Montana Seed Program Under New Leadership

Disease, finance topics of Montana Seed Potato Seminar

Published in the January 2009 Issue Published online: Jan 13, 2009
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The passing of the baton from 30-year veteran Dr. Mike Sun to Dr. Nina Zidack, new director of the Montana Seed Certification Program, occurred at the organization’s annual meeting in Missoula on Nov. 4-5.

Zidack began the position one month earlier, following the retirement of Sun, who led the effort to built a rigorous disease testing program along with a state-of-the art lab at Montana State University in Bozeman during his career there.

Zidack, who was reared on a ranch in Montana, has been at MSU for 14 years and for the past three years has served as the plant disease diagnostician.

The transition of leadership was carefully planned, with Zidack learning the ropes last summer under the guidance of Sun.

Zidack already knew growers, varieties and growing conditions, and is now familiarizing herself with the industry as a whole. She welcomes the input of growers, customers and colleagues and appreciates their partnership.

Reporting on the 2008 Montana crop, Zidack said it was a good year for the state, which will provide 14.4 percent of the U.S. seed crop in 2009.

It was a year of extremes with a cold, wet June which delayed planting and slowed emergence, followed by a July hail storm categorized as a 100-year storm. Although growers expected devastation, the crops recovered well and produced favorable harvests. Disease levels this year were extremely low, and all indications point to high-quality seed being shipped to customers in the spring.


A common topic at the Montana Seed Potato conference is Potato Virus Y (PVY), and this year Dr. Phil Hamm, plant pathologist at Oregon State University, presented a recent finding on the disease and talked of practices for reducing PVY. While PVY may have been seen as a simple disease with common methods of identification and testing, in actuality it has many recombinant forms.

For instance, the recombinant PVYntn is recognized as a tuber necrotic strain, where PVYo used to be regarded as the only strain that affected tuber quality. In addition, the standard ELISA test cannot detect the difference between the common PVYo strain versus a recombinant PVYn:o, thereby confusing test results and ultimately, management plans.

Hamm believes that the best prevention is to use disease-free seed. Aphids carry PVY and pass the infection from plant to plant, field to field.

Hamm said his team tested for PVY by taking the top eight varieties and running identical test plots in Hermiston, Ore., and Othello, Wash., 100 miles apart. Each plant was tested as it emerged and at several times throughout the growing cycle.

In addition, the team grew six cultivars in a screen house where aphids could not affect the growth and infected them with six virus strains. Here they observed the effect of PVY during the life cycle of the plant and concluded that the virus makes the plant die early and certainly affects yield. They saw how differently the same necrotic strain appears and behaves from one cultivar to another.

In all they learned that not all isolates infect plants at the same frequency and that cultivars resistant to PVYo can still succumb to PVYn.

Hamm believes that the action of PVY in the plant needs to be studied and additional high-tech testing developed.

PVY was also a concern of Dr. Mark Pavek, extension researcher at Washington State University. WSU has been conducting seed lot trials annually for the past 20 years, funded in cooperation with the Washington Potato Commission. These trials provide the industry with third-party information and tend to improve the overall quality of seed.

This year’s trials used 41 percent of its seed from Montana in a mix of varieties, 26 percent from Idaho and the remainder from Oregon, Washington and Colorado. Montana seed varieties had the least severe disease infection in the five-state group and fewer than average disease occurrences.

Still, PVY could be a concern for other seed-growing regions, too. From 2007 seed lots, over 40 percent displayed the presence of PVY with Altura, showing the greatest vulnerability and higher rates of infection than in previous years. Mosaic virus seems to be on the rise as well.



Taking the group through a CSI-like investigation to discover answers, Dr. Gary Secor of North Dakota State University posed the question, “Is the seed grower to blame for plant disease problems?”

While potatoes can be affected by over 60 major diseases, there are eight diseases that are seed- and soil-borne. If the source of infection can be identified, more effective management and minimized losses may result. For instance, a 1 percent Rhizoctonia occurrence causes an average loss of $255/acre. A recognized management practice is crop rotation every 3 to 4 years in commercial fields. Seed growers have some control with fungicides, as well.

Dr. Secor said that although late blight isn’t a factor in Montana, seed can be implicated. Multiple tactics have to be used to control late blight, beginning with culling infected plants, applying fungicides throughout the growing season, avoiding a wet harvest and letting tubers harden off before putting them in storage.

Powdery scab can come from either the soil or the seed and can continue to live in the soil from eight to 16 years. Growers can plant clean seed to prevent scab from inoculating the soil.

Vines that die early due to Verticillium wilt can affect the fields for three to five growing cycles and reduce harvest for up to 10 years. While seed introduces Verticillium, management includes crop rotation, soil fumigation and planting a green manure crop to recharge the soil.

Pink rot is a soil-borne disease surviving for long periods in the soil with the potential to lead to serious problems. While soil treatment is thought of as the best management, researchers have seen some resistance to them.

While the best management for silver scurf and black dot may be disease-free seed, Secor admitted that black dot is ubiquitous. Seed is the main source of inoculum for silver scurf, late blight and black dot.

It was Secor’s colleague, Dr. Neil Gudmestad, also from North Dakota State University, who argued for better testing methods for bacterial pathogens that affect potatoes.

Gudmestad has developed a real-time PCR assay which is highly sensitive and produces immediate results in testing for bacterial ring rot. The North American Free Trade Agreement requires ELISA testing to prevent the sale of seed infected with BRR, and Gudmestad argues that ELISA isn’t accurate enough and the new PCR method would better protect interstate and international trade.

The zebra complex is Gudmestad’s latest puzzle. It is a bacteria-like organism that can’t be cultured in a lab. It was first noticed in Mexico in 1994, has been moving north and now can be found in Kansas, Colorado, California, Wyoming and Nebraska. Although zebra complex looks like purple top wilt, it’s more deadly, killing the plant. Its method of infection is unknown, but Gudmestad suspects that it is spread by an insect.



The topic of discussion moved from diseases to our ailing economy and its own set of blights, scab and wilt.

Jay Penick of Farm Credit Services for the northwest offered advice and his perspective. He cautioned producers that borrowing money over the next 12 to 24 months will cost more, and the only break might be through strong, well-funded community banks.

Penick warned of teaming with equity partners that might not understand the volatility of agriculture. Partners may have credit issues of their own or be undercapitalized, which could pressure seed growers into premature loan repayment and put them in difficult situations.

Although the price of potatoes is strong, Penick expects wide swings and recommended growers maintain liquidity and not be tempted to overproduce. He believes that the winners in these economic times will be those who are positioned well one to two years from now to take advantage of new markets and opportunities. The losers, he expects, will be those who have taken major expansions in their businesses based on 2007-08 prices.

Closing off a busy day, Bruce Tainio of Tainio Technology presented his innovative approach to minimizing stress on potatoes and other crops through feeding plants—any plants, not just potatoes—what it needed to resist infection and insect pressure.

His studies have shown that every healthy plant has a leaf sap pH of 6.4, and at this reading, the plant naturally resists disease. Tainio has consulted with growers of all kinds of crops, showing how to bring proper nutrient levels to the plants using special amendments that are more efficiently absorbed by the plant.

He believes in testing plants for the essentials, N-P-K, and micro-nutrients as well and suggested that well-balanced plants also bounce back after such things as hail storms and early frost.



In closing, Brent Clement of Potato Country magazine showed photos of Montana growers and their families from his photo collection of 33 years. Many of the families in attendance were represented with some of their elder statesmen only there in pictures and memories.

Overall, Montana growers are confident in their seed products and the programs they have worked to build.