DISEASES OF PLANTS 241 



sulphur. (California Experiment Station, Bulletins 165, 

 172.) 



Other rusts. Rusts are also common on stone fruits, 

 almonds, blackberries, beets, alfalfa, carnations, chrys- 

 anthemums, hollyhocks, and roses (figure 139). They 

 are not troublesome except in dry weather. 



SHOT-HOLE FUNGI 



Peach blight. The spores of the fungus germinate dur- 

 ing thftwjntgr rains, a.nd in a short time both the leaves 

 and shoots of the peach tree (and later the young fruit) 

 show numerous gummy spots or streaks which may be 

 an inch in length. Many of the buds are killed out- 

 right. Small spots of dead tissue fall out of the leaf, 

 causing the so-called shot-hole effect. Around the dead 

 spots on the new wood, masses of gum are formed, espe- 

 cially in wet weather. The new growth in the spring 

 is often killed completely, causing a total loss of the crop. 



The disease may be entirely prevented by one spray- 

 ing with Bordeaux mixture applied late in the fall; 

 if possible, the trees should be pruned before spraying. 

 Figure 140 shows how spraying checks the disease. 

 (California Experiment Station, Bulletin 191.) 



The same fungus also attacks the apricot and some- 

 times kills large branches. The most common effect 

 is a scabbing of the fruit. Many of the buds are killed 

 as on peaches, but the gumming of the twigs is not as 



