Dan Egel

Clinical Engagement Associate Professor
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I have received several calls about pumpkins recently. This article will outline a few steps growers should think about to prevent diseases in pumpkins. Virus diseases – There are several virus diseases that affect pumpkins in the Midwest. The most important diseases include: papaya ring spot, watermelon mosaic and zucchini yellow mosaic virus. Aphids transmit all these diseases. Many of the aphids responsible are carried up from the south each year on winds. Therefore, aphids with virus are more common later in the summer; pumpkins planted later in the season are more likely to be affected with one of the virus diseases listed above. Plant pumpkins by about June 15 to avoid having the fruit set during the period of high virus disease pressure. Powdery mildew – It is nearly impossible to find a pumpkin vine in August without powdery mildew. However, this disease does not have to affect production. The first decision a[Read More…]

Southern blight of tomato thrives under hot, dry conditions. Usually, such conditions are more common in August than early July. However, 2016 has been relatively hot and dry in southwest Indiana. Perhaps for this reason, I have observed this disease in my own tomato plots. This article will discuss the symptoms, biology and management of southern blight of tomato. Southern blight has a wide host range affecting many vegetable, field and ornamental crops. Tomato is the most important host. The disease is caused by the fungus Sclerotium rolfsii. This fungus is related to the one that causes white mold. The first symptom one is likely to observe of southern blight is plant wilt. At the base of the plant, one is likely to notice a canker with sclerotia that may be as large as a sesame seed (Figure 1). These sclerotia are survival structures for the fungus and allow the disease to occur[Read More…]

This disease is more likely to develop during periods of heavy rains in relatively poorly drained soils. June started out dry for many areas of Indiana, however recent rains increase the likelihood of Phytophthora diseases. Phytophthora fruit rot of watermelon causes large, soft areas to develop on mature watermelon fruit. These lesions can be several inches across and are often covered with a white mold. The lesions usually form first on the bottom of the fruit, close to where the fruit comes into contact with the soil. Further development of the disease often results in lesions on the top of the fruit as well. The first application of a systemic fungicide for this disease should occur when watermelon are about softball stage. Since Phytophthora does not usually affect the foliage of watermelon, there is no need to apply fungicides for this disease until fruit are present. Applications to small fruit may include[Read More…]

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…]