Submitted to: Journal of Nematology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/1/2002
Publication Date: 12/2/2002
Citation: Bradley, C.A., Noel, G.R., Grau, C.R., Gaska, J.M., Kurtzwell, N.C., Macguidwin, A.M., Wax, L.M., Hartman, G.L., Pederson, W.L. Interaction of herbicides on soybean growth and reproduction of heterodera glycines. Journal of Nematology;35:88-97. Interpretive Summary: Soybean cyst nematode (SCN), Heterodera glycines, is a serious pest of soybean throughout soybean production areas in the United States, causing an estimated annual production loss of 80 million bushels or $400 million. Most soybean fields in the Midwest are infested with SCN. Soybean production relies on herbicides to control weeds. Some pesticides are known to have nontarget effects on various organisms. Since some herbicides are applied to the soil where SCN lives, it is possible that these herbicides might affect some aspect of SCN biology that might increase the severity of SCN damage. Similarly, herbicides applied to above ground portions of soybean might affect root physiology and thus affect SCN. This manuscript reports results of a two-year field study in Illinois and Wisconsin and greenhouse study in Illinois that investigated the effects of several herbicides on SCN reproduction and population dynamics and soybean yield. There was no reproducible evidence that the herbicides affected SCN numbers or population dynamics. Herbicides and SCN did not interact to reduce yield. Thus, soybean producers should use herbicides that provide the most profitable weed control in their individual fields because choice of herbicide will not increase damage caused by SCN or affect long-term control of SCN.
Technical Abstract: Several abiotic and biotic stresses can affect soybean in a growing season. Soybean cyst nematode, Heterodera glycines, reduces yield of soybean more than any other pathogen in the United States. Field studies at Champaign, IL, Monmouth, IL, and East Troy, WI, and greenhouse studies were conducted to determine the effects of soybean stress caused by preemergence and postemergence herbicides on reproduction of H. glycines on susceptible and resistant soybean cultivars, and to determine the effects of interactive stresses caused by herbicides and H. glycines on soybean growth and yield. H. glycines reproduction varied among years in the field studies, but reproduction generally was less on resistant than susceptible cultivars resulting in a yield advantage for resistant cultivars. The yield advantage of resistant cultivars was due to more pods per plant on resistant than susceptible cultivars both years at Champaign and Monmouth, IL. Pendimethalin reduced H. glycines reproduction factor (Rf) on the susceptible cultivars in 1998 at Champaign, IL, and in greenhouse studies reduced dry root weight of H. glycines resistant and susceptible cultivars, therefore reducing Rf on the susceptible cultivars. The interactive stresses from acifluorfen or imazethapyr and H. glycines reduced the dry shoot weight of the resistant cultivar Jack in a greenhouse study.