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.
Rust
Orange to brown raised pustules on the undersides of leaves, with yellow spotting on the upper surface. Heavy infections cause leaves to yellow and drop.
Remove and destroy infected leaves. Avoid overhead watering and improve air circulation. Apply a sulfur or copper-based fungicide if it spreads. Clear plant debris in fall.
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
Crioceris asparagi →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.