RASPBERRY DISEASES 409 



speck develops on the end, but soon the entire surface is 

 involved. As the fruit matures the surface of the lesion 

 becomes depressed. If affected while small, the drupels 

 remain firm and finally become dry. Fruit-pedicels may be 

 attacked, in which case the fruit dries up and dies. 



Cause. 



The anthracnose lesions just described are caused by the 

 fungus Glceosporium venetum. Details of its full life-history are 

 as yet unpublished, but the facts as generally known will be 

 discussed. The winter is spent in the canes. It is very 

 likely that in addition to mycelium, immature fruiting structures 

 are concerned in this connection. In the spring conidia are 

 f jrrned on the old diseased areas by the fungus. These spores 

 are disseminated about the time the plants are from six to ten 

 inches high. Apparently the exact origin of the conidia is not 

 generally known. The perithecial stage has recently been 

 described, but as yet is not named. The ascospores developed 

 within the perithecia are shot forcibly into the air and later 

 germinate by budding. These buds are identical with the 

 conidia ; they may be referred to as such. Conidia probably 

 also are developed in acervuli. These spores attack and 

 their germtubes penetrate only the tender growing parts of the 

 cane, as evidenced by the smaller and younger spots at the tip 

 and the older ones at the base (see Symptoms) . Following the 

 germination and penetration processes mycelium ramifies in 

 the cortex of the cane where the cells are killed. Subsequently 

 conidial fruit-bodies are developed from which conidia are 

 liberated. These initiate secondary infections on the canes, 

 leaves and fruits. These secondary infections continue 

 throughout the summer. In the winter the fungus again 

 remains dormant in the canes. 



Control. % 



Diseased canes should be eradicated before the spring season. 

 It is preferable that this be done at the end of the fruiting-sea- 



