4 BULLETIN 162, U. S. DEPARTMENT OF AGRICULTURE. 



before it finally succumbs. This disorder or disease is known locally 

 as chlorosis. 



Another serious disease which has caused much trouble is root-rot. 

 This disease is believed to be due to a fungus (a species of Ozonium) 

 which lives in the soil and is often more destructive than chlorosis. 

 Some species are particularly susceptible to root-rot, though certain 

 individuals may escape it for some years, probably because of lack 

 of infection. 



Crown-gall 1 is a disease that occurs frequently in the San Antonio 

 soils, and there are a large number of species of soil-inhabiting nema- 

 todes which are parasitic on the roots of cultivated trees and shrubs. 



It is not clear in every case just what causes the disease or 

 death of the plants. It is probable that in many instances there are 

 several causes working together. These causes are, however, located 

 in the soil and separately or together constitute a serious problem, 

 both to fruit production and to experimental work with fruit trees. 



SCOPE OF THE EXPERIMENTS. 



The horticultural work of this field station has been directed along 

 two major lines: (1) To find which varieties are best adapted to the 

 local conditions and (2) to find what varieties or species can be used 

 as stocks that will be relatively immune to soil troubles and will 

 permit the use of desirable but susceptible varieties as scions. In 

 addition, some work has been started in the way of making hybrids 

 between the native species and related domesticated varieties. 



When this work was begun in 1906 and 1907, a collection of varieties 

 was assembled, chiefly from commercial nurseries. This collection 

 has been added to from time to time, and the Office of Foreign Seed 

 and Plant Introduction has placed at the station many new varieties 

 of fruits. In all the tests of varieties, at least two individuals of each 

 kind have been used in the experiment. Sufficient information has 

 been acquired in the tests here reported to prove that a reasonably 

 large list of fruits can be produced by every farmer with which to 

 supply at least his own needs. A number of peach varieties, which 

 ripen from the middle of June to September, have proved adapted to 

 the section. Plums, the most satisfactory fruit of this region, quality 

 and reliability considered, furnish a large list of varieties from which 

 to select, although their ripening season is comparatively short. A 

 fairly large number of varieties of grapes can be grown successfully, 

 although for table use their quality is low. Pears have been grown 

 in the vicinity for a long period and the results observed from the 

 better managed orchards in favored situations indicate that certain 



» This disease and its causal organism are described in detail in Bureau of Plant Industry Bulletin 213, 

 entitled "Crown-Gall of Plants; Its Cause and Remedy,"' by Erwin F. Smith, Nellie A. Brown, and C. O. 

 Townsend, issued Feb. 28, 1911. 



