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  • Author or Editor: P.B. Lombard x
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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.

Open Access

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.

Open Access

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.

Open Access

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.

Open Access

Abstract

The effects of root anaerobiosis on root respiration and leaf conductance (kl) were determined in solution culture experiments. Respiration of feeder roots (<2 mm diameter) in air (21% O2) of Pyrus betulaefolia Bunge, Pyrus calleryana Decne, Pyrus communis L. (‘Old Home’ × ‘Farmingdale 97’) and Cydonia oblonga Mill. ‘Provence BA 29’ was reduced by no more than 50% after 21 days of anaerobiosis. In contrast, root respiration of Prunus persica (L.) Batsch ‘Lovell’ was reduced by 80% with anaerobiosis, whereas that of Salix discolor Muhl. increased. Reductions in kl with anaerobiosis generally were more pronounced than reduction in root respiration when measured in air. Respiration rates of aerobically or anaerobically treated pear roots were inhibited by 25% to 50% when incubated in 0.5% O2 compared to rates in air. More work is required in order to delineate the relationship of root respiration and kl with anaerobiosis.

Open Access

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.

Open Access

Abstract

Field and laboratory studies of host preference and resistance of Pyrus species and cultivars to the pear psylla, Psylla pyricola, were conducted in Southern Oregon from 1964–1968. Asian species were generally less attractive to oviposition than those from Asia Minor, North Africa or Europe. Attractiveness of P. pyrifolia and P. communis cultivars was higher than for P. ussuriensis.

Susceptibility of Pyrus was based on differences between total egg deposition and resulting nymphal populations. Using this nymph/egg ratio the results indicated that Asian material was more resistant than material from Asia Minor or Europe. The Asian species P. fauriei and P. calleryana exhibited both a high degree of unattractiveness to oviposition and resistance to nymphal development.

Open Access

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.

Open Access

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.

Open Access

Abstract

During 1982–84, pollen tube growth rate in styles of ‘Napoleon’ sweet cherry (Prunus avium L.) was related to genotype and temperature. At temperatures of 7.3° and 9.9°C, ‘Corum’ pollen tube growth was the slowest, ‘Bada’ the fastest. Maximum stigma receptivity of ‘Napoleon’ occurred for 5 days after anthesis at 9.4°. Ovules were functional for at least 13 days after anthesis. Hand pollination of ‘Napoleon’ resulted in a high fruit set irrespective of pollinizer source or weather conditions during the 3 years. Open pollination developed adequate fruit set for a commercial yield in all 3 years, although it was variable, 24% to 50%. Data in 1984 suggest that insect pollinators were active below 13°.

Open Access