Monday, 15 November 2004
D0114

Speed scouting for soybean aphid

Erin W. Hodgson, hodgs005@tc.umn.edu, Eric C. Burkness, burkn001@umn.edu, William D. Hutchison, hutch002@umn.edu, and David Ragsdale, ragsd001@umn.edu. University of Minnesota, Entomology, 219 Hodson Hall, 1980 Folwell Ave, St. Paul, MN

In 2000, the soybean aphid, Aphis glycines Matsumura (Homoptera: Aphididae), was discovered in North Central United States soybean, Glycine max L., and is considered a significant economic pest. An economic threshold of 250 aphids per plant through the pod set plant stage (R4) was established in 2003 based on observations in multiple locations. However, exhaustive counts can be tedious and time consuming especially when aphid populations are very high. Cooperators and consultants have over 4 million ha of soybean to sample in Minnesota every year, and a more efficient sampling plan is needed to make practical management decisions. To minimize sampling time (cost), we developed a binomial sequential sampling plan for soybean aphid in commercial soybean through the pod set plant stage. The "Speed Scouting" sampling plan is based upon a 3-year study (2001-2003) where 89 data sets were collected in central and southern Minnesota. Simulation software estimated the proportion of correct treat and no-treat decisions based on the current economic threshold in combination with a range of field-collected soybean aphid densities. Results indicated that 40 aphids per plant was the most efficient tally threshold for presence/absence sampling. On average, only 11 plants are required to make a treatment decision using the Speed Scouting sampling plan. Discussion will include specific directions on how to use Speed Scouting with guidelines for successful implementation of the sampling plan into an integrated pest management program.


Species 1: Homoptera Aphididae Aphis glycines (soybean aphid)
Keywords: binomial sequential

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