101 



inroUed niaroius. One season is usually sufficient to com- 

 pletely kill the affected tree. In some cases, however, 

 a tree niaj- live two years, especially if it is not at- 

 tacked in all parts at once; but when a tree is once at- 

 tacked it never recovers. 



Prevention. — The same preventive measures suggested 

 for yellows apply also to rosette, and particularly should 

 all diseased trees be promptly dug up and burned. 

 Fence rows and hedges where peaches and plums are 

 Growing should be watched and affected trees de- 

 stroyed. By a series of experiments, Dr. Erwin F. 

 Smith,* of the U. S. Department of Agriculture, deter- 

 mined that it can be communicated by bud inoculation, 

 it being necessary, however, for the tissues of the bud 

 and stock to unite before inocculation is effected. Fur- 

 ther than this its manner of spread is unknown. Dr. 

 Smith suggests that possibly the disease may enter 

 through the roots, but this has not yet been proved. It 

 is certain, however, that it does spread naturally and 

 that a few affected trees left standing in an orchard will 

 in time cause the destruction of the entire orchard. 

 Hence the importance of rooting up diseased trees. 



THE WOOLLY APHIS. {Schizoneura lanigera.) 



This insect is especially injurious to young apple trees, 

 first in the nursery and then in the orchard. It is most 

 abundant and does its principal damage on the roots of 

 the trees, but spreads also to the bark above ground, 

 where it is particularly likely to appear on the young 

 sprouts which start up from the root of an injured or 

 unhealthy tree. Where abundant it forms bluish-white 

 cottony patches, not unlike some kinds of mould, which, 

 on careful examination, are seen to consist of a crowd or 

 layer of minute sluggish insects, their bodies covered 

 with a cottony coating v. hich gives the general effect de- 

 scribed. They are usually most abundant on the roots, 

 but sometimes appear above ground also on the bark of 



*Farmers' Bulletin, No. 17, U. S. Dept. Agr., page 17. 



