A. Insect pests Insect pests in the form of worms are of major concern to crucifer growers. Two pest monitoring procedures and two action thresholds have been developed for this group of pests. One system is based on counting the number of insects on plants. While this method is more time consuming, it also provides more detailed information for pest management decision-making. The other system, based on percent of plants infested with any of the three insect pests, is less time consuming in the field but sacrifices some information.
Specific thresholds are still under development for broccoli.
Onion thrips constitutes another major economic insect pest for cabbage. Plants are monitored to determine when insecticides should be applied. If pressure from onion thrips is high, chemical sprays can offer only limited control. While a biological control alternative is currently available, it has not proven to be effective in commercial settings. Varieties do exhibit differences in resistance to this pest, but our database on resistant varieties is limited at this time.