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  • Author or Editor: D. O. Ketchie x
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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

A cooperative experiment begun in 1980 was designed to evaluate the productivity and other characteristics of 16 spur and 12 standard strains of `Delicious' apple on two rootstocks (M.7 EMLA and MM.111 EMLA). All trees were propagated at one nursery, and plantings were established in Michigan, Washington, Oregon, Idaho, Indiana, and British Columbia. In Michigan, trees of standard strains were consistently larger than trees of spur strains 8 years after planting. Early yields were greater on M.7 EMLA than on MM.111 EMLA, but trees were more subject to leaning under heavy crops on M.7 EMLA. In general, spur-type strains yielded more fruit per unit trunk cross-sectional area than standard strains. Yield was more closely associated with fruit-setting ability than with flower density, and fruit size declined as fruit set increased. Length/diameter ratios and biennial bearing indices also differed significantly among strains.

Free access

Abstract

Electrolytic conductance was measured from acclimated and nonacclimated seedlings of apple, pear and citrus which were frozen and unfrozen. A close correlation between electrolytic conductance and survival was shown. A comparison was made between conductance and injury of apple and pear trees in the natural freeze of 1968-69 in Washington. Procedures are outlined for using conductance as a measure of cold tolerance among cultivars or treatments within the same cultivar. The use of T10 and T90, which describes the transition range of injury, is outlined and described. Procedures are also outlined for following acclimation or deacclimation through the year and for determining freeze-injury from natural freezes.

Open Access

Yield components of spur and non-spur strains of `Delicious' apple, on 2 rootstocks were compared over 4 years (5th through 8th leaf). Yield per unit trunk cross-sectional area was higher in spurs than in non-spurs with but few exceptions. Differences in fruit set, rather than in flower density or fruit size, were largely responsible for this difference in yield. Yields were higher on EMLA 7 than EMLA 111 rootstock, partially because of earlier bearing. When cropload was factored out, fruit size was slightly greater on EMLA 7 than on EMLA 111.

Free access