Weed management programs in ‘Superior’ potato with PRE and POST rimsulfuron treatments were investigated during 1992, 1993, and 1994 in Virginia on a State sandy loam soil. Common ragweed control by PRE combinations of metolachlor with linuron or metribuzin was higher when treatments included PRE or POST rimsulfuron. Common lambsquarters control was 93 to 96% by treatments that included POST rimsulfuron. In the absence of PRE herbicides, POST applications of 35 g ai/ha rimsulfuron plus 280 g ai/ha metribuzin controlled weeds comparable to sequential applications of this combination. Potato recovered from occasional terminal leaf chlorosis caused by rimsulfuron, rimsulfuron plus metribuzin, and organophosphate insecticides combined POST with rimsulfuron plus metribuzin. These studies demonstrate that rimsulfuron can be a useful component of weed management programs that include metolachlor, linuron, and metribuzin.

Persistence of four insecticides (prothiofos, Bacillus thuringiensis Berliner, fenveralate and methamidophos) were evaluated against the larvae of Plutella xylostella (L.), under field conditions. The effective biological action of the chemicals against the larvae varied with different instars. The insecticides were biologically effective for 6 to 8 days after treatment against first and second instars, and their index of persistent toxicity was higher than that for third and fourth instars. They were effective against third and fourth instars only for one day after spraying. Prothiofos and B. thuringiensis were more toxic to all the instars than methamidophos or fenveralate.