302 MANUAL OF FRUIT DISEASES 



In the spring, March and April, conidia coil out in long, 

 reddish brown masses from the fruiting bodies already men- 

 tioned. The process is favored by quiet, damp weather, and 

 it takes place in a few hours following the advent of favorable 

 conditions. The spores are scattered by the wind, rain and 

 probably by birds. Within twenty-four to forty-eight hours 

 germination occurs, and the germtube enters the bark through 

 a bud or through a wound of any sort. The germtube soon 

 develops a copious growth of mycelium which is found between 

 the outer bark and the wood in grayish mats. Numerous 

 gum pockets are formed in the cambium and inner bark; 

 many of these unite to form larger ones. The gum thus formed 

 exerts a pressure on the bark, which is ruptured, and an exuda- 

 tion follows. This gum-flow, sometimes referred to as gum- 

 mosis, is characteristic of the peach and other stone-fruit trees 

 when injured (see page 303). 



The fungus may grow down the twigs into the branches, 

 and in this manner large limbs and even trunks become in- 

 fected. On all affected parts pycnidia are developed in abun- 

 dance. They occur most abundantly, however, on twigs, while 

 perithecia are most common on the limbs and trunks; the 

 two kinds of fruiting bodies may be intermingled on trunks 

 and larger limbs. Ascospores are discharged from January 

 to April, while conidia, as noted above, are disseminated in 

 March and April. 



Sometimes the advance of the fungus is halted, and affected 

 parts may outgrow the disease. Frequently, however, the 

 fungus remains active until late in the fall ; its progress is 

 then interrupted by the first freezing weather. With the return 

 of favorable weather the fungus renews activities and the 

 mycelium spreads. 



Control of die-back. 



The fungus is ever-present on stone-fruit trees, and shows a 

 marked preference for trees already in a poor condition as a 



