localities and then breeding cold hardiness into them. This probably accounts for the rela- 

 tively large number of State agricultural experiment stations currently engaged in strawberry 

 breeding work, four of them in cooperation with ARS. The work of selecting and breeding 

 blossom-hardy strawberries is complicated by the fact that critical temperatures may not occur 

 each year. To help overcome this, an objective screening method for freezing blossoms arti- 

 ficially in the field is needed. However, the great improvements already made in strawberries 

 through breeding and selection provide encouraging evidence of what can be accomplished 

 in the future. 



Cranberries 



Although cranberry plants, like other evergreen fruit plants, are not truly winter hardy, 

 they are grown commercially as far north as Massachusetts and Wisconsin. This is done by 

 simulating the swamp conditions under which wild cranberries are found. The fruit is 

 grown in bog fields that can be covered by water during the winter months. In western 

 Washington where cranberries are winter hardy but subject to blossom damage from late 

 spring frosts, the bogs are equipped with sprinklers. A fine spray of water over the vines 

 prevents injury from freezing temperatures as low as 20° F. during bloom. 



No new cranberry breeding has been started by ARS but final evaluation of 14 selec- 

 tions for cold hardiness and other desired characteristics is continuing. Of three new varie- 

 ties recently introduced in cooperation with the Massachusetts Agricultural Experiment Station, 

 none is outstandingly cold hardy. 



TREE NUTS 



With demand for edible nuts exceeding production and most commonly grown kijids 

 and varieties subject to cold damage in varying degrees, hardier varieties of most species 

 are needed to stabilize production. Because of their early-blooming habits, almonds are par- 

 ticularly liable to frost damage but other kinds of nuts are also susceptible to low winter 

 temperatures and late spring frosts. Tung, an important nonedible nut used as a source of oil 

 in the manufacture of paint, is also extremely liable to frost damage because of its early 

 blooming characteristics. 



Almonds 



Commercial production of almonds at the present time is limited almost entirely to a 

 few relatively small areas in California because of the almond's exacting climate require- 

 ments. The almond requires a definite, although short, period of complete dormancy but is 

 among the earliest of the deciduous tree fruits to bloom in the spring. In this country, the 

 almond's blooming period is from January to March, which makes its blossoms extremely 

 vulnerable to frost damage. 



To help stabilize production in present almond-growing areas and extend the climatic 

 range in which almonds can be grown successfully, ARS and the California Agricultural Ex- 

 periment Station are emphasizing late blooming along with other desired traits in their co- 

 operative almond-breeding experiments at Fresno. At present no variety combines disease 

 resistance, late bloom, and high productivity of nuts containing small flat kernels desired by 

 the candy trade. 



Numerous crosses aimed at producing a late blooming variety which escapes spring frosts 

 or produces small kernels have been made and nine promising selections chosen from pro- 

 geny of the crosses are currently being field tested. Almond-producing areas are also being 

 explored for promising chance-seedling trees or sports. These, together with the controlled 

 crosses, are evaluated for possible use as commercial varieties or use in breeding. Evaluation 

 of untested selections for hardiness and other characteristics is hastened by taking buds from 

 young seedlings as soon as they develop and budding them on mature trees. 



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