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Applied Research Results on Field Crop and Vegetable Disease Control

The research described in this book was designed to evaluate strategies for improving disease control and the efficiency of crop production in Delaware and Maryland. Commercial products are named for informational purposes only. Delaware Cooperative Extension and University of Delaware, do not advocate or warrant products named nor do they intend or imply discrimination against those not named.

The primary purpose of this book is to provide cooperators and contributors a summary of the results of field research. Many data summaries and conclusions in chapters from this book have been submitted to the American Phytopathological Society for publication in Plant Disease Management Reports in 2015. Other work may be published in other peer reviewed scientific journals as appropriate. Reprints of these publications are available upon request.

The University of Delaware Nematode Assay Service ran a total of 38 samples for the 2015 calendar year on vegetable and field crop samples. Thirty-five samples originated from Delaware and three samples were from Kent County Maryland. Twenty-nine of the samples originated from Sussex County, Delaware. Six samples were submitted from Kent County Delaware. Over 80% of the samples were submitted by private consultants or agribusiness (ex: Pioneer, Syngenta). Only one sample was submitted directly by a grower. The remaining samples were submitted by UD county Ag agents in Kent and Sussex Counties. Overall the service was not directly used by growers in Delaware, which is consistent with past growing seasons.

All samples requested a troubleshooting assay, with 19 of the samples also requesting soybean cyst nematode egg counts. Soybean cyst juveniles were detected in 12 of the 38 samples (32%). Lesion nematodes were the most common plant pathogenic nematode, occurring in 68% of the samples. Spiral nematodes were the second most common, occurring in 55% of the samples. Stunt and lance nematodes were found in 32% and 29% of samples, respectively. Root knot nematode was detected in 24% of samples. Stubby root and dagger were the least common nematodes detected in the assays, at 16% and 8%, respectively. Two samples had low numbers of ring nematode. The majority of samples (68%) had low levels of nematodes that would likely not affect crop production. In these cases some other factor was the cause of issues in these fields.

Overall, nematodes, with the exception of root knot, soybean cyst, and occasionally lesion, did not occur at levels that would significantly impact crop production in most Delaware crops. This is consistent with observations and past assay results. Other nematodes detected in the assays, although characterized as being pathogenic, do not often cause sufficient damage to impact yields or their numbers are not consistently tied to plant damage.

Download the complete Applied Plant Pathology research booklet for Delaware and Maryland in 2015 [pdf format]


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