Organic Potato Variety Trial in Michigan's Upper Peninsula

2013 Annual Report for FNC13-941

Project Type: Farmer/Rancher
Funds awarded in 2013: $2,245.77
Projected End Date: 12/31/2015
Region: North Central
State: Michigan
Project Coordinator:
Michael Wixtrom
Wixtrom Natural Farms

Organic Potato Variety Trial in Michigan's Upper Peninsula


Replicated trial of selected potato varieties under organic growing practices

• Reviewed performance of formerly grown potato varieties and researched possible new varieties, including those in recent Michigan State University tablestock trials.
• Ordered and received seed using grant funds for the following potato varieties:

o Reba
o Desiree
o King Harry
o German Butterball
o Canela Russet
o Green Mountain
o Purple Sun
o Elba
o Adirondack Blue

• Prepared potato variety trial site within a good area of my potato production field, enough room was set aside to accommodate 36 forty-foot rows, which allowed for 4 replications of each variety. Same rotation and fertilizer as production field. Grant funds covered field expenses and partial labor.
• Worked with MSU Extension Upper Peninsula Field Crop Educator, Jim Isleib, to design the plot layout as follows:

• Planted plots on June 10, 2013
• Hilled potatoes along with production field
• Held public field day on August 18, 2013; 9 in attendance. The handout with project details was distributed (following 2 pages).
• Plots were maintained with hand control of Colorado Potato Beetles
• Plots were harvested on October 9. Each individual plot sample was bagged separately. Three replications of one variety (Reba) were mixed accidentally.
• Samples were stored during remainder of harvest season.
• Samples were graded and weighed by size component on November 8.
• Statistical analysis of plot data was done by MSU Extension educator, Jim Isleib

Objectives/Performance Targets

Project results and what we learned

Project results:




Grades A+B+C



Grade A


Grade B


Grade C




King Harry




































German Butterball


















Adirondack Blue


















Purple Sun






















































Canela Russet


















Green Mountain


















*LSD = 13.1 (P=0.05)

Statistically, there were real differences among the varieties. When grades A, B and C were combined (column 2 in the table above), the coefficient of variation was 19.09% and least significant difference was 13.1. King Harry, Elba and German Butterball were the best performing varieties in the trial.

Wixtrom Natural Farms received a SARE grant in 2013 to test certain potato varieties under organic growing conditions. Nine varieties were selected for trial and they are: Reba, Adirondack Blue, Desiree, Green Mountain, King Harry, German Butterball, Canela Russet, Purple Sun and Elba.

Planting was on June 10, 2013 with most varieties being certified organic seed. Some were sustainable seed and some were certified seed saved by the farmer from the previous year.

Weather on planting day was normal for this area, with moderate to slightly dry moisture. Rainfall through the summer is as follows:

June – 1st Week = 0 inches                      July – 1st Week = .6 inches
2nd Week = 1.5 inches                                     2nd Week = .2 inches
3rd Week = .5 inches                                       3rd Week = 1.2 inches
4th Week = 1.25 inches                                    4th Week = 2.8 inches
Total of 3.25 inches                                          Total of 4.8 inches

Aug – 1st Week = .25 inches                     Sept – 1st Week = .1 inches
2nd Week = .6 inches                                        2nd Week = .55 inches   
3rd Week = 0 inches                                          3rd Week = .6 inches
4th Week = .8 inches                                         4th Week = 0 inches
Total of 1.65 inches                                           Total of 1.25 inches
Oct – 1st Week = 1.0 inches
2nd Week = .5 inches

Rainfall was 12.45 inches over the 18 week period, averaging .69 inches per week. Potatoes usually require 1 inch per week during the growing season. This trial did not include any irrigation and relied solely on rainfall. Also keep in mind, when looking at the results that the 2nd week of July and the 3rd week in August were weeks when temperatures were over 90 degrees, severely drying out the fields and setting the plants back and you could see the leaves on the plants were curled and withered and obviously showed heat stress from lack of moisture. Had irrigation been applied, during these weeks, yield results would have been dramatically increased. Also after these hot spells subsided, it was observed that it took two weeks of rainfall before the leaves uncurled and showed vigor. It was noted that,  this severely set back the plants and when they started growing again, they had run out of season and frost killed the vines before they died back on their own. The rains in October were not helpful for harvesting and temperatures were very cold into the high 20’s with snow. Weeks with much rainfall, where weeks where temperatures were in the low 60’s, resulting in a situation where plants did not grow at their best. All in all the weather could be summarized as being good at the wrong time.

