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Some Cold Facts

Posted Jun. 1, 1997

The late freeze in April of this year inflicted severe damage to crops of some tree fruits and pecans in several areas of Oklahoma and north Texas. If it seems to you that cold weather damage to certain crops has become increasingly common in recent years - here are some statistics that agree with you.

The first fruit trees were planted at the Oklahoma State University (then Oklahoma A&M) Horticulture Research Station at Perkins, Oklahoma in 1933. Since 1933 the station has suffered seven total crop losses of peaches (including this year) to critical cold temperatures either in the fall, winter, or spring. Partial crop losses are not included. Three of the seven crop losses occurred during the years 1933- 1989. That's about one total crop loss in every 18 years- not bad, most growers can live with that.

That means then that four of the seven crop losses since 1933 have occurred during the 90's, a cold statistic that's hard to live with.

Asian Pear is a tree fruit that has become increasingly popular with U.S. fruit connoisseurs in recent years. These pears are often called 'apple' pears because they are crisp and juicy like apples but with a different distinctive texture. Some cultivars are shaped similar to an apple; however, they are not apples, being no closer botanically to apples than they are to the European pears (i.e. Bartlett and Kiefer) that most of us grew up with.

Asian pears comprise a large group of pears that have been grown commercially in Asia for centuries. Japan, China, and Korea have been the main sources, but plantings are increasing in the U.S. especially in the west coast states of Washington, Oregon, and California. These pears differ from European pears in that they are best left to ripen on the tree as their texture and quality usually does not improve in storage. They are touted as being more tolerant to the dreaded disease Fireblight than the European types, but they are not immune.

Varieties being grown and marketed in the U.S. include Shinseike, 20th Century, Ya Li, Hosui, Kikusui, Tsu Li, and Chojuro. Since we don't have a great deal on documented data regarding the adaptability of these cultivars to Oklahoma growing conditions, I usually recommend 20th Century simply because the name is easier for an ole boy from eastern Oklahoma to pronounce.

Two cultivars should be planted together for good pollination. The Asian pears are partially self-fertile, but a second cultivar adds insurance for good pollination. The European pears will aid in pollination of the Asian cultivars. Pollination is also enhanced with the presence of bees.

Rootstocks commonly used are Pyrus betulefolia, P. communis, and P. calleryana. Spacings vary, but most plantings are similar to peaches in the vicinity of 20ft x 20ft. Some planting on the west coast are 15ft x 15ft and 12ft x 18ft. Production is obtainable the third year after planting.

It remains to be seen if these pears can be successfully grown in Oklahoma. We have a test planting in the Noble Research Institute Demonstration Orchard and will view them during the June 10, 1997 Horticulture Twilight Tour here on the headquarters farm. We invite you to attend.

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