Bok Choi Problem
Photos and text by Debbie Roos, Agricultural Extension Agent.
Vegetable Weevil Damage
Holes in bok choi indicated a chewing pest. Close examination of the bok choi plants revealed small beetle larvae hiding down at the base of the leaves in the crown of the plant. These are the larvae of the vegetable weevil, a beetle that feeds on numerous vegetable crops as well as weeds. The larvae and adults feed on leaves and roots of host plants. Larvae seek shelter during the day and emerge to feed at night. Growers often don’t know what is to blame for the holes in their crop because they never catch this “stealth” pest in action! The vegetable weevil is primarily a cool-season pest that is active fall, winter, and spring but becomes dormant during the summer.
Vegetable weevils pupate in the soil, so fall and winter cultivation can reduce populations. Row covers and crop rotation can decrease pest numbers. Entrust®, a Spinosad product that is OMRI-approved for organic production (as of April 2006), can be used to help control weevil larvae. (See Pesticide Use Guidelines). As of April 2006, there is no Bt product that controls beetles that is approved for organic production. Natural enemies include ground beetles and rove beetles which search for prey at night.
* These recommendations apply only to North Carolina. They may not be appropriate for conditions in other states and may not comply with laws and regulations outside of North Carolina. Certified organic growers should consult their certifier before using a new pesticide. Unless otherwise noted, these recommendations were current as of April 2006. Individuals who use pesticides are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any pesticide. For assistance, contact your county Cooperative Extension Service agent. The use of brand names and any mention or listing of commercial products or services in the publication does not imply endorsement by the North Carolina Cooperative Extension Service nor discrimination against similar products or services not mentioned.