Radishes, rutabagas, turnips, kale, kohlrabi, and mustard are other crucifers that benefit from seed protectants.

Seeds of cucurbits, such as cucumbers, muskmelons, watermelons, and squashes and pumpkins may be disinfested with mercuric chloride if the organisms causing anthracnose or angular leaf spot are suspected.

The procedure consists in soaking the seeds for 5 minutes in a solution of 1 ounce of mercuric chloride in 7.5 gallons of water, thoroughly rinsing them in running water, and drying. A protectant should be used afterwards. Captan or thiram, alone or in combination with an insecticide such as lindane or dieldrin, are beneficial, especially on the larger seeded cucurbits.

Onion seeds may be protected against decay by materials like captan or thiram, but the primary purpose in treating onions is to give protection against the soilborne smut fungus. Pelleting the seeds with thiram or captan has largely replaced the old standard formaldehyde-drip method. An insecticide, such as aldrin, may be included in the pelletant to control maggots.

Peas are treated with a protectant to control seed rots and seedling blights. chloranil formerly was used, but cap-tan and thiram, alone or in combination with an insecticide, have largely replaced it. The rate of seed flow through the drill is retarded somewhat by both captan and thiram, so that a compensatory change in seeding rate must be made or graphite added as a lubricant at the rate of 1 ounce per bushel.

Seeds of tomato, eggplant, and pepper often require disinfectant treatments as well as protectants. They can be disinfected by soaking them in hot water (122 ) for 25 minutes. Immediately afterwards, the seeds should be plunged into cold water, drained, and spread out to dry.

Pepper seeds sometimes are disinfected in a mercuric chloride solution instead of in hot water. The procedure is to soak the seed for 5 minutes in a solution containing one-fourth ounce of mercuric chloride in 5.5 gallons of water, rinse thoroughly in running water, drain, and dry.

Some States require that tomato seed be treated with an organic mercurial, such as Ceresan M, before plants are certified for export. Seeds treated with mercurials should not be treated again with other chemicals as this may cause injury. Protectants are beneficial to seed treated with hot water or not previously treated.

GREAT QUANTITIES of apple, pear, cherry, peach, plum, and lesser quantities of almond and apricot seeds are sown each year. It is common practice to soak the seeds in water for several hours before planting, but treatment with a fungicide is uncommon. Occasionally damping-off causes losses in stand. The losses could be reduced by the use of a good protectant.

SEEDS OF many kinds of ornamental plants benefit from treatment. Some large producers of flower seeds use treatments to reduce losses from seed rots and damping-off.

Thiram, captan, chloranil, and Semesan are commonly used. They usually are applied as dusts. Hot-water and chemical-soak treatments also are used to eliminate seedborne pathogens. Little of the packeted seed sold to home gardeners is treated.

Seeds of China aster sometimes are treated with a mercuric chloride or Semesan-soak treatment to prevent the introduction of wilt organisms (Fusarium and Verticillium) into clean soil. Treatment will not control wilt if the soil is already contaminated.

The standard treatment for wilt is to soak the seeds for 30 minutes in a 1:1000 mercuric chloride solution, which can be prepared by dissolving one 7.5-grain tablet of mercuric chloride in a pint of water. Treated seeds should be rinsed immediately for at least 5 minutes in running water and then dried for 24 hours at room temperature.

Instead of mercuric chloride, seeds may be treated in a 0.25-percent Semesan solution (two teaspoons of Semesan to 1 quart of water) for 30 minutes. Either treatment also helps to reduce the incidence of Septoria, Ascochyta, and other seedborne pathogens that incite leaf spots.

Stock seeds infected with the bacterial blight organism should be given a hot-water treatment, which consists of soaking it for 10 minutes in water at 129 -130 , plunging it in cold water to cool, and then drying it. A plastic. screen bag makes a good container for submerging the seed during treatment, because it permits instantaneous con-. tact of all the seeds in the bag with the hot water and facilitates quick and easy drainage. Timing is important. Stock seeds also may benefit from a protectant.

Sweetpeas frequently are treated, with captan, thiram, or chloranil to prevent seed rots and seedling blights.

Zinnia seed is sometimes soaked in hot water (125 ) for 30 minutes to kill seedborne Rhizoctonia solani, a fungus that causes damping-off.

SEEDS OF FOREST TREES frequently are treated before sowing in nurseries to control seed rots and preemergence and postemergence damping-off. Most of the pines, Norway spruce, and con-color fir are treated routinely. Thiram and captan are commonly used. Other chemicals are sometimes added to protect against insects, birds, and rodents.

Hardwoods and some of the large-seeded southern conifers like loblolly (Pinus taeda) and slash pine (P. caribaea) can be protected by simply dusting the seed with thiram or captan. The conifers with smaller seeds (more than 20 thousand seeds to the pound) usually are pelleted.

Dosages of fungicides vary with the species to be treated and the chemical used. Lower dosages are required for large-seeded than for small-seeded species and for seed sown in the spring than for fall-sown seed. Approximately twice as much captan as thiram is needed. For red pine (P. resinosa) 4 ounces of 50-percent thiram or 8 ounces of 50-percent captan per pound of seed commonly are recommended.

In pelleting, an adhesive, such as methyl cellulose, Dow Latex 512 R, or Flintkote Asphalt-Emulsion C-13 HPC, is required, and this must be applied first to the seed.

The amount of sticker required per pound of seed depends upon the size of the seed, the sticker to be used, and the amount of dust to be fixed to the seed. To apply 4 ounces of fungicide per pound of red pine seed, 2 fluid ounces of 4-percent methyl cellulose are required. If 8 ounces of fungicide are to be used, 3 ounces of the sticker are needed. The next step is to apply the fungicide. If an insecticide is to be used it should be added at the same time. When a repellant is to be incorporated into the pellet, it should be added last just before the seed is to be removed from the mixer.

EARLE W. HANSON joined the Department of Agriculture in 1937. From 1937 to 1946 he was employed by the Division of Cereal Crops and Diseases of the Bureau of Plant Industry, Soils, and Agricultural Engineering to do research at the Minnesota Agricultural Experiment Station on the diseases of hard red spring wheats and to cooperate in the development of disease-resistant varieties of wheat. Since 1946 he has been employed jointly by the Crops Research Division of the Agricultural Research Service and the University of Wisconsin to investigate diseases of forage crops.

EARL D. HANSING has degrees from the University of Minnesota, Kansas State University, and Cornell University. Since 1940 he has served as a plant pathologist at Kansas State University and has conducted research on cereal and forage diseases.

W. T. SCHROEDER is a graduate of the Universities of Idaho and Wisconsin. From 1941 to 1943 he served as plant pathologist for the Green Giant Co. of LeSueur, Minn. He moved in 1944 to the New York State Agricultural Experiment Station of Cornell University at Geneva, where he is a professor in the department of plant pathology and conducts research on the control of vegetable diseases through fungicides and disease resistance.