Important considerations for RPA 201772 utility

Greenhouse and laboratory studies were conducted to examine certain charact eristics of RPA 201772 and how they may affect its utility. C-14-RPA 201772 was used to determine the stability of RPA 201772 in various pH spray solu tions over time. After 24 h, degradation of RPA 201772 was 20, 36, and 93% in spray solutions adjusted to pH 4.0, 7.0, and 10.0, respectively. The maj or metabolite was diketonitrile (DKN), which is herbicidally active. In add ition, 9 and 15% of the RPA 201772 had degraded into an inactive benzoic ac id derivative at pH 7.0 and 10.0, respectively. The differences in herbicid al activity of RPA 201772 and its metabolite DKN were also evaluated. Corn seeds and velvetleaf seeds readily imbibed RPA 201772, but only low levels of DKN were imbibed. Preemergence (applications of RPA 201772 and DKN were equally active on corn and velvetleaf, Further studies determined that the principal sites of uptake of RPA 201772 by corn was roots and seeds for fou r different corn hybrids. Another study determined that light was required for RPA 201772 activity. Corn shoots from seeds germinated under 14 h of li ght exhibited rate-dependent injury, while corn germinated and grown in the darkness was not injured.