458 INSECTS AFFECTING VEGETATION 



tirely. Some of the cells remain firm a long time. When fruit is 

 completely rotted it mummifies and often remains hanging on the 

 tree. Usually, however, infected apples fall prematurely. This fun- 

 gus also invades the tissue of the limbs and produces rough, black 

 wounds, known as cankers. These wounds usually occur on last 

 year's fruit spurs and smaller limbs although the larger limbs and 

 even the trunk may be invaded. Both winter and summer spores are 

 formed in these wounds. Such wounds frequently develop at the 

 base of infected fruits. 



Four applications of Bordeaux mixture, at intervals from two 

 to three weeks will control the disease. Mr. W. M. Scott (U. S. Dept. 

 Agr., Farmers' Bulletin 283, p. 18.) recommends that the first appli- 

 cation be made six weeks after the petals fall. The second should 

 follow the first within two weeks, while the intervals between the sub- 

 sequent applications may be extended to three weeks unless the sea- 

 son be unusually wet and warm. (Mo. State Fruit Exp. Sta. 16.) 

 Apple Blotch.* This is one of the most serious diseases of the 

 apple. It is of comparatively recent discovery, as it was first reported 

 on apples in 1902 and not until 1907 was it known to be serious. On 

 the apples, at first, the very small spots are light brown and look 

 somewhat like a cluster of dark fibres just under the skin. As the 

 spot grows it becomes darker and has a very ragged and fringed edge. 

 Several spots may run together to make a large blotch. The spots 

 are not deep in the flesh of the apple, but often cause cracking. On 

 different varieties they vary somewhat in appearance. The older 

 spots are often dotted with black raised dots, which do not bear spores 

 as a rule. 



On the leaves the spots are very small, sunken and pale. They 

 ore not conspicuous and are easily overlooked. On the twigs this dis- 

 ease makes small, rough cankers, which often encircle the twigs. 

 Only rarely are the cankers large enough or deep enough to do serious 

 damage to twigs or limbs. The principal damage is to tne fruit, which 

 is spotted so as to be unsalable as fresh fruit, and if the disease is very 

 bad it does not peel easily and is undesirable for evaporating. From 

 all the studies made so far on this disease it seems that it is spread 

 from the twig cankers entirely. It begins to spread to the leaves and 

 fruit from a month to six weeks after the blossoms have fallen. It 

 seems to spread in moist weather more than in dry. (Ark. E. S. 

 Cir. 7.) 



TREATMENT FOR APPLE BLOTCH, ETC. 



The treatment for apple blotch conforms closely to that for apple 

 bitter-rot and with one or two additional applications all the other 

 important fruit and leaf troubles may be controlled. The following 

 course of treatment is therefore recommended for orchards in south- 

 ern sections, especially where apple blotch and bitter-rot occur. 



First Application. When the cluster buds are well out, just be- 

 fore the blossoms open. This is the first treatment for apple scab and 

 is of special importance for badly scabbing varieties, such as the Wine- 

 sap, Arkansas, Arkansas Black, and Red June. It may be omitted 

 from the Ben Davis, Gano, Jonathan, and York Imperial, which scab 



* See page 267 for illustration. 



