MABKET DISEASES OE APPLES, PEAES, QUINCES 15 



Brown rot occurs almost always as a rather soft but not mushy 

 decay, in spots which are brown at first but which as they enlarge, 

 ultimately involving the whole fruit, become black all over or in 

 irregular blotches (pi. 1, D). In a moist, warm atmosphere the 

 fungus appears on the outside as grayish spore-bearing tufts varying 

 in size from mere pin points to patches half an inch or more across. 

 Under dry cool conditions the tufts are rarely seen. 



Brown rot often resembles black rot so closely that positive diag- 

 nosis is difficult. There are some points of difference, however, which 

 should be kept in mind. Apples in the early stages of brown rot 

 frequently show circular black spots about one eighth of an inch 

 across, each with a lenticel at the center, scattered over the other- 

 wise uniformly brown, rotted area (pi. 1, D). Apples in the early 

 stages of black rot have either a solid reddish-brown color or alter- 

 nating zones of light and dark brown. As the two diseases develop, 

 brown rot becomes darker, sometimes almost black all over, and the 

 characteristic gray fungous tufts appear; black rot becomes merely 

 darker brown and shows numerous small black pycnidia (fruiting 

 bodies) scattered over the rotted area. Apples affected with brown 

 rot show some degree of blackening at an earlier stage, and they 

 shrivel sooner than do those affected with black rot ; in both rots a 

 black, wrinkled mummy is the final result. Black rot is much firmer 

 than brown rot ; in fact, it is the firmest of all apple rots, with the 

 possible exception of Phytophthora rot. 



CAUSAL FACTORS 



Brown rot of apples, pears, and quinces is caused by the same 

 fungus that causes brown rot of stone fruits. It is sometimes found 

 on apples while they are still on the tree, especially in orchards 

 where stone-fruit trees have been planted as fillers, but usually does 

 not attack them until after they are harvested. So far as known, 

 the rot attacks pears and quinces only during the process of 

 marketing. 



CONTROL 



Brown rot is checked by low temperature, but more so in very early 

 stages than after it becomes well established in the fruit. Like most 

 other apple rots, therefore, it can be controlled fairly well after har- 

 vest by placing the fruit under refrigeration as soon as possible. 

 Control in the orchard can usuallv be obtained by the use of sulphur 

 sprays. (^^, 97, 100, 11 J^,, 196.) 



BRUISES 



BRUISES BEFORE HARVEST 



Bruises produced before the apples are mature, by thinning shears, 

 ladders, orchard machinery, harness, or by the rubbing of fruit 

 against limbs or twigs, are usually hard and dry compared with 

 other types described below and often resemble drought spot in the 

 ripe fruit. They can sometimes be distinguished from drought spot 

 by a more distinct margin, a more irregular shape, and sometimes 

 by a sponginess likely to be absent in drought spot. 



