NOTES ON PLANT PESTS.
Prepared by Section of Insect Pests, A. G. Ruggles, and by Section of Plant Diseases, E. C. Stakman, University Farm.
Buy spray materials as soon as possible. The orchardist will probably notice very little difference in the price of his spraying materials, like arsenate of lead and lime-sulphur, as compared with last year; but those who still think that Paris green is the only good stomach insecticide, will be astounded by this year's price. At the present time, in one pound lots, the retailer cannot sell Paris green for less than 50c per pound—over twice what it was last year. In large quantities, it is doubtful if it can be purchased for less than 45c per pound. Fortunately arsenate of lead, a better stomach insecticide than Paris green, has not advanced materially in price, the powdered form being obtained for about 25c per pound. One and one-half pounds of this powder is used in fifty gallons of spray mixture. In our experiments, we have found arsenate of lead superior to Paris green as a remedy for potato bugs and all orchard insects. It is not necessary, therefore, to allow any injurious biting insect to live simply because Paris green is high in price. Arsenate of lead, if properly applied at the right time, will keep any of these insects in check.
A dormant wash does little good in controlling scab. Hence, on account of the high price of spraying compounds, do not spray when unnecessary.
Many diseases of nursery stock are controlled by spraying. Begin spraying as soon as leaf buds unfold, with lime-sulphur 1-40 or Bordeaux mixture 4-4-50.
Copper-sulphate has also advanced 15c or 16c per pound. Lime-sulphur has not advanced materially; therefore, plan to use lime-sulphur or some of the made-up (paste) Bordeaux instead of Bordeaux mixture, whenever possible. Potatoes can not be sprayed with lime-sulphur.
The aphis problem is usually a very serious one, because they are such persistent little breeders. The trees or shrubs most affected are roses, snowball, currant, apple, plum and elm. The eggs of the plant lice pass the winter on the bark or buds of these plants and hatch as the buds begin to swell. Spray with the lime-sulphur (1-9) at this time. As soon as the leaves appear, spray with nicotine-sulphate as per directions on the container.
If plum pocket was bad last year, the trees should be thoroughly pruned. Then spray with copper-sulphate, one pound to nine gallons of water, or lime-sulphur, one gallon with nine gallons of water, before the buds open. Follow with one to forty lime-sulphur or other spray as for brown rot. Control methods for plum pocket are not well worked out, so these methods cannot be depended upon entirely.
Be sure and look over the apple trees carefully; cut out and burn all cankers. Black rot has been increasing in the state, and since a great deal of early infection may come from cankered limbs, it is important that cutting out and burning be resorted to.
Last year the spring canker worm was just as active in the state as the fall canker worm; therefore, just as soon as possible, trees affected last year should be banded with the tree tanglefoot. The moths come out of the soil the first two weeks in April and at that time attempt to crawl up the trunks of the trees to lay their eggs on the limbs.
When raspberries are uncovered, be sure to cut out and burn all dead canes missed last fall. The gray bark disease and anthracnose, also snowy tree cricket and red-necked cane borer, are controlled in this way.
Plan to keep the young canes covered with a protective spray of resin-Bordeaux mixture. Try it on at least part of the patch. The benefit will not be apparent for a year.
Spray currants and gooseberries as soon as leaf buds begin to unfold, with either Bordeaux mixture 4-4-50 or lime-sulphur 1-40, to prevent powdery mildew and leaf spots.
For further information write to the section concerned. Inquiries will receive prompt attention.