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George Ouma and Frank Matta

Experiments were conducted in 1995 and 1996 to investigate the effect of Accel and Carbaryl on apple fruit on three apple cultivars (Empire, Jon-A-Red, and Braeburn) at the Mississippi State Univ. Aricultural Experiment Station, Pontotoc. The treatments consisted of Accel 25 ppm, Accel 50 ppm, Accel 75 ppm, Carbaryl 0.05%, Carbaryl 0.2%, and an unsprayed control. Trials conducted over 2 years showed that Accel and Carbaryl consistently reduced the fruit set of three apple cultivars. There were interactions between the bioregulators and cultivars only in 1996. In all the bioregulators, treatments reduced fruit set, while in 1996, Carbaryl and Accel at all concentrations except Accel 25 ppm reduced the fruit set of `Empire', `Jon-A-Red', and `Braeburn'. Carbary 0.2% and Accel 75 ppm were the most-effective concentrations in `Empire', `Jon-A-Red', and `Braeburn', respectively, in 1996. The treatments generally increased yield and sugar content, while pH was either not affected, increased or decreased, depending on the apple cultivar.

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Mari Marutani and Veronica Endirveersingham

The effect of shade covers on degradation of insecticide, carbaryl on field-grown pakchoi (Brassica rapa subsp. chinensis) was examined by a commercial enzyme-linked immunosorbent assay (ELISA) kit. Carbaryl at a.i. 10.6 g·L-1 (1.42 oz/gal) was applied to the plants grown under five different shade treatments including control without any coverings. The experiment was arranged in a randomized complete block design with three replications. Pesticide residue on leaf tissues was examined on dates of 1, 3, 5, and 7 days after pesticide application. On all sampling dates, pesticide residue was greater with treatments with higher shade percentage. Both linear and quadratic relationship of shade (independent variable) and the concentration of remained carbaryl (dependent variable) were significant (P < 0.05). The half-life of carbaryl on pakchoi leaves ranged from 2 days for control to 9 days for the heaviest shade (75%) treatment with rain protection.

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Justin M. Vitullo and Clifford S. Sadof

of floral scents, flowers are even more preferred by beetles than foliage ( Held and Potter, 2004 ). Due to the long flight period of adult beetles (usually >8 weeks), multiple foliar applications of persistent insecticides like carbaryl are typically

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Richard P. Marini

Chemical fruit thinners were applied to limbs or whole trees of spur `Delicious' at various stages of fruit development as indicated by fruit diameter. Carbaryl, naphthalene acetic acid (NAA), and ethephon all reduced fruit set when applied at a fruit diameter of ≈4 to 15 mm. Fruit thinning for NAA and carbaryl, alone or combined, generally was greater when applied at an average fruit diameter of 8 mm, rather than at 4 mm. Repeated applications of NAA or carbaryl were no more effective than single applications. NAA + carbaryl applied at 9 mm was more effective than NAA applied at 4 mm followed by carbaryl at 8 mm. Applied when fruit diameter averaged 17 to 22 mm, ethephon and ethephon + carbaryl were effective fruit thinners. When applied at full bloom to ≈10 and 20 mm, the insecticides ethion and oxamyl, respectively, were effective fruit thinners.

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F.G. Dennis Jr.

In 1994, benzyladenine (BA, formulated as Accel, containing 1.8% BA and 0.18% GA4+7) was evaluated as an apple fruit-thinning agent. Naphthaleneacetic acid (NAA, 10 ppm) and carbaryl (60 g·liter–1) were also used, as well as combinations of these chemicals with BA. Whole trees were treated with either an airblast sprayer or a hand gun, BA being used at 15–20 g/acre. Good responses to BA were obtained in one of two trials, with both `Empire' and `Gala', but `Jonagold' and `Jonathan' were not responsive (one trial each). In general, response to NAA and carbaryl was more consistent. In only one orchard (`Gala') did BA appear to increase fruit size without reducing crop load. Combinations of BA with NAA or carbaryl were generally no more effective than one chemical alone, but such combinations overthinned in one experiment with `Empire'.

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R.E. Byers, J.A. Barden, and D.H. Carbaugh

Terbacil applied to whole-spur `Delicious' apple (Malus domestica Borkh.) trees reduced photosynthesis and fruit set. The addition of the surfactant X-77 to terbacil sprays increased fruit thinning and leaf injury. Terbacil sprays applied to leaves only (fruit covered with foil) were as effective as when applied to leaves plus fruit. Dipping fruit alone in a terbacil solution did not cause abscission. Shading trees for 4 days with 92% polypropylene shade material reduced fruit set =50%. Spraying trees with carbaryl reduced fruit set by 25%. The combination of shade + carbaryl spraying reduced fruit set by 89%. Chemical names used: l-naphthalenyl methylcarbamate (carbaryl); 3-tert- butyl-5-chloro-6-methyluracil (terbacil); 2-chloroethylphosphonic acid (ethephon); alkaryl polyoxyethylene alcohols (X-77).

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Peter M. Hirst

Russet is a disorder of apple (Malus×domestica) fruit where the formation of cork cells leads to a cosmetic blemish which is commercially undesirable. One of the many causes of russet is low temperature damage early in fruit development. Following frost damage to fruit, a study was initiated to determine whether carbaryl chemical thinner was more effective in thinning russeted fruit than nonrusseted fruit. With no chemical thinner application, russeted fruit abscised at a greater rate than nonrusseted fruit. Following the application of carbaryl to the fruit however, there was no difference in the retention of fruit among the treatments. Chemically thinning with carbaryl therefore is not a technique that growers could use to preferentially thin russeted fruit.

Open access

Norman E. Looney and John N. Knight

Abstract

Fruit set on mature spurs and on 1-year-old wood (lateral bloom) was followed as a step in the development of a chemical thinning protocol for ‘Greensleeves’ apple trees. Initial set (fruit firmly attached 15 days after full bloom) was a reasonable predictor of final set on spurs but not on lateral clusters. High initial set values on lateral clusters reduced final set. Likewise, initial and final set values on either spur or lateral clusters were inversely related following a 1000 ppm carbaryl treatment, although lateral clusters were more readily thinned than spur clusters by carbaryl. Without the carbaryl treatment, final set per cluster was comparable on spur and lateral clusters, and final set on lateral clusters was improved by defruiting alternate clusters on these 1-year-old branch sections 15 days after full bloom.

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Ronald H. Meyer

Abstract

Methyl N’N’-dimethyl-N-[(methylcarbamoyl)oxy]-1-thiooxaminidate (oxamyl)-thinned fruit of ‘Golden Delicious’ and ‘Starkrimson Delicious’ apples (Malus domestica Borkh.), as did naphthaleneacetic acid (NAA) and 1-naphthyl N-methyl carbamate (carbaryl). At 12- and 13-mm diameter fruit size, an increase in concentration of oxamyl sprays increased thinning. Oxamyl produced increasingly severe russet on ‘Golden Delicious’ at concentrations above 300 ppm.

Open access

Estaban Herrera-Aguirre and C. R. Unrath

Abstract

Thinning spray combinations of naphthaleneacetic acid (NAA), (2-chloroethyl) phosphonic acid (ethephon), and 1-naphthyl N-methyl carbamate (carbaryl) were applied to ‘Delicious’ apples (Malm domestica Borkh). In 1975, 280 dekaliters per hectare (DPH) showed large variation over 3 locations. In 1976 applications based on “tree row volume” (TRV) showed uniform thinning across the same (1975) locations.