The crown gall disease of the apple : a discussion of the malady in general as applied to Missouri : experiments with the disease

Abstract

With ever increasing frequency for the past few years attention has been called to the existence of an affection of apple trees known as Crown Gall. This trouble, which is also known as "root gall", consists of galls or knots which occur on the roots of our apple trees. The name Crown Gall is given the disorder because it often attacks the trees at or near the surface of the ground on that part of the plant known as the crown. In view of the fact that there is no exact knowledge pertaining to the treatment of Crown Gall in the apple, and that the fruit growers are calling for such information, the writer began some experiments along this line in the spring of 1902. There was a long list of fungicides to select from, but in the first experiments it was decided to choose only a few of the most prominent ones in general use among horticulturists. No knowledge was available as to the effects the different remedies would have on the vitality of the trees, and but little information was obtainable as to their toxicity on the Crown Gall. Nothing was known as to the best method of treating diseased trees or whether it was possible to treat them with any degree of success while growing in the field. The matter of the advisability of treatment before planting was also uncertain. The thing of most immediate interest was to learn whether certain remedies which it was practically certain would kill any germ of fungi or bacteria, could be used without killing the trees, and if so what strength and in what combinations they could be safely employed. Realizing that it is possible for the fruit grower to treat affected trees either before or after planting, it was decided to experiment under both conditions.