The County Record

Seed Potatoes.

So far as known, the fungus which causes the common "rust" or late blight and rot of potatoes, lives over winter only in the potato tubers. It is, of course, possible that it may exist in a resting stage in the soil or the blighted vines or decayed tubers, but most persistent search has failed to discover this. If this belief is correct, and the only place where the fungus lives through the winter is in the infected tubers, then the development of the disease each succeeding year is a direct result of the planting of some such infected tubers. All observations are in harmony with this explanation.

The unusually early and general development of the fungus the past summer is thus explained for there was enough of the rot in the autumn of 1901 to cause the widespread infection of the tubers from which the seed of 1902 was selected. It follows that the still worse development of rot this season is prophetic of a disastrous occurrence of this disease in 1903, providing soil and weather conditions next summer are at all favorable.

The practical question is what can be done to lessen this danger? There is no method known of disinfecting such diseased seed. Surface washes are useless, for the fungus is safely housed in the depths of the living potato tissue - and any known means of killing the fungus by chemicals will kill the potato also.

It has been suggested that heating the seed potatoes six hours or longer at 108 degrees F., or thereabouts, dry heat, would kill the fungus without injury to the potato. This has not been fully demonstrated, and would not prove practical to most farmers in case it is reliable.

The Vermont Experiment Station authorities can only recommend two things as practical. The first is that unusual pains be taken this autumn to secure and preserve for next year's seed purposes, early-planted potatoes grown on light, well-drained soil, which escaped the blight, or else those from fields so well sprayed as to be protected. The second is that next summer every potato grower be prepared beforehand with spraying outfit and chemicals ready for prompt application of the bordeaux mixture when needed. Even in so discouraging a season as the last one this remedy has proved perfectly effective when used promptly and thoroughly. In the well-sprayed fields at the Vermont Station at Burlington, a considerable portion of the vines were still green and growing on October 1, and preliminary diggings have shown practically no rot. - American Cultivator.