204 THE NURSERY-MANUAL 



drop from the tree. The sickly yellow curled foliage and the 

 distorted shoots of the young buds are the striking characters 

 of this disease in the nursery. Also, the badly affected trees 

 are considerably shorter than the healthy stock. 



Cause. The disease is caused by the fungus parasite 

 Exoascus deformans. Although not definitely determined, it 

 is presumed that spores of some kind which propagate the fun- 

 gus are lodged by wind or rain among the hairs of bud-scales 

 of the host plant in spring, and remain dormant over winter. 

 In spring the spores germinate during rains, which cause the 

 buds to swell, and the germ-tube of the spore, passing in be- 

 tween the loosened bud-scales, penetrates and establishes the 

 parasite within the young leaf tissues. 



Control. Bordeaux mixture or lime-sulfur solution 1 to 

 16 is very effective in the control of peach leaf -curl. Only one 

 spraying is necessary, but it is essential that this application 

 be made before growth starts in the spring and the buds have 

 started to swell. Every bud must be completely coated with 

 the fungicide. It is advisable to spray each year as an in- 

 surance against the disease. The spraying should be done 

 as soon as the peach stocks are "snagged" and before the rush 

 of spring work begins. If it is desired to control San Jose 

 scale also, an application of lime-sulfur solution 1 to 9 will 

 control both the scale and the leaf-curl disease. 



LEAF-BLIGHT OF PEAR AND QUINCE. In the nursery the 

 leaf-blight disease is usually found in abundance on budded 

 quince stock and pear seedlings; it also occurs on cratsegus 

 and apple. All standard varieties of quince and pear are 

 affected. Frequently the disease causes heavy defoliation. 



Description. The disease appears first on the leaves as 

 small discolored areas on the upper surface. The spots be- 

 come carmine-red in the center, with dull borders and finally 

 penetrate to the lower surface. The color soon changes from 



