Immature seeds may seem to be of good planting quality. If they are pressed between the thumb and forefinger, however, the seedcoats break with a distinct popping sound, and the seeds are found to be only partly formed. These seeds are known as pops, and have little value as planting stock.

Seed that has a low weight per bushel but appears good in other respects contains a high percentage of pops and usually will not be satisfactory for planting. Recleaning the seed with a gravity table or a strong air-blast, or both, should remove the lightest seed and improve the value of the seed for planting.

Castorbeans are poisonous to people and animals. Precautions must be taken to prevent mixing the seeds with food or feed crops.

SESAME does best on fertile, well-drained soils of medium texture with a neutral reaction.

Commercial fertilizers suitable for cotton are satisfactory for sesame on the same soil.

The seedbed should be mellow, warm, and moist.

Sesame seeds are small. One pound contains about 150 thousand seeds. The seedlings emerge from the soil quickly when conditions are favorable, but the small plants make slow growth at first.

It is harder to establish a good stand of sesame than some other oilseed crops. The crop requires a warm soil and warm weather. A cool period after planting may destroy the stand. A heavy rain after planting may compact the soil and prevent uniform emergence. Replanting may be necessary then.

Sesame is normally planted about 1 pound per acre in rows 36-42 inches apart. Vegetable planter boxes are used. Ordinary cultivating equipment used for corn, cotton, and grain sorghum may be used to control weeds.

The small, rather soft seeds are easily damaged in harvesting, particularly threshing.

Two types of sesame are grown. One is dehiscent that is, the capsules open when dried after maturity, and the seeds spill out. This type requires little mechanical work to remove the seeds from the capsules.

The other type has indehiscent cap- rules, which are difficult to thresh.

Since little effort is required to remove the seeds from dehiscent capsules, the cylinder on the combine may be set as far as possible from the concave. Slow cylinder speeds of not over 500 revolutions a minute for 21-inch cylinders, 580 for 18-inch, or 700 for 15-inch cylinders should be used. A slower speed may be used if all the seed is removed. The threshing surface may be increased to at least double the standard area by increasing the number of cylinder bars, concave bars, or both. Tailings should be returned directly to the shakers and not the cylinder.

Undesirable seeds, such as seeds of johnsongrass, that are harvested with sesame are extremely difficult and expensive to remove. Every effort should be made to eradicate johnsongrass plants before harvest.

Considerable success has been attained in breeding indehiscent varieties that do not shatter their seeds at maturity. Although indehiscent varieties available in 1961 were not widely grown, improved varieties may be developed that will have acceptable yield and quality of seed and can be grown by complete mechanization.

Threshing indehiscent varieties is more difficult than for dehiscent varieties and requires extra care. The plants are cut and windrowed with standard machinery. Most sesame is grown under irrigation, and the windrows are placed on the rows and not in the irrigation furrows, where pickup would be difficult and seed damage from rain- water standing in the furrows might occur. The plants should be dry and brittle before combining is attempted. This may be 2 or 3 weeks after windrowing.

The capsules of nonshattering varieties are hard. The seeds are soft and easily damaged. Even microscopic cracks in the seedcoat can reduce the viability of the seeds.

Cylinder speeds should be reduced below the requirements for small grain or sorghum to approximately 500, 580, or 700 revolutions per minute for 21, 18, or 15-inch cylinders, respectively. As for dehiscent sesame, the threshing surface should be doubled by adding additional cylinder bars, concave bars, or both. Cylinder clearance should be set to one-eighth inch. Unthreshed capsules should be returned to the cylinder.

Indehiscent seeds sustain more mechanical damage than dehiscent seeds. A rough estimate of damage can be obtained if 100 seeds are examined for injury. If fewer than 20 percent have injuries, one can assume the combine is doing an acceptable job. Both sides of each seed should be examined.

A number of serious diseases of sesame are carried on the seed. Some measure of control can be attained by producing seed free from disease and by proper seed treatment. If seed free from seedborne diseases is sown on ground not in sesame for several years and if the harvested seed is protected from weather and mechanical damage, the danger from seedborne diseases will be diminished.

J. O. CULBERTSON is Leader, Industrial Crops Investigations, Oilseed and Industrial Crops Research Branch.

H. W. JOHNSON is Leader, Soybean Investigations, Oilseed and Industrial Crops Research Branch, Beltsville, Md.

L. G. SCHOENLEBER is Leader, Special Crops Harvesting and Processing Investigations, Harvesting and Farm Processing Research Branch, Stillwater, Okla.