EXPERIMENT STATION BULLETINS. 373 



causing them to turn brown. When the fungus gains an entrance into wounds 

 on branches it may cause a kind of canker from which a flow of gum is the 

 result. The writer has frequently seen "gumming" of the shoots of the flowering 

 almond with consequent death of the upper portion due to this fungus. 



Treatment. — A fungus which can thrive on so many hosts is not easily pre- 

 vented from occurring in the orchard. The fact, however, that the mummified 

 fruits serve to carry this fungus through the winter should indicate the need 

 of gathering and burning them instead of leaving them, as is usually the case, 

 to serve as centers of infection. Thorough spraying with Bordeaux mixture 

 and other fungicides, while reducing the amount of the brown rot, seldom suc- 

 ceeds in entirely preventing it. It has been found that where insecticides are 

 used, thereby reducing the attacks of the curculio that the brown rot is less 

 severe. This is 'also the case when the trees are jarred for the same purpose. 

 This process serves not only to remove the curculio to quite an extent but also 

 causes most of the rotting plums to fall off, thus removing one cause of the 

 spread of the fungus. Thinning the fruit will aid in controlling this disease. 

 The trees should be thoroughly sprayed before the buds open, with poisoned 

 Bordeaux or a solution of copper sulphate, one pound to twenty-five gallons of 

 water, then again with Bordeaux just before blooming, and again just after 

 blooming to be followed by another spraying when fruit is three-quarters grown. 

 Ammonia-copper carbonate'solution should be used when the fruit begins to color. 



PLUM POCKETS. 



• (Exoascus pruni Fckl.) 



The disease known as plum pockets or bladder plums is due to a fungous para- 

 site which is closely related to that of the leaf curl disease of the peach. Like 

 that disease it possesses a hybernating mycelium which lives in the tissues of 

 the twigs and young branches. When growth begins in spring this mycelium 

 grows out into the young ovary of the blossoms. Soon after the petals fall the 

 young fruits become swollen and often lengthened or distorted. When cut open 

 they are found to be hollow and without a pit as the stone fails to develop. These 

 bag-like fruits are at first yellowish tinged with dingy red and later appear to 

 be covered with a whitish bloom. This appearance is due to the numerous 

 minute spore-sacks (asci) which cover the surface of the diseased plums. After 

 the spores are discharged from these spore sacks the plums turn dark and fall 

 off. 



Treatment. — Trees which are once affected with this fungus continue to bear 

 bladder plums year after year. Cutting off those branches which show the 

 disease, as soon as noticed, will tend to prevent its further spread. However, 

 when a tree is thoroughly infected so that all the fruit is diseased it may better 

 be dug out and burned. Plum trees which are spi'ayed each season are not liable 

 to be infected with this fungus. 



SHOT-HOLE FUNGUS. 



(Cylindrosporium padi Karst.) 



Several fungous diseases are known to produce shot-hole effects on the leaves 

 of plants. The above named fungus, however, is most commonly associated with 

 that trouble on the foliage of plum and cherry. Affected leaves become disfigured 

 with numerous small spots of dead tissue which soon separates from the healthy 

 portion and drops out leaving perforations suggestive of the name shot-hole 

 disease. The spores are produced in minute pustules in these dead pieces of leaf 

 tissue. When severe, the leaves fall off prematurely thus causing a serious check 

 to the maturing of fruit and wood. 



Treat7nent. — Where this disease is prevalent about two or three sprayings of 

 Bordeaux mixture will be needed to prevent it, although a single application may 

 prove very beneficial. The first application should be made when the leaves 

 are well out and before they are inoculated by the spores of the disease. The 

 other applications, if needed, may be used at intervals of two or three weeks. 



