Untreated Buffer Research Articles

Greenbug Control in Grain Sorghum, 1975

Abstract Plots were arranged in a randomized complete block design with 3 replications in 2 tests in Hale Co., Texas. Each plot was 1 row 50 ft long. Plots were separated by 1 to 3 untreated buffer rows. Liquid formulated insecticides were applied by the use of a compressed CO2, back-pack sprayer equipped with a boom fitted with 2 hollow-cone nozzles (3x) which directed the spray to the sides of the plant. Sprays were applied at the rate of 5 gal per acre. Granular treatments were applied by hand-shaking the insecticides from a glass jar with a perforated lid onto the tops of the plants. Relative effectiveness of the treatments was evaluated by counting live greenbugs on each of 5 plants selected at random from each plot prior to treatment and at 3 and 7 days after treatment. Percent control was calculated using Henderson and Tilton’s 1955 formula.

Plant Response to Herbicide Placement in Soil

Greenhouse and growth chamber studies were conducted to investigate effects of herbicide placement in soil on toxicity to emerging seedlings. The use of a technique involving a plastic bag over the plants for 3 to 4 weeks to reduce soil moisture loss did not change the apparent site of 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) uptake by green foxtail (Setaria viridis(L.) Beauv.) or oats (Avena sativaL.). Atrazine was more effective on oats through root exposure and more effective on green foxtail through shoot exposure when an untreated buffer zone around the seed was used. But in subsequent studies without the buffer zone, atrazine was most active when placed immediately below the seed of both oats and green foxtail. Proximity to the seed increased effectiveness of atrazine,S-ethyl dipropylthiocarbamate (EPTC), and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron). Also, a narrow concentrated layer of these three herbicides adjacent to the seed was more effective than a wider dilute layer above or below the seed. A diurnal fluctuating temperature regime with a low night temperature increased toxicity of EPTC to oats through root exposure, when compared to a constant temperature regime.

Absorption and Penetration of Picloram in Potato Tuber Discs

Discs of potato (Solanum tuberosum L.) tuber tissue were immersed in buffered (pH 4.0 to 8.0) solutions of 4-amino-3,5,6-trichloropicolinic acid (picloram) (5 × 10−4M to 5 × 10−3M) for 1 to 36 hr. Uptake of picloram during incubation, and leakage after return of the discs to untreated buffer, were determined by gas chromatographic analysis of extracts of the tissue and ambient buffer. Picloram absorption increased with concentration and with time up to 24 hr. Maximum uptake occurred at pH 4.0 and very little picloram was absorbed at pH 7.0 and 8.0. Both absorption and leakage were temperature dependent. The rate and extent of leakage was greatest at the highest concentration. Typically, more than 90% of the picloram absorbed from 5 × 10−3M was lost to fresh buffer within 12 hr.