Impact of Bagrada Bug on Desert Cole Crops from 2010-2014 (May 13, 2015)

The bagrada bug, Bagrada hilaris, first occurred on desert cole crops at damaging levels in the fall of 2010, and has since become an established pest. In an attempt to document the severity of Bagrada bug infestations on direct-seeded and transplanted cole crops, and the intensity of chemical management, we have annually surveyed growers and PCAs from Yuma, Imperial and Maricopa counties since 2010. We recently conducted our survey in early April. Since 2010, the cole crop industry has experienced widespread bagrada bug infestations throughout the desert from September into November, although some years have been less intense than others. Last fall (2014) was one of the lighter years. Based on seasonal population abundance studies of adults infesting non-treated broccoli plants at the Yuma Ag Center (see graph below), bagrada bug infestations in the fall 2014 were much lower than we had observed the previous two seasons. However, with the warmer temperatures this winter, spring populations occurred very early and at higher numbers than in the previous 4 years. Estimates of stand losses from bagrada bug infestations at stand establishment in both direct-seeded and transplanted crops has decreased by almost 50% over the past 5 years. Lower losses in 2014 are likely due to the lower pressure experienced last season. Plant injury, defined as plants with multiple heads, forked terminals, and/or blind terminals resulting from Bagrada feeding, was also lower in 2014 compared with 2010. These data suggest that PCAs have adopted effective management programs to protect seedling crops during stand establishment. Insecticide usage to control this pest remains high, but a lower percentage of acreage was treated in 2014 than in previous years. Pyrethroids remain the primary product used for controlling bagrada bug adults either via chemigation or with foliar spray applications. Based on survey results, products that have contact activity appeared to provide the most effective control against bagrada adults on both direct-seeded and transplanted cole crops. However, more neonicotinoid products (Venom, Endigo) are beginning to be implemented into PCAs IPM programs. Overall, the results of the PCA survey are consistent with results obtained in research trials conducted at the Yuma Agricultural Center over the past four years. A summary of the 2010-2014 survey results can be found in the following report: Impact of Bagrada Bug on Fall Cole Crops, 2010-2014.

Remember, When in Doubt . . . . . “SCOUT”