The control of the insects and diseases that affect crops is essential to production. In handling, mixing, and applying poisonous insecticides and fungicides, wear a respirator that protects the entire face. After working with pesticides, wash the hands or any exposed parts of the body thoroughly. Containers in which materials are kept or stored should be plainly labeled and placed under lock and key.
Unless the poison residues can and will be removed by washing or stripping, dust, solution, or bait that contains such materials as Paris green, calcium arsenate, cryolite, barium fluosilicate, sodium fluosilicate, sodium fluoride, tartar emetic, corrosive sublimate, calomel, or DDT, when foliage or fruit that is intended to be eaten is from the plants. Apply all chemicals as sparingly as is consistent with effective control. Apply a light, even coating.
General methods of insect control
Small seedlings may be protected from insects, excepting those living in the soil, by covering the plants with an inverted glass jar or wholly covering them with a light paper or muslin hood, about 8 inches in diameter, supported by wire or wooden hoops and sealed to the ground by covering the edge of the hood with soil. Hand-picking of the larger beetles, caterpillars, and plant bugs will often give satisfactory control in a small garden and eliminate the need for applying insecticides. Hand-picking is most effective if begun early enough to catch the first insect attracted to the vegetables.
Good garden practice:
The methods of gardening essential to the production of good crops are also an aid in disease control. These practices include: the use of fertile, well-drained soil,, the proper application of fertilizers of a type suited to the soil and crop, the planting of crops suited to the soil and climate, and clean cultivation.
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At the end of the season all diseased crop refuse, including the roots, should be disposed of by burning. Do not compost the remains of disease plants. Obtain disease-free seed. Where certified seed is available, as with tomatoes and potatoes, endeavor to get it. Cabbage, cauliflower, bean and pea seed grown in the far West is ordinarily free from certain disease-producing organisms. Never save seed from rotten or spotted fruits or wilted plants.
Resistant varieties offer the most effective means of disease control, but such varieties are as yet available in the case of only a few disease of certain crops. Chemical seed treatment is used for two purposes: protection against the decay of seed in the soil and the damping-off small seedlings, and the disinfection of the seed to kill any parasite fungi or bacteria that may be present on its surface.
DDT is poisonous to higher animals and man and therefore its usage in the garden on leafy vegetables is limited. A dust mixture containing 3 percent of DDT is effective against the Colorado beetle, the potato flea beetles, potato and lean leafhopper, cabbage looper, the imported cabbage worm, the diamondback moth larva, and some species of cutworms which feed on the foliage of cabbage. A higher strength of dust will be needed for the control of aphids on potatoes and thrips on onions.