Monday, November 13, 2006

Can Aldicarb be used to Manage SCN in Iowa?.

Vladimir A. da Costa, Iowa State University, 2104 Agronomy Hall, Ames, IA 50011 and Palle Pedersen, University of Iowa, Dept. of Agronomy, Ames, IA 50011.

Soybean cyst nematode (Heterodera glycines Ichinohe; SCN) is a pathogen which causes the largest yield losses on soybean [Glycine max (L.) Merr.] in Iowa. Previous studies have shown that aldicarb is more effective than any other nematicide in increasing soybean grain yield in Iowa. Our hypothesis is that we may need to use aldicarb as a supplement to current SCN-management recommendations for Iowa. The objective of this study was to determine the effectiveness of aldicarb on grain yield and on the control of SCN in infested fields. The experiment was conducted at two northern and at two southern locations in Iowa from 2004 to 2006. The experimental design was a randomized complete block in a split-split-plot arrangement with four replications. Main plots were two planting dates (early versus late May). The sub-plots were three rates of aldicarb (0.8, 1.7, and 2.5 kg a.i. ha-1) and the sub-subplots were ten soybean varieties with different reactions to SCN (PI88788 derived, Peking derived, Hartwig derived and susceptible). Soil samples were collected from each plot at planting and at harvest to determine the initial (Pi) and final (Pf) population densities of SCN. Planting date data will not be presented. Very few differences were found using aldicarb in this study. A nematicide by variety interaction was observed influencing grain yield at one southern location in 2004. Susceptible varieties had 618.1 to 772.7 kg ha-1 more grain yield on the control (0.0 kg a.i. ha-1). A nematicide by variety interaction was observed influencing Pf on susceptible varieties at one of the southern locations in 2005. The control averaged 1,700 egg 100 cm-3 less than the two highest nematicide rates. It was concluded that aldicarb consistently did not influence Pf, or grain yield in Iowa.   

Handout (.pdf format, 212.0 kb)