20 MISC. PUBLICATION 168, U. S. DEPT. OF AGRICULTURE 



ing increases with the length of the storage season and after 

 withdrawal from storage. Control can best be effected by prompt 

 storage at a temperature of 36° to 40°. 

 (See 7, 12, 59, 70, 97, U0.) 



Brown Rot 

 (Sclerotinia fructicola (Wint.) Rehm 5 ) 



OCCURRENCE AND SYMPTOMS 



Brown rot may affect apple, pear, and quince in practically all 

 producing sections of the eastern United States. It is more common 

 on early than on late varieties, but it has been found on Graven- 

 stein and other fall varieties in the humid districts of Washington 

 and Oregon. The rot occasionally occurs on fruits on the tree, but 

 it seldom causes serious loss in commercial shipments or storage 

 lots. 



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

 decay. The spots are brown at first (pi. 5, H) ; but, as they enlarge 

 and ultimately involve the whole fruit, they become black all over 

 or in irregular blotches. 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 % inch or more in diameter. 

 Under dry, cool conditions the tufts are rarely seen. 



Brown rot often resembles black rot so closely that positive 

 diagnosis 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 % i ncn 

 across, each with a lenticel at the center, and scattered over the 

 otherwise uniformly brown, rotted area. Apples in the early 

 stages of black rot at harvesttime have either a solid reddish- 

 brown color or alternating zones of light and dark brown. Black 

 rot becomes darker brown or even black and may have numerous 

 small black fruiting bodies (pycnidia) scattered over the rotted 

 area. As brown rot develops it becomes darker, often black. At this 

 stage the surface of the rot has a velvety sheen, and characteristic 

 gray fungus tufts may appear. Apples affected with brown rot 

 show some degree of blackening at an earlier stage than those 

 affected with black rot, and they shrivel sooner. 



CAUSAL FACTORS 



Brown rot of apple, pear, and quince 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 

 it does not attack apples until after they are harvested. 



CONTROL MEASURES 



Brown rot is checked by low temperatures, more readily 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 harvest by placing the fruit under refrigeration 

 as soon as possible. Recommendations of the local agricultural 

 experiment station should be followed for control in the orchard. 



(See 12, 59, 65, 11U.) 



5 Syn., Monilinia fructicola (Wint.) Honey. 



