heavy rains in May triggered a case of Pythium root rot in one cantaloupe field in South Carolina in the past 2 weeks. Another name for Pythium root rot on mature cucurbits is “sudden wilt” to distinguish it from the more common damping-off…
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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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Field Scouting and Identification of Diseases on Cucurbits in South Carolina
From Clemson Plant Pathologist Tony Keinath For anyone who missed the Preplant Cucurbit Meeting on Feb. 7, 2025, at the Edisto Research and Education Center, here is a recap of the main points on scouting fields for cucurbit diseases. Table 1 shows which diseases are most likely to show up on different crops. Use this…
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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…
The South Carolina Grower 