8 
BULLETIN 756, U. S. DEPARTMENT OF AGRICULTURE. 
that the feeding roots of the pecan are distributed through the surface 
soil, and in proportion as this is deep and fertile the tree does well, 
but where the surface soil is of insufficient depth and lacking in 
humus and fertility the tree is likely to become rosetted. Prolonged 
hot, dry weather not infrequently kills many of the feeding roots in 
shallow surface soils. In plowing such land large numbers of roots 
Fig. 4. — A 10-year-old pecan tree, showing taproot and main laterals intact. Practically 
all the laterals originated within 18 inches of the surface of the soil. Nearly all the 
small feeding rootlets originating on the laterals were found in the upper 6 to 8 inches 
of soil. 
up to an inch or more in diameter are cut by the plow, and it appears 
that this must aggravate the disease in some degree. 
It remains for experimentation to determine just how serious a 
matter is this drying out and cutting of the roots of rosetted trees. 
Meantime it would appear to be the part of good practice to develop 
a deeper surface soil between the rows of trees by the use of cover 
crops and by deepening the plow furrows from year to year until 
8 to 10 inches of fertile surface soil is established and to a^void as 
