754 ANNUAL REPORT OF THE Off. Doc. 



main cool, the loss ki unsprayed fields would be slight. If it be very 

 hot and showery he should not expect with confidence immunity from 

 partial attack of early blight, no matter how well he may have spray- 

 ed. It is an open question, and the grower should be governed by 

 his variety planted, the probable market price and his past experi- 

 ence. "^ 



It is my personal experience that it is feasible to depend much 

 upon the resistance certain varieties offer to attack of early blight. 

 We now have a few varieties that will not blight seriously until a 

 good crop has been. made. When such are planted in a rich soil, and 

 are given the best culture, the danger of loss is reduced to a mini- 

 mum. If other varieties are planted, and the planting has not been 

 done very early, it is usually best to give the protection afforded 

 by thorough and repeated sprayings. Where late blight threatens, 

 spraying is to be advised. This blight, followed by rot, is a serious 

 menace to the crop in cool latitudes. The spraying will not be found 

 a sure preventive unless it is very thorough, and the blight may not 

 appear at all, but there is more reason for undertaking the work in 

 sections threatened by it than in those subject only to attacks of 

 early blight, w'hich is difficult to ward off. 



I have no desire to detract from the importance of Bordeaux mix- 

 ture as a preventive of the blights. ~ Its use must increase as disease 

 increases. But in seeking to state facts as they appear to be, an ef- 

 fort is made to keep on safe ground, not urging heavy investment of 

 labor and money upon all growers, but only upon those who cannot 

 evade loss by selection of soil and varieties, and who reasonably 

 should expect frequent loss if sprayings are not given. The practice 

 of spraying potatoes will increase because disease will grow moie 

 virulent, and there is reason for believing that thorough repeated 

 spraying will prove itself in time to be financially profitable to most 

 growers. One or two sprayings before the tops fill the middles is al- 

 waj'S to be advised, as more vigor is insured. 



Tip-Burn. — In addition to the early and the late blight, there is an 

 appearance of blighting of potato vines often seen that is not at- 

 tributable to a fungous disease at all, but is the result of the direct 

 heat of the sun, usually in connection with drouth. It is called tip- 

 burn, and we take from Bulletin 49 of the Vermont Station the 

 following description: 



"The disease we term 'tip-burn' is characterized by the death of 

 the potato leaves at their tips and margins, which portions dry, 

 blacken and roll up or break off. This trouble has occurred quite 

 commonly in Vermont during the dry, hot weather of mid-summer in 

 1894 and 1895, and as before stated, it was observed to a worse de- 

 gree in Michigan and Wisconsin where the drouth was more severe. 

 In its earlier stages the dead tissues are often quite free from inva- 



