^ PLANT BREEDING. 12/ 



make the difference between profit and loss in the returns from 

 a given crop. The disease known as couloure, or the falling of 

 the flowers and young fruit of certain of the finest raisin grapes 

 in California is a case in point. An investigation by officers of 

 the Department of Agriculture has shown that this trouble is 

 mainly due to unfavorable climatic conditions at the time of 

 blooming. If, now, the time of blooming should be delayed 

 somewhat until the season of settled weather, or if the varieties 

 should be rendered slightly hardier, so as to resist the unfavor- 

 able conditions, a service of untold benefit would be rendered to 

 the raisin industry of California. In the attempt to meet the 

 emergency, some 20 thousand crosses have been made between 

 the two best raisin grapes — Muscat of Alexandria and Muscatel 

 Gordon Blanco — with the Malaga, a vigorous, hardy, thrifty sort 

 which, though an excellent raisin grape, is inferior to the sorts 

 named.''' As the seedlings resulting from these crosses come 

 into fruitage the hardiest and most resistant types will be 

 selected in the hope of securing the desired end. 



A similar problem confronts the growers of citrus fruits in 

 Florida and Louisiana, — a fact again emphasized by the recent 

 severe losses from freezing. Here, again the Department of 

 Agriculture is doing an important work in crossing the more 

 valuable varieties of the orange with the Citrus trifoUata, which 

 is hardy as far north as Philadelphia. Several hundred hybrids 

 have been produced and are now growing ; many of them show- 

 ing varieties intermediate in character. Of course the end in 

 view is to secure, by a sufficient number of crosses, a variety 

 which shall combine the good qualities of the common orange 

 with the hardiness of the trifoliate parent. The same method 

 may be looked to in the production of hardier varieties of other 

 subtropical fruits. 



Another problem in citrus culture is the production of an 

 orange with the skin of a tangerine. Hybrid seedlings to the 

 number of a thousand or more have been produced, and results 

 are awaited with interest. The breeding of pine-apples of 

 superior quality, and resistant to disease, is also receiving spe- 

 cial attention in the subtropical laboratory of the Bureau of Plant 

 Industry, the crosses of this fruit running up into the thousands. 



* Yearbook, U. S. Dept. of Agriculture, 1898, 265. 



