There has been much speculation and research for the cause of the black knot on plum trees. Some persons have supposed it caused by an insect. Some years ago I opened the knot and examined it, but did not discover any appearance of an insect, nor the eggs of one. So far as I know, it has not been satisfactorily learned what causes the knot.

The gardens of my adjoining neighbors are full of plum trees. All the trees are filled with the black knot, so as to appear as if a flock of small birds had lighted on the branches. Some-years ago, I advised the owners to cut off the knots so soon as they appeared, or they would lose the trees - they thought best to leave them to the course of nature. The second and third sot of their trees are now in the condition I have described, while my trees arc free from knots. I have always looked for knots when in the garden, and when one appeared, I cut it off at any season, whether it was loaded with fruit or not. The trees soon put out other shoots, which filled out the place of the limb cut off. and my trees are in full size, as if no limb had been cut off, and there is not a knot to be seen on them. From this treatment, I am of opinion, that if a knot is suffered to remain on a limb, the disease soon spreads, like a canker, and fills the whole tree, as it has the trees of my neighbors. It is a misconception, that when a tree is set, it does not require further treatment.

D. Tomlinson. Cultivator.