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  • Author or Editor: Max W. Williams x
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Two chemicals being tested as blossom thinners for apple are effective for bloom thinning of peaches and nectarines. Monocarbamide dihydrogen sulfate (Wilthin) and Endothall applied at 90% of bloom open reduced fruit set by 50%. Fruit size and quality of the crop were improved. Both of the above chemicals gave adequate fruit removal without serious phytotoxic effects on leaves, buds or shoots. With chemical rates which over thinned, no fruit marking occurred on either nectarines or peaches.

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Abstract

Aminoethoxyvinylglycine (AVG), an inhibitor of ethylene synthesis, applied to ‘Delicious’ apple trees (Malus domestica Borkh.) 2 weeks before harvest reduces loss of flesh firmness of apples in storage and increases vegetative growth in the following growth season. When applied to ‘Delicious’ or ‘Golden Delicious’ trees after full bloom, the “June drop” was completely eliminated; thus, fruit set was significantly increased.

Open Access
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Abstract

Moderate to high vigor and maximum light penetration must be maintained in deciduous fruit trees to assure high yields of good quality fruit. To accomplish the balance between vigor and light penetration, control of excessive shoot growth is required. Dwarfing rootstocks and spur type scion cultivars are reasonably successful in controlling vegetative growth. However, some species have few adequate rootstocks or spur type scions to help control tree growth. Furthermore, even with the best possible combination of rootstock and scion for a particular orchard site, there are periods in the life of the orchard when additional control of vegetative growth is needed. Vigorous growth is necessary in the early years to fill the allotted space with a viable fruiting surface. Fruit set then is increased by controlling excessive vegetative growth. Periodic control of growth can be accomplished by pruning and training of shoot growth, but these methods are often inadequate for maximum fruiting efficiency, since they are labor intensive and cannot always be accomplished in a timely manner.

Open Access

Abstract

Cytokinins applied to axillary buds of apple shoots overcame apical dominance. Axillary buds on actively growing apple shoots produced spurs and lateral branches when treated with cytokinins. Buds on shoots that had not received sufficient chilling to break rest were also induced to grow with cytokinins.

Open Access

Abstract

Few agricultural commodities have enjoyed the tremendous success achieved by the Washington State apple industry. The apple acreage in Washington has increased from about 80,000 to over 125,000 acres in recent years. The production reached 72 million boxes in 1981 and will increase to about 85 million by 1985. This expansion is directly related to the improved technology in the production, storage, and marketing of the fruit, which has provided a constant supply of quality fruit to consumers for 11 to 12 months of the year. Much of the success is credited to a strong research effort and the immediate application by the fruit industry of the new technology developed from research.

Open Access

Abstract

The determination of sugars and sugar alcohols in horticultural crops is time-consuming and often difficult because of interfering substances. The quantitative deteimination of the individual sugars in a sample has until recently been very difficult. The work of Sweeley and co-workers (2), on the formation and subsequent gas chromatography of trimethylsilyl (TMS) ether derivatives of carbohydrates and related polyhydroxy compounds, has made it possible to determine individual sugars quantitatively.

Open Access

Abstract

The chemical 2,3,5-triiodobenzoic acid (TIBA 1,2) has been reported by workers in the United States (1,2,3,4,8) and other countries (6,7) to influence flower bud initiation and branch angle of apple trees. This report describes injury to fruits and pedicels of Golden Delicious and to foliage of Golden Delicious, Delicious and Winesap apple trees from the application of 25 ppm TIBA about 4 weeks after bloom in North Central Washington.

Open Access

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