2014
Determining soybean pest and pesticide interactions as a means to optimize soybean yield
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Contributor/Checkoff:
Iowa Soybean Association
Category:
Sustainable Production
Keywords:
Biotic stressCrop protectionField management Pest
Parent Project:
Evaluation plant pest interactions to optimize soybean yield
Lead Principal Investigator:
Erin Hodgson, Iowa State University
Co-Principal Investigators:
Aaron Gassmann, Iowa State University
Gregory Tylka, Iowa State University
+1 More
Project Code:
Contributing Organization (Checkoff):
Iowa Soybean Association
(n/a)
Institution Funded:
Iowa State University
(n/a)
Brief Project Summary:

The soybean cyst nematode (SCN) is widely considered to be one of the most damaging pathogens in most soybean-producing areas of the United States, including Iowa. Iowa soybean farmers have been battling SCN since it was discovered in 1978. The results of soybean-checkoff-funded surveys of Iowa in the mid-1990s and again in the last decade reveal that approximately 70-75% of Iowa fields are infested with the nematode. Yield losses of only 2-5 bushels per acre occur in growing seasons with adequate to excess moisture, but losses of 50% or more are common in very dry growing seasons.

Traditionally, SCN has been managed by growing a nonhost crop (typically corn) in rotation with SCN-resistant...

Unique Keywords:
#best management practices, #insects and pests, #soybean aphid (sa), #soybean cyst nematode (scn), #soybean disease management, #soybean educational activities
Information And Results
Final Project Results

The two field locations were scouted weekly for soybean aphid populations starting in late June and through mid-September when the populations decreased by more than 75% after one week. Cumulative aphid days (CAD) were generally lower this year compared to last year’s data. At the northeast location, aphid-susceptible plots had an average of 1172 ± 196 CAD; for the northwest location, only 188 ± 11 CAD. During the second week of October, both locations were harvested. Soil samples were taken on the days of harvest and will be processed for determining fall populations of soybean cyst nematode (SCN).

Harvest data for the northeast location was put into a mixed-model analysis of variance (ANOVA) and shows significant effects of seed treatment and its interactions with host plant resistance for soybean aphid or SCN. Pooling together all four varieties of soybeans, the plots with the Avicta Complete seed treatment yielded an average of 51.9 bushels/acre compared to the naked (no seed treatment) plots that yielded 44.1 bushels/acre. The same pattern holds true when we only look at the two nematode-susceptible beans. Again, the Avicta Complete treated beans yield significantly higher than the untreated beans. Once we have quantified SCN populations, we can determine whether or not the pest directly impacted yields and if the seed treatment helped to suppress the pest.

Eric Clifton will present data from both the 2013 and 2014 seasons of this project for a ten-minute competitive talk at the Entomological Society of America’s annual meeting that is being held Portland, Oregon on November 2014.

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.