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  • Author or Editor: C. B. Cordy x
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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

Recently, Stephen (1) found that pear pollen was carried at least ¾ mile by wind. He was able to collect appreciable amounts of such pollen on glycerine-treated slides placed at various heights and distances from pear trees. Fully seeded Anjou pears were found scattered throughout solid-block plantings, particularly in the border rows and in the tops of trees. Some of the data were difficult to explain on the basis of known bee-flight patterns, inasmuch as the varieties tested are self-sterile.

Open Access

Abstract

Pear plots established in 1923 and 1926 with trees composed of several rootstock and trunk combinations were assessed for tree size, susceptibility to pear decline and for fruit quality. In general, Pyrus ussuriensis Max. and P. pyrifolia Burm. & Nak. rootstocks resulted in small trees, P. communis L. and P. calleryana Decne. intermediate, and P. betulaefolia Bunge large. The latter was most resistant to decline, followed by P. calleryana and P. communis, with P. pyrifolia and P. ussuriensis susceptible. The use of the oriental hybrid cvs. Variolosa and Tolstoy as interstocks increased the severity of pear decline symptoms though all trees were not uniformly susceptible. The use of the P. communis cv. Old Home as a scion rooted trunkstock decreased the degree of decline. Fruit quality was good on most combinations but was generally better on P. calleryana than other rootstocks. Pyrus betulaefolia caused cork spot and poor quality of ‘Anjou’ but this same rootstock resulted in outstanding quality of ‘Seckel’.

Open Access