High concentrations of arsenic (As) may be expected on Coastal bermudagrass forage harvested soon after application of organic arsenicals for weed control. Stage of plant development at treatment, rainfall between treatment and harvest, rate of application of arsenical herbicides, and the amount of growth between treatment and harvest are factors influencing As residue levels in harvested material. Regrowth following removal of treated growth had a lower As concentration. Treatment application on short grass and removing and discarding the treated foliage appeared to be the most effective means of reducing As residues.

Corn was grown in soils containing root residues of giant foxtail (Setaria faberii Herrm.), yellow foxtail (Setaria glauca (L.) Beauv.), and crabgrass (Digitaria sanguinalis (L.) Scop.). The effect of these residues on corn root growth was studied using a new technique which measures root response to soil properties with a single plant. Giant foxtail was the most inhibitory. Implications of these data are discussed in terms of the dominance and competitive ability of giant foxtail.

Five rates of 1-(2 methylcyclohexyl)-3-phenylurea (siduron) were applied to Cohansey and IaGreen cultivars of creeping bent-grass (Agrostis palustris). Siduron had no effect upon leaf respiration or photosynthesis of either cultivar. Cohansey was tolerant to 100 lb/A of siduron while top growth of IaGreen was reduced 90% at 1.5 lb/A. Siduron inhibited new root growth of the IaGreen cultivar and decreased root respiration.

The herbicide 0-(2,4-dichlorophenyl) 0-methyl isopropylphosphoramidothioate (DMPA) applied either as a preemergence spray or in mixture with the alkanolamine salt of 4,6-dinitro-orthosec-butylphenol (DNBP) at the “ground-cracking” (emergent) stage increased the yield of peanuts from 1960 to 1965. Average yield increases from DMPA treatments for the 5-year period were highly significant statistically if DMPA treated peanuts were compared with peanuts either cultivated, handweeded, or sprayed with standard herbicide mixtures.

The U.S. Department of Agriculture World Collection of Flax Germ Plasm was screened for resistance to 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine). A single plant selection of CI 719 was the most resistant. It produced dry matter equaling 33% of the control in soil treated with atrazine at 1 lb/A while Amy produced 10%. In another experiment, the selection of CI 719 produced 44% as compared to only 11% for Koto. The atrazine-resistant selection was not resistant to 2-chloro-4,6-bis(ethylamino)-s-triazine [simazine]. Seed of this selection of CI 719 have been entered in the World Collection and assigned the number CI 2484.

Four new biodegradable alkylpolyoxyethylene glycol surfactants (15-S-9, DN-65, 15-S-3, and 15-S-3A) provided excellent visual wetting of corn foliage in spray solutions of 1,1′-dimethyl-4,4′-bipyridinium salt (paraquat), 2,2-dichloropropionic acid (dalapon), and 3-amino-1,2,4-triazole (amitrole) and many combinations were equal or superior to standard surfactants Tween 20, X-77, and Osamul 95 in enhancing phytotoxicity. Exceptions were observed, apparently due to specific but incompletely understood herbicide-surfactant-plant surface interactions. All four biodegradable surfactants and Osamul 95 were slightly toxic when sprayed alone on corn foliage.

A laboratory sprayer, designed to make herbicide applications to potted plants and to study spray distribution patterns with different nozzles, is described. An activated charcoal air filter was installed to minimize herbicide contamination to adjoining greenhouse-laboratory facilities during the spraying operation.