John Bonkowski

6 articles by this author

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Red crown rot of soybean has become a new concern this season in Indiana after a few localized occurrences have been found in previous years (see map, Figure 1A). We also have our first reports for 2024. This disease is caused by the soilborne fungus, Calonectria ilicicola. At this point in the field season, we are on the hunt to determine how widespread the issue may be here in Indiana. Therefore, we need your help in documenting red crown rot and collecting samples. What to look for: The disease may appear in patches in a field similar to our other soilborne diseases such as sudden death syndrome (SDS) and brown stem rot (Figure 1B). Early foliar symptoms may also mimic these diseases, which include chlorosis (yellowing) and necrosis of leaf tissue between leaf veins (Figure 1C). Therefore, it is important to take a few plant samples and check out the[Read More…]




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Early planted corn in Indiana is reaching late vegetative stages and tasseling in the south. Therefore, it is time to start monitoring for diseases to make an informed decision if a fungicide is necessary. This week we have found a low incidence of tar spot, gray leaf spot, northern corn leaf spot, Anthracnose, and common rust in the lower canopy.


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Wheat has greened up and is actively growing across Indiana (except during these last few cold spells).


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The last two weeks have shown an increase in samples for stalk rots and ear rots/moldy grain at the Purdue Plant and Pest Diagnostic Laboratory, which is signaling that fields are in the middle of or nearing the end of harvest. Dr. Darcy Telenko has provided two great resources (Stalk Rots Getting You Down? & Ear and Stalk Rots) to help in identifying stalk rot diseases and how to manage them. Determining the type of pathogen is paramount in determining your management options, such as selecting hybrids with resistance to a particular pathogen, determining if/what pesticides will protect your crop, and what cultural practices will help mitigate the damage done (if only for future years). Multiple corn leaf spot or root rot pathogens also infect the stalk and/or ear. Other ear rots can move in due to insect feeding, exposed ear tips subject to the environment, or rain getting underneath[Read More…]