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.
here to download plans and build your own no-till cover crop
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
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
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.
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
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
here for the full ATTRA entry on cutworms.
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