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- Author or Editor: Donald Sowers x
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`Redhaven' peach [Prunus persica (L.) Batsch] trees were shaded to five light levels [100%, 45%, 23%, 17%, and 9% photosynthetic photon flux (PPF)] for four different periods. Net photosynthesis (Pn), measured under the various shade levels, increased nonlinearly with increasing percent PPF. After 18 days of shading, specific leaf weight (SLW) was positively and linearly related to percent PPF. After shade removal, Pn and SLW returned to control levels in 26 and 4 days, respectively. Flower density was positively related to percent PPF when trees were shaded from 16 June to 4 July or 4-31 July, but not from 31 July to 30 Sept. of the previous year.
`Norman' peach [Prunus persica (L.) Batsch] trees were trained to the central-leader or open-vase form and were planted at high (740 trees/ha), or low (370 trees/ha) density. A third density treatment was a HIGH → LOW density, where alternate trees in high-density plots were removed after 6 years to produce a low-density treatment. From 3 to 5 years after planting, trunk cross-sectional areas (TCA) increased most for low-density trees. After 9 years, TCA was greatest for low-density and least for high-density trees. Because of differences in tree training, central-leader trees were taller than open-vase trees and tree spread was greater for low-density than for high-density trees. Annual yield per hectare was 15% to 40% greater for high-density treatments than for low-density treatments, but tree form had little influence on yield. Average fruit weight tended to be greater for low-density than for high-density treatments, but cumulative marketable yield was greatest for high-density and lowest for HIGH → LOW treatments. Income minus costs for 9 years was nearly $4200/ha higher, and net present value was about $2200/ha higher, for open-vase than for central-leader trees (P = 0.08). Cumulative net present value for the 9 years was about $2660/ha higher for high-than for low-density trees (P = 0.36).
In 1993 a factorial experiment, involving nine apple cultivars on M.9 root-stock and six fungicide regimes, was established. The cultivars included `Delicious', `Golden Delicious', `York Imperial', `Redfree', `Freedom', `Liberty', NY 74828-12, NY 73334-35, and NY 74840-1. The fungicide treatments included earlyseason sprays of Bayleton or Dodine, separately or combined, and late-season sprays of Captan plus Benomyl alone or combined with early-season sprays of Bayleton plus Dodine. Non-sprayed trees served as a control. In 1995 leaves and fruits were evaluated for disease symptoms. Leaf spot (symptoms caused by black rot or alternaria leaf blotch) was most severe on `Redfree' and NY 73334-35, and least severe on `Delicious', `Golden Delicious', and `York'. By late summer NY 74828-12 had the most leaf abscission, whereas NY 74840-1, `Liberty', and `Delicious' lost the fewest leaves. Early-season fungicide sprays did not reduce early leaf abscission. Sooty blotch and fly speck, but not rots, were nearly eliminated by late-season applications of Captan plus Benomyl. Averaged over all fungicide treatments, more than half of the fruits from `Delicious', `Redfree', and NY 74828-12 were free of disease symptoms. Cultivars with <25% of the fruits without infection included `York', `Liberty', NY 74840-1 and NY 73334-35. `York' and `Redfree' had >25% of the fruits with rots, while all other cultivars had <9% fruits with rots. `Delicious' and NY 73334-35 had the fewest rotten fruits. Rots were not controlled by any fungicide treatment. `Liberty' and NY 73334-35 had the most flyspeck and `Redfree' had the least. `Liberty', NY 74840-1 and NY 73334-35 had the most sooty blotch and `Redfree' and NY 74828-12 had the least.
`Sweet Sue' peach (Prunus persica L. Batsch) trees were subjected to a factorial arrangement of treatments. At planting, trees were headed at 10 or 70 cm above the bud union and trees were trained to an open-vase or central-leader form. For the first 4 years, high-headed trees were larger than low-headed trees. After 7 years, open-vase trees had larger trunk cross-sectional area, tree spread, and canopy volume than central-leader trees. Open-vase trees had higher yield and crop value per tree, but lower yield and crop value per unit of land area or unit of canopy volume than central-leader trees. Crop density and yield efficiency were similar for all treatments.
Abstract
Various chemicals were applied to whole-tree, quarter-tree, or single-limb units to determine their efficacy for delaying apple (Malus domestica Borkh.) fruit abscission. NAA and the herbicides fenoprop, dicamba, triclopyr, lontrel, fluroxypyr, and chloroxuron delayed fruit abscission. Benzoic acid, calcium acetate; the growth regulators lactidichlor ethyl, mefluidide, BA, GA4+7, and chlormequat; and the herbicides pronamide, pendimethalin, chloramben, and DCPA did not delay fruit abscission. Chemical names used: benzoic acid,3,6-dichloro-2-methoxy,2-ethoxy, 1-methyl,2-oxoethylester (lactidichlor ethyl); 1-naphthaleneacetic acid (NAA); N-(phenylmethyl)-1H-purin-6-amine (BA); gibberellin (GA4+7); N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl]amino] phenyl]acetamide (mefluidide); 3,5-dichloro(N-1,1-dimethyl-2-propynyl)benzamide (pronamide); N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin); 3,6-dichloropicolinic acid (lontrel); 3-amino-2,5-dichlorobenzoic acid (chloramben); 2-chloro-N,N,N-trimethylethanaminium chloride (chlormequat); 4-amino-3,5-dichloro-6-fluoro-2-pyridinyl oxyacetic acid (fluroxypyr); butanedioic acid mono 2,2-dimethylhydrazide)4-chlorophenyl)methyl]-(1,1-dimethylethyl)-1-H-1,2,4,triazol-1-ethanol (paclobutrazol); N'-[4-(4-chlorophenoxy)phenyl]-N,N-dimethylurea (chloroxuron); dimethyl tetrachloroterephthalate (DCPA); 3,6-dichloro-2-methoxybenzoic acid (dicamba); 2-(2,4,5-trichlorophenoxy) propanoic acid (fenoprop).
Abstract
Five apple (Malus domestica) cultivars were treated with NAA at 10 mg·liter–1 and dichlorprop at 5, 10, and 15 mg·liter–1 during 2 years. Although the response varied with cultivar, NAA generally delayed fruit abscission compared to the control. Preharvest drop was usually reduced by dichlorprop at 5 mg·liter–1 more effectively than by NAA. Preharvest drop of ‘Stayman’, ‘Rome Beauty’, and ‘Winesap’, but not ‘Delicious’, was inversely related to concentration of dichlorprop. Fruit redness, flesh firmness, soluble solids content, and starch ratings were not affected consistently at harvest or during storage by any treatment for any cultivar. Residue levels of dichlorprop in the fruit were related to treatment concentration and persisted until harvest. Chemical names used: naphthalene acetic acid (NAA); 2-(2,4-dichlorophenoxy) propanoic acid (dichlorprop).