Summaries of stories appearing in this issue.

July/August 2007

WSPC Releases Tools to Help Growers Comply with GAP Requirements

New tools to help Washington potato growers understand and implement the federally mandated Good Agricultural Practices (GAP) program will be available July 1. Ellie Charvet, chairman of the Washington State Potato Commission, calls the “how to” kit prepared by the Commission “one of its most significant contributions ever.”

Several other potato commissions as well as the National Potato Council have requested copies as soon as they become available.

Mandated Practices
Effective July 1, the U.S. Department of Agriculture is mandating that all commodities, including potatoes, intended for distribution through federal procurement programs be GAP certifi ed. This means that both fresh market shippers and processors who want to sell potatoes to the federal government for distribution through USDA-sponsored
programs must grow them under GAP standards.

After July 1, like it or not, all growers are going to have to be GAP certified or run the risk of being unable to deliver product to market, Charvet warns. This includes product sold to fresh packers and shippers, processors, chippers and dehydrators – anybody doing business with the federal government.

Under the GAP program, at the growers’ expense, a qualified inspector must come to the farm annually and verify all GAP records and signature sheets before the product can be transported to market. Besides documentation of good farm practices, worker training is an important part of the GAP requirements.

The WSPC has boldly taken the lead in putting together important GAP certifi cation information, Charvet announces. All Washington growers will receive a binder with printed material and sign-off sheets, an electronic version for downloading and a video. The goal is to provide growers with a step-by-step approach to meeting the new standards. The electronic version on CD can be downloaded in a computer and adapted to specifi c circumstances for each operation.

Company names and logos, for example, can easily be added to the top of documents to customize them for the operation’s own GAP plan. ...


Powdery Scab

By Nadav Nitzan, Dennis Johnson,
Dallas Batchelor and Chuck Brown

Introduction
Powdery scab of potato is caused by Spongospora subterranea. Potato cultivars that are susceptible to the disease present sponge-like galls on the roots and stolons (Fig.1), and scabby lesions on the tubers (Fig.2). Potato plants that are infected with the pathogen develop necrotic and deformed roots, which may affect plant vigor.

The reduction of plant vigor can potentially influence the development of large tubers (10 oz. and above) that are needed for processing. The development of scab on the tubers reduces the quality of tubers for both the fresh and the processing markets. As a result, the disease may reduce the useable potato yield.

Pathogen characteristics
The powdery scab pathogen is biologically classified as a Plasmodiophorid and is also known as an intracellular parasitic slime mold. Its characteristics include:

obligate parasitism, which means that it can develop only on a living tissue . i.e., a functioning potato root, or developing tuber;

 the formation of intracellular plasmodium inside the roots and the tubers . a sack-like structure with multiple nuclei (Fig.3); ...

USPB Researches Chinese Potato Industry

U nited States Potato Board (USPB) staff recently conducted a commercial potato production research mission to China. Purpose was to investigate Chinese commercial potato production, processing and marketing, and better determine the future strategy the USPB will be able to develop in China.

The large-scale study to assess China’s potential was contracted by the USPB to Promar International with Nick Young as the head of the project and coordinator of the research mission. USPB Board Members Lon Baley of Malin, Ore., and David Radtke, of Sanford, Colo., were joined by USPB International Marketing Manager Susan Weller.

Additionally, USDA Foreign Agricultural Service (FAS) Washington, D.C. Marketing Specialist, Krista Dickson, and the USPB’s China representative, Daniel Chen, were present for the tour. Jiang Junyang from the U.S. Ag Affairs offi ce in Beijing and USPB International Marketing Vice President John Toaspern joined the team later in the schedule.

Visits included tours of key production regions in Inner Mongolia and Shandong province, processing facilities, wholesale and retail markets and numerous presentations and workshops about the Chinese potato industry. Members of the group also met with USDA FAS personnel to discuss market access to China and USPB programs.

“The research mission defi nitely accomplished its objective of providing the USPB staff and research team with an increased understanding of the Chinese potato industry,” Toaspern said. “It is a huge country with varying levels of development, so we were only able to see snap-shots, but I think they were the important ones.”

The group fi rst traveled to Inner Mongolia where newly established large-scale production has been developed to supply fry and chipping plants elsewhere in China. Presentations were made by various Chinese industry experts. Topics of discussion included the history of production in China, which started in 1550 with the introduction
of potatoes from the Netherlands. Potato production trends, utilization, the seed production situation and how some Chinese associations are working with farmers to improve marketing were the themes for other presentations. ....

Washington Produce Rail Car Pool Already Moving Preharvest Produce

Last fall, Rail Logistics, operator of the Washington Produce Rail Car Pool, was wondering “Where’s the spuds?” This season, the Rail Logistics Cold Train has been moving before the harvest season even starts.

“Even though the program got off to a slow start with only 77 loads last year, as of early May this year all 31 cars were either loaded and moving or returning empty for reloading. We forecast that we will need an additional 20 cars to meet expected demand this summer,” says Mike Lerner, a Rail Logistics managing partner.

“We have contracts with potato shippers that will take us right through the season,” adds Mike Begnaud, director of sales for the Overland Park, Kansas company. Besides potatoes, users include other fresh produce shippers and cold storage companies from both sides of the Cascades.

The Right Time
The Washington State Department of Transportation (WSDOT) inaugurated the program in the summer of 2006, when it leased 31 refrigerated railcars from Rail Logistics Cold Train to create the Washington Produce Rail Car Pool for the use of Washington produce shippers. The Washington Produce Rail Car Pool is a unique plan to supply refrigerated rail cars, in short supply in the Northwest, to Washington fresh and frozen produce shippers.

