34 BOARD OF AGRICULTURE. 



the necessity of greatly increased exertion on the part of the friends 

 of agricultural education. 



Thrown upon our own resources, we have studied the symptoms of 

 disease in the fields during every period of the growth of the potato, 

 and have noted the indications of derangement in the organic action 

 of the plants as they have occurred, and these we propose to speak of 

 in the first place. 



Early in June most potato fields exhibited, to a greater or less 

 extent, a blackened appearance of a portion of the leaves, commencing 

 generally at the tip of the leaf, but sometimes upon its side, and 

 gradually extending until often the whole organ in a short time was 

 entirely deprived of vitality. Such leaves subjected to the microscope 

 manifested no indications of the depredations of insects, but appeared 

 to have been cast ofi" by a natural effort, as though having performed 

 their functions they had simply died because their sources of nourish- 

 ment were cut off. This appearance of the leaf gradually increased 

 until so many were involved that they could be seen at a long distance 

 from the field. It does not however appear to have been a precursor 

 (of any value) of the future local disease of the tuber, since many 

 fields which were most affected by it presented very little indication 

 of disease upon harvesting the crop. 



About the last of June, Chenango potatoes planted without forcing, 

 displayed their blossom buds freely. On the first day of July it was 

 found that a very slight jar of the stem caused them to fall to the 

 ground, leaving only the bare flower stalk. 



This condition of the bud proved a tolerably good indication of the 

 future development of the tuber, since in all cases which were exam- 

 ined, where this blight of the buds occurred, either the tubers were 

 very little developed in size or quantity, or they manifested a great 

 propensity to take on the form of disease to be hereafter described. 



Those fields which had a healthy inflorescence, and matured their 

 seed, with a single exception, gave a good return of healthy tubers. 

 The above affections, both of leaf and bud, although appearing first 

 in the Chenango potato, afterwards became common to many, if not 

 most others. On the eighteenth day of August, after an extremely 

 sultry period of weather, during which the tops of the potatoes looked 

 as vigorous and healthy as at any previous period in the season, there 

 occurred a severe thunder shower, followed by a clearer and cooler 

 condition of the atmosphere. This change was immediately followed 

 by a very marked change in the appearance of the leaves and stalks 

 of the potato vine, the leaf dying more or less over the field, and 

 becoming somewhat shrivelled as though frost bitten, but less black 



