Low-Maintenance Pest Control in the Garden

What do I do about insects that damage crops? I observe
them (primary research). I identify them and do a little
secondary (book) research. And then I wait to see if the
damage is significant enough to justify concern. When I say
I do nothing, and that isn’t always my response, I mean
that I do nothing to interrupt the life cycle of the
insect–no spraying, no picking, no sticking, no
luring, or zapping–simply keeping low-maintenance pest control in the garden.

Some will say that is all well and good for people living
in Maine and similar climates, because the insects are
killed in the winter. I am not going to argue the point. I
am going to be specific about the insects that eat or have
eaten vegetables in my Maine garden. People can draw their
own conclusions.

Insects do significant damage to apples and pears that I
have tried to grow. I have not tried very hard to grow
fruit crops so I can’t say with confidence that the
philosophy and methods I use for vegetables will work for
fruit. Be assured that I will not give up on the philosophy
until I have done everything I can think of to make it
work. Even then I may conclude that I just haven’t found
the key, rather than that the philosophy is flawed.

The philosophy is that healthy plants do not attract insect
“pests.” Think of insects that damage crops as indicators
that a plant is not healthy rather than as pests. Their job
is to clear away poor-quality living things so that general
health will prevail.

One of my favorite examples of this happened in my second
garden. I planted four rows of turnips. Don’t ask me why I
planted so man) turnips. It was just one of those things. I
guess there were enough seeds in the packet. Whatever. The
plants were looking beautiful, until one day when I noticed
some of them were wilting. I looked more closely and found
the stems of the plants were covered with black aphids.
They were infested.

I couldn’t believe it. Since I didn’t know what to do and
didn’t think I would miss the turnips anyway, I did
nothing. The result was a mystery that puzzled me for
several years. The aphids did not destroy all the plants.
They got the plants they were covering; but as the attacked
plants got weaker and weaker, I noticed that the plants at
the ends of the rows were fine. Here were four 25-foot rows
of turnips in which the center section of all four rows had
been basically annihilated, while about four feet on either
end of the rows were left virtually untouched.

It was three years later when I was working on
illustrations for my book that I came upon an explanation
to the mystery that suits me. The illustrations were garden
plots for each year drawn to scale and placed on the paper
in the same relationship one year to another. I found that
the turnip rows of the second garden crossed the corn patch
of the first garden. The aphids had destroyed the turnips
that were growing in soil that had hosted corn the year
before. Rows of other vegetables crossed the corn patch
without incident. The turnips did fine in ground previously
inhabited by beans, beets, lettuce, and potatoes. My
non-scientific conclusion was that the corn took something
from the soil that I did not replace and that the turnips
needed.

There have been scientific studies conducted that support
the claim that insects attack plants that are not receiving
a proper balance of nutrients. There have also been more
examples in my garden over the years.

The principal things that I do to protect my crops from
insects are rotating the crops, maintaining a high level of
humus by adding some bulk organic material every year, and
changing the bulk material every so often (horse manure
with shavings, chicken manure or seaweed, hay, leaves,
etc.). A soil test every other year or so also helps keep
me on track.

The probable reason I did nothing about aphids was that I
realized I had planted too many turnips, especially since
they are not a favorite vegetable of mine. In subsequent
years, I have found aphids on nasturtiums. The irony is
that the nasturtiums were planted to repel aphids. I won’t
mention any of the books that recommend that, but I came to
the conclusion that nasturtiums would be better listed as a
catch crop for the aphids. Planting crops for the purpose
of repelling or attracting insects is called companion
planting. Nasturtiums, marigolds, and aromatic plants are
generally mentioned in this regard. Frankly, I am not a
great fan of companion planting. It doesn’t do any harm and
it may do some good, but when you see nasturtiums or
marigolds in my vegetable garden it is because they are
pretty kind of nice to have around.

What do I do about aphids? I haven’t noticed any in my
garden since 1974. For some this is just one of those
mysteries of organic agriculture. Clearly aphids can
destroy crops in Maine–more specifically, in my
garden. Yet they were only here in my second and third
garden.

What I recommend for anyone who has a problem with aphids
is an immediate soil test. Get humus in the soil. Get the
soil nutrients balanced. Use this indication of a soil
problem to improve the health of the garden for next year.

The first insect to cause me to panic was the cabbage worm
or cabbage looper. These are two different insects, but the
difference is of no value other than to make gardeners who
know the difference feel superior to gardeners who don’t.
At the time of my first encounter, I didn’t know the
difference.

I should back up a bit. I did not grow cabbage or any
members of the cabbage family in my first garden. Potatoes,
corn, onions, cucumbers, zucchini, tomatoes, green beans,
peas, spinach, beets, lettuce, and radishes all flourished
without any insect damage. The reason, of course, was my
purity. Perhaps luck in starting on fertile soil and in a
place where no garden crops had been for several years had
something to do with it, too. But when you are young and
pure and self-righteous . . . well, I’m afraid I did not hide
my light under a bushel basket that winter. Several more
experienced growers with whom I came in contact asked what
I had done about cabbage worms. When they found that I
hadn’t grown any of the crops that attract this green
fellow they just gave me a superior smile.

