Insecticides And Fungicides
( Originally Published 1909 )
The gardener hardly expects, nowadays, to mature a crop of vegetables or small fruits without having to fight insects and diseases of a fungoid character. So prevalent has the practice become that he prepares for it at the beginning of the season. Knowing that in all probability insects will come and that fungus will appear sooner or later, it behooves him to act on the offensive, or, in other words, to get the start of plant-enemies, for it is easier to keep them away than it is to get rid of them after they have taken possession of one's plants. Don't wait for them to put in an appearance. Take measures to prevent their doing so by the occasional use of reliable insecticides and fungicides about the time they may be expected to arrive.
We have many formulæ for the preparation of these applications, some of them so elaborate that not one person out of twenty-five would ever think of making them up. The very look of the recipe is so formidable that the average gardener thinks he will take his chances with the insects rather than be to the trouble of attempting work that seems fitted only to the chemist. I have satisfied myself, from some years of personal experience, that these elaborate preparations are really no more effective than the simpler ones. I shall therefore give the formulæ of a few standard preparations for fighting plant foes, believing that the intelligent use of these will be quite sufficient to meet the necessities of most cases.
SOAP INFUSION, OR KEROSENE EMULSION
This insecticide kills by contact, doing most excellent work among insects that sap the vitality of a plant by sucking its juices. It can be used with admirable results about the roots of plants to destroy larvæ in the soil and the lice which sometimes do most destructive work underground. While intended, primarily, for the destruction of sucking insects, it is very effective among leaf-eating sorts.
Kerosene 1 gallon
Shave the soap and put it into the water as soon as the latter comes to a brisk boil. When wholly dissolved, remove from the fire and add the kerosene. Churn the mixture with force-pump or syringe, until a creamy emulsion is secured. If perfect union takes place you will have a jelly-like substance which will readily emulsify with water when the latter is added. Much depends upon the force used in churning the mixture. It must be agitated thoroughly, rapidly, and until there is a complete union of the several ingredients.
For scale, use one part of this emulsion to nine parts water; for soft insects, like plant lice, one part emulsion to twenty parts water; for other insects, one part emulsion to fifteen parts of water.
Apply with a sprayer, taking pains to have the mixture reach all parts of the plants. If you are fighting an enemy that hides on the under side of the foliage, it is well to have some one bend the plant over while you apply the insecticide, as success depends to a great extent on the thoroughness with which the preparation is used.
The following is the official formula for the preparation of this standard fungicide, as sent out by the United States Department of Agriculture :
In a barrel that will hold forty-five gallons, dissolve six pounds of copper sulphate, using eight or ten gallons of water, or as much as may be necessary for the purpose. Slake four pounds of fresh lime in a tub by pouring water over it until disintegrated. Then add enough water to make it about the consistency of thick cream. Stretch a coarse gunny sack over the head of the barrel containing the copper sulphate, and strain the lime mixture through it. Then fill the barrel with water. Stir thoroughly, and the preparation is ready for use.
Because the quantity seems large, the idea may prevail that the cost must be considerable. Such is not the case, however. The cost per gallon of the mixture will not exceed one cent, as copper sulphate can be bought for seven cents a pound, and lime is about thirty cents a bushel, which will make your four pounds cost less than five cents.
In all cases it is desirable to use powdered copper sulphate, as it dissolves much more readily than that in the lump. It is of the utmost importance that perfectly fresh lime should be used. Air-slacked lime is worthless.
The above directions can be depended on as absolutely reliable, for the Department of Agriculture recommends nothing that has not been thoroughly tested.
If Paris green is added to this mixture we have a combined insecticide and fungicide, which can be relied on to do most excellent work. As insects and fungi usually exist together to a considerable extent, it is well to make use of the combination for general applications.
When used on peaches, plums, and other stone fruit, two ounces of Paris green to forty-five gallons of the mixture, or in that proportion, will be sufficient.
For other fruits, berries, and the like, four ounces of Paris green to the same quantity of mixture may be used, or in that proportion.
The writer is well aware that many persons hesitate about using Paris green on vegetables and fruits. The following from Farmers' Bulletin No. 7, United States Department of Agriculture, shows how harmless the article is when used properly:
" Paris green and London purple have been used extensively in this country, for many years, for insecticidal purposes, and not one instance of fatal poisoning from their use has been subtantiated. The only danger lies in keeping them about, in bulk. Keep them where they belong,—and that is out of the way of children and meddlesome persons,—and there is nothing to, fear."
In the department of this book in which the various kinds of vegetables are treated individually, I shall indicate such special applications as may be necessary to successfully combat the peculiar enemies of the plant under consideration.