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United States Department of Agriculture

Agricultural Research Service

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2012 Annual Report

1a. Objectives (from AD-416):
Develop integrated pest management of the potato psyllid and Liberibacter in a multicrop system.

1b. Approach (from AD-416):
Conduct insect transmission studies under laboratory conditions to determine Liberibacter acquisition and inoculation access time required for the potato psyllid to effectively transmit the bacterium and induce diseases. Determine the impact of Liberibacter on different plant growth stages under controlled field cage conditions. Determine density of potato psyllid required for this insect pest to effectively cause diseases in potato, tomato, and pepper.

3. Progress Report:
This is the final report for this project. “Zebra Chip” (ZC) is an emerging and economically serious disease which severely reduces the quality of potatoes used for potato chips, other processed potato products, and fresh potatoes. The symptoms in diseased tubers often appear as stripes or streaks, thus the name zebra chip. The disease is caused by a bacterium that is transmitted to potatoes by the potato psyllid. Because of the occurrence of this pathogen, growers are faced with several problems. First, there is little information regarding how or where to best sample for the insect. We developed and published the first sampling plan for the pest on potatoes providing growers a scientifically valid technique for estimating field populations and timing insecticide treatments. An additional sampling program is being developed for peppers. Second, because control of the psyllid requires expensive pesticides, and the psyllids have a proven capacity to develop pesticide resistance, we have evaluated a series of 'green' materials that have potential to repel the psyllids before they feed (and thereby transmit the pathogen). Several of these appear promising and are being incorporated in field trials as part of integrated pest management programs that control psyllid populations while minimizing effects on the beneficial insects we documented previously. These results provide useful information on the biology of the potato psyllid, role of different crops, effects of pesticides, and suggest new biological control strategies for this important insect. ZC was first reported on potatoes in OR, WA, and ID, in the summer of 2011. Since then, research is focusing on potential overwintering hosts of the potato psyllid in the Pacific Northwest. Also, genetic differences in populations of the potato psyllid were previously reported and these differences are being investigated in psyllids collected in these states in 2011 and 2012. This information will provide insight into the population dynamics and genetics of the potato psyllid in this important potato-growing region. This project studies the transmission and effects of the zebra chip bacterium on potatoes which contributes to objective 2 of the related in-house project, "Determine host resistance options, epidemiological parameters and develop diagnostic tests for emerging pests and pathogens of potato".

4. Accomplishments

Last Modified: 06/27/2017
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