Management of Potato Psyllid Nymphs on Potato, 2016*

Potato psyllid management in the state of Washington is challenging and threatens producers’ profitability. Potato psyllids can cause feeding damage characterized as psyllid yellows under high densities, in addition to their ability to transmit the bacterial disease known as Candidatus Liberibacter solanacearum (CLso), or zebra chip. Zebra chip infected tubers are unmarketable and can result in complete crop loss. A study was performed in Pasco, WA to evaluate the efficacy of four insecticides applied by foliar and chemigation application to control potato psyllid nymphs on Ranger Russet potato. The plots were 11.33 ft wide by 30 ft long in a RCB Design with four replicates per treatment. Foliar applications were made with a tractor mounted plot sprayer using seven air induction flat fan nozzles spaced 20 inches apart spraying 20 gpa at 25 PSI, and with a boom height of 20 inches. Chemigation applications were made using a pull-type sprayer fitted to mimic applications made through a center pivot irrigation system. The boom was three ft high with 7 Full Jet ¾ inch nozzles spaced 20 inches apart applying 2,715.43 gal of water per acre. The pesticides were mixed in a three liter bottle and injected into the water spray at 34 psi using compressed CO₂. Applications were made on 12 Aug 2016.

Evaluations of the trial were made by gathering 10 compound leaves per plot and enumerating the number of psyllid nymphs on each leaf. The data were subjected to ANOVA; treatment means were separated using Fisher’s PLSD (P< 0.05). The evaluations on 24 Aug 2016 showed significantly fewer potato psyllid nymphs in the plots treated with a foliar application of Exirel than a foliar application of Brigade (Table 1). In previous experiments, similar trends occurred where synthetic pyrethroid applications resulted in increased potato psyllid densities compared to other more effective insecticides. No treatments were significantly different than the untreated check (Table 1).

Author notes