Paul Kassel, Field Specialist-Crops, Northwest Area
The soybean disease survey was joint effort of the Plant Pathology Extension, the Iowa Soybean Promotion Board and the Extension FS/crops. Soybean plants were collected from three fields in each county in Iowa at four different dates. The objective of the survey was to document the presence and the severity of different soybean diseases in Iowa. Plant pathology staff at Iowa State University examined the soybean plant samples and documented the diseases that were present.
I selected three farmers in each of my seven counties and selected one of their fields for the survey. Background information on tillage, variety, and planting date was gathered on each field. I obtained contact information for each cooperator. I checked each field for diseases, insects and soybean cyst nematodes. Disease and/or insect problems were relayed to the cooperator after each farm visit. Results of the soybean disease survey were sent to the cooperators after the season.
Leaf and stem diseases were the primary focus of this survey. However, soybean aphid and soybean cyst nematode (SCN) problems were present in many of the fields. Therefore, several of the fields were treated for soybean aphids. The insecticide application for aphid control was timelier as a result of my visits for the soybean disease survey. Several of the fields had high levels of SCN. The producers that had these high levels of SCN were unaware of this problem. The producers with the high levels of SCN were consulted about the potential problems from SCN. I was not able to quantify the actual impact from these communications on aphids and SCN. However, the use of SCN resistant varieties can easily improve soybean yields by five to ten bushels per acre.
142 - Integrated Pest and Crop Management
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February 20, 2007
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