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.
3. Progress Report:
The work summarized in this progress report relates to objective number 3 of the Project Plan for 018-00D: 3. Develop economical, sustainable, and ecologically sound methods for control of aphids, wireworms, and secondary pests of potatoes; and objective number 2 of the Project Plan for 020-00D: 2. Develop bio-intensive methods to manage insect vectors of zebra chip and purple top diseases. 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 disease spread to zebra chip-free areas. For a third year, field experiments at Texas AgriLife in Weslaco, Texas, 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 sprouting and development of plants from tubers of disease-free plants fed on by disease-free psylllids are not significantly affected by Liberibacter. It was confirmed that zebra chip-infected potato tubers generally do not sprout and if they do produce disease-free and short-lived potatoes, thereby significantly limiting disease spread. This information will greatly benefit the potato seed industry and promote national and international trade of fresh potatoes.