Tag: disease management
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Question of the Week – Fire Blight
What’s causing this apple shoot tip to wilt and droop? This picture shows very early symptoms of fire blight disease on a young apple shoot. Fire blight, caused by the bacterium Erwinia amylovora, is a disease that affects apple trees and can move quickly through young, tender growth. Early on—like in the shoot shown here—the…
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Question of the Week – Root Collar Excavation
Why are the roots of this peach tree exposed? One of the biggest disease issues peach growers in South Carolina face is Armillaria Root Rot (ARR). The main reason this disease is so challenging is that we currently do not have a foolproof option for controlling its spread. The best and most effective way, researchers…
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Strawberries Showing Signs of Gray Mold After the Freezing Temperatures
Lindsey Thiessen and Guido Schnabel South Carolina is warming up following several bouts of freezing temperatures. Many used frost-protection covers to keep fruit crowns from freezing. To add some additional stress following the freezing temperatures, growers are reporting significant gray mold presence after frost protection covers have been removed. Gray mold is caused by a…
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Spray Strategies for Strawberry Disease Control in South Carolina
Guido Schnabel, Extension Plant Pathologist Disease management is essential for growing high-quality strawberries in plasticulture. While Botrytis fruit rot (BFR) is a disease you can expect every year, Anthracnose fruit rot (AFR) and the more recently introduced Neopestalotiopsis fruit and crown rot (Neo-P) may or may not appear (Fig. 1). This largely depends on how…
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2025 Recommendations For Fall Chemical Treatments In Strawberry Crops
By Guido Schnabel, Clemson University; Phil Brannen, University of Georgia; Bill Cline and Caleb Bollenbacher, North Carolina State University Whether or not Neopestalotiopsis (Neopest) will harm your strawberries this season depends on many factors – including the quality of the transplants, the cultivar, sanitation practices, soil inoculum levels, weather conditions, and the fungicides you use.…
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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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Why Reusing Watermelon Plastic for Watermelon is a Very Bad Idea and Other Plant Pathology Horror Stories
From Clemson Plant Pathologist Tony Keinath Extension agents have recently received some questions from growers about reusing plastic from a spring watermelon crop for a fall watermelon crop. This scenario is what I call a classic plant pathology “horror story.” It is literally the worst thing a watermelon, cantaloupe, or cucumber grower could do for…
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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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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…
The South Carolina Grower 