Wisconsin seed potato outlook remains optimistic

Wisconsin had its weather challenges for 2018. Much of potato ground in Wisconsin received a major snow dump while seed shipping was in full swing and commercial planting season was underway. 

The abnormally cool month of April and 18-20 inches of snow delayed frost coming out of the northern soils, truck availability for seed shipping and seed cutting operations for many seed growers.

Despite this, May was one of the mildest in recent years, with relatively low precipitation and warm temperatures. Late May had very high temperatures and early June brought rain, delaying some planting and hilling operations into early and mid-June.

Seed potato acreage planted was up again in 2018, with slightly over 9,300 acres. The increase includes cultivars used for fresh market russets, specialty potatoes and potato chips. Acreage in the certified seed potato program has gradually increased since 2013, up 1,000 acres over that time period. 

The sun and warm temperatures pushed along all crops, and the seed potato crop emerged quickly with very few disease concerns; blackleg was difficult to find, and mosaic levels were very low. 

During mid-summer, growers noticed that tuber set was quite variable with notable exceptions on either side of the norms.

Dry vegetative period

Most of the vegetative portion of the growing season was drier than in recent years, with northern Wisconsin growers running irrigation pivots far more often than in recent memory. The dearth came to an end during mid-to-late bulking and vine-killing stages of the crop. Dryland corners are showing a marked difference in yield and tuber size.

With the dry and heat, growing degree days pushed Colorado Potato Beetle and cutworms to the forefront. Fortunately, we have many chemistries to handle the pressure.

No late blight was found in the northern Wisconsin seed areas, with relatively low amounts of white mold present, and only in susceptible varieties. Aerial blackleg was also quite low in 2018.

There were no mosaic rejections (PVY >1 percent) for the season, and at the end of season, only a handful of lots were down-classed to certified (PVY .25-1 percent).

Harvest began with great digging weather, followed by half-day harvests with above average high temperatures, switching dramatically to consistent mist and rain, and cool and cloudy conditions pushing harvest into early October. 

The bulk of harvest has had nice cool nighttime temperatures for running air systems. Quality has been generally very high throughout the harvest period. Depending on the cultivar, some yields have been reportedly lower than average, and in some cases, much higher.

Retired seed growers

Ron and Ken Mach of Mach’s Sunny Acres retired in the spring of 2018. The brothers grew Red Lasoda, Superiors, Atlantics and Accumulators.

Ron was active with potato industry organizations, and in 2011, was named the National Potato Council Seed Potato Grower of the Year. We congratulate them and are glad to see their farm and facilities continue in seed potato production.

As we look forward to the post-harvest testing in Hawaii, Wisconsin will continue to PVY ELISA test all latent varieties, and all seed lots re-entering certification will be ELISA tested. All Wisconsin seed lots receiving a Wisconsin certified seed tag must be post-harvest tested, and the upper tolerance for PVY is 5 percent.

The University of Wisconsin (UW) has begun recruiting for a UW-Madison seed potato pathology faculty position within the Department of Plant Pathology (see “Badger Beat” this issue).

This position will be associated with Wisconsin’s prominent seed potato industry. The certification program looks forward to partnering in making new discoveries related to seed potato issues.

Crockford is the program director for the Wisconsin Seed Potato Certification Program