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  • Author or Editor: S. C. Weller x
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Abstract

Sprays of 0.5% poly-1-p-menthen-8-9-diyl (Vapor Gard), an antitranspirant, decreased fruit size but had no influence on russet or fruit quality of field-grown ‘Golden Delicious’ apple (Malus domestica Borkh.). Laboratory experiments in growth chambers with potted ‘Golden Delicious’ apple trees indicated that: 1) Vapor Gard at concentrations of 0.25, 0.5, 1.0, and 2.0% tended to decrease net photosynthesis (Pn) and transpiration (Tr) for 1 to 7 days under optimum soil moisture conditions; 2) under conditions of low soil moisture, 2.0% Vapor Gard sprays reduced Pn and Tr significantly, but did not reduce symptoms of injury from moisture stress; and 3) Vapor Gard did not affect shoot growth over a 21-day period.

Open Access

Abstract

Terbacil at 0, 0.28, 0.56, 0.84, and 1.12 kg·ha−1 was applied immediately after planting to strawberry (Fragaria xananassa Duch.) cultivars Surecrop, Honeoye, Guardian, Redchief, and Delite. Plant vigor and number of mother plants were reduced by all herbicide rates >0.28 kg·ha−1. ‘Delite’ plants were less vigorous at the time of planting than other cultivars. There were no differences between cultivars in number of rooted runners, but terbacil at rates >0.28 kg·ha−1 reduced runner rooting. Yield the year following planting was dependent on terbacil rate and cultivar. Vigorous cultivars (i.e., ‘Redchief) had superior yields. Terbacil at 0.28 kg·ha−1 was safe when applied to newly planted strawberries on soils with organic matter content of at least 1.0%. Chemical name used: 5-chloro-3-(l,l-dimethylethyl)-6-methyl-2,4(1H,3H)-pyrimidinedione (terbacil).

Open Access

Abstract

Field studies conducted for 2 years showed that glyphosate [N-(phosphonomethyl) glycine] or mixtures of glyphosate and preemergence herbicides applied as preplant and directed postplant sprays were effective in providing season-long weed control in commercial nurseries. Oryzalin [3,5-dinitro-N 4,N 4-dipropylsulfanilamide] at 2.2 or 4.5 kg ai/ha, and mixtures of simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] at 1.1 kg ai/ha with diphenamid [N,N dimethyl-2,-2-diphenylacetamide] at 6.7 kg ai/ha, napropamide [2-(α-naphthoxyl)-N,N-diethylpropionamide] at 2.2 kg ai/ha, alachlor [2-chloro-2’,6’-diethyl-N-(methoxymethyl) acetanilide] at 2.2 kg ai/ha or oryzalin at 4.5 kg ai/ha were effective treatments when used after preplant application of glyphosate (2.2 kg ai/ha) or when combined with glyphosate (2.2 kg ai/ha). None of the herbicide treatments reduced growth of red maple (Acer rubrum L.), Norway maple (A. platanoides L.), or creeping juniper (Juniperus horizontalis Moench). Japanese spurge (Packysandra terminalis Sieb. and Zucc.) survival was reduced by treatments containing oryzalin.

Open Access

Abstract

Three formulations of oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl) benzene], 25% wettable powder (WP), 1% granular (G), 0.24 kg liter-1 emulsifiable concentrate (EC), and 2% G oxadiazon [2-tertbutyl-4(2,4-dichloro-5-isopropoxyphenyl)-Δ2-1,3,4-oxadiazolin-5-one] were compared for weed control and their effects on growth of Cotoneaster apiculatus Rehd. & E.H. Wils., Euonymus fortunei (Turcz.) Hand.-Mazz. ‘Colorata’, and Juniperus horizontalis Moench. ‘Glenmore’. Both herbicides provided acceptable weed control at recommended rates. The EC formulation of oxyfluorfen provided the best weed control, but injury to euonymus and juniper was also most severe with the EC, while injury to cotoneaster was most severe with the EC and G.

