Testing the Use of a Modified Crop Rotation System to Control Colorado Potato Beetle

Final Report for FNC02-396

Project Type: Farmer/Rancher
Funds awarded in 2002: $6,000.00
Projected End Date: 12/31/2003
Region: North Central
State: Minnesota
Project Coordinator:
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Project Information


The Food Farm consists of 200 acres of cropland, pasture and woods located 25 miles south of Duluth, MN. We operate 8 acres of certified organic vegetable cropland, the production of which goes to the approximately 200 members of our Community Supported Agriculture program. We are also the largest local wholesaler to the Whole Foods Co-op in Duluth. We have a 900 square foot root cellar which allows us to supply squash, cabbage, and root crops to the co-op and CSA members through the winter. We also produce pasture-raised chickens, turkeys and eggs for our CSA members. The farm employs 4 people, plus interns and some hired labor. We use many well recognized “sustainable” practices, such as cover cropping, crop rotations and composting, but are continually striving to find creative ways to lower off farm inputs. Perhaps the most effective practice has been pastured poultry. We included pastured chickens and turkeys in our rotation system about 8 years ago and it has become an important part of our soil building plan.

Our objective for this project was to “reduce our reliance on current methods used in the control of Colorado potato beetle by improving our present crop rotation system.”

Environmentally, we wanted to see a decrease in the amount of Bt, propane and gasoline used on our farm through decreased need for controls such as spraying and flaming. Biologically, we set out to compare beetle pressure by recording dates of first colonization, first reproduction (egg clusters), emergence of larvae, and approximate population levels. Data collected in 2002 was to be compared with that in 2003, when the crop was to be moved to new fields ½ mile away.

We wished to increase economic well being by decreasing costs for inputs and labor.

In order to meet these goals, the main focus of the grant became tracking beetle pressure, inputs, and labor used in their control. In 2002, even before we were notified of approval, we began collecting information on when the first beetles arrived in the field, how much time it took to hand pick them, when the first larvae appeared, spraying time, and amounts of Bt we used. We spent a lot of time each summer (2002 and 2003) scouting the fields to see where and how concentrated the population was. Scouting 3-5 times per week ended up taking much more time than anticipated, especially after the fields were moved far from the rest of the operation. The site for the new fields was chosen because it is the farthest removed from both our own fields and from other farms in the area and is nearly surrounded by wooded areas, ravines and pasture.

Others involved in the project included our extension agent, Troy Salzer, the Northeast coordinator of the Sustainable Farming Association of MN, Jenifer Buckley and Ted Radcliffe, an entomologist with the University of MN in St. Paul. My consultations with Professor Radcliffe were largely limited to the grant writing phase, because I carried out the bulk of my research and planning for the project in writing the grant. Troy Salzer and Jenifer Buckley were primarily involved in publicizing the event.

The results of the project are as follows:
Significant dates:
6/15 first beetles found in 2001 field (volunteer plants)
6/18 first found in main field
7/6 first larvae found and first application of Bt
7/13 second application of Bt
7/25 third application of Bt
7/29 fourth application of Bt
Total time spent spraying: 55 hours

6/16 first beetles in trap crop (very few beetles showed up: 2-5 adults per picking)
7/22 trap crop tilled under after emergence of larvae
7/30 first beetles and larvae in new field
Total time spent picking:

We clearly spent much less time on beetle control in 2003 versus 2002. This time would likely have been reduced even more had we been able to spray Bt upon first seeing larvae in the new field, but it rained nearly every day that week, making Bt ineffective. Thus, we used no Bt in 2003, as compared to 2 gallons, 3 ½ cups in 2002.

Even after the beetles arrived, their numbers remained quite low and seemed to concentrate in a few areas of the field, rather than populating the entire 2 acres, as they had in 2002.

As with any experiment, we will have a much better idea of how successful it is when we have continued the long distance rotation for a few years. A number of factors made this year unusual. 1) Our beetle pressure last year was much less than usual, especially in the early season, possibly because last year’s field was also new ground. We generally have a heavy infestation of beetles in the field days, rather than weeks, from the time of the crop’s emergence in early June. 2) Beetle pressure in this year’s trap crop was surprisingly low, possibly because we had a cold winter with no snow cover. This in turn may have delayed and lessened the impact on this year’s crop producing field. 3) We usually experience a large number of adults in the field late in the season, when vines are beginning to die down and beetle predation will have little impact on production. However, both in 2002 and 2003 there were very few beetles in the field after mid/late August. We had a difficult time finding beetles to show the field day attendees on August 16.

The results of this project were for the most part as I had anticipated; in particular, beetle predation was delayed but not eliminated. I had guessed that the beetles, once they had found the fields, would populate the entire field rather quickly. Thankfully, they did not, their numbers remained low. The fact that there were so few beetles in evidence late in the season makes me hopeful for next season’s population levels, but the 3 mitigating factors discussed above keep me nervous about the effectiveness of this new system. Time will give a much better perspective. The advice I would give other producers is that this method will very likely reduce their problems with potato beetles. If they have a field that is at least ¼ mile from their existing fields, has many natural barriers as possible (trees, water, etc.) and can be brought into production easily this would be an ideal way to improve their operation. However, if it would be very costly to do so (road building, clearing timber, etc.) a more comprehensive analysis with longer term information would be in order.

- We held a field day at our farm from 2-5 pm, August 16, 2003. We sent press releases to local newspapers and a number of periodicals.
- Duluth News – Tribune community events calendar
- Arrowhead Leader of Moose Lake
- Pine Journal of Cloquet – Small article
- Organic Broadcaster
- Land Stewardship Letter (did not publish)
- Cornerpost (MN SFA publication)
- Northeastern Farm and Market
- Carlton County Extension Connection

Our field day was not as well attended as we had hoped. We had field days here in 2001 and 2002 that were very well attended with the same publicity. This may have contributed to a smaller number of attendees this year. It was also opening weekend for the Carlton County Fair and a very hot day for northern MN (91 degrees). However, having only 12 people in attendance made it much easier to have in depth conversations with each person and fully explain the way our farm operates than we were able to in years with 50-60 attendees. Fortunately, by the time of the field day, we had all of the data that was included in this final report, making it possible for us to give complete information at the time of the tour. We still receive calls from interested farmers who were unable to attend the tour but would like more information about the experiment.


Participation Summary
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.