Minnesota Plant Diseases. 



357 



which are small, black cushions formed under the skin of the 

 apple. When the spores are ripe the skin is ruptured, and the 

 spores issue in a long cylindrical gelatinous mass which is some- 

 what spirally twisted. Rainwater dissolves the spores apart, 

 and the latter are washed to other fruits, again causing infec- 

 tion. The winter or sac spores are formed in small black cap- 

 sules which are produced in the 

 cankers on the twigs. These 

 cankers are usually found at 

 the bases of infected fruits. 

 The m y c e 1 i u m and winter 

 spores preserve the fungus 

 through the winter. The my- 

 celium, which produces the 

 winter spores, can apparently 

 live sapn phyticallv. 



Decayed fruit, whether in 

 storage or in the orchard, 

 should IK? destroyed. Diseased 

 twigs should als:> be pruned 



FiC.lW.-itterrotof,pple. After Clinton. 1)ack a (I ^royed. Spraying 



with Ixirdeatix mixture begin- 

 ning with a winter spraying, and continued frequently MI the 

 growing season, wili hold the disease in check. . \mmoniacal 

 copper carbonate should be substituted for the bordeaux as the 

 fruit approaches maturity. 1'otassium sulphide has also been 

 used to advantage. 



Brown rot of apples. See Urown R>t of I'luius (this 

 chapter). 



Brown rot of plum|.SV/v'/////'</ frnstigi'n<j </'. ) Sclirt.]. This 

 is a very common dis'.'as.' of plums and may als > attack cherries 

 and apples, though the latter rather rarely. In state> where the 

 peach is grown, this fruit suffers most of all fron. the brown r<>'.. 

 The fungus attacks the fruit at about tin- beginning of the ripen- 

 ing period, but may also extend to the twigs, haves and flowers. 

 The attacked portions of the fruit turn brownish, forming brown 

 spots which arc soft and rapidly gmw in she. On these spots 

 arise the summer spores in small clusters which are arranged in 

 circles in the spot. The spores are formed in chains. Hke strings 



