DISEASES AND ENEMIES OF FRUIT. 851 



atmosphere. A board covering twenty or twenty-four inches wide is also said to be very 

 effectual as a preventive. 



Web Worm. This worm is a very destructive caterpillar which attacks many kinds of 

 fruit trees as well as other trees. The worms are small, light-yellow, with a black head and 

 feet, a broad, dark-colored stripe on the back and another stripe beneath which is thickly 

 covered with white hair. The eggs are laid on the under side of the leaf near the end of the 

 twigs and branches. These are soon hatched, and the larvae commence eating the tender 

 portions of the leaves, leaving only the skeleton, while they are always very active spinning 

 their webs, which they do by weaving from one leaf to another, thus attaching three or four 

 leaves together as a framework for the web. They appear in May and may be seen even in 

 October, and sometimes leave trees looking brown and dead as though they had been burnt 

 by fire. For exterminating these pests, the same methods are recommended as for cater 

 pillars (which see). 



Woolly Aphis (Aphis lanigera), sometimes called the American Blight, is a minute, 

 white, downy insect that makes its appearance in the branches, usually in the crotches and 

 crevices, and resembles mildew. These lice increase with great rapidity, and if not inter 

 fered with, will be likely to produce a diseased condition of the whole tree. They are, how 

 ever, very easily destroyed by applying a wash of strong soap-suds, lye made of wood ashes, 

 or whitewash made of unslacked lime with a little sulphur added. A wash of a half pint of 

 kerosene oil mixed with a gallon of soap-suds is also an excellent remedy; also a wash of half 

 an ounce of carbolic acid and a half pint of water will prove effectual. 



Yellows. No disease has proved so destructive to the peach as the yellows. It is 

 characterized by a yellow appearance of the leaves, the production of very slender, wiry 

 shoots a few inches in length upon the branches, the premature ripening of the fruit, a dis 

 coloration of the flesh, and spots of purplish-red externally. The disease spreads without 

 actual contact, and frequently destroys large orchards. It may be communicated by contact 

 of the roots, by pollen from the flowers of diseased trees, and by using a pruning knife upon 

 healthy trees that has been employed in pruning diseased ones. The yellows has generally 

 been regarded as incurable. Some of the most recent experiments, however, seem to indicate 

 a remedy in a copious application of potash, or of some of its compounds, as promising a pre 

 vention, if not a positive cure, muriate of potash having been used for this purpose. This 

 remedy is based upon the theory that the vessels of the diseased tree are surcharged with 

 starch, which the potash dissolves and dissipates. 



Dr. Goessmann, of the Massachusetts Agricultural College, found on examining a peach 

 orchard, that the trees which grew upon the top of a knoll were much diseased, while those 

 on low and richer ground, and which had made a more vigorous growth, were exempt from 

 it. Also, that in analyzing the fruit and branches of both healthy and diseased trees, the 

 greatest difference in the fruit was, that the diseased specimens contained nearly twice as 

 much lime as the healthy ones, and more phosphoric acid. In the branches analyzed, the 

 diseased portions also contained the most lime, but much less potash. Other analyses showed 

 an accumulation of starch in the diseased trees. 



The experiment was made of treating the affected trees with three or four pounds of 

 muriate of potash, together with the usual quantity of a phosphatic fertilizer, for each tree, 

 and the diseased branches were cut back once or twice to the healthy wood. The new growth 

 of branches soon regained a green color, and the trees were shortly in a vigorous condition. 

 Subsequent examinations made by Professor Penhallow showed that healthy wood had but 

 little stored starch, while the diseased wood showed the invariable presence of large quantities 

 of starch, and also an abundance of fungous growth, whidft first appears on the surface. The 

 fungus is found on trees which, once diseased, have been restored by the treatment 



