Be on the Lookout for Southern Blight
Ethan Grundberg, Vegetable Specialist
Eastern New York Commercial Horticulture
Southern Blight is caused by the fungal pathogen Sclerotium rolfsii and has historically only been a concern to growers in southern states. However, Cornell pathologist Dr. Sarah Pethybridge has seen an
increase in the incidence of Southern Blight in New York over the past several years. This winter, Dr. Pethybridge confirmed the presence of S. rolfsii on golden storage beets in Dutchess County. Given the broad host range of the pathogen that includes over 1,200 crops and weeds, it is imperative that growers who suspect a possible Southern Blight infestation on their farm contact extension to confirm the diagnosis to assist with optimizing crop rotations to reduce soilborne inoculum.
The most common symptom observed in the field is wilting or collapse of the plant. Upon closer inspection, affected plants often have reddish-brown dry lesions at the soil line. Fungal mycelium is also usually present as a thick white mat around the base of the stem. The Southern Blight pathogen also produces overwintering bodies called sclerotia under the right environmental conditions (typically high humidity with temperatures about 80 °F, but sclerotia were found on beets in cold storage at 40 °F). The sclerotia formed by S. rolfsii are a key identifying feature; they are small balls similar in appearance to Dijon mustard seeds that change in color from white to golden to reddish-brown (see image). These sclerotia can survive in the soil for years and endure temperature extremes and drought while waiting to germinate in the presence of a host plant under the right environmental conditions.
Crops that are most commonly affected by Southern Blight are tomatoes, peppers, snap beans, onions, garlic, and Jerusalem artichokes; however, as indicated above, the pathogen can grow and reproduce on a much broader range of plants. Like with most diseases, early detection and proper identification are critical! Infested plants should be removed and destroyed if possible. Symptomatic plants should NOT be placed in compost, as they may contain sclerotia that will then be spread with the compost to other fields. Some small grains and corn are less susceptible to Southern Blight and can be used in rotation in heavily infested fields, but crop rotation is typically not a viable strategy for management of this pathogen given its broad host range. Initial research in New York suggests that deep plowing of infested fields to bury sclerotia and infested residue at least 6-inches deep can lower the pathogen's survival rate.
Several effective chemical controls are available to conventional growers, but they must be applied preventatively. Labeled formulations of azoxystrobin (Quadris), pyraclostrobin (Cabrio), and penthiopyrad (Fontelis) have been effective for growers in the south. Some research has suggested that OMRI-approved biocontrol agents, such as Trichoderma harzianum (RootShield, TerraGrow) and Gliocladium virens (SoilGard), may also help reduce the number of Southern Blight sclerotia and prevent colonization of host plant tissue by the pathogen.




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Cornell Winter Fruit Webinar Series 2025

January 17, 2025
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: Cornell Winter Fruit Webinar Series 2025
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Remote Produce Safety Alliance Grower Training Course
February 17 - February 18, 2025
REMOTE Produce Safety Alliance Grower Training Course
Monday, Feb. 17 and Tuesday, Feb. 18, 2025
8 am - 12:30 PM
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Includes printed course manual ($60 value), certificate of course completion ($35 value) and online food safety resources.
All produce growers are encouraged to attend this course to learn more about food safety practices recommended for all farms. This course contains NEW information contained in the finalized Subpart E rule on agricultural water. The PSA Grower Training Course is one way to satisfy the FSMA Produce Safety Rule requirement outlined in § 112.22(c) that requires 'At least one supervisor or responsible party for your farm must have successfully completed food safety training at least equivalent to that received under standardized curriculum recognized as adequate by the Food and Drug Administration.' If you've already earned your PSA certificate, retaking this course is a great way to refresh your memory and learn about the new water requirements!
After attending the entire course, participants will be eligible to receive a certificate from the Association of Food and Drug Officials (AFDO) that verifies they have completed the training course.
From Seed to Success: Turn Your Idea into an Actionable Plan
January 7, 2025
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February 4, 2025
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March 4, 2025
: From Seed to Success: Turn Your Idea into an Actionable Plan
Do you need a business plan for your farm? Do you have an idea for a new venture, but aren't sure if it will work? This program is for you!
This course is designed for existing farm businesses or those planning to undertake a new farm business venture. Students will work with their farm's data, and the goal of the class is for participants to have a draft of a written business plan for a specific business venture.
During the course, you will learn to:
- Assess whether or not a business idea is a good fit for you.
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This online course meets from January 7-March 4, 2025. All course content is available online so you can work on it at your own pace. There will be weekly webinars where you can meet other students and interact directly with the instructor on the content. These webinars will be recorded.