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  • Author or Editor: J. P. Sterrett x
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Abstract

Herbicides were introduced into the vascular systems of 20-and 22-year-old Chinese elm (Ulmus parvifolia Jacq.), pin oak (Quercus palustris Muenchh.), and 20-year-old white ash (Fraxinus americana L.) with a syringe-type pressure injector. Concentrations of triclopyr [[(3,5,6,-trichloro-2-pyridinyl)oxy]acetic acid] triethylamine salt ranging from 90 to 360 g/liter were as effective on all species with 2 injection sites per tree as the combination of picloram (4-amino-3,5,6-trichloropicolinic acid) triisopropanolamine salt + 2,4-D [(2,4-dichlorophenoxy) acetic acid) triisopropanolamine salt at dosages ranging from 8 g/liter + 30 g/liter to 32 g/liter + 120 g/liter. Over 80% kill of Chinese elm tops occurred within 2 months after injection, whereas maximum kill of white ash and pin oak did not occur until the following growing season.

Open Access

Abstract

Low levels of 7-oxabicyclo(2,2,1)heptane-2,3-dicarboxylic acid (endothall), ranging from 37.5 to 300 ppm, combined with 1000 ppm of (2-chloroethyl)phosphonic acid (ethephon) and sprayed on pin oak (Quercus palustris Muenchh.) seedling sprouts in the greenhouse caused temporary defoliation during the initial stages of leaf development. Defoliation was 75 to 86% with a 75 ppm endothall/1000 ppm ethephon combination applied during the first 27 days of leaf expansion. In field trials a 75 ppm/1000 ppm, endothall/ethephon combination defoliated 85% of 17 year-old pin oak trees in the expanding leaf stage. Shoot damage was negligible and foliar density of field trees reached 90% of control 10 weeks after defoliation.

Open Access

Abstract

A miniature pressure injector (mini-injector) was designed specificially to introduce solutions into the vascular system of seedlings and branches of woody plants for research purposes. The mini-injector consists of modified Vise-Grip locking pliers, a stainless steel tapered barrel and disposable syringe. Azo sulfamide dye was successfully injected into 4 species of container-grown fruit trees and 12 species of shade trees. Injections were more consistently effective in June, August, and October than in April. Diffuse-porous species were generally more receptive to injection, especially before bud break, than ring-porous species.

Open Access

Abstract

7-Oxabicyclo (2.2.1) heptane, 2-3-dicarboxylic acid (endothall) alone was not an effective chemical abscissor of bean leaves (Phaseolus vulgaris L. cv. Red Kidney) until a concn of 30 to 40 mg/liter was attained, but in the presence of 800 mg/liter (2-chloroethyl)phosphonic acid (ethephon) abscission began at 5 mg/liter endothall. Low pH (1.5) significantly lowered the break strength of abscission zone explants of leaves sprayed with ethephon and endothall compared to pH 6.0, and endogenous ethylene production from endothall alone was higher at pH 1.5 than pH 6.0.

Open Access

Abstract

Six species of seedling trees were foliar-treated in greenhouse experiments with 7 - ox ab icyclo(2,2,l)heptane-2,3-dicarboxylic acid (endothall) mixed with (2 chloroethyl) phosphonic acid (ethephon). A range of 75 to 100% abscission was obtained within 14 days with little or. no damage except on Chinese elm (Ulmus parvifolia Jacq.).

Open Access

Long-term goals of reducing environmental impacts associated with agricultural activities must include economic sustainability as well as production feasibility. This study compared the potential economic and environmental impact of two specific cropping systems [wheat/soybeans (w/s) vs. selected vegetable crops with wheat/soybeans (veg/w/s)]. Profitability of w/s was lower than the veg/w/s system but demanded a smaller, less extensive resource base of labor and machinery with fewer conflicts in resource utilization rates. The PLANETOR computer program (Univ. of Minnesota) was used to analyze the potential negative environmental effects of growing a particular crop mix within these two systems. Although some of the vegetable crops exceeded the targeted soil loss tolerance value (T-value) of 3 t/ha, the weighted average of the veg/w/s system was below the target T-value for soil erosion. Analyses suggest that the profits from vegetables in the veg/w/s production more than offset the negative impacts on soil erosion and the veg/w/s system would be more economically feasible than w/s. Potential impact of pesticide leaching and runoff from vegetable production as calculated by PLANETOR was less than that from w/s. Specific cultural practices, including soil/tissue testing to manage nutrient applications, could reduce nitrogen/phosphorus movement. The veg/w/s system may offer the necessary profit margins to allow adoption of more environmentally friendly production alternative.

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