Asparagus is a long-lived perennial vegetable grown for its tender spring spears. A well-tended bed produces for 15 to 20 years, so it is worth siting permanently in a spot that will not be disturbed by annual tilling.
Plants are grown from one-year-old crowns set in trenches. Do not harvest the first year, and harvest lightly the second year, to let the root system build. After harvest ends, let the ferny foliage grow all season to feed the crowns; cut it down only after it yellows in fall.
Asparagus Rust
Orange to reddish-brown pustules on stems and fern foliage, later turning black. Heavy infection yellows and weakens fronds, reducing next year's yield.
Cut and remove infected ferns in fall. Improve air circulation with wider spacing, avoid overhead watering, and plant rust-resistant varieties. Apply a labeled fungicide if pressure is high.
Fusarium wilt
Sudden wilting, brown streaks in stems, yellowing leaves. Affects sweet basil varieties most.
No cure. Remove and destroy plants. Do not replant in the same spot for 3+ years. Choose resistant varieties.
Asparagus Beetle
Blue-black or spotted beetles feed on spears, leaving brown scarring and bent tips. Dark eggs stand upright on spears and ferns; larvae defoliate the fronds.
Handpick adults and larvae and crush eggs. Keep the bed clean of debris where beetles overwinter. Harvest spears promptly and use spinosad or neem if populations are heavy.