Linuron (3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea) and diphenamid (N,N-dimethyl-2,2-diphenylacetamide) were applied at 5 and 25 lb/A to 13- x 3-inch columns of Wheeling sandy loam and Maury silt loam soils and leached with 1, 2, 4, and 8 inches of water. Linuron remained at or near the soil surface; diphenamid was leached more readily.

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.

Silvex, [2-(2,4,5-trichlorophenoxy)propionic acid], impregnated (20% ae) on clay granules, applied at a rate as low as 20 lb/A ae gave excellent control of well-rooted alligatorweed [Alternanthera philoxeroides (Mart.) Grieb] growing in less than 18 inches of water. The 2-ethylhexyl ester of silvex was more effective than the potassium salt. Silvex was not effective on floating-mat alligatorweed or in water over 18 inches deep.

Alhagi pseudalhagi (Bieb.) Desv. (camelthorn) was in troduced into California about 1915, and into the State of Washington about 1935. Here, it was declared a primary noxious weed in 1955. Seeds scarified with sulfuric acid germinated 90–98 per cent at 25 C. Some seeds were viable after burial one year in soil or submergence for 9 months in running water. Seedlings in the infested area were found only in bovine manure. Tests indicated scarification and transportation of seed in the rumen could accelerate the spread of camelthorn. Lack of favorable moisture and soil temperature at the same time prevented establishment of camelthorn planted at several locations. Eradication resulted from treatment with 2,3,6-trichlorobenzoic acid (2,3,6-TBA). Three repeated sprays with esters of 2,4-dichlorophenoxyacetic acid (2,4-D) within a growing season gave control; however, control did not appear to be directly related to depletion of reserve foods in the roots.

Factors influencing injury to oats from 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) and 2-chloro-4,6-bis(ethylamino)-s-triazine (simazine) residues in the soil were studied over a period of five years. Initial rate of triazine application was highly important with significant injury in about one-half of the trials on plots treated with 2 lb/A the year prior to planting oats, and on all plots treated at 4 lb/A. No material difference was found on plots treated with equivalent rates of atrazine and simazine. Granular preparations of atrazine left a residue that was more injurious than wettable powders. Disking the seedbed for oats, rather than plowing, resulted in greater injury. Cultivation of the corn between the rows after treatment did not influence the injury the following year. Soil type did not have a marked effect on injury in this study. Above-normal average mean air temperatures appeared to reduce injury the following year in some instances. Experiments initiated in years of abundant rainfall during April to October tended to have less injury the next year than experiments initiated in years when rainfall was limited.

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.

Cotton plants were treated with C14-ring-labeled 2-methylmercapto-4,6-bis(isopropylamino)-s-triazine (prometryne) which was soil-incorporated or placed in solution cultures. C14-labeled material accumulated in the lysigenous glands of roots, stems and leaves. No evolution of C14-carbon dioxide could be detected. Unaltered C14-prometryne was present in stems and leaves 23 weeks after treatment, but no radioactive materials could be detected in the seed. Small amounts of hydroxypropazine were isolated from the stems and leaves of plants grown in soil, but none was detected in plants grown in solution culture. Both water-soluble and acetone-insoluble radioactive materials accumulated in the leaves, stems and roots of all treated plants.

The morphological symptoms of 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) and 3-(p-chlorophenyl)-1,1-dimethylurea (monuron) toxicity were expressed in the light but not in the dark. Various wavelengths of narrow band light were produced by the use of colored plastic filters. Oats, var Kanota, and red kidney beans were used. The degree of injury was a function of light intensity, the higher the light intensity the greater the injury. The action spectrum indicated that chlorophyll was the principal absorbing pigment involved in this injury.

Diquat (6,7-dihydropyrido[1,2-a:2’,1′-c] pyrazidiinium salt) was applied to several emergent, submersed, floating-leaved, and free-floating aquatic plants common in Central Illinois ponds. At relatively low rates, it was effective in controlling several submersed aquatic plants but not American pondweed, Potamogeton nodosus, and cabomba, Cabomba caroliniana. This herbicide also was effective on several common emergent species.

Greenhouse evaluation of 13 herbicides indicated that several were suitable for preemergence weed control in sesame. CIPC appeared best and was field evaluated for 2 years. This herbicide provided adequate to excellent annual weed control without plant injury or reductions in yield.

These herbicides at rates of .01 to .25 lb/A caused moderate to severe morphological effects on soybeans and significant yield reductions. Soybeans treated in the vegetative stage were injured more than those treated in the bloom stage. The herbicide 2-(2,4,5-trichlorophenoxy)propionic acid (silvex) injured soybeans most followed by 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), 2,4-dichlorophenoxyacetic acid (2,4-D), and 4-(2,4-dichlorophenoxy)-butyric acid (2,4-DB), in that order.

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.

3-amino-2,5-dichlorobenzoic acid (amiben) and N-1-naphthylphthalamic acid (NPA) were applied to soybeans and 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) and 2-chloro-N, N-diallylacetamide (CDAA) to corn as sprays and as granules. Except where excellent weed control was established by the herbicides, rotary hoeing 2 weeks after application of the herbicides usually improved the degree of weed control without any detrimental effect on performance of the herbicides.

Six herbicides were applied to young stands of Kentucky bluegrass at weekly intervals in treatments beginning 5, 7, 9 and 11 weeks after seeding bluegrass. In both years the arsenical containing herbicides were effective when applications were started 7, 9 or 11 weeks after seeding. Applications started five weeks after seeding were unsuccessful in 1962 but gave excellent control in 1963. Reduced stands of Kentucky bluegrass and generally poorer crabgrass control were obtained with phenyl mercuric acetate than with the arsenicals.

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.

Listed on the basis of visual ratings in Sept. 1961, in the order of increasing toxicity to Kentucky bluegrass sown in April, 1961, and treated May 31 and June 6, the herbicides were 2,3,5,6-tetrachloroterephthalic acid (DCPA), amine methylarsonate, diphenylacetonitrile (diphenatrile), calcium propylarsonate, disodium monomethylarsonate (DMA), N,N-dipropyl-2,6-dinitro-p-toluidine (dipropalin), calcium arsenate, O-(2,4-dichlorophenyl) O-methyl isopropylphosphoramidothioate (DMPA), polychlorodicyclopentadiene isomers, and alpha, alpha, alpha-trifluro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin). All herbicides except DCPA and DMPA (liquid) persisted after two years of use until March 1963 in the top 2 inches of soil.

A chromatographic method with silver nitrate reagent detected dalapon extracted from quackgrass (Agropyron repens (L.) Beauv.) rhizomes. Minimum detectable quantity was 2×10-7 grams. Following field applications of dalapon, the amounts recovered 1 hour after spraying were low for plots receiving 4 lb/A while relatively high amounts were found initially from 8 lb and 12 lb/A treatments, but several days later, these relations were reversed.

A plastic envelope device is described which allows separate exposure of seeds, roots, and coleoptiles of emerging grass seedlings to soil-incorporated herbicides.

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.

Dodder seedlings become attached to another plant by first twining about some part of the host. Twining is dependent on action of light. Chlorophyll also forms after exposure to light. Diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] was applied to dodder seedlings to determine the nature of light action in twining. Diuron had no effect on twining but blocked photosynthesis.