Why Is My Asparagus Turning Brown?

Planting

• For optimal planting and asparagus production, purchase year-old, disease-free crowns from a mail-order company or a garden center. The crown is the compressed stem and attached root system of a young asparagus plant. One crown can produce 1/2-lb. of spears annually. For the best growing conditions, plant asparagus after the soil has warmed up to 50 degrees Fahrenheit. If exposed to wet, cold soil for a prolonged period of time, asparagus plants can become susceptible to disease and rot. Natural fertilizers for asparagus include livestock manure, bone meal, blood meal and wood ash. Considered a hardy plant, asparagus can exhibit a rusty, brownish color when affected by rust and fusarium.

Rust

• Rust (puccinia asparagi), one of the most common asparagus diseases, can cause areas of brown discoloration on the plant. Identifying characteristics of rust include small, oval, yellowish spots on the stems and branches that become surrounded by yellowish-orange, cup-shaped structures as the disease worsens. As the rust takes over, the plant displays oblong, reddish-brown powdery masses (hence the name "rust") that become darker in color and eventually turn black. You can treat rust by applying an approved fungicide spray.

Fusarium

• Fusarium, a species of fungi that affects asparagus, is present in all asparagus-growing regions in the United States. When the fungi infect an asparagus plant, the stalks wilt, turn yellow and their growth is stunted. As the disease progresses, the spears can turn brown. This type of soil-dwelling fungi is long-lived and feeds on decaying asparagus residues and organic matter in the plant's surrounding soil. To limit asparagus exposure to fusarium, plant new asparagus crops in areas not previously affected by the fungi, fumigate the soil before planting and use treated seed.

Storage

• Because it's very perishable, harvest asparagus in the morning when the air temperature is cool. Immerse picked spears in ice-cold water to remove any heat from the plant then place them in plastic bags. When refrigerated at an optimal temperature of 38 to 40 degrees, asparagus will keep for one to two weeks.