746 ANNUAL REPORT OF THE Off. Doc. 



tatoes to rot, it so injures the foliage that the growth is checked 

 long before maturitj- and instead of the potatoes being full grown 

 they are undersized and immature. It is very possible for the 

 early blight to attack a field of potatoes and its presence never be 

 recognized by the farmer, it being mistaken for a case of early ma- 

 turity. This may be the reason the early blight fails to attract as 

 much attention as the late blight and it no doubt does far more dam- 

 age than is generally accredited to it. 



"It is diflScult to describe its characteristics definitely as so ma^v 

 variations occur, and as it frequently is confounded with the late 

 blight, it being sometimes scarcely possible to recognize the differ- 

 ence without the aid of a glass. It usually makes its appearance 

 during the latter part of June or during July and may even appear as 

 late as August. 



"The parts of the foilage first attacked are likely to "be the edges of 

 the leaves, the disease manifesting itself in several places on the 

 same leaf, and affected area as first being circular in outline. The 

 color of the foliage ^-hanges from a green to a russet or dark brown 

 or even black and the edges curl as the tissue dies. A dnstinguish- 

 insr characteristic of the early blight is the general appearance of the 

 tissue of the leaf beyond the most seriously affected portions. In- 

 fctead of retaining the green color of healthy foliafre. it assumes a 

 yellowish appearance similar to that of matured plants, this pre- 

 mature ripenincr probably being caused by the general weakening 

 of the plant. This appearance no doubt is the cause of the general 

 supposition that when potatoes are effected with the early blight the 

 death of the vines is due to natural causes and is simply a case of 

 earlv ripeninsr when in reality it is premature and due to the blight 



"One remedy for early blight will have been suggested by what has 

 been said regarding the predisposing causes. It attacks plants 

 which have been for some cause weakened or injured. Treatment, 

 then, should begin with the preparation of the land. Deep plowing 

 to furnish an adequate feeding ground and a reservoir for moisture, 

 seed cut in pieces of good size, the surface soil crust broken with a 

 harrow before plants are up and then thorousrh tillage and protec- 

 tion from both the flea-beetles andi the Colorado beetles. If th** 

 plants are kept in vicrorous growth, they will largely possess im- 

 munity to the early blight. 



"Bordeaux mixture is the standard remedy for this as well as 

 other fuTigons diseases. Tf it has used in early sprinar in combating 

 the flea-beetles, and if when Paris green is used to kill the Colorado 

 potato-beetles it is applied in Bordeaux mixture, there is but slight 

 chance that the early blight will appear. The treatment in the man- 

 ner above described serves a double purpose. The foliage is kept 

 vigorous and healthy, free from attacks of the insect pests, and this 



