Vegetative propagules of sago pondweed (Potamogeton pectinatus L.) and American pondweed (P. nodosus Poir.) grown under a 14-hr photoperiod of light varying in chromatic composition produced plants with longer internodes and more extensive shoot and stolon development under red light than under blue. Pondweeds grown for 4 weeks under 25 to 400 ft-c of light made progressively more growth at the higher light intensities. Plant weight, branch number and stolon development increased while shoot length and shoot-root ratio decreased with increased light. Pondweeds grown under each of 5 light intensities at temperatures of 60, 70, or 80 F were treated with emulsified xylene or alkyl tolyl methyl trimethyl ammonium chloride. Pondweeds cultured at the higher light intensities and higher temperatures were progressively more injured. Injury from treatment with either herbicide increased with age and plant maturity from early vegetative to flower-bud stage. Equivalent injury was produced on plants of equivalent maturity regardless of chronological age. Pondweeds cultured under 400 ft-c of light and a 14-hr photoperiod required approximately 900 degree-days over a 49 F threshold to reach flower-bud stage.

Amine salts of 2,4,5-trichlorophenoxy-propionic acid (silvex) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) were applied to tall larkspur, Delphinium barbeyi Huth, at 2, 4, and 8 lb/A on three dates. Leaf and stem samples collected 1, 2, and 3 weeks after treatment yielded significantly higher concentrations of alkaloids than did controls. Leaves and stems from plants treated with silvex contained more alkaloids than did those treated with 2,4,5-T. Alkaloid concentration in the leaves varied directly with the rate of herbicide following the first treatment in mid-July, but this relation was not apparent in samples obtained from the third treatment in August.

This plot sprayer was designed to possess the advantages of versatility and of being self-propelled and so not competing for a tractor during the busy planting season.

The sprayer illustrated in Figure 1 is mounted on four adjustable-width, rubber-tired wheels and is self-propelled by a 2 1/2 horse-power air-cooled engine which also operates an air compressor for agitating and distributing spray materials through nozzles on the booms. The assembly of five booms can be operated singly or together and can be adjusted for broadcast or band treatment of any row width or any combination of rows up to 200 inches wide.

The sprayer was built primarily for applying pre-emergence herbicides, but the boom assemblies can be adjusted anywhere from six to twenty-four or more inches above the ground, hence postemergence spray treatments are possible. The booms are attached to a conduit support and consist of nozzles connected at 20-inch intervals by 3-inch rubber hose. Two booms extend full length along the front and back of the support with nozzles offset to provide one every ten inches. The other three booms are short. All nozzle spacings may be adjusted to varying row widths.

Stands of Russian knapweed (Centaurea repens L.) were reduced over 80 per cent by several combinations of crops, cultivation and herbicides. Two of the best crop rotations in a 4-year trial were: (1) a short season of intensive cultivation and a mid-August seeding of bromegrass that was sprayed with 1 lb/A of butoxyethanol ester of 2,4-dichlorophenoxyacetic acid (2,4-D) during June and 1 or 1½ lb/A during August of the second and third years. (2) Bromegrass seeded with an oat companion crop sprayed with ⅓ lb/A of 2,4-D ester the first year and annual applications of 2,4-D in June and mid-August during the second and third years. The best use of non-selective herbicides in two 2-year trials was spring application of 4 lb/A of diethylamine salt of 2,3,6-trichlorobenzoic acid (2,3,6-TBA) or 6 lb/A of diethylamine salt of polychlorobenzoic acid (PBA), plowing 10 days later, and a corn crop sprayed with ⅓ lb/A of 2,4-D ester followed by a spring-seeded oat crop sprayed with d13 lb/A of 2,4-D ester and postharvest application of 4 to 6 lb/A of 2,3,6-TBA and 6 to 8 lb/A of PBA, and plowing 10 days later. Reinfestation from established plants was not prevented, but annual application of 2,4-D prevented reinfestation from seedlings.

During 1962, barnyardgrass (Echinochloa crusgalli (L.) Beauv.) seedlings were infested by the larvae of Hyperodes humilis Gyll. The larvae attacked the growing points and the youngest tissues in the crown as well as meristematic tissues of intercalary growth. These infestations produced considerable decreases of barnyardgrass growth and yields, suggesting the possibility of effective biological control of barnyardgrass.

A quick-coupling sprayer tank, a pressure introduction and release valve, and a device for measuring the time elapsed during a spraying run are described.

Weeds in row crops of the Lower Coastal Plain in Alabama were sampled by line transects in both April and August. More than 100,000 feet of transects were assayed, with detailed questioning of producers in the area. The most important weeds of summer and fall and of winter and spring are listed, with per cent coverage and per cent frequency for weeds of row crops.