American wormseed, or Jerusalem oak (Chenopodium ambrosioides anthelminticum), is a coarse weed, occurring commonly in waste places and often in cultivated ground throughout the eastern and southern parts of the United States. The seeds (fruits) and the volatile oil distilled from the tops of the plant are employed in medicine.

This plant grows well under cultivation in almost any soil, but a good sandy loam is preferred. It is now cultivated for oil production only in a small area in Carroll County, Md. The seed is sown in well-prepared beds about March 1, and between May 15 and June 15, when the seedlings are 4 to 5 inches tall, they are transplanted and set about 10 inches apart in rows about 3 feet apart. The soil is kept entirely free from weeds by shallow cultivation throughout the growing season.

Harvesting is usually begun early in September or as soon as the seeds have taken on a black color, but before the plants have turned brown. If harvesting is delayed until the plants are fully mature there will be considerable loss through shattering and a diminution in the yield of oil when they are distilled. The crop is harvested with large knives or sickles, either by cutting off the entire plant at the ground or by cutting the branches separately. The latter method saves the labor of handling a quantity of useless woody material and also requires a smaller still capacity to handle the crop. After cutting, the plants are laid out on the ground in rows and allowed to cure for about three days before they are distilled.

In the South wormseed has been grown successfully as a seed crop. The ground is prepared in February and laid off in rows about 4 feet apart. A furrow is opened in each row, in which a complete fertilizer is applied at the rate of 400 to 500 pounds per acre. The soil on each side of the row is thrown in with a turnplow, forming a low ridge, which is then flattened with a light roller. The seeds are sown on this ridge with a drill. The plants are thinned to stand 18 inches apart in the row and are given frequent shallow cultivation.

The crop should be ready for harvesting late in July or early in August and should be cut before the tops begin to take on a brown color. The plants are cut either with a mower or old-style grain reaper and are left in the field until thoroughly dry. They may be housed and the seed thrashed out when convenient, but, since the seeds shatter easily, waste will be avoided if the plants are thrown upon large canvas sheets and the seed thrashed out in the field. The seed is light and not easily cleaned, but wire sieves of suitable mesh have proved very satisfactory for this purpose.

The yield of seed per acre averages about 1,000 pounds. The yield of oil varies, but under favorable conditions about 40 pounds per acre is regarded as a fair average. The area planted varies according to the price of the oil and may range from 175 to 450 acres. The average annual production of oil is estimated by producers to be 10,000 to 12,000 pounds.

The prewar price of wormseed ranged from 6 to 8 cents a pound. The price in June, 1920, was about 15 cents a pound. The prewar price of the oil ranged from $1.40 to $5.50 a pound. The price in June, 1920, was $9 to $9.50 a pound.