News

New Team
A new team consisting of Jiwan Palta, Felix Navarro and Bryan Bowen is in place and is excited about the opportunities at the Potato Breeding Program in Rhinelander. Jiwan Palta recently took over the leadership role while Felix Navarro has replaced Horia Groza. Palta, Professor of Horticulture at UW-Madison, has extensive experience in potato research spanning the past 25 years. Over the last decade he has merged physiological and biochemical tools to understand potato genetics and develop elite breeding lines. Navarro, a recent Ph.D. graduate from the Plant Breeding and Plant Genetics program at UW-Madison, has completed a successful project geared to breed root rot resistance in snap beans. Bowen, Superintendent at the Rhinelander Agricultural Research Station has been part of the breeding program for many years, developing a strong relationship with the potato industry.

History
The UW-Potato Breeding program began in the early 1930’s when professor Gus Rieman was hired by the UW Horticulture department to work with potatoes. It was under his program direction that the breeding farm in Rhinelander was established in the 1940’s and Rieman continued until his death in 1960. Shortly thereafter Dr. Stan Peloquin took leadership and went on to have an outstanding career training graduate students in potato cytogenetics as well as guiding the development and release of the Snowden variety.

Successes of Recent Past
After Dr. Peloquin’s retirement, Dr. Jiming Jiang and Dr. Horia Groza joined Bowen making up an expanded breeding team. During this period, molecular biology tools were incorporated in the breeding program especially incorporating late blight resistance. Following is a brief description of five recent releases from the breeding program.

White Pearl
Previously known as W1355-1, White Pearl was a chipping line selected for resistance to cold sweetening. In the late 1990’s several years of chipping data confirmed White Pearl’s ability to fry after six months of cold storage (42 degrees). Field trials and observations identified additional qualities in this line such as high tuber set (up to 30 tubers/plant), medium to small size tubers and late vine and tuber maturity.

In an attempt to gain exposure, the Wisconsin program had a limited quantity of mini-tubers produced which were sold to a Wisconsin seed grower in 2000. From this source, several small acreage tests on commercial fields pointed to concerns over high set and small tuber size. Discussions between growers and a professional storage consultant led to two farms planting White Pearl in 2004, each with somewhat different results. In both cases, tuber size was smaller than Snowden but still considered acceptable with yields comparable to Snowden.

In the best of two storage scenarios, bin temperature was gradually lowered to 47 degrees and held until mid-May when the bin was shipped with excellent fry color. Some pressure bruising was noted but in hindsight, this issue may have been due to dry soil and prolonged harvest date leading to tuber dehydration in the field. The grower commented, “I sleep a whole lot better with White Pearl in storage than counting on Snowden for late contracts in May or June.”

Millennium Russet (W1348rus)
This variety was one of the first to pass through the SPUDPRO initiative and has been seen on a number of farms in Wisconsin and Minnesota. Its strengths have been uniform tuber shape, consistent length-to-width ratio, high dry matter and lower sugar accumulation than Russet Burbank for processing. There was an initial attempt to develop Millennium Russet as a dual-purpose potato with a hope that it would find a niche with McCain Foods in Wisconsin. Trial data support the fact that high sets and later bulking than Russet Burbank create a yield drag due to a majority of tubers falling in the 4-6 oz. range. Spacing and nitrogen trials have not been able to consistently manipulate size profile upward. In 2001, McCain conducted a 30 acre factory test, concluding that tuber size was an issue along with blackspot bruise. In following years, McCain has not pursued this variety in Wisconsin, however processing trials in Washington state have proven the larger size and yield potential of Millennium with a longer season.

There have been numerous fresh market grower experiences with Millennium over the last five years. Generally the US#1 count is high, tuber type is consistently long and uniform with size averaging around 5 oz. An excellent packing potato according to Justin Isherwood of Isherwood Company, Plover, Wisconsin, but the yield and size does not quite meet with Goldrush. In 2004, Okray Family Farms of Plover, Wisconsin was pleased with Millennium as a late shipper and opted to plant larger acreage in 2005.

MegaChip (W1201)
Previously known as W1201, MegaChip is best used as an Atlantic replacement off the field or from early storage. It has a vigorous vine and produces medium to large sized tubers with high specific gravity. W1201 was almost dropped from the breeding program in the mid 90’s according to Bowen. “Although I don’t like to admit it, we were down to 25 lbs. when a seed grower called one day and asked if we had any scab resistant chipping lines. While I couldn’t vouch for true resistance I didn’t recall ever observing scab on W1201 and so we went forward.” Scab screening trials in subsequent years from Rhinelander and Antigo indicate tolerance to scab in different environments but not full immunity.

