Search Results

You are looking at 1 - 10 of 16 items for

  • Author or Editor: Larry J. Kuhns x
Clear All Modify Search

Fine fescues are immune to two common graminicides, fluazifop-p-butyl and sethoxydim. This study was initiated to determine the tolerance of three fine fescues; chewings, hard, and creeping red, to clethodim alone or with a crop oil concentrate (COC) or non-ionic surfactant (NIS). Clethodim at 0.25 or 1.0 lb/a was applied on 23 Oct. 1995 and evaluated on 22 May and 9 July 1996. Clethodim at 0.25, 0.5, or 1.0 lb/a, was applied on 31 May and evaluated on 9 July 1996. Applied in the fall at 0.25 lb/a alone or with NIS, clethodim had little effect on chewings or creeping red fescue. Some injury to hard fescue was evident on 22 May, but it recovered by 9 July. The addition of COC resulted in moderate injury to all three species, with only partial recovery by 9 July. Severe injury of all species from clethodim applied at 1 lb/a was evident on 22 May. The amount of recovery that occurred by 9 July was dependent on the spray additive used. With none, all of the grasses recovered fairly well. With NIS, moderate injury to hard fescue persisted; and with COC, unacceptable injury to all species persisted. Similar results were obtained when the treatments were applied in the spring. The 0.5 lb/a rate caused an intermediate degree of injury. Though none of the clethodim treatments totally killed any of the fine fescues, unacceptable injury was caused by the 0.5 and 1.0 lb/a rates, regardless of additive, and by the 0.25 lb/a + COC treatment.

Free access

Weeds must be controlled to produce marketable crop yields, for human safety, and for aesthetic reasons. Physical methods of weed control are highly labor and/or energy intensive, and in many cases are more dangerous to crops and people than herbicides. They are not practical solutions to most weed problems in developed countries. To properly work with and apply herbicides, researchers, and applicators should have a knowledge base that includes information on weed taxonomy, anatomy, and biology; herbicide chemistry and modes of action; spray adjuvants and carriers; soil characteristics and environmental factors that affect herbicide performance; application equipment technology; the development of herbicide resistance; alleleopathy; and the biological control of weeds. Herbicide use, in terms of product used or expenditures, is greater by a wide margin than that of insecticides and fungicides combined. Also, about two thirds of all pesticides produced in, and exported from, the United States are herbicides. Finally, about 40% of all of the herbicides used in the world are used in the United States. Only 32% of the insecticides and 14% of the fungicides are used in the United States. On the average, the leading universities in the country have only three faculty teaching courses in weed science, and they teach only two undergraduate and three graduate courses each year. Few are in horticulture. By comparison, there are 15 faculty teaching 13 undergraduate and 19 graduate courses in the leading entomology programs in the country. Weed control is an essential element in the production and management of all horticultural crops. Who is going to provide the education and training in weed science for the researchers, horticulturists, and consultants of the future?

Free access

A study was initiated to determine how well plants would grow in potting media available to consumers through garden centers and national chain stores. Nine media were evaluated. The chemical and physical characteristics were determined, and six geraniums (Pelargonium sp) and six marigolds (Tagetes patula) were grown in each of the media. Three of each six were fertilized, three were not. The plants that were fertilized received 100 ppm N and K and 50 ppm P once a week. Three months after seeding the flowers, flowers and buds on the marigolds were counted and the plants were harvested. Dry weights were determined. Nitrate-N ranged from 6 to 627 ppm, pH from 4.9 to 7.1, phosphorus from 88 to 502 pounds/A, potassium from 1.0 to 6.9 meq/100 g, magnesium from 1.4 to 10.8 meq/100 g, calcium from 5.2 to 30.0 meq/100 g, soluble salts from 20 to 151 mmhos, and CEC from 13.0 to 43.8 meq/100cc. Bulk density ranged from 21 to 53 g/100cc, water holding capacity from 32 to 53 ml/100cc, percent air-pore space from 2.7 to 15.7, and total porosity ranged from 65% to 78%. Unfertilized marigolds weighed between 0.1 and 9.6 g; fertilized marigolds weighed 1.4 to 17.2 g. Unfertilized geraniums weighed between 1.4 and 23.3 g; fertilized geraniums weighed 4.4 to 56 g. There were 1.3 to 16 flowers on unfertilized and 7 to 24.3 flowers on fertilized marigolds.

Free access

Large bare-root liners of Gleditsia triacanthos `Moraine' and Pyrus calleryana `Aristocrat' were planted in spring, 1989. Five trees of each species were pruned by removing 50% of the length of each shoot at planting; 5 control trees were not pruned. After 4 months the trees were harvested and the following measurements were taken on the season's new growth increment: total number of elongated shoots and unelongated shoots (< 1 cm in length), total and average length of elongated new shoots, stem and leaf dry weights.

Growth responses of the 2 species to treatments were nearly identical. Pruned trees had fewer shoots than controls but a much higher proportion of elongated to unelongated shoots. This could be the result of a release of apical dominance. The average new shoot length of pruned trees was 2-3 times that of controls, and the total new shoot length was significantly greater. New stem dry weights of the pruned trees were also greater than the controls, but leaf dry weights were not significantly different. Total shoot weights (stems plus leaves) were not different. In this study there was no difference between treatments in the total seasonal growth increment as measured by weight. An equivalent amount of new growth was distributed on fewer, but more rapidly-elongating branches in the pruned trees.

