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  • Author or Editor: D. O. Ketchie x
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Five different pruning techniques were begun in 1990 on Anjou pear trees to determine their effect on fruit set: (1) unpruned; (2) central leader, (3) central leader modified to Verner method; (4) stubbed into 2- to 4-year-old wood first year and then developed to central leader; and (5) mold-and-hold. Half of each treatment was spread, the other half not spread. Half of each of the combination training and spreading were tipped back to the first fruit bud at cluster bud time. The trees were 9 years old and on OHXF97 rootstock. The unpruned trees had the highest yield, 81 Kgm/tree. The other treatments ranged between 52 and 58 Kgm/tree. Regardless of pruning treatment, the spread trees out yielded the non-spread trees by 16 Kgm/uee.. There was essentially no difference between trees tipped in the spring and those that were not tipped.

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Abstract

The croprotectants, polyvinylpyrolidone, glycerol, ethylene glycol and dimethyl sulfoxide were applied individually or in combination with each other in the form of a spray on whole apple (Malus domestica Borkh.) trees in the greenhouse and by terminal feeding apple and pear (Pyrus communis L.) trees in the field. The trees were tested both by artificial and natural freezing. The cryoprotectants increased cold resistance, however, different cultivars showed different effects with the various protective agents. Factors other than the colligative properties appeared to modify the effects of cryoprotectants.

Open Access

Abstract

In ‘Delicious’ apple (Malus domestica Borkh.) trees affected by dead spur disorder (DS) no over-all deficiency was in N, P, K, Ca, amino acids, proteins, sugars or phenols as compared with healthy (CK) trees. N, amino acid and protein contents were higher in DS than in CK spurs on 1- and 2-yearold limb sections. Relatively low nutrient levels in DS spurs on 3-4-year old limb sections indicated that translocation of nutrients to these spurs was restricted. Phenol contents were lower in DS than in CK spurs. P and K contents were higher in DS than in CK spur leaves.

Open Access

Abstract

Pink phloem was found during the winter months in all spurs on ‘Delicious’ apple (Malus domestica Borkh.) trees affected by dead spur disorder and was less frequent the remainder of the year. On healthy trees pink phloem was found in young spurs, but seldom at the base of older spurs. The pigment was identified as the anthocyanin cyanidin-3-galactoside.

Open Access

In the past, the laborious and time-consuming method of defoliation was used to determine vegetative maturity (VM) of various deciduous plants. Other methods such as water potential and electrotrical impedence have been explored without a positive response. A change of freezing events of water in plant tissue may be associated with VM. Differential thermal analysis (DTA) was tried to determine if the freezing events of water are related to VM. `Golden Delicious', `Gala', `Red Fuji' and `Antonovka' apple (Malus domestica Borkh.) trees were used to determine VM by defoliation. Different sets of 1-year-old trees grown in pots in the greenhouse were defoliated weekly from 1 Aug. until it was assured the trees had reached VM. Samples from the same trees were taken for DTA. The trees were observed for regrowth 2 weeks after they were defoliated, and the exothermic patterns from DTA were examined for the appearance of an exotherm at about –35 to –40°C. The comparison of regrowth from trees defoliated from a specific date were compared to the exothermic pattern of the same date. An exotherm appeared between –35 and –40°C ≈2 weeks before the apple trees ceased to show regrowth from the defoliation treatment. The exotherm appeared on 30 Aug. for Antonovka and `Golden Delicious' and regrowth of the trees ceased on 12 Sept. Regrowth ceased on 9 Oct. for `Gala' and `Fuji' preceded by the exotherm on 2 Oct. The conclusion was that the appearance of the exotherm at –35 to –40 °C could be used to determine VM.

Free access

Abstract

A method is described for introducing small quantities of chemicals by gravity flow into terminal shoots of young apple trees. The destruction of acid fuchsin and 14C labelled growth regulators by this method was down the main stem, out to the lateral branches, and into the leaves.

Open Access

Abstract

Limb units and whole trees of ‘Delicious’ and ‘Golden Delicious’ sprayed in the fall with 250 ppm, 500 ppm and 1000 ppm Ethrel significantly decreased fruit set and vegetative growth the following season.

Open Access

Abstract

Spur wood and spur bark of ‘Delicious’ apple (Malus domestica Borkh.) trees affected by dead spur disorder (DS) grew more vigorously than those of healthy (CK) trees the first 2 years. Buds were smaller on DS than on CK trees. Leaves were smaller on DS than on CK trees on 2-year-old and older limb sections. DS trees produced most fruit on 2-year-old limb sections, whereas CK trees produced most fruit on 3-year-old limb sections. Length and diameter growth of the limbs was unaffected, but the internode length was shorter on DS than on CK trees. Death of the spurs was preceded by bud failure in the spring.

Open Access

Abstract

Cold resistance of current season shoots and trunk bark of ‘Red Delicious’ apple trees were compared with seasonal temperature through 4 winters. Cold resistance was measured by electrolytic conductance and recorded as T10 and T90. There was correlation between cold resistance and the temperature during 7 days preceding cold acclimation measurement. Sustained temperature below 0°C increased cold resistance more than did very low temperature interrupted by short periods above freezing.

Open Access

Abstract

“Dead spur” is a disorder which affects the spurs of ‘Delicious’ apple (Malus domestica Borkh.). The spurs die on 2-year-old and older sections of the tree. A survey of ‘Delicious’ sports showed Royal Red, Earlistripe and Sharp have a higher incidence of dead spur than the other sports. There was no relationship of the disorder to rootstock, but the interstock Ottawa 292 increased the severity of dead spur.

Open Access