not is a serious disease of the plum and of the
cherry tree. It attacks the branches of the tree; it is well
illustrated in Fig. 132. Since it is a contagious disease, great care
should be exercised to destroy all diseased branches of either wild or
cultivated plums or cherries. In many states its destruction is enforced
by law. All black knot should be cut out and burned some time before
February of each year. This will cost little and save much.

[Illustration: FIG. 132. BLACK KNOT]

=Peach Leaf Curl.= Peach leaf curl does damage amounting to about
$3,000,000 yearly in the United States. It can be almost entirely
prevented by spraying the tree with Bordeaux mixture or lime-sulphur
wash before the buds open in the spring. It is not safe to use strong
Bordeaux mixture on peach trees when they are in leaf.

[Illustration: FIG. 133. MOLDY PEACHES]

=Cotton Wilt.= Cotton wilt when it once establishes itself in the soil
completely destroys the crop. The fungus remains in the soil, and no
amount of spraying will kill it. The only known remedy is to cultivate a
resistant variety of cotton or to rotate the crop.

[Illustration: FIG. 134. PEACH MUMMIES]

=Fruit Mold.= Fruit mold, or brown rot, often attacks the unripe fruit
on the tree, and turns it soft and brown and finally fuzzy with a coat
of mildew. Fig. 133 shows some peaches thus attacked. Often the fruits
do not fall from the trees but shrivel up and become "mummies" (Fig.
134). This rot is one of the most serious diseases of plums and peaches.
It probably diminishes the value of the peach harvest from 50 to 75 per
cent. Spraying according to the directions in the Appendix will kill the
disease.

[Illustration: FIG. 135. HALF OF TREE SPRAYED TO PREVENT PEACH CURL
Note the difference in foliage and fruit on the sprayed and unsprayed
halves of the tree, and the difference in yield shown below]

CHAPTER VII

ORCHARD, GARDEN, AND FIELD INSECTS

SECTION XXXI. INSECTS IN GENERAL

The farmer who has fought "bugs" on crop after crop needs no argument to
convince him that insects are serious enemies to agriculture. Yet even
he may be surprised to learn that the damage done by them, as estimated
by good authority, amounts to millions and millions of dollars yearly in
the United States and Canada.

[Illustration: FIG. 136. ANTS]

Every one thinks he knows what an insect is. If, however, we are willing
in this matter to make our notion agree with that of the