Summer 2013 Field Observations
Bagrada bug exclusion is best option for organics
The Bagrada bug, Bagrada hilaris (Burnmerister), has become a serious pest of on selected crops in nurseries. The primary plant hosts are plants in the Brassicaceae (Cruciferae) family, which includes important foods like cabbage, kale, turnip, cauliflower, mustard, broccoli and radish. They especially like the invasive wild mustard (shortpod or black). In nurseries, however, they prefer ornamental kale, alyssum and stock, and they prefer organically grown crucifers. Field-grown ornamental crucifers — especially stock — are also showing significant damage from this pest.
Growers are reporting that the Bagrada bug can be killed relatively easily with insecticides, but contact or coverage is difficult and some portion of the population always survives. Therefore, consistent applications are necessary. Chemical control options are few, however, due to the restrictions on labels. Remember, the products used have to be registered for nurseries and/or greenhouses. It also has to be registered for food crops if it is a vegetable headed for the garden. Options are especially limited for organic food crops grown in the nursery or greenhouse: One grower observes good kill using insecticidal soap, but the bugs just keep coming, and they have to consistently reapply.
Since there are few chemical control solutions for organic vegetables produced in the nursery, some growers have committed to protecting their plants behind insect exclusion screening. The Bagrada bug adult is large relative to whiteflies, but hatchlings are small. A screen that would exclude whiteflies would probably work very well.
If you want more information about Bagrada bugs, visit the following web site: http://cisr.ucr.edu/bagrada_bug.html. Also see Julie Newman’s “Regional Report” in this newsletter and the handout she mentions which has a list of resources.
James A. Bethke
Farm Advisor, Nurseries and Floriculture
UC Cooperative Extension San Diego, North County Office
151 E. Carmel St., San Marcos, CA 92078
(760) 752-4715 phone, (760) 752-4725 fax