Efficacy of Using Split and Postplant Applications of Aldicarb for Control of Helerodera schachtii on Sugarbeet.

Soil temperature at planting and initial population densities (Pi) significantly affected (P < 0.05) the chemical control of Heterodera schachtii on sugarbeet, Beta vulgaris. The fumigant 1,3-dichloropropene (1,3-D) at 9.4 g/m of row effectively controlled H. schachtii, resulting in increased sugarbeet yields over the nontreated control treatment at soil temperatures at planting of 8, 12, and 16 C and Pi of 4.7, 10.4, and 18.3 eggs/cm(3) at planting. A split application of aldicarb, 1.3 g/m of row at planting (AP) and 28 days later (PP), and a single at-planting (AP) treatment of 2.1 g/m of row were less effective in controlling H. schachtii than 1,3-D at the three soil temperatures and Pi. The sugarbeet yield from the AP plus PP treatment, however, was greater than the sugarbeet yield from the AP treatment and was equivalent to the yield from the 1,3-D treatment at temperatures of 8 and 12 C and a Pi of 4.7 eggs/cm(3). Sugarbeet yield from the AP treatment was significantly (P < 0.05) greater than the AP plus PP application at a Pi of 18.3 at a planting temperature of 8 C and Pi of 10.4 and 18.3 eggs/cm(3) at soil planting temperatures of 12 and 16 C. Postplant application of 2.1 g/m of aldicarb, applied 28 days after planting, significantly increased sugarbeet yields at all soil temperatures at the lower Pi levels.