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Abstract
In a test designed to study the effect of cross pollination on pear fruit set Stephen (4) found that seeded fruits result almost entirely from cross pollination rather than selfing. He found also that seedless set was mainly from selfing, although a small proportion was parthenocarpic. When he first caged entire trees against insect pollination during the period of open bloom, an average set of seedless fruits resulted. However, after caging during bloom each year for four years, seedless set was gradually reduced to only a few fruits. Stephen extended this study and found (5) that renewed exposure of the caged trees to cross pollination resulted in a good set of seeded fruit. If only one leader of a previously caged tree was exposed to cross pollination, it alone produced fruit. The following year, however, when the entire tree was again caged to prevent cross pollination, a substantial set of seedless fruit occurred on all leaders.
Abstract
The pear cultivars ‘Anjou,’ ‘Bartlett’. ‘Bose,’ ‘Cornice,’ ‘Seckel’ and ‘Packham's Triumph’ grown on 9 rootstocks were observed for tolerance to pear decline, tree size, bloom density, yield, fruit weight and leaf nutrient content. Cultivars on Old Home clonal rootstock or Old Home on nurse roots of Mailing Quince A, Winter Nelis seedling or Bartlett seedling were smaller, had lower yield efficiency and greater uptake of Ca, Mg and Mn than when worked directly on Winter Nelis or Bartlett seedling rootstocks or Pyrus calleryana Decne. Winter Nelis and Bartlett seedling rootstocks were similar in performance but Winter Nelis seedlings had a lower yield efficiency than did Bartlett seedlings. Both had better uptake of Fe and Zn but were less precocious than P. calleryana. Fruit size was increased on P. calleryana and P. betulaefolia Bunge seedling rootstocks, particularly when topworked with ‘Seckel’. Cultivars with Call rootstock had greater uptake of K than other rootstocks. A hybrid of P. nivalis Jacq. as a rootstock was inferior to other seedling rootstocks.
Abstract
Temperatures for several post-bloom periods were correlated with days from full bloom to ‘Bartlett’ pear maturity. Date of maturity based on pressure test showed a high negative correlation (r = -.88) with mean temp above 40°F for the 36 days following bloom. The peak thermal period occurred 26-30 days after bloom, with the highest correlation on the 28th day. Days to maturity had a higher correlation with accumulated mean temp above 45°F than with degree hr above 45°F for the same periods. Base temp of 38.5°F to 50°F gave r values greater than -.85 in this prediction method. Mean temp between 41.5°F and 68.5°F on the 28th day had a linear correlation r of -.71 with days to maturity. Equal temp increments were more effective at min levels than at max levels for accelerating maturity. The post-bloom thermal period affecting maturation coincides with the stage of cell division and most effective time for application of chemical thinning sprays.
Abstract
Overtree irrigation of pear trees following application of pesticides by speedsprayer resulted in lowering most insecticide deposits by 30-90%. Addition of a spreader sticker to pesticide sprays did not reduce pesticide loss.
Abstract
Potted seedlings and cuttings of various tree species were submerged to 5–10 cm above the soil level for up to 20 months in order to determine flood tolerance based on leaf conductance (kl), growth, and survival. Flooding induced a decline in kl at soil oxygen diffusion rates of 30, 22, 20, and 15 × 10−8g cm−2 min−1 for Prunus persica (L.) Batsch, Halford seedlings (peach), Pyrus communis L. cv. Bartlett (Bart), Pyrus calleryana Decne (Call), and Pyrus betulaefolia Bunge (Bet), respectively. The leaves of some species, particularly Pyrus communis L. cv. Old Home × Farmingdale 97 (OH × F 97), abscised shortly after a decline in kl, yet leaves of most other Pyrus species did not abscise despite months of maintaining a kl near zero. Growth rates were reduced for all fruit tree species except Bet and Call after one month of spring flooding. One month of fall flooding reduced the growth of all fruit tree species the following spring. Bet survived 20 months of continuous submergence; however, only Salix discolor Muhl. (willow) grew well under these conditions. Flooding promoted adventitious rooting of willow, Cydonia oblonga Mill. cv. Provence BA 29 (quince) and Malus domestica Borkh. cv. MM 106 (apple); anthocyanin pigmentation in leaves of apple and all Pyrus species; leaf chlorosis of quince, apple, and peach; and hypertrophied lenticels on the submerged stems and roots of all species. The tolerance, based upon kl, growth, and survival, was: willow > Bet > Call = quince > Bart > OH × F 97 = Pyrus pyrifolia (Burm.) Nak. (Pyri) = Pyrus ussuriensis Maxim. (Ussuri) = apple > peach. Although the survival of pear rootstocks with and without a ‘Bartlett’ scion were similar, flooding symptoms often were quite different.
