We mentioned last month that Bagrada bugs were starting to show up in light numbers at the Yuma Ag Center (YAC) and on both transplanted and direct seeded crops throughout the Yuma area. It was suggested that PCAs keep their eyes peeled for damage and adults on seedling Cole crops. Obviously, they have; numerous reports in the past 2 weeks indicate that Bagrada have been invading young seedlings throughout the area. Much of the pressure appears to be in Bard and Dome Valley but reports of their presence have come in from throughout Yuma County. We’ve also had numerous reports of Bagrada in the Imperial and Coachella Valleys. In most cases, PCAs have noted that adult pressure was high enough to justify spray treatments. Remember, it doesn’t take much damage to result in significant yield losses. Our research has shown that yield/quality losses in broccoli, cauliflower and other cole crops occur when feeding damage exceeds 5% of seedling plants in fields. In my estimation, bagrada bugs have been numerous enough this fall in many local growing locations to cause yield loss if not controlled, including the Yuma Ag Center (north Yuma Valley). To put into perceptive Bragada’s presence relative to previous years, the chart below illustrates Bagrada abundance on untreated broccoli at YAC. The data clearly shows that Bagrada are trending upward so far this fall in much higher numbers than what we’ve seen in the past 5 years. In fact, we’ve had enough bagrada pressure to conduct efficacy trial, which is something that I haven’t done since 2015. The fact they are rapidly moving into direct-seeded crops further suggests that the populations successfully over-summered in the area, presumably on cotton, alfalfa, grass crops and desert vegetation. This is not surprising given the wet spring which likely enhanced their survival. More information on bagrada bug management on can be found in: Bagrada Bug Management Tips for the Low Desert 2019.

Note: based on research from recent and previous bagrada efficacy trials your best options for residual control of bagrada are two-fold. Pyrethroids such as bifenthrin (e.g., Brigade, Bifenture, Sniper) or lambda-cyhalothrin (e.g., Warrior II, Lambda-Cy) should provide about 4-5 days of residual control. Neonicotinoid combinations such as Endigo ZC (thiamethoxam+Lambda-cyhalothrin) and Scorpion/Venom (dinotefuran)+bifenthrin are showing extended residual (~7 days). Finally, remain vigilant; bagrada will likely be abundant for the next 2-3 weeks assuming normal our weather. As George Herman Ruth Jr once quipped “It's hard to beat a person who never gives up.” And who can forget the other great Yankee, “It ain’t over till it’s over”.

Name that Pest

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

To contact John Palumbo go to:jpalumbo@ag.arizona.edu

For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
College of Agriculture, The University of Arizona, Tucson, AZ.