University of Idaho Extension Seed Potato Specialist Dr. Phillip Nolte and his team of four technical support staff operate several potato research and extension projects out of their headquarters at the UI Research and Extension Center in Idaho Falls. In addition to research on Potato virus Y (PVY), seed piece treatments, in-furrow treatments and wound healing, the group also operates a potato disease diagnostic laboratory.
IPC Research Activities
Seed Potato Quality Improvement. Research and extension activities on seed potato quality improvement are some of the most important work performed by Nolte's group. PVY has always been one of the most important of the potato viruses, but recent changes in the virus have made this common disease a much greater headache. The reason this virus is more problematic is that newly discovered strains cause milder foliar symptoms in potato, making it more difficult for seed producers to manage.
Leaves from the Ranger Russet in Figure 1 show the range of symptoms caused by these new PVY strains. The robust-looking leaf on the right is the healthy one. In addition, and perhaps more importantly, some of these new virus strains can cause both internal and external tuber damage.
Research at this laboratory and others across the nation indicates that the best management recommendation for PVY is to plant seed with zero or very low levels of PVY. The best way to ensure that seed is free of or very low in PVY is to subject seed lots to more intensive PVY testing. One fact has become abundantly clear: Visual detection of PVY is no longer adequate, especially for seed potatoes that are going back into a seed-increase program. Nolte's group performs sophisticated laboratory tests (ELISA) on seed potatoes to determine PVY infection levels.
Positive PVY samples are sent to Dr. Alex Karasev's laboratory on the UI campus in Moscow for characterizing strain type. The Nolte and Karasev laboratories have also been testing seed planted in the Idaho seed program for PVY content to compare to the documents supplied with the seed by the agency that certifies it. This activity is intended to determine how well the certification agencies, Idaho's included, are performing in regard to testing for PVY.
Due partially to the research on PVY performed in this laboratory, the Idaho seed industry has converted completely over to using ELISA to determine PVY in the winter seed grow out in California. The result? Over the last five years the Idaho industry has seen a dramatic reduction in the amount of PVY in Idaho seed potatoes.
Extension Potato Specialists. Another grant from the Idaho Potato Commission funds the extension activities of Dr. Nolte and Dr. Nora Olsen from Kimberly, Idaho. Dr. Olsen's activities will also be featured in a future article. This funding is utilized for numerous UI Extension activities from extension bulletins on current problems in the industry to presentations delivered across the state to the late blight hotline to articles like this.
The famous UI Potato Conference ("Potato School") held every January in Pocatello, Idaho, is the flagship product of these extension activities. IPC funds are also used to partially fund the technical support personnel necessary to perform in-field research on new chemistries and new formulations of seed piece treatment and in-furrow applied materials to combat such diseases as Fusarium dry rot, Rhizoctonia canker/black scurf, silver scurf and late blight, among others.
Other Research Activities. Nolte's group has also developed a technique to investigate suberization and wound healing in cut seed. Employing both light and fluorescent microscope techniques, this protocol has been utilized to determine if new and experimental seed treatments have any negative effects on the healing of cut seed. It has also been used to investigate the effects of alternative sprout inhibitors (DMN or dimethylnapthalene) on the wound healing system in potato. Detection of such problems early in the development cycle of a new seed treatment product or sprout inhibition material can save a lot of money and heartache later.
Funding from the extension specialists' grant has also provided support for the development of new materials to be applied post-harvest to combat diseases such as Fusarium dry rot, early blight, late blight, silver scurf, pythium leak, pink rot and black dot. Ever since the reduction in effectiveness of Mertect due to widespread pesticide resistance in the mid 1990's, the industry has been in need of effective post-harvest treatment materials. Some of these new materials are slated to become available within the very near future.
Disease Diagnostic Laboratory. The potato disease diagnostic laboratory handles 50 to over 300 samples per year. The number of samples is reflective of the prevailing disease problems during any given season. During the severe late blight outbreaks of the late 1990's, for instance, the laboratory processed over 350 leaf samples. The laboratory encourages walk-ins and personnel can also be contacted for field or storage visits if needed. The lab is equipped with microscopes, autoclave (sterilizer) as well as a laminar flow hood (used to work with disease organisms in a sterile environment), and all of the equipment necessary to diagnose potato viruses.
The first sample of a new disease, zebra chip of potato (Figure 2), was brought into this laboratory. The Idaho Falls diagnostic laboratory is looking for potato tubers with possible zebra chip symptoms. Contact someone at the lab at (208) 529-8376 if you have suspect tubers.
The Seed Potato Quality Improvement project and the Extension Potato Specialists project both have the goal of improving seed potato quality, reducing risks to all aspects of the industry and keeping the industry informed of current and future threats. Input from the Idaho potato industry is always welcome. If you have questions or comments, feel free to contact Dr. Nolte at (208) 529-8376 or email him at pnolte@uidaho.edu.