Psyllid problems do not occur every season. In some areas of the state, Cooperative Extension pest alerts provide warnings of psyllid outbreaks. Homeowners not able to properly identify psyllids may wish to routinely treat susceptible plants. Protectant treatments may be needed from when plants are 6 inches tall until midsummer. Well-established plants with abundant foliage usually can tolerate late season infestations with little yield loss.
Thorough application is required for control.
Preharvest interval requirements for Diazinon are 35 days on potatoes and one day on tomatoes. Apply soaps and detergents so that the psyllids are covered with the spray mixture. Some plants may be injured by soap or detergent sprays, so always test sprays first on a small area of the plant. Increased hairiness of the leaves is reported to make plants less favored by psyllids. 1 Colorado State University Cooperative Extension entomologist and professor, bioagricultural sciences and pest management.