PECAN ROSETTE IN RELATION TO SOIL DEFICIENCIES. 9 
much as possible the cutting of the roots by plowing shallow close 
te the trees. 
Figure 4 shows a 10-year-old pecan tree which was carefully dug 
so that as much of the root system as possible might be obtained. 
This tree was growing on a stiff clay hilltop where the soil was only 
moderately fertile. The white band indicates the ground line. The 
taproot and all of the main lateral roots are shown intact. The chief 
point of interest is that practically all of the laterals originated 
within 18 inches of the ground line, and even at 12 to 15 feet from 
the tree they were rarely found deeper than 20 to 24 inches below the 
surface. The small fibrous roots originating on the main laterals 
may be seen plainly. Practically all of these small roots were found 
in the surface soil. 
PREVENTION AND CONTROL. 
The experimental and other evidence indicates very strongly that 
pecan rosette is a sign of a soil deficient in humus, fertility, and 
moisture supply, and certain conclusions with reference to the con- 
trol of the disease in established orchards as well as its prevention in 
those yet to be planted may be drawn therefrom. 
In setting new orchards it would be the part of sound judgment 
and economy to plant only on good land or land which is susceptible 
of rapid and permanent improvement. Deep sand, clays underlain 
by sand, and eroded hillsides should be avoided. 
After the orchard is planted the cultural practices should be such 
as to increase the depth, humus content, fertility, and moisture- 
holding capacity of the surface soil as rapidly as possible and to 
conserve moisture during dry periods. Prolonged periods of dry 
weather during the spring are the rule rather than the exception in 
the southeastern United States. Consequently, the interplanting of a 
diseased orchard to shallow-rooted crops which require frequent 
cultivation, as, for example, cotton or peanuts, appears to be a desir- 
able and economical way of obtaining this result. The constant 
addition of large quantities of humus-forming materials, thereby 
both bettering the physical condition of the soil and increasing its 
water-holding capacity and fertility, is absolutely necessary to pro- 
duce healthy trees from those already diseased and to prevent the 
development of new cases of rosette. : 
THE USE OF COVER CROPS. 4 
These results can be obtained in a variety of ways. Legumes, such 
as cowpeas, velvet beans, or soy beans, may be sown in the orchard in 
June and turned under in the late fall or winter. Fall and winter 
cover crops, either leguminous or nonleguminous, may also be used 
