Master of Science (MS)


Plant, Environmental Management and Soil Sciences

Document Type



Indeterminate and determinate soybean (Glycine max (L). Merr.) cultivars were treated with the harvest aids, paraquat and sodium chlorate, when moisture of seed collected from the uppermost four nodes of plants averaged 60, 50, 40, 30, and 20% (+ or - 2%). Harvest aid application at 60% seed moisture reduced yield of the Maturity Group (MG) IV indeterminate cultivar 15%, but yield was not affected with application at 50% seed moisture. For MG V and MG VI determinate cultivars, application at 60 and 50% seed moisture reduced yield 4 to 22%, but yield was not affected when harvest aid was applied at 40% seed moisture. Soybean treated with harvest aid was harvested 8 to 15 days before the non-treated. The value of paraquat harvest aid was also evaluated when used in fungicide and insecticide IPM programs. Fungicide (pyraclostrobin plus thiophanate-methyl at R3) application increased soybean green leaf retention, green stems, and seed moisture. Failure to control stink bug resulted in increased green pods, seed moisture, and seed damage. Application of harvest aid decreased green leaf retention, green stems, and seed moisture. When harvest aid was applied and stink bug was not controlled, seed quality deductions for moisture, foreign material, and damage were < $63.10/ha. When stink bug was controlled at the maximum level (acephate plus cyfluthrin when population reached 2 to 3 per 25 sweeps) or the intermediate level (lambda-cyhalothrin when population reached threshold of 8 to 9 per 25 sweeps), deductions were < $30.24/ha. When harvest aid was not applied, seed quality deductions across all fungicide/stink bug control programs were 3.8 to 6.4 times greater than when harvest aid was applied. Increase in net return due to harvest aid was greatest when fungicide was applied and stink bug was controlled at either level ($171.49 and $169.89/ha) and lowest when fungicide was not applied ($94.81 and $78.49/ha). Even so, net returns were more than enough to offset the cost of a paraquat harvest aid application. At a second location, net returns, regardless of harvest aid application, tended to be highest when fungicide was applied and when stink bug was controlled.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Griffin, James