Dan Egel

Clinical Engagement Associate Professor
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Figure 2: We often observe Fusarium wilt in transplant trays in a clustered distribution. We believe that Fusarium wilt may spread from plant-to-plant within a transplant tray, perhaps by soil splash or spores that have been observed on diseased seedlings.

Fusarium wilt is one of the most serious diseases of watermelon in the Midwest. The disease often causes a one-sided wilt 2-3 weeks after transplanting. Whether a plant is affected, and to what degree, depends on the population of the long-lived spores in the soil that the roots contact. However, Fusarium wilt of watermelon is not known to spread from plant to plant in the field. This is in contrast with a disease such as anthracnose which can spread from plant-to-plant rapidly in one season. Occasionally, Fusarium wilt can be observed affecting commercially produced watermelon transplants in new trays and virgin soilless mix. The most likely explanation for such outbreaks is the introduction of Fusarium wilt on seed. The distribution of Fusarium wilt from seed should appear random. However, we often observe a clustered distribution of affected seedlings as seen in Figure 1. We conducted an investigation to determine whether[Read More…]

This backpack sprayer has three nozzles on a boom and a hand-pump that can be worked constantly.

The use of tractor drawn pesticide sprayers is not practical for many smaller growers. Two alternatives are garden-sprayers or backpack sprayers. I will argue here that garden-sprayers are not suited for most commercial pesticide use. The typical garden sprayer that may be found at a garden shop or hardware store usually has a 1 or 2-gallon capacity and a nozzle whose output may be manually adjusted from stream to spray (Figure 1).  Such sprayers use air pressure generated by a hand pump. Some models have a valve to quick-release air pressure. While such sprayers may be useful for cleaning tasks, they are not appropriate for commercial pesticide applications for the reasons stated below. Let’s start off discussing the adjustable nozzles on garden sprayers. These nozzles may be inadvertently moved to provide a different stream or spray. That is, the output may be changed from a full spray to a more[Read More…]

The following updates have been made to the Midwest Vegetable Production Guide for Commercial Growers 2017 (ID-56) since it was published in December. These updates have been made to the PDFs published on-line at mwveguide.org.  If you have a hard copy of the ID-56, please note these changes. Page 59-Additional plant families and example crops have been added to Table 22. Page 82-Dual Magnum entries under asparagus weed control have been updates to include Michigan only language. Page107-Velum Prime has been added to powdery mildew control for cucurbits; 6.5-6.84 fl. oz/A. May cause a mild yellowing of leaf margin.  May be applied through drip. Page 116- Velum Prime has been added to root knot nematode control for cucurbits; 6.5-6.84 fl. oz/A. May cause a mild yellowing of leaf margin.  May be applied through drip. Page 117-Entry for Luna Sensation should read “All cucurbits” under comments. Page 190- Velum Prime has[Read More…]

Small vegetable growers may find pesticide applications with a tractor driven sprayers impractical. Such growers may turn to hand sprayers. In a separate article, I argued that garden sprayers are not appropriate for most commercial pesticide applications.  In this article, I will discuss the use and calibration of a backpack sprayer, an excellent alternative to a garden sprayer for small growers. The remainder of this article will discuss one method of calibrating a backpack sprayer. Most pesticides are labeled for use on an area basis, typically an acre. Therefore, the first task in calibration is to measure the area to be treated. Let’s say that tomatoes are grown in a greenhouse where the production covers 30 X 100 feet = 3,000 square feet. For our staked tomato example, we will use a volume-based method of pesticide measurement. For this method: Determine the volume of water required to cover the fully-grown crop[Read More…]

These tomato plants are exhibiting epinasty or a downward growth of the leaves in response to ethylene produced from a malfunctioning heater in a greenhouse. The topmost leaves are growing normally because the plants were removed to a separate greenhouse after exposure to ethylene. (Photo by Dan Egel).