Researchers and growers in Michigan have been optimistic with the performance of Megachip relative to scab and seed has been moving in that direction the last couple of years out of Wisconsin. A commercial planting in Missouri looked good this spring. There was some concern about tubers hanging onto stolons and going over the back of the harvester. This characteristic has been observed in some Wisconsin seed harvests and is tied to late plant vigor.

Villetta Rose (W2275-3R)
This red variety can be uniquely identified as having a near spherical shape. It is very uniform in both size and shape along with shallow eye depth. The line was accelerated out of the third year field selection based on tuber shape and bright red color. Tuber set is higher than Dark Red Norland and size is generally smaller. Yields have been satisfactory in grower fields and color consistently darker than Norland. One grower concern has been the observation of brown netting in some growing environments. Villetta Rose is not early maturing but does hold skin color in storage so mid- to late winter shipping should be an option—something Wisconsin has been looking for. Also, growers have noticed less Colorado Potato Beetle feeding on this variety.

In 2000 Del Monte Corp. began looking at processing more potatoes out of Plover, and found Villetta Rose to have superior brine stability, slicing and taste qualities. One interested grower has also investigated production for potato salad and soup contracts. Seed acreage is increasing based on positive feedback from commercial growers and shippers.

Freedom Russet (W1836-3rus)
If Millennium Russet has lacked tuber size, then growers should look toward Freedom Russet to solve that problem. Freedom, named by a Wisconsin grower who is its best promoter, has been gaining interest in both fresh and process markets. Freedom Russet tubers are blocky in shape and carry a medium dark netting similar to Goldrush. Eye depth can be slightly greater than Goldrush in some environments. Maturity is medium-late so a full season approach is recommended to achieve maximum yield and tuber size. Internal qualities are very good, tubers have been rated resistant to scab (National scab trial 2004) and tuber size > 10 oz. has been attractive for McCain’s interest in Wisconsin.
In a 10 acre processing trial in 2004, >10 oz. ran above 40%. Specific gravities are slightly lower than Russet Burbank. With yield/acre driving many successful varieties, Freedom Russet is in a good position to make inroads to new variety listings in seed directories.

Early exposure to growers has been made possible by distributing breeder’s seed directly out of the breeding program. This accounts for the majority of seed acreage represented by new Wisconsin varieties (Table 1). Each of the varieties in this article has been part of the SPUDPRO program, with the exception of White Pearl. Of these, additional foundation seed will be shipped in the spring of 2006 (Table 2). Wisconsin seed growers have shown strong support for the program signaled by all seed being sold out a year in advance of shipping. According to Wisconsin Seed Potato Certification Program Director Bob Coltman, “While a seed volume target of 160 cwt. was established by the program committee, extra volume was possible and encouraged by growers wanting the seed. That is always a good sign.”

.	Seed Acreage	Licensed Growers
Freedom Russet	35	5
Millennium Russet	12	3
MegaChip	50	5
Villetta Rose	68	5
White Pearl	11	4
Total	176	.

Table 1. 2005 Certified Seed acreage of new varieties from the WI Breeding Program and licensed seed grower numbers as of August 9.

SPUDPRO Varieties	State Farm Production
.	Ship date	cwt
Millennium Russet	April 05	120
Freedom Russet	April 06	470
MegaChip	April 06	550
Villetta Rose	April 06	350

Table 2. Projected SPUDPRO seed volumes at the WI Elite Foundation Seed Farm. All seed has been sold out.

Bringing the tools of physiology and biochemistry to potato breeding is unique and affords exciting and interesting new opportunities. The breeding program will continue to capitalize on the past successes and emphasize breeding for improved chip and fry quality as well as disease and pest resistance. In addition, a major new effort will be directed at improving tuber quality. This will include breeding for reduced bruising incidence, reduced internal defects and improved skin quality.

Jiwan Palta, Felix Navarro and Bryan Bowen evaluating newly developed breeding populations at Rhinelander. September 2005.

As we march forward, we will continue to seek desired genes from wild potato sources in collaboration with Shelley Jansky and John Bamberg. Successful releases of new elite lines will require fine-tuning of production strategies, including fertility and disease and pest management. We are fortunate that we have the expertise and willing input from many UW-Madison scientists, including A.J. Bussan and Walt Stevenson, to help achieve our goals.