The compound α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) inhibited mitosis in onion (Allium cepa L. ‘Yellow Globe’) and wheat (Triticum aestivum L. Thorn’) root tips. Photomicrographs showed that trifluralin affected mitosis in the same manner as colchicine. Arrested metaphases, c-pairs, micronuclei, amoeboid nuclei, and polyploidy were observed at various times after treatment. An increase in the percentage of arrested metaphases and a decrease in anaphase and telophase figures after 3 hr showed that mitosis was being blocked at metaphase. Prophase did not appear to be affected. Centrifugation of treated root tips displaced the chromosomes of arrested metaphases indicating that the spindle apparatus was disrupted.

Imazaquin (Scepter) is a new, broad spectrum herbicide that is being marketed under the trademark Scepter® herbicide by American Cyanamid Co., Princeton, NJ. It can be applied preplant incorporated (PPI), preemergence (PE) or over-the-top postemergence (POST) in soybean. Crop tolerance is excellent with all methods of application. Imazaquin was tested in the United States in 1984 and 1985 under an Experimental Use Permit (EUP). Section 18 Emergency Exemptions also were granted by the Environmental Protection Agency (EPA) in 1985 for control of sicklepod (Cassia obtusifolia) in five southern states. Imazaquin was registered by the EPA for use in the United States on soybean, in March, 1986, and was sold in 23 states that year. Marketing in four additional states in 1987 was approved by the EPA in October, 1986.

Pronamide [3,5-dichloro-N-(1,1-dimethyl-2-propynyl)benzamide] was most phytotoxic to oat (Avena sativaL.) when placed in the seed zone and to quackgrass (Agropyron repens(L.) Beauv.), when placed in the rhizome zone. Inhibition of part of the buds by pronamide on detached quackgrass rhizome sections did not influence other buds. Foliar applications of pronamide were not phytotoxic to established oat or quackgrass. Foliar-applied14C-pronamide showed little uptake by quackgrass. Application to the roots of established plants showed rapid root uptake and movement to the foliage.14C-pronamide was rapidly absorbed by oat seedlings for the first 0.5 hr and subsequently at a much slower rate. Over 60% of the pronamide taken up after 1 hr was exchangeable. Pronamide was adsorbed to the cell walls of treated roots, but little was associated with nuclear, mitochondrial, microsomal, or soluble protein fractions. Pronamide was adsorbed to varying degrees depending on soil type. Adsorption was more highly correlated with soil organic matter content than with cation exchange capacity, clay content, or pH.

During germination a decrease in both soluble and protein argmine occurs in pumpkin cotyledons (Cucurbita moschata Poir.) and this decrease parallels the decrease in total nitrogen. Arginine is readily metabolized to urea and ornithine and the metabolism of the latter compounds were studied by allowing cotyledons of intact plants to absorb urea−14C and by incubating cotyledon discs with ornithine‐2−14C. Of the urea absorbed, 90 % of the label was metabolized to 14CO2 with little free urea remaining in the plant. Urease activity in the cotyledons reached a maximum at 4 to 6 days of germination. Ornithine was extensively metabolized with 37 % of the label being incorporated into protein by 3 h. Soluble and protein arginine accounted for 23 % of the label suggesting that Krebs‐Henseliet cycle enzymes were present.