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

Anthracnose of garlic, a new disease to Indiana, may cause sunken, orange lesions on scapes.

Earlier this summer, sunken lesions were observed on garlic scapes on a small farm in east central Indiana. Lesions started out a cream or tan color (Figure 1), however under rainy or humid conditions, spore production caused lesions to turn orange (Figure 2). Larger lesions resulted in the collapse of the scapes. It is estimated that 45 to 50 percent of scapes were affected. Lesions ranged from ¼ to ½ inch long. Samples of these scapes were sent to the Purdue Plant and Pest Diagnostic Laboratory in West Lafayette where they were diagnosed as anthracnose of garlic, a new disease to Indiana. This new disease is caused by the fungus Colletotrichum fiorinae. This fungus has also been reported on elephant garlic in New York. Reports from New York suggest that onion is unaffected. In the US, C. fioriniae has also been reported as an Apple post-harvest decay, causing bitter rot on[Read More…]


The 2019 production season started with above-normal rains. The wet conditions affected agriculture production, including watermelon and cantaloupe. In this article, we will review some of the watermelon and cantaloupe problems that are often associated with wet conditions. Manganese toxicity– This nutrient disorder occurs more often on cantaloupe that is grown in soils with pH lower than 5.5. Although liming before planting is a common practice, it is not unusual that we see soil pH that has dropped below 5.5 in sandy soil, especially during wet years. Manganese exists in soil solution as either reduced (Mn2+) or oxidized (Mn3+) form. Plants take up manganese in the reduced form (Mn2+). The proportion of exchangeable Mn2+ increases dramatically as soil pH decreases, and this reaction is promoted in waterlogged soils with low oxygen condition. As raindrops fall through the air, they dissolve CO2 and form enough carbonic acid to lower the pH of[Read More…]


Anthracnose of strawberry causes sunken lesions.

At the Southwest Purdue Ag Center, we are studying annual strawberry production on plastic mulch. Our hope is to gather information on the best methods and varieties to use for annual strawberry production in Indiana. As we learn about insect and disease problems, we will pass this information on to producers. This article is about the diseases we have observed in our strawberries which were planted in March 2019. Strawberry leaf spot-Lesions on leaves start out purple. As the lesions enlarge, the center becomes gray-brown (Figure 1). Under rainy conditions, lesions may coalesce across leaves and cause large necrotic areas. Lesions on stems and petioles may cause dieback. Yield or fruit quality loss can be caused by leaf spot under severe conditions. Although leaf spot symptoms are spread throughout our trial, this disease has not become serious for us. There are several cultural methods of managing leaf spot. Host resistance[Read More…]


Figure 1: A cantaloupe plant surrounded by striped cucumber beetles that have died after feeding on a plant treated with an imidacloprid product.

I know this may not come as a surprise to most of you, but it is rare that we get to observe the effectiveness of insecticides in such a dramatic way as we encountered when visiting a melon grower in southern IN recently. And in this case, the decision to apply an insecticide at transplant was a good one. In the photo below (Figure 1), one can see an accumulation of dead striped cucumber beetles that have fed upon a cantaloupe seedling that was treated with an imidacloprid soil drench (Trade names include: Admire Pro®, Macho®, Midashe Forte®, Montana®) at transplant 14 days prior to the photo being taken. The beetles are dead because they fed upon the cantaloupe plant and ingested the imidacloprid. Therefore, the plants were protected from defoliation by the beetles, but what about bacterial wilt? Did the act of feeding, however brief, cause bacterial wilt to[Read More…]


Seed Corn Maggot in cucurbit stem. Photo credit John Obermeyer.

In addition to delaying much of our fieldwork, the cool set spring has wreaked havoc on some of the plants we have been able to squeeze in during brief dry periods. We have received reports of damage caused by seedcorn maggots (Figure 1) and wireworms (Figure 2). In preparation of this article I browsed the Vegetable Crops Hotline archives and came across eight articles published by Rick Foster. What do they have in common? Associations with weather and limited strategies for control. Capture LFR® remains the only product labeled and for wireworms only. Rick Foster did some work with this product and had some promising results. Seedcorn maggots typically lay their eggs in organic matter and feed on seed in the soil, however, they can also cause damage in cucurbit transplants. The adults are active in April and May laying eggs in the field. When soil temperatures reach 70°F the[Read More…]


Figure 1. Watermelon seedlings planted in a week

In the past week, we have observed a few cases where newly planted watermelon seedlings were severely damaged or dead (Figure 1). In some fields, we observed rotted roots and lower stems caused by fungal pathogens. However, such diseases were in response to the cold soils and would not normally cause problems in warm soils. Most of the dead plants had intact stems, although growers did report seedcorn maggot and wireworm in the stems of a few dead plants. The same thing happened in May 2016. Coincidentally, rain, cloudy days, and lower than normal temperatures were observed in the same period in both years. Since early May, We have had consecutive days with the lowest temperatures in the 40s°F. There was no risk of frost damage, however, this temperature was low enough to cause chilling injury on young cucurbit plants.  This article ‘Protect Early Planted Warm-Season Vegetables from Low Temperature’[Read More…]


Figure 2. Wilt of watermelon seedlings due to grown in a high EC medium.

Producing healthy transplants is a critical step for a successful growing season. Choosing the proper growing media is an important first step. Supported by a USDA Specialty Crops Block Grant through the Indiana State Department of Agriculture, researchers from Purdue have been evaluating different organic growing media with and without adding supplemental organic fertilizers for tomato and cucurbit transplant production. In this article, we have highlighted a few transplant symptoms that are associated with growing media with excessively high or low electrical conductivity (EC) or pH. It is always a good idea to test EC, pH, and other important nutrient content of a medium when you are making your own or using an unfamiliar media. Most soil laboratories provide a saturated media extract test that provides information on these important parameters. More information about this test and suggested range of EC and pH can be found in this article http://www.soiltest.uconn.edu/factsheets/InterpSMEGreenMedia.pdf[Read More…]


Figure 1: Bottom rot of lettuce often causes stunting and wiling.

Although Indiana is not known for lettuce production, an increasing number of growers find that augmenting retail sales with leaf lettuce can be profitable. Since lettuce is a cool season crop, field planted leaf lettuce around Indiana may be reaching harvest stage. Leaf lettuce can generally be grown with few pests. However, lettuce drop was recently observed in a field of mixed lettuce varieties. Lettuce affected with lettuce drop often first appears stunted. A closer inspection may reveal that outer leaves are wilted and necrotic (Figure 1).  Eventually, the entire plant may die. If the plant is removed from the ground and observed, the leaf ribs that touch the ground may exhibit dark, rotten appearing lesions (Figure 2). The lesions may be associated with dark fungal bodies known as sclerotia (Figure 3).  Fortunately, lettuce drop does not often spread from plant to plant. The plants that are diseased will most[Read More…]



Ever year, I put together fungicide schedules for cucurbits. These may be found at purdue.ag/pumpkinfs and purdue.ag/melonfs. They may be downloaded as PDFs on legal sized pages.  Please use these tables along with the MW Vegetable Production Guide and the fungicide label.  If you have trouble with accessing the tables or have other questions. please let me know.


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