Wisconsin State Horticultural Society / Annual report of the Wisconsin State Horticultural Society for the year ending July 1, 1921
Vol. LI (1921)
Roberts, R. H.
Off-year apple bearing, pp. 72-78 PDF (1.8 MB)
_.l~' 0 - em. ' (. Adz- V - WISCONSIN STATE HORTICULTURAL SOCIETY 75 cases between off-year trees and regular bearing trees is -the difference in the formation of blossom buds on second-year wood. The off-year tree as we find it about the state makes a short terminal growth, rarely over five or six inches. Generally one or two small spurs form on the second-year wood of the off-year tree. On the other hand, regular bearing trees make a terminal growth of ten, twelve, or fifteen inches. They form a number of spurs along this growth the next season and these spurs are generally more vegetative than those of the off-year trees and many of them are fruiting spurs, so that the regular bearing tree is regular in bearing very largely because blossom buds form on spurs of second-year wood each season. The new spurs of off- year trees do not form blossom buds unless the whole tree is coming into bearing. The spurs of regular bearing trees form blossom buds irrespective of whether the tree is fruiting or not, and that is one of the most important differences between regu- lar bearing and biennially bearing trees. When you get a vegetative condition in the trees, that gives one of these situations, usually you get all four of them coming together. The second big difference is, instead of some to many spurs remaining undervegetative and unfruitful year after year, they make enough growth during a fruiting year to form blossom buds while other spurs are fruiting. This gives regular bearing through different spurs fruiting in different years. The third difference is that some spurs blossom in successive seasons. This does not have a very great bearing, however, on regular fruitfulness, because it is unusual for a spur to produce fruits in- successive years. It is generally the spur which drops its blossoms early in the season which produces a blossom bud again that year. - A fourth difference between regular bearing and off-bearing trees is that there is some terminal fruiting on the regular bear- ing tree, and quite a little bit of lateral blossom bud formation. That is, blossom bud formation on the current season's growth. So we propose that blossom bud formation on off-year bearing and regular bearing trees is related to growth conditions in apple trees. Now the question comes up, if we attempt to produce regular bearing in the orchard, what to do from the cultural, fertilizer and
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