Another type is the tined windrower, which consists of a series of metal tines each one progressively longer fastened to the back of the mower cutterbar so that the material being cut rolls into a continuous roll as the mower moves through the field.

The wheel windrower consists of two tined wheels mounted behind the mower cutterbar so that they come in contact with the ground and slowly rotate and gently fold the outer edges of the cut material toward the center to form a swath.

The width of material cut and put into the windrow should be about the same as the width of normal cut of the combine that is to be used to thresh the seed. Swathing the straw for the seed to cure is a method used to harvest seed crops such as bentgrass, alfalfa, bermudagrass, Merion bluegrass, buffalograss, and many others.

CHEMICAL SPRAYS may be used to hasten the curing of standing seed crops. They make it easier to combine a crop before the seeds shatter excessively.

Chemical curing has been effective in reducing cost and losses in the harvesting of seed in sunshine areas where the temperature is moderate to high. The chemicals give uncertain results in areas where cool nights, heavy dews, fogs, and cloudy days occur. For example, in the Willamette Valley of Oregon, a treatment may be worthless one time; the next time the chemical will dehydrate the leaves, seed pods, and stems enough so that the standing crop can be combined without damaging the seed or the roots. In California, where the temperature is higher and the humidity is lower, nearly all the alsike clover is chemically cured and direct combined with the aid of chemical sprays. The practice is used on Ladino clover, alfalfa, red clover, birdsfoot trefoil, sudangrass, Alta fescue, and orchardgrass.

The advantages are many where chemical dehydration and direct combining can be practiced. It saves the labor and equipment required to windrow a crop. The loss of seed caused by cutting, windrowing, and the pickup operations are saved by direct combine harvesting.

The rapid development of new agricultural chemicals has led to the appearance of many unproved desiccants on the market. To prevent the possibility of poor seed production, one should use only the chemicals that have been tested and recommended by agricultural experiment station specialists or county agents.

TIMING the harvest is important.

Tests in the Willamette Valley have shown that a day's delay in harvesting may result in severe loss of seed due to shatter. As an extreme example, yields of birdsfoot trefoil were found to be reduced about 25 percent over a 4-hour period of hot, sunny weather after several days of cool weather.

A 3-year study was made at the Oregon Agricultural Experiment Station of the effect of mowing time on the amount of pure, live seed collected in the combine grain bin. It showed that proper timing could increase by 75 percent the seed saved of crimson clover, 36 percent of Alta fescue, and 60 percent of subterranean clover.

Early harvest does not work on all seed crops, however. In the same test, the take of pure live seed of birdsfoot trefoil was reduced substantially by early harvest. The first seed set was beginning to shatter before the germination of harvested seed was high enough to meet the requirements of State and interstate seed laws.

Enough nutrients were left in the windrowed straw of crimson clover for the seed to finish maturing. The result was the largest amount of seed, the highest germination, and the lowest percentage of damaged and shriveled seeds.

Records were kept of the appearance of the stems, the leaves, the floret, the seed, and the moisture content of the seed. Color pictures were used as guides to pinpoint the time to harvest a crop for maximum yields. Only the seed moisture at the time of cutting was a true indication of the time to windrow the crop each year.

Results of research studies indicate that a seed is at its peak in quality at maturity and that it should be harvested immediately in order to get the highest percentage of quality seed. Seeds start deteriorating immediately upon reaching maturity, and all man can do is to retard the change by regulating the time and method of harvest and treatment after harvest.

JESSE E. HARMOND is Head of the Small Seed Harvesting and Processing Section, Agricultural Engineering Division, Agricultural Research Service. He began research in agricultural engineering in the Department in 1939. He established the Seed Cleaning Research Laboratory on the campus of Oregon State College in 1953.

JAMES E. SMITH, JR., is field plant materials technician for the Soil Conservation Service in Texas, stationed at Temple, Tex.

JOSEPH K. PARK is an agricultural engineer in charge of research in the harvesting of small seed, conducted by the Department of Agriculture and Clemson Agricultural Experiment Station, Clemson, S.C.