RASPBERRY DISEASES 



413 



blight no insect burrows are found. The disease has also 

 been confounded with drought and winter-injury. Drought- 

 injured canes dry up slowly and more uniformly ; blighted canes 

 die suddenly. Winter-injured canes do not put out new leaves 

 on the affected portion ; blighted canes 

 develop new leaves on the affected parts. 



The berries dry up as a result of cane- 

 wilt (Fig. 120) . They are also susceptible 

 to direct attack. This is evidenced by 

 the fact that a single berry in a cluster, 

 or even one side of a berry, may be dis- 

 eased. The normal green color is slightly 

 tinted as if ripening prematurely; fi- 

 nally, the tissues gradually turn brown 

 and a dry rot results. 



Cause. 



The brown mass of reproductive bod- 

 ies, already mentioned, which ooze out 

 on the affected bark are the conidia 

 of the causal fungus, Leptosphceria Con- 

 iothyrium. These spores are dissem- 

 inated from plant to plant probably FIG. 121. Cane-blight; 



i /, . -. , x . j j fruit bodies of the patho- 



by insects (tree crickets), wind and gene on raspberry 'cane, 

 dashing rain, by pickers, pruners and 



cultivating tools. The spores germinate on the canes, and 

 evidently the germtubes are capable of penetrating the un- 

 broken epidermis of the canes. The fungus also enters the 

 canes through wounds; stubs left exposed in heading-back 

 and injuries made by the snowy tree cricket ((Ecanthus niveus) 

 are common points of entrance. Berry-infection doubtless 

 occurs through the flowers and very young fruit. The mycelium 

 works between and within the fleshy parts^ of the drupelets, 

 but not in the embryo or stony part. It passes from the 

 fruit down the pedicels and thence upward to other berries of 



