Dan Egel’s Veggie Disease Blog

Dan Egel is an extension plant pathologist with Purdue University who works with vegetable growers across the state of Indiana. This blog will highlight recent disease issues, management options, meeting dates and new publications relevant to vegetable growers. Dan is located just north of Vincennes at the Southwest Purdue Agricultural Center.

Contact Information

Dan Egel
Southwest Purdue Agricultural Program
4369 N. Purdue Road
Vincennes, IN 47591
Phone: 812-886-0198
Email: egel@purdue.edu

www.watermelondr.info

Figure 1. A common symptom of gummy stem blight of watermelon is a watersoaked area where the seed leaves attach to the stem.

1. What caused the water-soaked stem of this watermelon transplant? A-damping-off B-gummy stem blight C-Lightening strike Correct Answer: B 2. Is this problem likely to spread to other transplants? Yes 3. Will this problem likely spread in the field? Yes More information about gummy stem blight can be found in the article Cantaloupe and Watermelon Transplant Diseases in this issue.


Figure 3. Anthracnose lesions on watermelon often appear jagged.

Many cantaloupe and watermelon growers are either growing transplants in a greenhouse or are expecting delivery of transplants in the next few weeks. Either way, growers should inspect transplants for disease before planting in the field. Below I will describe several common transplant diseases of cantaloupe and watermelon as well as management options. Gummy stem blight on transplant seedlings may be recognized by the watersoaked area of the stem near the seed leaves (Figure 1). The watersoaked area may eventually turn brown and woody. A closer look at the woody area may reveal the small, dark fungal structures of the gummy stem blight fungus. Medium brown, irregular lesions may also be observed on true leaves. A watersoaked area near the soil line is more likely to be damping-off (Figure 2). More information about damping-off can be found in previous issue’s article Damping-off of Vegetables. The fungus that causes gummy stem[Read More…]



If it hasn’t happened already, vegetable growers will soon drop seeds into transplant trays in preparation for the 2020 season. Or, in a few weeks, vegetable growers may drop seed into the ground. In either case, it is possible that one of several fungi that survive in the soil may attack the seed or seedling as it emerges from the ground. This disease is known as damping-off. The symptoms of damping-off range from a poor stand of seedlings when the fungus kills the seedlings before it emerges from the soil to seedlings that have fallen over due to a lesion of the stem (Figure 1). There are several fungi which may cause damping off. These include Pythium, Rhizoctonia, Theleviaopsis, Fusarium spp. and many more. The identity of the culprit may seem unimportant, but if the problem persists, knowledge of the causal fungus may help one to know how to alter[Read More…]


As Indiana growers start the 2020 season, it is important to remember to clean and sanitize equipment and tools. In this article, I would like to discuss the importance of and how to sanitize. Bacteria and fungi that cause plant disease may survive on some types of equipment. Examples include: stakes, transplant trays, shovels, greenhouse benches etc. Equipment can be contaminated by diseased plants in close contact with the surfaces. For example, a tomato with bacterial canker may rub up against a wooden stake, transferring some of the bacteria to the stake. Such bacteria may cause disease problems next year. A transplant tray of cantaloupe with a damping-off problem may have the same disease next year if the tray is not properly cleaned and sanitized. It is important to clean the equipment of crop debris or soil prior to the use of one of the sanitizers described below. Equipment free[Read More…]


In a normal year, vegetable growers may drop samples by the SW Purdue Ag Center in Vincennes Indiana for problem identification. However, this is far from a normal year. Due to concerns about the coronavirus, SWPAC is closed to walk-in visitors. We do not know how long this situation may last. We have devised an alternative method of dropping off samples that will avoid face-to-face contact. Follow these instructions to drop off samples. Contact Dan Egel or Wenjing Guan before stopping by or attempting any drop off (see contact info below)! There will be a sign on the front door with instructions about how and where to drop off a sample. Do not try to enter the front door. When leaving the sample, include as much info as you can about the sample. You will be contacted as soon as possible about the sample by phone or email. Leave only[Read More…]


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While many growers use high tunnels to extend the growing period for warm-season crops such as tomatoes or cucumbers, it is also possible to grow cool-season crops such as spinach well into winter. The winter over much of Indiana has been rather mild; spinach and other cool-season crops should be doing well. However, disease and insect pests may be a problem. In the first week of March, I observed leaf spot on spinach growing in a high tunnel (Figure 1). Note that the lesions occur on a cluster of plants indicating possible spread of a fungus. A closer look shows that the center of the lesion may be dark with fungal sporulation (Figure 2). I was able to confirm the disease as Cladopsorium leaf spot of spinach. Little is known about the biology of the fungal pathogen. However, the disease is favored by rainy or at least moist weather. The[Read More…]


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One concern for every vegetable grower is finding solutions to pest management problems quickly. An example would be anthracnose of watermelon. You recognize the disease or you have had it officially diagnosed. Or perhaps you anticipate this disease every year and want to start applications of a fungicide early in the season. Where do you find recommended products and application details? For years, vegetable growers have reached for the Midwest Vegetable Guide for Commercial Growers (known in Indiana as the ID-56). This annually updated guide includes disease, insect and weed recommendations as well as detailed info about such subjects as food safety, soil fertility and organic production. Starting in 2020, growers may choose to reach for their phones instead of a hard copy. While the hard copy is still available at the same $15 price, the guide is now searchable from data phones, tables, laptops and desktop computers. Read on[Read More…]


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The fungus Rhizoctonia can be a nuisance to many vegetable growers. Readers may recognize this unusual name as a cause of many diseases such as damping off and root rot in many different crops. This article is about Rhizoctonia as the cause of wirestem in broccoli. Rhizoctonia may affect several brassica crops such as broccoli, cauliflower, Chinese cabbage and radish. Recently, a disease known as wirestem was observed on broccoli. The first symptoms that growers are likely to observe is a wilt of very young broccoli plants. When the plants are examined more closely, it can be observed that the stem has rotted away, as if to a wire (Figure 1). This can cause the plant to wilt and collapse. The Rhizoctonia fungus may survive in the soil for long periods without a host. And, as mentioned above, the fungus has many hosts. Rhizoctonia diseases are favored by warm soil[Read More…]


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This disease was recently observed in southern Indiana. Moderate damage to leaves in broccoli does not usually cause yield or quality loss. However, Alternaria leaf spot may also affect Chinese cabbage, bok choy and leafy brassicas such as cabbage. The most common symptom is a leaf spot (Figure 1). The lesions start out small; as lesions become larger they may have a light brown border with a light gray center. Lesions may also occur on leaf petioles. Under conducive conditions, some defoliation may occur, affecting the size or quality of broccoli heads. In severe cases, broccoli heads may be affected by this disease (See article in this issue about heat damage to broccoli heads). There are two species of the fungus that may cause Alternaria leaf spot. The species that was isolated recently (Alternaria brassicicola) is favored by temperatures from 68 to 86°F and 12 hours of 90% relative humidity.[Read More…]


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