Jasper County Democrat, Volume 14, Number 4, Rensselaer, Jasper County, 19 April 1911 — BLACK KNOT. [ARTICLE+ILLUSTRATION]

BLACK KNOT.

One of the Worst and Most Common of Chsrry and Plum Diseases. i Black knot of plums and cherries is pne of the most common and destructive of the plant diseases affecting our orchard trees. It is marked by large black swellings or knots appearing on the limbs of certain varieties of cherries and plums. In some sections this disease is exceedingly common and destructive. It is

caused by a fungus living as a parasite in the bark and wood of the plum or cherry. This fungus reproduces itself and spreads by means of spores which are carried by the wind and lodge in the crevices of the bark or on the buds, where they germinate, penetrate the living bark and by their presence and growth irritate the cambium, the growing part of the limb. The plant responds to this irritation by the increased growth of this

part at the point [Er °m circular Vlraffected which &»nia agricultural exanectea, wnicn periment station ] eventually results in the black knots so characteristic of the disease. It takes approximately two years for the fungus to complete its development in the tree —that is, from the time the spores first lodge on the twig until the knots have matured and their'last crop of spores has been distributed, says H. H. Whetgel, plant pathologist, writing in the Rural New Yorker. The period of infection— that is, the time when the tree may take the disease—is probably from May to July. The knots do not appear on the limbs until the following spring, when in the month of April or May they burst forth and in June become covered with a green felt upon which are produced great numbers of summer spores or conidia. These are scattered by the wind and produce new infections in June and July. The knots then gradually become black in color and in March or April of the second year produce another set of spores in minute pockets all over the surface of the knots. These so called winter spores are distributed in May or June, causing another new set of infections. It is thus evident that the knot may cause new infections for two years in succession. These knots are not caused by insects, as is very often supposed. The most satisfactory means of controlling this disease consists of a surgical operation—namely, removal of all limbs and twigs bearing knots, cutting at least three or four inches below the knot in every case. The proper time for cutting out the knots is early in the spring, say not later than May, and again in the fall as soon as the leaves are off the trees. Permanent relief from the trouble cannot be expected unless an effort is made to eradicate the disease from the entire neighborhood, at least for considerable distances in the direction of the prevailing winds. Old cherry and plum trees should be very carefully pruned out and put in shape or else cut down arid destroyed. All knots should be burned promptly after cutting from the tree. Selecting Seed Wheat. According to the Kansas wheat growers, the idea that large kernels of wheat germinate better than small ones is a mistake. The germinating power is, rather, dependent on the density of the kernels.

When you take an inventory of the farm do not fail to make note of its healthful surroundings and its attractive features for a happy home.

BLACK KNOT.