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

Below, I will briefly discuss four diseases that I have observed on tomatoes recently. White mold of tomato – Perhaps the most common symptom of white mold of tomato is the light brown area on the lower stem (Figure 1). This brown area is essentially dead and will result in the wilt and death of the tomato plant above that point. Either on the outside of this dead area or inside the stem, dark, irregularly shaped fungal bodies can usually be found. These fungal bodies (known as sclerotia) are diagnostic of white mold. The fungal spores responsible for white mold are released early in the spring from a very small mushroom (several mushrooms could fit on a dime). The spores will enter a plant where tissue is dead or senescent, such as old flower petals. Fortunately, white mold, once established, will not spread from tomato to tomato plant. However, growers may observe more symptoms as later[Read More…]


The vegetable extension team at Purdue University is always looking for innovative ways to get information to clients quickly. For this reason, we are trying out a new program called veggie texts. The idea is that if we have your mobile phone number and the name of your phone carrier, then we can send you text alerts of 160 characters or less. What type of information should you expect with veggie texts? We may contact you with weather information such as forecast freezes, disease alerts such as late blight of tomato or insect alerts such as corn earworm populations. Cantaloupe and watermelon growers may be contacted when there is a large increase in MELCAST values. Since the alerts are relatively short, we may include links to additional information. To sign up for the veggie text program, please contact us with – Your mobile phone number The name of your phone carrier. Common[Read More…]


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Recently I observed lesions of leaf mold of tomato in our high tunnel at the Southwest Purdue Ag Center.  I thought I would share these photos since the lesions can be variable.   More information about this disease can be found at here.


This disease has been observed in the southern part of Indiana. To identify bacterial wilt, look for the characteristic wilt and beetle feeding on the leaves and stem (Figure 1). The bacterium that causes this disease, Erwinia tracheiphila, is spread by the striped or spotted cucumber beetles. Once bacterial wilt is observed in the field, there is no treatment. To reduce the spread of bacterial wilt, treat for the striped or spotted cucumber beetles. Cucumbers are also susceptible to bacterial wilt. Pumpkins and squash are much less susceptible to bacterial wilt than cantaloupe or cucumbers. Watermelon are not susceptible to bacterial wilt.


Individuals who have visited Dan Egel’s blog will notice a new look when they next visit. All articles have been migrated to a new site that will be maintained on the Vegetable Crops Hotline site. There is no need to change your bookmark and the same URL veggiediseaseblog.org will work. However, the site is new and improved. All of the articles that Dan writes for the Hotline and for Veggie Extras will be housed at the new blog site. 


If you visit the Vegetable Crops Hotline on-line, be sure to visit our new addition: Veggie Extras.  The articles that you’ll find when you click on the Veggie Extra link include brief observations, photos, research updates or in-depth subjects  that we hope the vegetable professional might find interesting.  Articles that are in the Veggie Extras might not be of immediate importance; therefore, Veggie Extra articles will not be included as part of regularly scheduled newsletters. However, we will keep you informed of new Veggie Extra posts with announcements through email. Thank you for your continued support of the Vegetable Crops Hotline.


I have observed leaf mold of tomato in greenhouses and high tunnels recently. This article will discuss this disease and management options. In the last issue of the Hotline, I discussed Botrytis gray mold. I noted how gray mold is favored by the cool, cloudy weather we experienced earlier this spring. The warmer and sunnier weather we have experienced more recently should favor leaf mold over gray mold. Leaf mold is caused by the fungus Passalora fulva. Cercospora leaf mold of tomato is rare in Indiana and is discussed here (https://vegcropshotline.org/article/cercospora-leaf-mold-of-tomato/). The first symptom of leaf mold one is likely to notice is a pale yellow lesion on the top side of the leaf (Figure 1). When the leaves are turned over, the fungal mold that gives the disease its name becomes evident (Figure 2). Leaf mold often becomes a problem under humid conditions (85% humidity or greater) and temperatures between 71 and 75°F, although leaf[Read More…]


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We recently published an article in the Hotline about gray mold of tomato.  That article and more details about this disease can be found here. In this short note, we want to share examples of the relationship of gray mold and tomato plant injury. In the figure 1 above, a pruning injury of tomato in a commercial greenhouse has become necrotic and a gray mold infection is starting. Figure 2 is from our research high tunnel.  In the photo, one can see where there was an abrasion, probably due to tying the plant in the greenhouse. This injury allowed the gray mold fungus to begin to grow.  Not only will this infection cause a die-back, but the spores produced may cause the disease to spread.  We clipped off this branch to stop the spread of the disease. The photo is taken outside of the greenhouse for better lighting. The lesson here is[Read More…]


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White mold of watermelon – Usually when I write about a vegetable disease it is because the disease may cause important economic loss. Once in a while, however, a disease I find is more a curiosity than a real problem. So, go ahead and read this article about white mold of watermelon. But please don’t worry about this disease. Simply, watch for these symptoms and let me know if you have questions. Readers may have heard me ‘talk’ about white mold of tomatoes. The fungus that causes white mold, Sclerotinia sclerotiorum, has a wide host range. Important hosts include bean, cabbage, potato, lettuce and sunflower in addition to tomato. More about the disease on tomato can be found here. If you have never heard me talk about white mold of watermelon, don’t feel left out. I don’t talk about white mold of watermelon since I have only observed the disease twice in 21[Read More…]


Figure 2. Wilt cucumber plants in a high tunnel

  Last week, we were called by a few watermelon growers who reported their newly planted watermelon seedlings were dead (Figure 1 ). After closely inspecting the affected plants, we did not find any pathogens. This reminded us of what happened to our cucumbers back in early April in our high tunnel. We will review the cucumber story first, and rethink what might have happened to the watermelons. Cucumbers were planted on March 30 in a high tunnel located at Southwest PurdueAgricultural Center (SWPAC), Vincennes, IN. The lowest air temperature after planting was recorded at 37.5°F inside the high tunnel, which should not be low enough to cause frost damage. However, we lost 40% to 80% of the newly planted cucumbers depending on varieties. The symptoms were similar to water deficiency-caused plant wilt (Figure 2 ). Most of the dead plants had intact stems, however, we did find wire worms[Read More…]


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