Other factors that effected the growing season:

1. Despite rotating crops, we observed a high amount of Colorado Potato Beetles. Despite hand picking frequently, they still caused moderate/severe damage to the plants. King Harry was chosen specifically because it was advertised to be resistant to Colorado Potato Beetles. We observed a huge difference between King Harry and other varieties and would agree that it is resistant to not all but most of the Beetles. Purple Sun and Adirondack Blue potatoes got hit the worst by the Beetles. A possible reason for this may be because Adirondack Blue is high in antioxidants and Purple Sun is high in Vitamin C, meaning that the bugs knew which ones were better to eat. Our observation was that hand picking definitely helped, but is not a viable method for high acreage plots.

2. The weed pressure was light until late July when weeds seemed to grow by leaps and bounds, especially during the 90 degree weather, when the potatoes were not growing. Toward the end of the season, weed pressure was moderate to severe. Plots were hand weeded on several occasions, but it was observed that this wasn’t enough to stay ahead of the weeds and is not a viable method for high production fields.

3. Test plot yields may have been affected by the kind of seed that was planted. Namely what generation it was. King Harry, which had the best yield was new certified seed as was Elba, German Butterball, Purple Sun and Reba. Desiree and Canela Russet were saved seed, by the farmer, from the previous year. Green Mountain, which had the lowest yield, was saved by the farmer from two years ago. A possible conclusion to these observations may be that a dramatic difference in yield exists between 3rd, 4th, 5th and 6th generation seed.

4.  Plants also were observed to be weak in nitrogen throughout the whole growing season.  Plants were small and showed less than optimal vigor.  A possible reason could be fertility levels in the field were lower than anticipated and organic fertilizer levels should have been increased or modified.
In conclusion, this variety trial was not meant to show fabulous results of organic production.  It was meant to show results of organic practices used in high acreage organic farms and the yields that one might expect in an organic farm. Our observation show that no bumper crops can be expected without better weed control, pest control and irrigation usage.  However, our results show that using 3rd and 4th generation seed and especially resistant varieties, like King Harry can dramatically improve yields.


Work plan for next year

The project was completed before the end of 2013, with exception of some additional distribution of information. I will use the results in planning for the 2014 and following potato crops.

Impacts and Contributions/Outcomes

How we shared our information with others

Nine people attended the field day on August 18, 2014. The event was publicized in the local newspaper, through the electronic communications of the Marquette Food Coop, and an invitation notice was sent to all commercial potato producers in the Michigan Upper Peninsula region who were listed with the Michigan Potato Industry Commission.

An article was written by Jim Isleib, MSU Extension and published on the MSU Extension webpage at:

Jim Isleib will also submit a similar article to the MSU Extension U.P. Ag Connections newsletter, which reaches about 900 farmers in the Upper Peninsula region of Michigan.

A taste testing event is scheduled with the assistance of the Marquette Food Co-op, to find out which varieties the consumers preferred and associated information.  The results of this event will be forth coming in the final report. 


Jim Isleib
Crop Production Educator
Michigan State University
E9526 Prospect Street, Suite1
Munising, MI 49862
Office Phone: 9063872530
Matt Wixtrom
Wixtrom Natural Farm
4697 Fence River Road
Republic, MI 49879
Office Phone: 9063762136
Mike Wixtrom
Wixtrom Natural Farms
4697 Fence River Road
Republic, MI 49879
Office Phone: 9063762136
Rachel Wixtrom
Wixtrom Natural Farm
4697 Fence River Road
Republic, MI 49879
Office Phone: 9063762136