Location: Temperate Tree Fruit and Vegetable Research
Project Number: 2092-22000-022-025-T
Project Type: Trust Fund Cooperative Agreement
Start Date: May 1, 2022
End Date: Jun 30, 2023
Objective 1: Optimize FANA application methods to reduce zebra chip symptoms in potato. Objective 2: Develop and test RNA-based biopesticides to suppress potato psyllids.
Objective 1: Optimize FANA application methods to reduce zebra chip symptoms in potato. In 2022, we will conduct a field study to test whether FANA treatments reduce zebra chip symptoms under field conditions. We will test the most effective FANA treatment from our previous study (Hunter, Cooper, et al. 2021) in single and double doses as soil drenches or as foliar applications. Controls will include water and scramble FANA (mock) for a total of eight treatments. We will use a Randomized Complete Block design with 3 replications (24 cages). Each replication will consist of a short row of 6 potato plants confined within hoop cages. Plants will be inoculated with the zebra chip pathogen by releasing 3 colony reared Liberibacter-infected potato psyllid males at the base of each plant in mid-July. Potatoes will be harvested by hand in autumn and will be sliced to observe the presence or absence of zebra chip symptoms. Objective 2: Develop and test RNA-based biopesticides to suppress potato psyllids. In 2022, we will conduct greenhouse trials using potted plants to test several potato psyllid RNA targets. RNAi targets will first be tested by confining nymphs to excised leaves that have the cut end placed in water or in an RNAi solution. The nymphs will be collected after 3 days, and quantitative PCR will be used to compare target gene expression between treatments. After verifying RNAi targets, the RNA-biopesticides will be applied as slow-release pellets at several different rates. Each plant (15 per treatment) will be inoculated with 3 colony-reared potato psyllid females. The number of living offspring will be counted 21 days after insect releases. We anticipate conducting field trials by year 3 of the study.