The effect of the herbicide isoxaben on the incorporation of radiolabeled glucose, leucine, uracil, and acetate into acid insoluble cell wall material, protein, nucleic acids, and fatty acids, respectively, was measured. Dichlobenil, cycloheximide, actinomycin D, and cerulenin, inhibitors of the incorporation of these precursors into these macromolecular components, functioned as expected, providing positive controls. The incorporation of radiolabeled glucose into an acid insoluble cell wall fraction was severely inhibited by isoxaben at nanomolar concentrations. Amitrole, fluridone, ethalfluralin, and chlorsulfuron, as well as cycloheximide, actinomycin D, and cerulenin did not inhibit incorporation of glucose into this fraction, ruling out a general nonspecific effect of herbicides on glucose incorporation. The evidence thus suggests that isoxaben is an extremely powerful and specific inhibitor of cell wall biosynthesis.

LY195259, 5‐(Aminocarbonyl)‐l‐(3‐methylphenyl)‐1H‐pyrazole‐4‐carboxylic acid, has been physically characterized in the laboratory and has been evaluated as a male sterilizing agent under greenhouse and field conditions on several plant species, including wheat (Triticum aestivum L.). Male sterilizing agents are useful in producing hybrid seed. Under optimum conditions, the compound when applied as a foliar spray to wheat at rates as low as 1.12 kg a.i. ha−1 has produced > 95% male sterility. It also has been effective when applied in the spring as soil‐surface treatments. Over 100 cultivars have been tested and had at least 90% male sterility when treated with LY195259. Some crosses made with wheat cultivars treated with LY195259 and a properly nicked pollen source with good pollen load had 80% of the seed set of the selfed male parent. No physical distortion of the hybrid seed was apparent, and no other phytotoxic effects were visually evident from rates as high as 3 times the mean effective dose.

The response of Chrysanthemum morifolium Ram. to drench applications of ancymidol was reduced if the potting media contained high quantities of ground pine bark. Aqueous movement of ancymidol was restricted by pine bark and sand in leaching tests. Bioassays with Setaria italica (L.) Beauv. indicated that the immobile ancymidol fraction in upper segments of pine bark and sand columns retained excellent biological activity.

No abstract

A series of 1-aryl-5-(aminocarbonyl)-1H-pyrazole-4-carboxylic acids were serendipitously discovered to be chemical hybridizing agents. Different synthetic routes were developed for the active analogs depending on whether an electron withdrawing group or electron donating group was present on the phenyl ring. Development of the "second generation gametocides" produced analogs which were 5-6 times more active than the original lead.