Mature hedgerows of `Anjou' pear (Pyrus communis L.) trees, planted north(N)-south (S) or east (E)-west (W), were used to study the effect of hedgerow orientation on fruiting and canopy exposure. In 1990, flower bud density tended to be lower on the E-W rows, especially on their N sides. Fruit set (FS) was highest on the S side of E-W rows and lowest on the N side, while the E and W sides of the N-S rows were intermediate. Crop density (CD) had a similar pattern as FS, with more fruit on the S than on the N side of the E-W rows. CD was more evenly distributed between the sides on the N-S hedgerows. Differences in FS and CD between sides were related to different levels of sunlight interception. Light exposure was lowest on the N sides of the E-W rows and highest on the S sides throughout the growing season and especially toward the equinoxes. Increased exposure to the sun on the S and W sides late in the season led to more fruit with solar injury. Fruit from E–W rows were larger and less firm. Accumulated yields over 11 years showed a 21.4% increase in the N-S rows over those of the E-W rows.
Abstract
Overhead sprinkler systems are not new to orchard management but have been used almost exclusively for irrigation. However, economic considerations would encourage a modification of this one-purpose system into multi-purpose usage. Potentially, with the correct physical arrangements of pumps, pipes, risers, and nozzles it would be possible not only to irrigate, but to have frost protection and summer environmental and pest control as well. The present paper examines the latter two uses of an overhead sprinkler system and the effects of the system on the pear tree.
Abstract
Tree survival beyond 2 years of intergeneric pear/apple graft combinations depended on the scion cultivar, the use of ‘Winter Banana’ apple interstock, and the specific rootstock. Trees with ‘Cornice’ scion and ‘Winter Banana’ interstem (on all six stocks) had higher survival (27%) after 11 years than those with ‘Bartlett’ scion (12%). No ‘Cornice’ tree on apple rootstock survived without the ‘Winter Banana’ interstem. Tree survival with ‘Winter Banana’ interstem after 11 years was 73% on M.26, 14% on M.7 and M.9 EMLA, 7% on MM.106 and MM.111, and 0% on M.9. Only trees of ‘Bartlett’ and ‘Cornice’ on M.26 and ‘Cornice’ on M.7 with ‘Winter Banana’ interstems produced fruit through the 11th year. Tree size ranged from 10% of standard for ‘Bartlett’ on M.26 to 25% for ‘Cornice’ on M.7 with the ‘Winter Banana’ interstem. Incompatability suppressed mainly foliar N and Zn but, to a degree, also P, Ca, and B.
Abstract
Decline- and fire blight-resistant clonal rootstock selections of Old Home × Farmingdale (OH×F), Pyrus communis L. were compared during a 12-year period with Bartlett seedling, P. calleryana Decne. seedling and clonal Old Home as understocks for ‘Bartlett’. Some OH×F clones were found to be more vigorous than Old Home rootstock, while others were much less vigorous. Only OH×F 51 was as dwarfing as East Mailing (EM) Quince A. Trees on some clones of each vigor class were more efficient (yield per unit of tree size) than others of the same class. Yield efficiency was not well correlated with rootstock vigor, but the semi-dwarf clones tended to induce more efficient yield than vigorous ones.
Abstract
Cider is a fermented drink from cider apples which are characterized by a bitter tart flavor and coarse texture. Cider is the cheapest alcoholic drink found in the English pub or markets, priced as low as 34 cents for a 38 ounce bottle. The drink, which is generally dry with a roughness uncommon to our apple juice, can be purchased as sweet or dry and as “still” or carbonated cider of 3 to 8% alcoholic content.