Cutworms challenge organic no-till in wet field
Timing and moisture conditions conspire to give cutworms the edge.

By Jeff Moyer, The Rodale Institute® Farm Manager
Posted July 13, 2006

Jeff Moyer is the farm manager at the 333-acre Rodale Institute research farm, and has been here for over 26 years, refining the farm's cover cropping and crop rotation systems. The farm has over 1,000 organic apple trees, a 3-acre CSA, 270 acres in a rotation of corn, small grains, hay, and edible soy beans for a Japanese market, and 25 acres of experimental research plots that have been used to test and compare the yield, soil health and environmental impact of organic and conventional systems for the last 22 years.

"It's been extremely rewarding to work at The Rodale Institute," says Jeff. "Working on projects and with people who are having a positive impact on family farm practices, economics, and environmental stewardship is very fulfilling. The positive changes I've seen on our own farm over the years—and farms around the world— convinces me that we're on the right road."

How to contact Jeff

Click here

611 Siegfriedale Rd.
Kutztown, PA 19530

Interest in planting no-till into cover crops without the use of herbicide continues to grow. It seems farmers from every corner of the globe are realizing that the best way to build soil and manage weeds is through cover crops. Check out the article Choosing cover crops for no-till organic soybeans for more information. Or click here to download plans and build your own no-till cover crop roller.

This year our farm grew some of the best cover crops I’ve ever seen. We had thick stands of hairy vetch that measured 8,000 pounds of dry matter biomass per acre, more than enough to supply the nitrogen requirements for our corn crop and suppress early weed germination. The rye we no-tilled soybeans into wasn’t as good, but still the beans look great.

Then ………. Well, then came lots of rain. The moist green mat of rolled hairy vetch became a haven for cutworms, which decimated the first planting. Sometimes it seems just as we move forward several steps, we move backwards one step. While most of our rolled/no-tilled corn fields worked out great, I had one 3-acre field that was completely eaten by cutworms. The little *#*##@@. At first I wasn’t sure what was happening, but a little exploration in the soil early in the morning turned up lots and lots of the critters.

I replanted the field and while the stand looks fine, I lost some of the early weed control afforded by the mulch. The replanting operation also disturbed the mulch, allowing more weeds the opportunity to emerge. The passage of time gives the weeds a head start, as well.

The cutworms seemed to like the cool, moist conditions under the layer of plant matter left by the cover crop roller. It gave them a great place to hide, and the corn was the perfect food source. As I was replanting the field, I could see the moths lifting off the soil as the pupated cutworms matured and left the field. The replanted corn was virtually untouched. So, it seems timing of the planting operation will be critical to the system's success.

I’m sure the weather had a lot to do with the population explosion of the worms. This isn’t a problem we’ve had in the past. But then we don’t always get these weather patterns. Several other growers in the area who were no-tilling also had cutworm damage. Of course now the question is: How can we design a management strategy to deal with this pest in the future? A quick look at the ATTRA web site shows the following practices and control measures as possible methods to attack this problem.

Biological controls

Cutworm larvae have a number of natural enemies. Predators include several species of ground beetles. Parasitoids include tachinid flies and braconid wasps. Cutworms may also be attacked by fungi, bacteria and nematodes. Understanding the biology of beneficial organisms is imperative in order to use them effectively as pest-control agents. For example, insect parasitic nematodes like Steinerema carpocapsae or insect-infecting fungi like Beauveria bassiana require adequate humidity to be effective. Other predators include spiders, minute pirate bugs, damsel bugs and lacewing larvae. Birds also prey on cutworms, so do not assume the birds in the field are causing the seedling damage. As with other pests discussed, farmscaping is a recommended means of increasing the numbers of beneficial predators and parasites that help to keep cutworms under control. An ATTRA publication that is a good starting point for biointensive IPM is Biointensive Integrated Pest Management.

Alternative pesticides and applications

Scout for the presence of cutworm larvae early in the season, and after destruction of adjacent habitats. Cutworms are best scouted at night, when they are most active, using a flashlight. Look for cut-off or damaged seedlings and dig around the base of the plant to locate the larvae.

Bait formulations, sometimes using bran or applying rolled oats with molasses containing Bacillus thuringiensis var. kurstaki, have been known to effectively control cutworm species when applied to the soil. Sprayed formulations may have variable results with cutworms, as the worms may not ingest enough of the toxin for it to be effective. Nightime spraying of Bacillus thuringiensis has shown to be more effective.

Research on the parasitic nematode species, Steinernematidae carpocapsae, has shown it to be a very successful control agent for cutworms, but make sure the soil is sufficiently moist to support nematode populations

Click here for the full ATTRA entry on cutworms.

Other recommendations

Other literature indicates that diatomaceous earth has some effect on the pesky critters as well. While we haven’t identified the practices we’ll try next year, we do know we’ll be looking at the economics and efficacy of each of these measures to determine what option has the best chance of success. We’ll also be re-evaluating our planting time, which is strongly linked to the flowering time of the cover crop.

Many of the control measures listed above just aren’t practical for this particular system, since they rely on clean culture and the removal of the very material we are trying to grow—namely the cover crop itself. Nature always has a way of throwing new challenges in our path. Solving one problem by changing parts of a complex living situation can open new challenges.

But hey, the soybeans no-tilled into rye had no ill effects from insects. Most of the corn was untouched by the cutworms and the replanted corn is going strong.

There’s always a positive note. Let me know if you’ve had similar experiences. Talk to you soon ……

From One Farm to Another