cold hardiness will help stabilize production in commercial peach-growing areas as well as 

 increase the possibility of having peaches adapted to growing in colder areas. 



Peach breeding research by USDA and the Washington Agricultural Experiment Station 

 at Prosser is directed at the development of bud hardiness and quality fruit for marketing 

 fresh and for canning. During 1961, 21 selections were made from among 1,100 seedlings 

 for further testing there and at other experiment stations. Among the Prosser selections now 

 being tested under various climatic conditions is one that has already proved especially 

 winter-hardy in Canada. 



At the Central Great Plains Field Station, Cheyenne, Wyo., several selections chosen 

 for cold hardiness have been propagated and distributed to experiment stations in States where 

 cold damage is a problem. 



Since hardiness in peach trees is affected by rootstocks, rootstock varieties which are cold 

 hardy are being sought. With rootstocks as in other areas of cold hardiness research, the 

 need to combine cold hardiness with other desirable characteristics enlarges the scope of the 

 task. For example, resistance to nematodes and root rot is very much needed in rootstocks 

 since damage from these sources has increased to such a degree that it is believed to account 

 for the decrease in the average life of commercial peach trees from 20 to 10 years. USDA 

 scientists have developed and recently introduced a nematode-resistant peach rootstock, 

 Nemaguard. However, since Nemaguard is not particularly cold hardy, plant breeders are 

 now trying to improve the rootstock by adding cold hardiness. 



In New Jersey, the State Agricultural Experiment Station has successfully used peach 

 selections brought home by USDA explorers in developing hardy canning peaches. Although 

 the original peach imports were not acceptable for commercial production they provided a 

 source of hardiness in crosses with peaches having other desired traits. The result is a num- 

 ber of promising introductions which are all extremely cold hardy and suitable for canning. 

 In the past, canning varieties hardy enough to stand cold Eastern winters have not been 

 available to New Jersey fruit growers and canners. 



Plums 



Plum varieties vary widely in their ability to stand cold. Most American varieties tol- 

 erate temperatures as low as —30° F. without serious damage when fully winter hardened. 

 European plums are more vulnerable but usually stand temperatures of —15° F. without 

 severe wood damage. However, buds of most plum varieties may be damaged at tempera- 

 tures somewhat higher than the absolute temperature for cold damage to wood. Also some 

 plum varieties are very early blooming and so particularly vulnerable to spring freezes. 



For more than half a century, American plant scientists have sought to obtain, by breed- 

 ing and selection, quality plums that are sufficiently hardy to grow successfully in areas with 

 long, cold winters as well as to survive the severe freezes that occasionally strike in milder 

 areas with a minimum of crop loss. 



A number of State agricultural experiment stations in northern areas have long-standing 

 plum improvement research programs which emphasize cold hardiness — stations in South 

 Dakota, Minnesota, New York, and Iowa among others. And stations in States with more 

 temperate climates, such as Washington and California, have also considered hardiness in 

 breeding and evaluating plum varieties. 



USDA crops researchers have likewise done considerable work aimed at selecting and 

 breeding improved varieties of hardy plums adapted to various sections of the country. Some 

 of this has been in Federal projects at the regional field stations and some in Federal-State 

 cooperative research projects at various State agricultural experiment stations. 



