Bodnar and Wedel (6) have reported fall seeding of rye in asparagus fields to improve subsequent crop quality, reduce handling, damage, and increase overall monetary returns. Rye provides a cover of mulch residue in the early spring when asparagus is harvested and improves the yield and quality of the spears, and allows better accessibility to fields in wet weather. They indicate that rye can be applied aerially or seeded using a high-clearance tractor with a seeder to clear the fern. Rye can also be applied by hand with a rotary-type broadcast spreader. They recommend seeding in the fall. To encourage germination and quick establishment, sow 2 to 4 bushels of rye per acre just before an expected rain.
Mowing off the shredded fern next spring will also mow back the rye cover. Let the rye grow back to a height of 6 to 8 inches, and then apply a contact herbicide to burn it off before harvesting.
Bodnar and Wedel cite several advantages resulting from the rye residue that remains after the herbicide treatment:
1. It prevents "goose necking," or curving of spears by wind or wind-blown sand.
2. It reduces soil erosion and the splashing of soil onto spears during periods of heavy rainfall.
3. It retards "ferning out," or early opening of spears, on hot days because the rye cover keeps the soil cooler.
4. The lower soil temperature will also tend to delay the emergence of spears and possibly help avoid late spring frosts.
5. The rye residue adds organic matter to the soil.
The rye stubble may be hard on a harvester's hands, but wearing gloves should rectify this problem.
Using one-year-old crowns of the new male hybrid varieties can increase yields several times over the use of the 'Washington' types. A grower can expect a yield of about 500 lbs per acre during the second year, and 1,000 to 1,500 lbs per acre during the third year. This can increase to 2,000 lbs per acre during the fourth year, 3,000 lbs per acre during the fifth year, and 4,000 lbs per acre during the sixth year (8).
Freshly harvested asparagus is highly perishable and loses quality rapidly at temperatures above 40 degrees F. Collect the harvested spears as soon as possible, protect them from the sun, immerse them in ice-cold water or hydrocool (a showering of cold 36 degrees F water on the asparagus) for 10 minutes, and store them at a temperature of just below 40 degrees F or market them as soon as possible.
Insure good cooling of the spears by harvesting in perforated hard plastic tubs where spears can be immersed into cold water tanks or hydrocooled (Figure 15). Asparagus can also be placed in wooden crates or reinforced fiberboard containers for hydrocooling.
The coolant water should be chlorinated to approximately 125 parts per million of chlorine to protect the asparagus from decay organisms (35). If temporary storage is required, maintain high humidity at temperatures between 32 and 36 degrees F. Asparagus can be stored in plastic bags for at least one week with little quality loss if optimum storage conditions are maintained between 32 and 36 degrees F with a relative humidity of 95%. Asparagus should be stored between 32 and 34 degrees F with a relative humidity of 90 to 95% if held up to three weeks. Asparagus is highly sensitive to freezing injury. It can turn the spear a deep dark green that will rapidly deteriorate. To maintain the highest quality, store asparagus in an upright position to avoid tips curving upward in response to light if stored in a prostrate position.
Bacterial soft rot, gray mold rot, and Fusarium are fungus diseases that can attack asparagus in storage if the spears are injured and if storage temperatures rise above 40 degrees F. If spears are held at temperatures below 34 degrees F for more than 10 days, spears will develop chilling injury, which is characterized by small pittings that develop on the spears, leading to premature breakdown and spoilage. Fresh asparagus deteriorates rapidly when low temperatures are not maintained. At room temperature, it quickly becomes tough and loses sugar content (46). Careful handling with proper storage temperatures will ensure maintenance of product quality and avoidance of losses from disease-causing organisms (40).
If asparagus is displayed at the retail level in refrigerated display racks, the spears are generally tied in one-pound bunches with the butt ends standing in ice water in shallow trays to replenish moisture loss (Figure 16). Water-absorbent paper that is periodically moistened throughout the day can also be used. Sprinkling the spears periodically with cold water will help preserve their tender quality. The use of clear plastic "clam shell" containers are used to display asparagus upright with the butt ends resting on a water absorbent pad placed at the bottom of the clam shell. They create a very attractive display.
Two federal grades apply to asparagus : U.S. No. 1 and U.S. No. 2. Usually, U.S. No. 1 requires stalks to be fresh, well-trimmed, and fairly straight. They should be free from decay or damage. Unless otherwise specified, stalks should be no less than one-half inch thick at the base, 7 to 9 inches in length, and color should not be less than two-thirds green (46).
There are several types of shipping containers for asparagus:
Foodservice packs
California Stalk Diameters
Asparagus should be graded and packaged according to local market demands. Wash the asparagus thoroughly and discard all spears that are too slender or crooked or those with open heads, broken tips, or contaminated with insect eggs. Also discard those damaged by insects, disease, wind, hail, or frost.