Woollyleaf Bursage Control with Monosodium Methanearsonate and Tillage 1

Abstract Woolyleaf bursage ( Franseria tomentosa Gray) infests approximately 70,000 ha of cropland in Great Plains states. Since susceptibility of this weed to MSMA (monosodium methanearsonate) was observed, MSMA and DSMA (disodium methanearsonate) were investigated under several conditions for control of woollyleaf bursage. The most effective control occurred when MSMA was applied in mid to late May after all shoots had emerged in the spring. Experiments were conducted in playa lakebeds on Randall clay (Udic Pellusterts). Woollyleaf bursage was consistently more susceptible to MSMA than DSMA. Roots were killed to depths of 30 cm or more. Mold‐board plowing of infested areas delayed, rather than reduced, shoot emergence. In contrast, a disking operation allowed weed shoots to emerge earlier and more uniformly, which resulted in greater effectiveness of MSMA. Soil moisture and crop yields were increased when MSMA was applied to woollyleaf bursage before planting cotton ( Gossypium hirsutum L.). One year after treatment with MSMA, woollyleaf bursage control was still evident and sudangrass [ Sorghum sudanense Stapp (‘Piper’)] yields were increased in treated areas.