Funded by federal monies secured by Senator Patty Murray, the rail car pool idea was introduced by the Washington State Potato Commission back in 2001. Congress provided $2 million for the project, while the Washington legislature provided funds to WSDOT for startup operations and contract performance monitoring. The contracted lease payment is $1,000 per month. In return, the Rail Logistics Cold Train program rebates $750 back to WSDOT for each shipment from a Washington shipper.

“The time is right for this kind of innovative pilot program because North American railroads have gone from negative growth to record profi ts,” says Chris Voigt, executive director of the Washington State Potato Commission. “The positive turn around has encouraged entrepreneurs like Rail Logistics and RailEx to enter the market.” ...

Potato Wart Eyes as Risk to Potato Production

While many may be familiar with potato late blight, the plant disease responsible for widespread potato shortages, the lesser known potato wart has the potential to be as devastating to economies that depend on potato production, say plant pathologists with The American Phytopathological Society (APS).

According to Gary Franc, plant pathologist with the College of Agriculture, Plant Sciences Department at the University of Wyoming, Laramie, Wyo., potato wart is a serious disease of cultivated potato that has been detected worldwide. Potato wart is caused by the fungus Synchytrium endobioticum, which is considered to be the most important worldwide quarantine plant pathogen of potato. While not harmful to humans, the disease causes unsightly growths that initially appear white, and then turn brown or black as they decay, rendering the potato tuber unrecognizable and inedible.

There is a zero tolerance for the fungus that causes potato wart. As a result, this disease has been placed on the USDA’s “Select Agent List” of plant pathogens deemed to
pose a severe threat to plant health or to plant products. Although direct losses from potato wart may be insignificant when fi rst detected, indirect economic losses resulting from zerotolerance regulations for potato wart can be devastating to growers. Indirect economic losses become especially evident in potato production areas that are subject to quarantine measures, as well as when the movement of commercial potatoes is restricted.

Russian Thistle

T he potato purple top phytoplasma, also called BLTVA, affects all cultivars of potatoes grown in the Columbia Basin.

It has a wide host range and infects many other crop plants and weeds. The phytoplasma is transmitted by the beet leafhopper from weed hosts to potatoes.

Although it was known that many wild mustard-type plants carried the phytoplasma, recent studies by Dr. James Crosslin of the USDA-ARS-PWA Vegetable and Forage Crops Research Unit, Prosser, Wash., have led to the discovery of BLTVA-infected “wild” Russian thistle plants, a common weed in the area.

“Since the Russian thistle is also a preferred host of the beet leafhopper, we feel that finding the phytoplasma in this plant has implications for the epidemiology of purple top
disease in the Columbia Basin,” Crosslin says.


Declining Tuber Moth Numbers Encouraging

There’s good news as far as tuberworm risk for Columbia Basin potato fields this year, according to Silvia Rondon and Andy Jensen, who have been tracking moth numbers over the past few years. Trap numbers are down, and down substantially.

“Compared to previous years, the number we’re seeing in Umatilla and Morrow counties in Oregon – the area in which I serve – are really down,” Rondon reports. “We’re in our fourth week of trapping (mid-June) now, and have been averaging just one moth per trap per week.”

On the Washington side of the river, Jensen says his traps south of Pasco are picking up a moth or two here and there and even less north of Basin City. Tuber moth numbers are very light, he observes.

Rondon is an extension entomologist with Oregon State University’s Hermiston Agricultural Research and Extension Center, Hermiston, Ore., while Jensen is director of research for the Washington State Potato Commission, Moses Lake, Wash.

Problems with potato tuberworm (Phthorimaea operculella) first began surfacing in 2002 in the Hermiston area. Numbers were extremely worrisome in 2003, 2004 and 2005, and then dropped off substantially in 2006, Rondon points out.

On the Washington side, Jensen began trapping tuber moth in 2004, when the pest fi rst became worrisome in the Pasco area. Both 2004 and 2005 saw elevated numbers in most of the state’s production areas and substantial tuberworm damage.

Factors infl uencing infestations include warm, dry weather in the summer; mild winters; increased tuber exposure, i.e., from shallow setting or soil cracking; improper sanitation; length of time the tubers remain in the ground after vine kill; contaminated seed; and dry soil (drought, ending irrigation).


Potato Varieties Differ in Current Season PVY Infection Rates

Washington and Oregon potato researchers have conducted a multiple-year study looking at current season PVY infection rates of Russet Norkotah, GemStar, Shepody, Gem Russet, Russet Burbank, Ranger Russet, Umatilla Russet and Alturas.

Involved in the study were Dan Hane, Phil Hamm, Laurie Leroux, Stacy Gieck and Nick David of Oregon State University’s Hermiston Agricultural Research and Extension Center and Mark Pavek with the Department of Horticulture and Landscape Architecture at Washington State University.

Their research was supported by the Washington State Potato Commission, Oregon Potato Commission and Oregon State University’s Agricultural Research Foundation.

Important Production Issues
Potato viruses are important production issues regardless of where potatoes are grown in North America. Two specifi c viruses, PVY (Potato Virus Y) and PLRV (Potato Leaf
Roll Virus) have been shown to be of major importance because of either reduced yield and/or reduced quality.

Probably the single most important and differing aspect of PVY from PLRV is its ability to move quickly through a potato field, regardless of normal management inputs, including the use of insecticides. This is possible because the virus acts as a contaminant on the stylet of vectoring aphids and is transferred to the potato plant as the aphid
probes, even if the aphid is eventually killed by insecticides.

Vectoring aphids produce “current season” infections, while tubers from these plants produce (seed-borne) infections the next year.