DISEASES OF CROPS 945 



which, when severe, may prevent normal ripening and cause the fruit to be 

 irregular in shape and to crack. 



Treatment. — See spray table for peach. 



Leaf Curl (Exoascus deformans [Berk.] Fckl.). — This very familiar 

 and very injurious disease causes the leaves to curl, reduces their value to 

 the tree and finally causes them to fall. With the appearance of the 

 second crop of leaves, the growers frequently suppose the tree to have 

 recovered. However, it has lost in vitality and vigor, which results in a 

 reduction or complete loss of the crop. 



Treatment. — Spray with lime-sulphur before the buds open. 



Shot Holes (Cercospora tircumscissa, Sacc, Phyllosticta circumscissa, 

 Cke.). — These "shot hole" diseases are quite common, but readily con- 

 trolled by the regular spraying treatments. 



Another shot hole (Bacterium pruni, Smith) is very common in the 

 Southern states and especially on Elbertas. It frequently causes the 

 foliage to fall in midsummer. It also attacks the fruit, causing a spotting 

 somewhat similar to the scab. It cannot be controlled by spraying. 



Crown Gall. — See Apple. 



Mildew (Sphcerotheca pannosa [Wallr.], Lev.). — Similar to the mildew 

 of the apple. It is of little importance and can be controlled by the regular 

 spray treatment. (See table for peach.) 



Yellows. — The cause of this very destructive disease remains a mystery. 

 In its earlier stages it causes a premature ripening of the fruit, accompanied 

 by a red blotching over the surface and through the flesh which is usually 

 insipid and frequently bitter. (Prematuring may also be caused by borers 

 or winter injury.) In its later stages it causes the so-called "willowing" 

 or formation of slender yellowish-green shoots on the trunk and larger 

 branches. The leaves on these shoots are small, narrow and greenish- 

 yellow. The foliage is frequently greenish-yellow, but when supplied with 

 nitrogenous fertilizers will not show this character. In its earlier stages, 

 one part of the tree may show the disease and the other parts appear 

 perfectly healthy, but in fact the entire tree is diseased. It can be trans- 

 mitted from tree to tree by contact and to young trees by budding. Buds 

 from the apparently healthy parts of very slightly diseased trees will trans- 

 mit the disease. Healthy nursery stock is of the greatest importance. 



Treatment. — Dig and burn the trees as soon as the disease appears, 

 using care to prevent the tree coming in contact with others. Young 

 trees can be set in the places from which the old ones were removed; the 

 disease does not persist in the soil. The greatest care should be used in 

 the selection of bud wood, to insure its freedom from disease. 



Little Peach. — The cause of this disease is also unknown, but it is of 

 the same nature as yellows. The fruit of diseased trees is small, ripens 

 late, is inferior in quality, frequently insipid and watery. The leaves are 

 frequently lighter than normal leaves or yellowish-green and often rolled 

 and drooping. 



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