Asparagus beetle activity is on the rise. The adult beetles hide in soil cracks or underneath residue during the heat of the day. Egg laying is often the most obvious sign of their activity. The presence of eggs on the harvest spears, may affect marketability. On young fern, heavy amounts of larval feeding has a negative impact on growth and development.
As harvest concludes, scout plantings regularly as the spears begin to elongate and develop a full canopy of fern. Spray thresholds are as follows:
Eggs: 2 /10 spears with eggs
Larvae: 50% of plants with larvae OR 10% Defoliation
Adults: 5-10% of plants infested
If controls are required during the harvest season, play close attention to the pre-harvest intervals. Products with a 24-hr pre-harvest interval include: malathion (Malathion 85E), cypermethrin (Mako, Upside 2.5 EC), and acetamiprid (Assail 70WP).