Free access

Large bare-root liners of Gleditsia triacanthos `Moraine' and Pyrus calleryana `Aristocrat' were planted in spring, 1989. Five trees of each species were pruned by removing 50% of the length of each shoot at planting; 5 control trees were not pruned. After 4 months the trees were harvested and the following measurements were taken on the season's new growth increment: total number of elongated shoots and unelongated shoots (< 1 cm in length), total and average length of elongated new shoots, stem and leaf dry weights.

Growth responses of the 2 species to treatments were nearly identical. Pruned trees had fewer shoots than controls but a much higher proportion of elongated to unelongated shoots. This could be the result of a release of apical dominance. The average new shoot length of pruned trees was 2-3 times that of controls, and the total new shoot length was significantly greater. New stem dry weights of the pruned trees were also greater than the controls, but leaf dry weights were not significantly different. Total shoot weights (stems plus leaves) were not different. In this study there was no difference between treatments in the total seasonal growth increment as measured by weight. An equivalent amount of new growth was distributed on fewer, but more rapidly-elongating branches in the pruned trees.

Free access

Abstract

Treatment of burlap with copper sulfate (CuSO4) or copper naphthenate (Cu Nap) retarded its deterioration in soil. Deterioration of CuSC4-treated burlap was independent of treatment concentration while deterioration of Cu Nap-treated burlap was directly related to treatment concentration. Burlap treated with CuSC4 had a higher Cu content and lower initial break strength than burlap treated with Cu Nap. At 24°C, burlap treated with CuSC4 retained effective strength an average of 27 weeks, with Cu Nap, between 8 and 72 weeks. The rate of deterioration was significantly lower at 2°.

Open Access

Abstract

Procedures were developed to extract protein and active enzymes from rose leaves. A suitable extraction medium, extraction time, and sample application rate was determined for each system in which bands could be separated. Sixteen enzyme systems and anionic protein were investigated, with only anionic protein, peroxidase, esterase, malate dehydrogenase, cytochrome oxidase, phenoloxidase, and polyphenoloxidase producing clear bands. Existing staining techniques were adequate for staining cytochrome oxidase, phenoloxidase, and polyphenoloxidase activity, but modifications of the reported anionic protein, peroxidase, esterase and malate dehydrogenase stains were required. Isoenzyme changes which occur during 0, 9, 12, and 16 weeks storage are discussed.

Open Access

Abstract

Protein and active enzymes were extracted from leaves of 8 rose cultivars. Extracts were run on polyacrylamide gels and stained for total protein, peroxidase, esterase, malate dehydrogenase, cytochrome oxidase, phenoloxidase, and polyphenoloxidase. Three leaf positions on each cultivar were sampled in an attempt to determine a sampling standard. Because of differences in growth habit among the cultivars, and different optimum locations for the enzymes, a standard location could not be set. Banding data were tabulated and used to prepare coefficient of similarity values and flow charts showing separations. All cultivars could be distinguished by differences in their enzyme banding patterns if results from several systems were employed.

Open Access

Abstract

Phytotoxicity of burlap treated with 6 concentrations of CuSO4 or copper naphthenate (Cu Nap) was determined by enclosing the root balls of Cotoneaster divaricata in the treated burlaps, observing their growth for 40 weeks, and analyzing root, stem and leaf tissue for Cu, Fe, and Mn. Burlap treated with up to 4.0% Cu Nap or levels of CuSO4 less than 0.2% was not phytotoxic. Burlap treated with solutions of CuSO4 ≥0.2% was phytotoxic. Tissue analyses indicate that the injury from CuSO4 treated burlap was the result of high Cu concentrations in the roots of enclosed plants.

Open Access

SpinOut is a commercial product containing copper hydroxide that is designed to prevent the development of circling roots in container grown ornamentals. Our objective was to determine the effect of two root-inhibiting herbicides (oryzalin and trifluralin) on the development of circling roots in container grown ornamentals when painted onto the inside surface of the containers or on stakes inserted around the walls of the containers. Rooted cuttings of wintercreeper euonymus (Euonymus fortunei Hand.-Mezz) were planted in a 1 peat: 1 perlite: 1 soil mix on 8 to 10 Feb. 1995. There were 16 containers for each of 20 treatments. Eight were rated for circling roots then harvested 17 to 22 May, and eight were rated and harvested 6 to 7 July 1995. Root circling was rated on a scale of 1 to 5, with 1 indicating no circling roots and 5 indicating many circling roots. Following harvest stem growth was measured and the dry weights of the roots, stems, and leaves were determined. Treated stakes did not prevent circling roots Trifluralin in Vapor Gard reduced the amount of circling roots, but not to acceptable levels. Trifluralin in latex paint was ineffective at 0.5%, slightly reduced the development of circling roots at 2%, and at 4% reduced circling rooting to the same extent as the SpinOut. Surflan at 0.5% in Vapor Gard reduced the development of circling roots to the same extent as the SpinOut. All other rates of Surflan, in both carriers, almost totally eliminated circling roots. There were no significant differences in root weight or total plant weight among any of the treatments at either date of evaluation.

Free access