Almost every year, I have a greenhouse tomato grower or two call me about tomato plants that are distorted and don’t seem to be growing right. The problem often turns out to be ethylene damage. This year, I have decided to write an article about it before I get those calls. Tomato plants with ethylene damage often have leaves that are curled down and stems that are twisted (Figure 1). Stems or leaves that are curled downwards are said to have epinasty (in botanical terms). Epinasty is a common symptom of ethylene damage. Ethylene is a common by-product of incomplete combustion of several different types of fuel. Incomplete combustion is often the result of heaters that are not working efficiently. Tomatoes are very sensitive to ethylene damage; however, other crops may also show ethylene damage. The tomato plants in figure 1 also have yellow seed leaves. Ethylene damage does not include yellowing.[Read More…]

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As Thanksgiving approaches, I have noticed that the gourds I set out before Halloween are starting to rot. But before I throw them away, what is causing the lesions? The circular lesions that can be seen in Figure 1 and 2 are symptoms of anthracnose of gourd.   That is, the pathogen that is causing the lesions in the accompanying figures is Colletotrichum orbiculare.   This is the same pathogen as the one that causes anthracnose on other cucurbits such as watermelon. (It is possible that the anthracnose is caused by a different species of Colletotrichum. Even if the pathogen is C. orbiculare, I am not sure of the race. More research would be required.)     A second question is how the pathogen contacted the gourd sitting in a basket in my house since early October.   This is a harder question to answer.   My guess is that the pathogen contacted[Read More…]

Vegetable growers are familiar with pesticide labels that specify how much of a product may be applied. As commercial growers, we usually think about such instructions as telling us how much pesticide is the right amount to apply to a crop to be effective. While such an interpretation is correct, there is more to the labeled rates of a pesticide. While many researchers (including myself) are involved with experiments to try to manage pests with pesticides, others are involved in trying to determine the pesticide concentrations that may safely exist in the produce we all eat. The latter is known as the pesticide tolerance. Both efficacies of the pesticide and human safety are involved in determining the label rates and timing of each pesticide. Indeed, some pesticides are not labeled for certain crops for reasons of safety. There is mostly good news in the just released 2015 Pesticide Data Program. Each year, the USDA’s[Read More…]

Last fall, my lab received a carrot sample with disease-like lesions (Figures 1 and 2). There are at least 3 carrot diseases that may appear similar. These diseases are: Alternaria leaf blight (late blight), Cercospora leaf spot (early blight) and bacterial leaf blight. Often an examination in the laboratory is necessary. My examination revealed the characteristic spores (conidia) of Alternaria dauci, causal agent of Alternaria leaf blight. Figure 1  shows a stand of carrots with several leaves that appear chlorotic (yellow) and necrotic. A closer examination reveals small lesions on the leaves (Figure 2). Loss of leaves may lead to fewer or smaller carrots. Sometimes severe infections can lead to the premature separating of the leaves and root. Alternaria leaf blight can be rapidly spread between plants by the conidia that are produced on the plant surface. I could easily find these spores on the surface of the carrot leaves brought to my lab. The conidia may[Read More…]

As Indiana growers finish up the 2017 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 of crop[Read More…]

Usually I wait until January before releasing information about the Midwest Vegetable Production Guide for Commercial Growers (ID-56).   For two reasons, however, I would like to talk about the 2017 ID-56 now. This year, we welcome Michigan growers and Michigan State University to the Midwest Vegetable Production Guide The Guide is now an 8-state publication. We expect the ID-56 to be available in mid-December this year, instead of the beginning of January. Read below to find many new changes to the 2017 ID-56. New and Revised Sections We added a chapter for Celery with the help of MSU. We added a section called Selected University Diagnostic Laboratory Services, which includes contact information for each state. We revised the organic section to list certifiers on a regional basis. The Soils and Fertility section has been modified and updated. Disease Management We updated the Disease Management section. We updated the Orondis® products[Read More…]