PEACH AND PEAR DISEASES 277 



SCAB OR BLACK-SPOT (Cladosporium carpophilum) . Black scab- 

 like spots on the fruit, often causing it to crack deeply. 



Control. Self-boiled lime-sulfur, as applied for BROWN-ROT. 



YELLOWS. A fatal disease of peaches ; also attacks nectarine, 

 almond, apricot, and Japanese plum. Cause unknown. The 

 first symptom in bearing trees is usually the premature ripening 

 of the fruit. This fruit contains definite small red spots, which 

 extend towards the pit. The second stage is usually the appear- 

 ance of " tips," or short, late, second growths upon the ends of 

 healthy twigs, and which are marked by small, horizontal, usually 

 yellowish leaves. The next stage is indicated by very slender 

 shoots, which branch the first year and which start in tufts from the 

 old limbs, bearing narrow and small yellowish leaves. Later the 

 entire foliage becomes smaller and yellow. In three to six years the 

 tree dies. The disease spreads from tree to tree. It attacks 

 trees of any age. Known at present only in regions east of the 

 Mississippi. Peculiar to America, so far as known. 



Preventive. Pull up and burn all trees as soon as the disease 

 appears. Trees may be reset in the places from which the 

 " yellows " trees were taken. Laws aiming to suppress the disease 

 have been enacted in most peach-growing states, and the enforce- 

 ment of them will keep the disease well under control. 

 Pear. BLIGHT (Bacillus amylovorus) . A very serious bacterial 

 disease. Bacteria winter just at the edge of the dead wood in 

 trees blighted the previous year. With the advent of warm spring 

 days they ooze through the bark in sticky drops and are carried by 

 bees and flies to blossoms. The blossoms blight, and the spur may 

 also blight. Plant-lice carry bacteria from blighted blossoms to 

 spurs and shoots. If a spur becomes blighted, the bacteria may 

 spread in the bark of the limb, causing a depression or canker. 

 This may girdle the limb and cause its death. The leaves turn 

 black and stick tenaciously, even through the winter. Succulent 

 water sprouts are very apt to blight and cause large cankers. 

 Generally distributed in North America, and known only in 

 America. Attacks apple, quince, mountain ash, hawthorn ; the 

 Spitzenburgh is specially liable to attack. 



Control Clean up hedgerows of hawthorn, old blighted 

 pear trees and apple trees. In early spring cut out the blight 



