Impact of Bagrada Bug on Desert Cole Crops from 2010-2013 (June 11, 2014)

We recently conducted our annual bagrada bug survey of growers and PCAs to estimate the impact of this new pest on desert cole crops. The bagrada bug, Bagrada hilaris, first occurred on desert cole crops at damaging levels in the fall on 2010, and since that initial outbreak it is clear that the invasive stinkbug has become an established pest of desert cole crops. In 2013, widespread infestations were reported throughout the desert growing area from September to well into November, comparable to the infestations growers experienced in the previous three years. Stand losses and yield/quality reductions to broccoli, cauliflower, cabbage and other Brassica crops were considered economically significant in most growing areas, and were reported at levels comparable to 2010. Insecticide usage to control this pest remains high, and consists mainly of pyrethroid chemigations and foliar sprays. In an attempt to document these impacts, we have surveyed produce growers and PCAs from Yuma, Imperial Valley and central Arizona on an annual basis since 2010 to estimate the severity of Bagrada bug infestations on direct-seeded and transplanted cole crops, and the intensity of chemical management. A summary of the 2014 survey results can be found in the following report: Impact of Bagrada Bug on Desert Cole Crops. Based on PCA estimates, bagrada bug infestations have been present on greater than 85% of the direct seeded and transplanted cole crop acreage over the past 4 seasons. In direct seeded crops, a greater % of the acreage was treated for bagrada adults than were infested. This is not surprising given the preventative nature of controlling bagrada infestations in order to reduce stand losses and plant injury. On average, about 80% of the acreage was chemigated 1.6 times, and about 88% of the reported acres were sprayed an average of 2.4 times in direct seeded-crops. When the number of chemigations and foliar sprays are combined over all three years, almost 4 insecticides applications were made to control this pest. Damage from bagrada bug infestations at stand establishment in both direct-seeded and transplanted crops has decreased by more than 50% from 2010 to 2012, but increased in 2013. PCAs also provided information on insecticides that provided effective control through both chemigations and foliar sprays. In general, they reported that products that have contact activity (i.e., Pyrethroids, OP/Carbamates) appeared to provide the most effective control against bagrada adults on both direct-seeded and transplanted cole crops. Overall, the results of the PCA survey are consistent with results obtained in research trials conducted at the Yuma Agricultural Center over the past three years.