Tomato (Lycopersicon esculentum Mill.) plants possess a high degree of tolerance to postemergence applications of 3-chloro-2-methyl-p-valerotoluidide (solan). Eggplant (Solarium Melongena L.) is highly susceptible to this herbicide. Differences in penetration, persistence and metabolism of solan by tomato and eggplant were insufficient to account for the differential susceptibility. Solan greatly inhibited the Hill reaction in isolated chloroplasts, and chloroplasts of both species were about equally sensitive to it. Radioactive solan (carbonyl labelled) sprayed on intact tomato and eggplant accumulated to about the same extent in chloroplasts of both species. The Hill reaction in isolated chloroplasts, carbon dioxide (C14O2) fixation in intact plants, and the level of high energy phosphates in intact plants were determined for tomato and eggplant previously sprayed with a selective rate of solan. Initially, all three reactions were inhibited in both species. Later, all three reactions returned to normal in tomato, but declined to a low level in eggplant. A resistant mechanism of cyclic photosynthetic phosphorylation was proposed as the mechanism of solan tolerance in tomato. Two types of light-activated solan injury were found. A rapid non-selective action, occurring at high doses of the herbicide, killed both tomato and eggplant. A delayed action occurred selectively on eggplant at low rates of herbicide. No solan injury occurred on plants placed in darkness after spraying, regardless of plant species or rate of herbicide applied.

Germinable seeds were non-existent below 4 inches in the undisturbed soils used for cranberry bed development. Seeds were found at greater depths in manipulated soils. The seed in the vines used for planting was a major factor in the infestation of a properly scalped bed. Movement of seeds in water caused an infestation of a weed-free bed. The highest movement of seeds per acre-inch of water flow occurred in September, next highest in October and third highest in April. A relatively weed-free planting was maintained through one season by fumigating the soil for seed eradication, erecting a fine mesh screen exclosure to prevent weed invasion by flood water, and washing the vines prior to planting.

Several ring-substituted derivatives of benzoic acid inhibited pantothenate biosynthesis in Escherichia coli. The metabolic site of inhibition was the conversion of ketopantoate to pantoate. This action caused pantothenate-reversible reductions in growth only in strains of E. coli with inherent limited capacities for biosynthesis of ketopantoate. Inhibition of pantothenate biosynthesis was tentatively concluded to be of little physiological significance as a site of action responsible for herbicidal activities of benzoic acids.

The addition of 2-chloro-4,6-bis(ethylamino)-s-triazine (simazine) to nutrient solutions of corn (Zea mays L.) increased the percent of N and total mg of N in one test regardless of the N level in the solution. Under the low N level, the magnitude of this increase was 90 percent with 0.5 ppm simazine. However, in a second experiment, under environmental conditions more favorable for corn growth, the total mg of N was not increased, although the percent nitrogen in the shoots was increased at the lower nitrogen level. Corn plants treated with hydroxy simazine responded similarly to the controls.

Herbicides incubated in Wymore silty clay loam soil at field capacity at 15, 25, and 35 C showed 3-amino-2,5 dichlorobenzoic acid (amiben) the most persistent, 2,3,6-trichlorobenzoic acid (2,3,6-TBA) intermediate, and 2-chloro-4-ethylamino-6-isopropylamino-5-triazine (atrazine) the least persistent to microbial and/or chemical breakdown. All herbicides persisted much longer at 15 C than at 35 C. The average annual temperature below the plow layer is about 12 C. This helps explain the persistence of leached herbicides under field conditions.

At Lincoln 20 lb/A of 2,3,6-trichlorobenzoic acid (2,3,6-TBA) destroyed Clark soybeans five seasons after application. Soil persistence of 2,3,6-TBA in the light textured soils and low rainfall of western Nebraska was less than at Lincoln. A 10 lb/A rate of 3-(p-chlorophenyl)-1,1-dimethylurea (monuron) reduced weed and oat yields at Lincoln the third growing season after its application. Applications of 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine), 2-chloro-4,6-bis-(ethylamino)-s-triazine (simazine), or monuron at 10 lb/A reduced oat yields at North Platte the third growing season after their application. Herbicide carryover is a greater problem in arid than in humid regions of the United States.

Seedlings of Siberian elm (Ulmus pumila L.) readily invade grasslands of the Southern Plains and are a serious economic problem. Siberian elm was not susceptible to foliage or basal sprays of phenoxy herbicides applied during 3 successive years. Individual trees were killed easily by 1 g (ai) per inch of trunk diameter of 3-(p-chlorophenyl)-1,1-dimethylurea (monuron) or 3-phenyl-1,1-dimethylurea (fenuron) applied in a ring around the tree. However, the dense population and rapidity of reinvasion make this treatment too expensive.

Indoleacetic acid (IAA) stimulates the incorporation of radioactivity derived from methionine-methyl-C14 into a fraction of sesbania hypocotyl that is insoluble in 80 per cent alcohol or 60 percent acetone, but is soluble in hot water. Incorporation of C14 into “hot water soluble material” was stimulated by IAA, 2,4-dichlorophenoxyacetic acid, 2,5-dichlorophenoxyacetic acid, 2,4,5-trichlorophenoxyacetic acid, naphthaleneacetic acid, 2,3,6-trichlorophenylacetic acid, 2-methoxy-3,6-dichlorobenzoic acid, 4-amino-2,5-dichlorobenzoic acid, and 4-amino-3,5,6-trichloropicolinic acid. All compounds were stimulative at 1 × 10-5M.