452 ANNUAL REPORT OF THE Off. Doc. 



relative severity or abundance should be known b}' tlie orehardist. 

 He should then determine by his own experience and by the ad- 

 vice of experts the least amount of spraying that will be sufficient 

 to protect his trees under his conditions. It is particularly desirable 

 to correlate and combine the s])raying for the insect pests and the 

 fungous diseases since the same spraying may distribute both ma- 

 terials. 



As a rule, where a fungous disease or an insect pest stands in 

 the way of successful crops, it will pay handsomely to do the neces- 

 sary spraying to prevent the same. This is especially the case where 

 the pest or combination of pests preventable by spraying constitute 

 the only unfavorable factor present. Where the orehardist has 

 done everything else in planting out the orchard, and caring for the 

 trees by cultivation, fertilizing, manuring, pruning, etc., and then 

 loses his crop through apple scab, or has his trees weakened in pro- 

 ductiveness by the leaf blight fungus, or has his crop ruined by in- 

 sects, it will pay many limes over to remove this last unfavorable 

 condition. On the other hand there have been some troubles con- 

 nected with spraying, particularly the russetting of the fruit, which, 

 unfortunately occurs in certain wet seasons even though the best of 

 materials have been used. 



Russetting. 



A great deal of the trouble in the russetting of apples through 

 spraying has been caused by copper sprays or by arsenical prepara- 

 tions containing free arsenic. Even the best of the arsenicals, name 

 ly, the arsenate of lead, from this point of view, has not always 

 proven safe, as some preparations, in certain localities and in certain 

 seasons have proven poisonous. Bordeaux mixture, on the whole, is 

 one of the least injurious of fungicides. When badly made with an 

 excess of copper or with air-slaked lime, it is quite likely to prove 

 somewhat injurious. Wlien properly made it is usually perfectly 

 harmless; but some seasons, especially when there are unusually pro- 

 longed periods of moist weather with dews and fogs, it has russet- 

 ted the fruit. Strange to say, the thick skinned Ben Davis is the 

 most susceptible apple to this russetting and it res})onds by making 

 abnormal puffy growths to the injury on its skin. Copper and 

 arsenical poisoning also frequently affect the foliage under the same 

 conditions, namely with prolonged moist and foggy weather. This 

 past season a great deal of trouble in the way of leaf fall occurred 

 on the apples all over Pennsylvania. A large part of this, how- 

 ever, was physiological and leaves dropped not only on sprayed trees 

 but on unsprayed apple trees and on other fruit and shade trees. 

 This, it seems to me, came from the abnormal spring. The foliage 

 developed in our very cool May was apparently unable to stand the 

 hot spell which came late in June and early in July, varying from 

 hot, rainy weather to hot, dry weather. The possibility of having 

 more trouble from russetting of fruit is a still further argument, 

 aside from the injury to the pocketbook, against over-spraying. 



Peach Yellows. 

 There has been a great deal of trouble over })each yellows this 

 year. In fact a large area, including the State of Connecticut. 

 Southern New York, Pennsylvania, West Virginia and a portion of 



