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Larry J. Kuhns and Tracey L. Harpster

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.

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Mary Ann Rose and Larry J. Kuhns

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.

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Mary Ann Rose and Larry J. Kuhns

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.

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Larry J. Kuhns, Tracey Harpster, and Clyde Elmore

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.

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Larry J. Kuhns and Tracey L. Harpster

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?

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Larry J. Kuhns and Tracey L. Harpster

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.

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Martin R. McGann, Dan T. Stearns, and Larry J. Kuhns

In discussions among industry representatives, faculty, and graduates of the department of horticulture at Penn State community service was identified as an important attribute of successful landscape contracting companies. To foster a sense of community service responsibility among students, service projects were integrated into three horticulture courses. Fifty-four students in a planting design course worked with township officials to develop a planting plan for a new park located 10 miles from campus. Students planted 120 trees, which were obtained from a nursery operated by the Pennsylvania Dept. of Corrections. Eighty-eight students in two classes, landscape planning and issues in landscape contracting, volunteered to work on a farm being developed as an environmental education center. Work included mechanical and chemical control of invasive species and planting of natives. In discussions following these projects, students expressed personal satisfaction and a willingness to participate in future community service projects.

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Larry J. Kuhns, Elizabeth A. Brantley, and Donald D. Davis

Homeowners are often troubled by the presence of slime molds, stinkhorns, and mushrooms growing in their landscape mulches; but, they are not harmful to landscape plants, and no known health hazards are associated with them unless they are eaten. They can be discarded or ignored and they will quickly decompose. The fruiting bodies of the artillery fungus are barely visible (tiny cream or orange-brown cups approximately 1/10 of an inch in diameter), but they are the source of serious problems, many of which have resulted in insurance claims and lawsuits. They are phototropic and orient themselves toward bright surfaces, such as light-colored siding on homes and automobiles. They “shoot” their black, sticky spore masses, which can be windblown to the second story of a house. The masses stick to the side of buildings and automobiles, resembling small specks of tar. Once in place, the spore masses are very difficult to remove without damaging the surface to which they are attached. When removed, a stain remains. A few of the spots are barely noticeable, but, as they accumulate, they may become very unsightly. To date, there are no known controls for this fungus, but a research program studying possible solutions has been initiated. We ask that anyone who has information or experience with the artillery fungus contact us to exchange information. A brochure describing the four common types of fungi growing in landscape mulches in the eastern United States—mushrooms, slime molds, bird's nest fungus, and the artillery fungus—has also been prepared to educate consumers.

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E. Jay Holcomb, Tracey L. Harpster, Robert D. Berghage, and Larry J. Kuhns

A set of studies was established in Summer 1998 to determine the tolerance of field-grown cut flower species to specific preemergence herbicides, the effectiveness of weed control by those materials, and to determine if productivity of cut flowers is affected either by the herbicides or by colored mulches. Pendimethalin provided excellent early season weed control, but poor late-season control. It consistently caused injury at 4 lb a.i./A and sometimes at the 2 lb a.i./A rate. Oryzalin provided good to excellent weed control, but slightly injured celosia and zinnia when applied at 4 lb a.i./A. Napropamide provided excellent early season weed control, but marginally acceptable weed control later in the season. Though napropamide caused some injury to celosia early in the season when applied at the high rate, no injury to any of the plants was observed later in the season. Prodiamine and trifluralin were the overall safest of the herbicides, but they provided the weakest weed control. OH-2 was very effective when placed on the soil surface, but was less effective when placed on an organic mulch. The organic mulch was designed to keep the OH-2 particles from splashing on to the crop plant and injuring the plants. OH-2 tended to be safer placed on a mulch than on the soil surface, but statice was slightly injured even when a mulch was used.

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James C. Sellmer, Ricky M. Bates, Tracey L. Harpster, David Despot, and Larry J. Kuhns