Summer is finally over. Brassica transplants are in the ground, and direct-seeded broccoli and lettuce plantings are now beginning. In the past week, I’ve observed or received reports from PCAs of key insect pests beginning to show up (or not) on melon and early produce crops in the desert.
Seedling pests: Flea beetles (FB) are beginning to show up in transplanted crops like they always do, but pressure has been light so far. We haven’t seen much in our experimental plots at YAC either. Remember, FB adults lay eggs in the soil of their favored local host plants (i.e., alfalfa, cotton, purslane, pigweed and nightshade) where larvae feed on the roots to later emerge as adults. So, keep in mind, the source of that FB infestations hitting your new stands may not just be freshly cut hay, defoliated cotton, or disked weeds. In some areas, crickets seem to be abundant. Crickets like moisture and are often found under sprinkler pipes but can also be found in cracks in soils around fields or in drainage areas.
Bagrada bug: No reports of bagrada bug adults in transplanted brassica fields yet. Fall populations have been very light over the past several years, but don’t fall asleep on these guys. It’s still early and they might surprise you as the season progresses. Look for those fresh feeding signs on cotyledons and young leaves. Experience suggests that they are most abundant after the monsoon humidity breaks.
Lepidopterous Larvae (worms): Worm pressure seems to be below normal. Trap catches so far show that Cabbage looper moths are almost non-existent, and no reports on melons to date. They should pick-up as we approach October. A few reports of Beet armyworm larvae on the earliest transplants, and areawide pheromone traps suggest that moth activity is about normal (highest in Tacna/Roll). But they will show up sooner or later, so get ready. You have numerous insecticide alternatives at your disposal to control them. Have had a couple of reports of Diamondback moth larvae on newly transplanted brassica crops. However, we’ve yet to capture moths on pheromone traps which suggests that adult immigration on high altitude winds associated with recent storms has not occurred yet. Remember, DBM disappear each summer and reestablish on desert crops via transplants or migrate in on monsoon/tropical storms. I strongly stress that you check your Cole crops closely this fall, particularly following storms or on plants originating from coastal CA.
Whiteflies: Area wide sticky trap captures have been above average for the past 2 weeks and whiteflies can migrate long distances on high winds. Reports in area melons range from light to moderate numbers so far, but there is still a lot of cotton out there yet to be picked. However adult numbers decreased dramatically on our experimental melons at the Ag Center over the weekend following the heavy rains we experienced (0.75”). Remember, you have several insecticide alternatives to control them in melons and produce.
For more information on IPM approaches for these pests visit:
