Nevertheless, the results of surveys in eight States create doubts as to whether all farmers understand the losses from cereal diseases. The percentages of untreated seed lots were 32 percent to 83 percent. The States are Oklahoma, Nebraska, Illinois, Wisconsin, Indiana, New York, Virginia, and South Carolina.

THE use of certified seed, as determined by the surveys, was limited, but it seems to be increasing.

Among 698 samples of oats collected in Nebraska in 5 years, only 4.7 percent represented certified seed. Five and four-tenths percent of all samples of oats, wheat, barley, and rye in the studies in Nebraska was certified.

In North Dakota, 5.2 percent of 192 samples of flax in 1953 was certified seed, and 4 percent of the wheat seed in 1954 was certified. In 1956, 861 samples of wheat contained 13.8 percent known to be certified seed. The increase apparently was due to the demand for the new Selkirk variety and for certain new varieties of durum.

In a survey in Arkansas, only 3.6 percent of the total bushels of oats seed, represented by 647 samples, was known to be certified; 22.4 percent of the wheat, covered by 392 samples, was certified.

The demand for seed of a new variety accelerates the use of registered and certified seed. Its genuineness and freedom from varietal mixtures is assured thereby. That may explain the higher percentages of certified seed among the samples gathered in the surveys.

After Clintland oats had been released in Indiana, a survey showed that 20 percent of the 312 samples of oats were certified Clintland. In Illinois, 604 samples of wheat in 29 counties included 12 percent certified; 39 percent of the samples of oats were certified.

Absence of weed seeds is a distinguishing quality in good seed, but the results of the surveys have been disappointing. Too many samples contain an excessive amount of weed seeds, usually because of lack of adequate cleaning. The more recent surveys show little improvement over earlier surveys in this regard. Many samples contained seeds of noxious and common weeds.

A survey of oats seed in Michigan disclosed that 115 of 372 samples contained seeds of noxious weeds; 106 contained quackgrass seeds. In Iowa, 23 of 117 samples carried seeds of quackgrass; 6 samples contained 3 kinds of noxious weeds. Samples of wheat and oats in Nebraska had an average of 135 weed seeds in a pound. Samples of oats and wheat in Oklahoma averaged 128 weed seeds in a pound.

Careful cleaning of seed grain should reduce the number of weed seeds to a maximum of 50 to a pound, but this degree of efficiency is not attained by the practices generally followed. Of 377 samples of seed wheat collected in North Dakota, 175 samples, or 45 percent, contained more than 100 weed seeds to a pound.

THREE systems of cleaning seed grain are in common use: Farm cleaning, with a small fanning mill; custom cleaning, with large, general-purpose cleaning machinery at country elevators; and custom cleaning at approved processing plants.

The practice of cleaning seed on the farm is declining. In North Dakota in 1954, 21 percent of the samples had been cleaned on the farm; in 1956, 15 percent. The farm-cleaned samples averaged 200 weed seeds to a pound in 1954 and 156 weed seeds in 1956.

The ordinary fanning mill, commonly found in farm granaries, cannot do a good job of cleaning. A few farms have large, power-driven cleaners, whose screens and air blasts may be adjusted for most kinds of separations needed for seed of small grain. If such cleaners are not available on the farm, custom cleaning may be advisable.

Country elevators generally are equipped with scalping machines of high capacity. They are made for removing dockage from commercial grain, but do not make the precise separations required for cleaning seed. The elevator legs, storage bins, and parts of the conveyors are not designed to permit convenient and thorough cleanup after each custom job. Furthermore, there is a tendency for operators to exceed the best capacity of the machines for effective work during the seasonal rush at seeding time. The country elevators generally are less satisfactory than the farm fanning mills for cleaning seed. In the North Dakota surveys, seed grain cleaned at country elevators averaged 175 weed seeds to a pound in 1954 and 187 in 1956.

Approved processing plants are equipped and operated in many States in accordance with the recommendation of seed-certification agencies and are approved by the agencies for custom cleaning of seed grain, including, certified seed. Besides general-purpose scalping machinery, these plants have special types of cleaners for specific problems in seed separation gravity mills, disk cleaners; magnetic separators, dodder removers, and many devices for specific separations. The conveyors, storage bins, and all parts in direct contact with the seed are built so they can be cleaned conveniently.

Systems of inspection, registering, and approving custom-cleaning plants for processing certified seed have been used successfully in several States, but the number of approved processing plants available for custom work is inadequate. The movement toward this solution of the cleaning problem is growing and deserves thorough study.

DRILL surveys lead us to the conclusion that the quality of seed grain that is generally planted is far from ideal.

We have no doubt that this phase of crop production could be strengthened by a simple, five-point program:

The use of certified or registered seed to establish new varieties, or to replace mixed stock. The best guarantee of trueness to variety is the certified tag.

The use of homegrown seed for planting commercial acreage, with precautions to avoid admixtures during harvesting, threshing, storing, and all other steps in production.

The custom cleaning of all grain to be used for seed. Approved processing plants should be used in preference to farm cleaning or country elevator work unless the farms or elevators are equipped with specialized seed-cleaning machinery and conveyors.

Testing for germination of all seed intended for planting. Representative samples should be sent to the State seed laboratory or a commercial laboratory. Sending samples early, before the seasonal rush develops, is the best way to obtain prompt service.

Treating all seed grain with fungicides to control the seedborne diseases. Manufacturers' directions should be followed exactly, especially as to the amounts of chemicals used.

E. R. CLARK became Head of the Seed Laboratory in the North Central States Region in 1940 at Lafayette, Ind., and later at Minneapolis, Minn. From 1920 to 1940 he was pure seed specialist at the University of Minnesota Northwest School and Station.

C. R. PORTER became secretary-manager of the Nebraska Hybrid Seed Growers Association, Lincoln, Nebr., in 1958. He was formerly associated with Kansas State University and the University of Nebraska in crop improvement work.