1a.Objectives (from AD-416):
To assess impact of. 1)liberibacter-free and liberibacter-infected psyllids on plant emergence, viability, disease incidence, and yield;. 2)zebra chip on potato seed quality of different potato varieties; and. 3)zebra chip on potato seed quality depending on timing of plant disease infection.
1b.Approach (from AD-416):
Tubers produced by potato plants of different cultivars exposed to liberibacter-free and liberibacter-infected psyllids will be planted in small field cages. Cages will be monitored for plant emergence, seed viability, zebra chip incidence, yield, and tuber processing quality. In addition, tubers produced by potato plants inoculated with liberibacter at different plant growth stages will be planted in similar small field cages and evaluated as above.
Little is known on zebra chip tuber transmission and the impact of this disease and its insect vector on potato seed quality. One major concern is that zebra chip-infected tubers may give rise to zebra chip-infected plants. Thereby increasing the risk of the disease spread to zebra chip-free areas. As a follow up on a study previously conducted at the ARS Wapato location, additional field experiments at Texas AgriLife in Weslaco, TX, assessed the effects of liberibacter-free and liberibacter-infected psyllids on plant emergence, viability, disease incidence, and yield of a dozen of commercial potato varieties under controlled cage conditions. It was confirmed that plant emergency rate and development from tubers produced by plants affected by liberibacter-free psyllids are not significantly affected. It was also confirmed that zebra chip-infected potato tubers generally do not sprout and if they do, produce disease-free potatoes, which limiting disease spread. This information will greatly benefit the potato seed industry. The work reported here addresses objective 3 of the parent project plan.