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  • Author or Editor: Max W. Williams x
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Abstract

Five-year-old ‘Anjou’ pear trees (Pyrus communis L.) were sprayed with (2-chloro-ethyl)trimethylammonium chloride (chlormequat) (1500 ppm), (2-chloroethyl)phosphonic acid (ethephon) (250 or 500 ppm), or succinic acid-2,2-dimethylhydrazide (daminozide) (1000 ppm) plus ethephon (250 ppm) 4 or 6 weeks after full bloom (AFB) for 2 consecutive seasons. Chlormequat increased fruit set after 1 application, but 2 applications of the other chemicals were required to increase fruit set. Two consecutive years of chlormequat applications increased yieid about 50%, 2,3,5-Triiodobenzoic acid (TIBA) (50 ppm) applied 4 weeks AFB did not affect fruit set, but induced many short shoots of ‘Anjou’ pear trees.

Open Access

Abstract

Gibberellins (GA) will stimulate parthenocarpic fruit development in apples (1, 4, 5, 9). Davison (4) found GA3 to increase fruit set in the Red Jersey variety to a greater extent than in Sturmer. Bukovac (1) observed that GA4 was more effective than GA3 in promoting fruit set in the Sops-of-Wine variety. Varga (9) reported that GA1, GA2, GA4, and GA7 promoted parthenocarpic fruit set in the Lombartscal-ville variety but not in the Winston or Golden Delicious varieties.

Open Access

Abstract

Paclobutrazol (PP333) is a promising new bioregulant for controlling size of trees and significantly reducing the need for dormant and summer pruning. ‘Delicious’ trees were treated with a high rate of PP333, which resulted in some smaller, flattened fruit with shorter pedicels. Application of either gibberellin A4+7 plus 6-benzylamino purine (Promalin) or gibberellin A3 (GA3) before or at full bloom increased fruit size, pedicel length, and leaf size on PP333-treated trees.

Open Access

Abstract

One of the more effective means of developing a smaller than standard apple tree is to graft the desired variety onto East Mailing (EM) IX rootstock. This combination results in a tree from 1/3 to 1/2 standard size. A decisive explanation for the mechanism of dwarfing by EM IX has not appeared in the literature. Of the suggested factors which might result in dwarfing by EM IX rootstock, those which involve organic constituents appear to be most plausible. It has been shown that EM IX is not deficient in fat, starch, reducing sugars, and disaccharides (3, 10). Also there is evidence to indicate that neither the root system (11) nor water (4) is limiting the growth of a dwarfing rootstock.

Open Access

Abstract

(2-Chloroethyl)phosphonic acid (ethephon) applied 3 weeks before normal harvest hastened most of the changes commonly associated with maturation and ripening of ‘Delicious’ apples. Red color development, increase in soluble solids, water core development and decreased susceptibility to storage scald were all hastened by the ethephon treatment.

Open Access

Abstract

In late September of 1981 and 1982, eight-year-old ‘Oregon-spur Delicious’ apple (Malus domestica) trees on M7 rootstock were sprayed immediately after harvest with 500 ppm AVG. The following spring of both years the number of spur leaves and lateral shoots on one-year-old wood was increased on treated trees. Total N was reduced and sucrose and fructose were increased in dormant one-year-old shoots of AVG-treated trees. Cold hardiness was not affected. Throughout the dormant period both apical and one-year-old lateral buds excised from treated trees and incubated in the dark at 24°C produced less ethylene over a period of 24 hr than buds from untreated trees. In situ ethylene production from apical buds of treated trees was also reduced as growth resumed in the spring. Chemical name used: N-(phenylmethyl)-lH-purin-6-amine (AVG).

Open Access

Abstract

Cytokinins and gibberellins applied to dormant buds on young apple trees significantly increased the number of growing buds and the angle between the main trunk and the new shoot. Total shoot growth on treated trees was nearly double that of control trees. Nursery trees treated with growth regulators several weeks before planting produced branches with wide crotch angles from which good permanent primary scaffold limbs could be selected.

Open Access

Abstract

Fruit color of ‘Golden Delicious’ apples was closely related to N content and color of leaves. This relationship was significant for both spur leaves and mid-terminal leaves. Prediction of fruit color from spur and mid-terminal leaves was obtained in late July and mid-September. Nitrogen content was higher in the mid-terminal leaves than in the spur leaves.

Open Access

Endothall [7, oxybicyclo (2,2,2) heptane-2-3 dicarboxylic acid] is an aquatic herbicide which has potential for use as a blossom thinning agent for apples. Trials conducted in Washington State, New Zealand and Australia on several apple cultivars indicate Endothall is a safe, consistent blossom thinner. Cultivars treated were `Golden Delicious', `Delicious', and `Gala'. Single and repeat applications were used in the New Zealand tests. With multiple applications of Endothall, no fruit marking occurred on any of the test cultivars. In temperate fruit zones with extended apple bloom periods, multiple applications of a low rate of Endothall may he beneficial for reducing fruit set and biennial hearing.

Free access

Endothall [7, oxabicyclo (2,2,1) heptane-2-3 dicarboxylic acid] is an aquatic herbicide with potential use as a blossom thinner for apples (Malus domestics Borkh.). Trials conducted in Washington, New Zealand, and Australia on several apple cultivars indicate that endothall is a safe, consistent blossom thinner. Cultivars treated were `Golden Delicious', `Delicious', `Royal Gala', and `Granny Smith'. Single and repeat applications were used in the New Zealand and Washington tests. With multiple applications of endothall, no fruit marking occurred on any of the test cultivars. In temperate fruit zones with extended apple bloom periods, multiple applications of endothall at a low rate may be beneficial for reducing fruit set and biennial bearing.

Full access