Crop Profile for Strawberries in California - Regional IPM Centers

Biological:
● General Predators. Bigeyed bugs (Geocoris) are the most important natural enemy of lygus
bugs. They feed on eggs and young nymphs. Damsel bugs also feed on eggs and nymphs, and
minute pirate bugs feed on lygus eggs. None of these natural enemies; however, is successful in
keeping lygus from reaching damaging levels when there is a heavy migration of adults into
strawberry fields when wild vegetation dries up in the spring.
● Anaphes iole. A parasitic wasp, Anaphes iole, which attacks lygus eggs, is available
commercially and can be used for inoculative releases. It can reduce lygus populations in
strawberry fields, but because thresholds for this pest are very low, economically acceptable
results have not been achieved.
Chemical:
Chemical treatments are applied to control lygus when they are at the most susceptible first and second
instar nymph stages. Insecticides applied to later nymphal stages and adults are much less effective.
Short residue insecticides do not control lygus bugs, necessitating repeated applications.
● Malathion. 3 day PHI. Malathion is the most important treatment for lygus immediately after
hatching. This chemical works well in IPM programs. Malathion is only effective against the first
3 nymphal instars. Effective control requires multiple applications, as residual is short-lived.
Very high levels of lygus bug resistance to this material have been identified in some growing
areas. Malathion is applied at an average rate of almost 2 lbs ai per acre to about 55% of
strawberry acreage. Statewide, the number of repeat malathion applications per year is 4. The
restricted-entry interval for malathion is 12 hours.
● Fenpropathrin. 2 day PHI. Synthetic pyrethroids such as fenpropathrin (DANITOL) are best
when used late in the season due, in part, to their disruption of beneficial insects and the resulting
infestations from other pests, especially spider mites. Pyrethroids are the most effective materials
currently registered for lygus control in strawberries but the potential for the development of
resistance to these insecticides is high. There is concern that excessive use of synthetic
pyrethroids, like fenpropathrin , may lead to the development of insecticide resistance in both
spider mites and lygus bugs. Lygus bugs should be the primary target pest for this material.
Fenpropathrin was applied at an average rate of 0.4 lb ai per acre onto about 14% of strawberry
acreage in 1996, with an average of 1 application per season though 2 applications/year are
allowed. The restricted-entry interval for fenpropathrin is 24 hours.
● Bifenthrin. 0 day PHI. Bifenthrin (BRIGADE) is a relatively new tool available to California
strawberry growers and is applied at a rate of 0.04 to 0.2 lbs ai/acre. Synthetic pyrethroids such as
bifenthrin are best when used late in the season due, in part, to their disruption of beneficial
insects and the resulting infestations from other pests, especially spider mites. Pyrethroids are the
most effective materials currently registered for lygus control in strawberries but the potential for