some evidence that long periods at 32° F. can cause excessive June drop. This lack of bud 

 hardiness has limited the culture of apricots to a small part of the U.S. and tends to make crop 

 yield erratic even in areas where apricots are grown commercially. The apricot makes a good 

 shade tree where it seldom produces fruit. However, crop researchers of USDA and the inter- 

 ested States are making progress in their systematic efforts to develop hardier apricots. 



Propensity of apricots to bloom early makes most varieties vulnerable to spring frosts. 

 Bud and flower hardiness, as well as late blooming and wood hardiness, are therefore im- 

 portant among the characteristics sought in apricot breeding programs. Plant explorers have 

 long been looking for varieties with these traits in cold countries where hardiness would be 

 essential for survival. Since 1925, hardy varieties from Manchuria have been added to the 

 Department's collection of selections available for possible use for fruit production, or use in 

 breeding improved varieties or as rootstock. Also, new varieties and mutations have been 

 sought domestically. In Michigan, for example, an apricot tree with superior fruit that had 

 survived the rigors of Michigan winters was located through a proprietary advertisement ofl'er- 

 ing a prize of $25. 



In 1957, following extensive testing, the Department recommended Mantoy (P.I. 65075),^ 

 a Manchurian introduction, for trial in milder sections of the Great Plains. Although the Man- 

 toy tree is reliably winter hardy, the fruit buds are subject to winterkilling and its early blooms 

 to frost damage. For this reason Mantoy cannot be expected to produce annual crops con- 

 sistently in the Great Plains area. Nevertheless, Mantoy represents an advance in hardiness 

 and has quality fruit which is larger in size than most Manchurian varieties. 



Studies have also been going forward since 1950 at the Irrigation Experiment Station 

 near Prosser, Wash., toward developing hardy apricots with fruit characteristics equal or 

 superior to present varieties. An early phase of the investigation evaluated different varieties 

 for their superiority as parents in transmitting hardiness to progeny in crosses with other varie- 

 ties. Among varieties studied, Riland and Perfection were found to be superior in transmitting 

 hardiness. This and similar research-developed information has helped to speed up the search 

 for hardy apricots. 



In 1957 the varieties Earliril and Blenril were introduced jointly by the Department and 

 the Washington Agricultural Experiment Station. Earliril, a Riland open-pollinated seedling, 

 survived a severe winter freeze which killed Tilton trees of comparable age and condition. With 

 this improved winter hardiness, Earliril combined improved firmness and texture with early 

 ripening, acceptable processing quality and medium size. It requires a pollinizer for good pro- 

 duction, however. Blenril combines a fairly hardy tree with excellent quality and good produc- 

 tion. 



Continuing progress from earlier studies, the Prosser Station in 1962 made 4 selections for 

 winter hardiness and high quality from among 350 hybrid seedlings having Earliril and larger 

 fruited varieties as parents. These are being further evaluated for use in the Pacific Northwest. 



At the USDA plant introduction station in Chico, Calif., seedlings of another foreign 

 plant introduction (P.I. 121466) from Turkey are currently being evaluated as a source of 

 hardiness and other characteristics contributing to consistent cropping. Following preliminary 

 evaluation, two promising seedlings from this Turkish introduction (P.I. 248779 and 255319) 

 were selected for long term observation. Their performance to date encourages plant re- 

 searchers to hope that they will prove to be a useful source of hardiness and other desirable 

 traits. In 1958, for example, P.I. 248779 and P.I. 255319 were the only apricot selections 

 out of a large test orchard that produced more than 8 to 10 fruits following a succession of 

 late frosts. Although neither selection is commercially acceptable, P.I. 248779 rates about the 

 same as Tilton for flavor quality. 



' P.I. refers to accession number of the New Crops Research Branch, Crops Research Division. 



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