Open Access

Abstract

Strip tillage was evaluated over a 2-year period as a cropping system for sites unsuitable for conventional tillage. Yields in clean cultivation and in 0.5- and 1.1-m strips tilled in established grass or grass/clover sod were compared in 1982 for sweet pepper (Capsicum annuum L.) and winter squash (Cucurbita maxima L.). Both interspecific and intraspecific competition were determined in 1983 for pepper. Squash yield was improved by a grass/legume sod, but pepper yield was unaffected. Both crops suffered severe competition in 1982 when grown in 0.5-m-wide strips, but yields per hectare in strips 1.1m wide equaled that in clean cultivation. In 1983, however, number of marketable fruit per hectare of marketable yield of pepper in 1.1-m strips was less than that in clean cultivated plots, although total number of harvested fruit did not differ. Both marketable and total pepper yields per hectare were significantly higher in clean cultivation in 1983 than in strips. Increasing the population density of pepper in the strip increased number of fruit harvested and total weight per hectare, and there was a significant benefit in using double rows. Competition in strips accompanying increasing population density seemed to be associated with increased water deficits.

Open Access

Southernpea is a major vegetable crop in Arkansas and Oklahoma for commercial production and home gardens. Complete weed control is necessary for this crop in commercial production to keep the peas free of contaminants and achieve high harvest efficiency. Several weeds like pigweed, cocklebur, velvetleaf, lambsquarters, hophornbeam copperleaf, nightshade, nutsedge, and morninglories are difficult to control in this crop because of limited herbicide options. Sandea (halosulfuron) is an excellent herbicide for nutsedge control and has activity on most of the weeds mentioned above. It has both soil and foliar activity. Sandea is labeled for several vegetable crops and southernpea may have enough tolerance to Sandea to warrant a label expansion. Experiments were conducted in Arkansas and Oklahoma between 2002 and 2005 to determine the tolerance of southernpea to Sandea and its efficacy on some weed species. In Oklahoma, trials were conducted in LeFlore County and at the Bixby Research Station in 2002 and 2003. Treatments consisted of various herbicides applied preemergence (PRE) or postemergence (POST), among which were some Sandea treatments. The doses of Sandea tested ranged from 0.024 to 0.048 lb a.i./A with some treatments applied with Basagran (bentazon), POST. Preemergence treatments were applied at 20 GPA and POST treatments at 30 GPA. Experimental units were arranged in randomized complete block design with four replications. The cultivar used was Early Scarlet. Plots were comprised of four rows, spaced either 30 or 36 inches, depending on location, 15 ft long. The crop at Bixby was irrigated, but not at LeFlore. In Arkansas, two experiments were conducted in 2005 at the Vegetable Station in Kibler. One experiment was setup in a split-plot design, with four replications, with cultivar as mainplot and Sandea treatments as subplot. Eleven advanced breeding lines and Early Scarlet were used. Four Sandea treatments, using doses of 0.048 and .096 lb ai/A applied either PRE, at 1 to 2-trifoliate (early POST), and at 3- to 4-trifoliate (late POST) were tested. The second experiment compared the responses of 16 advanced breeding lines and Early Scarlet to 0.096 lb a.i./A Sandea applied PRE. Plot size at Kibler consisted of 4 rows, spaced 36 inches, 20 ft long. Herbicide treatments were applied at 20 GPA spray volume and the crop was sprinkler irrigated as needed. In Oklahoma, the commercial rate of Sandea (0.032 to 0.048 lb a.i.) did not cause any injury to southernpea when applied PRE regardless of availability of irrigation. However, when applied POST, significant stunting (up to about 20%) of plants was observed in both locations. This level of injury did not cause significant yield loss. The trial at Bixby could not be harvested due to excessive pigweed biomass later in the season. Sandea controlled Palmer amaranth and carpetweed >90% when applied PRE, but had no activity on these species when applied POST. Conversely, Sandea had excellent activity (100%) on common cocklebur when applied POST, but ineffective when applied PRE. Trials in Arkansas were strictly for tolerance evaluation so no weed control data was collected. In Arkansas, the PRE timing was also safer than POST when 0.096 lb ai Sandea was used. The 11 advanced lines tested in trial 1 were among the top 15 lines selected for tolerance to Sandea from a preliminary screen. These selected lines still showed different levels of tolerance to high rates of Sandea, but may not show any difference among each other at the recommended rates. The best lines were 00-609 and 00-178, which showed no yield reduction when treated with 0.096 lb ai Sandea PRE. All advanced lines had higher yield than Early Scarlet without herbicide treatment. In trial 2, 01-103, 01-180, and 01-181 had 0% to 10% yield loss when treated with 0.096 lb ai Sandea, PRE. All three had similar or greater yield than Early Scarlet. The commercial standard incurred about 20% to 30% yield loss from the high dose of Sandea applied PRE in both trials in Arkansas. Sandea is safe for cowpea, PRE at recommended doses. However, some advanced lines can tolerate high rates of Sandea. Some weeds are controlled by Sandea PRE, but not POST and vice versa.

Free access