I was sure my methods would work for any crop. Cabbage,
cauliflower, and broccoli were planned for the next garden.
One of the controls you may come across when reading about
pest control is separating crops of the same family.
Insects that feed on one member of the family, say
potatoes, may also feed on other members of the same
family, tomatoes or eggplant, for example. The idea is to
make it difficult for insects to crawl from one crop to
another. I have observed a lot of insects and, with the
possible exception of the tomato horn worm, I have never
been able to detect insects moving from one plant to
another. My insects stay with the host upon which they were
hatched.

Nor have I seen anything that would lead me to believe that
a larger patch of one family is more likely to attract
insects in flight than an individual plant. Flying insects
get around and investigate just about everything that might
be of interest to them. Do you think you are more likely to
be bitten by a mosquito when you are in a crowd than when
you are alone?

I planted these three brassicas (members of the cabbage
family) next to each other. I planted them next to the
central garden path and close to the house where I could
keep an eye on them. And, lo, it came to pass that dark
green balls similar in size and color to capers appeared in
the center of the cabbage plants just as they started to
form heads. Upon close inspection, worms were discovered,
and they were eating the leaves of my cabbage plant. In a
panic I rushed to the Agway store for some Rotenone.
Rotenone is a poison that is derived from plants. It does
not hang around in the soil long and therefore poses no
problem through accumulation. It is, however, a contact
poison. It kills most insects with which it comes in
contact.

My trip to buy this poison sobered me somewhat. By the time
I got home I had decided to use it on only half of the
plants. I would leave the rest for observation. Once in the
garden with the Rotenone I decided to dust only a third of
the plants. I ended up dusting a fourth of them. I hated
it. I wasn’t wearing breathing apparatus or protective
clothing as should be worn. I got a taste in the back of my
mouth that was like sucking on pennies. Not pleasant. After
the deed, I changed my clothes and showered but still felt
contaminated. That was the first and last time I ever used
a poison in my garden. Natural or not, acceptable by
organic standards or not, it is not for me.

This decision was not based entirely on my dislike of the
poison and my role. If Rotenone were the only way I could
grow cabbage and get it to a harvestable stage, I would
probably use it. That first year I harvested all of the
cabbage I had planted. Threefourths of them had been left
mostly to their own devices. I may have hand- picked a few
worms. Who could resist? If I can get cabbage that pleases
me without using poisons, then why use poisons?

The cabbage looper–for those of you who want to feel
superior–has front and back legs and loops into an
omega shape when it travels. The cabbage worm has legs all
along its body and moves flat against the leaves. Just to
confuse you, they are both caterpillars.

“The cabbage looper, Trichoplusia ni. A native caterpillar
common throughout the country. It attacks all members of
the cabbage family–broccoli, Brussels sprouts,
cabbage, cauliflower, collards, horse-radish, kale,
kohlrabi, mustard, radish, turnip–and also feeds on
beet, celery, lettuce, parsley, pea, potato, spinach,
tomato; and on flowers–carnation, chrysanthemum,
mignonette, geranium, and others. The looper is said to be
a serious lettuce pest. It winters as a green-to-brown pupa
wrapped in a cocoon attached by one side to a plant leaf,
and transforms in spring into a moth with mottled brownish
fore wings, with a small silvery spot in the middle, and
paler brown hind wings. Wing expanse is just under 1 1/2
inches.” That is from The Gardener’s Bug Book, by
Cynthia Westcott. It goes on to give more information about
the insects and some methods of control. I have several
insect identification books, but this is my favorite. Her
chemical control methods are of no use to me, but she does
include natural methods when they make sense to her.
Control that I like is usually based on knowing the insect
well, and she gives me the information I need.

As for the cabbage caterpillars, I usually just pick them
off if I feel like it or let them eat. Picking them from
cabbage is difficult be cause they are hard to see. When
the sun is low in the sky you can sometimes see them better
using the sun to “x-ray” the leaves.

Despite the wonderful list of vegetables Cynthia says they
will “attack” and the fact that I grow most of these, and
despite the fact that I may see a dozen cabbage moths
fluttering over the garden on a given day, and that the
females lay several hundred eggs each, these caterpillars
have never been a problem on any vegetable in my garden. Go
figure.

When I was selling vegetables it was more important that
they look good if not perfect. The holes in the leaves of
the cabbage plants and the worms in the broccoli can be
eliminated with a very benign spray called Bacillus
thuringiensis (Bt). This is a bacteria that is only harmful
to Lepidoptera–butterflies and moths. Further, it has
to be ingested by the larval caterpillar-stage of the
insect. It will not kill anything on contact. If you spray
Bt on the leaves of plants you want to protect, it will
only kill the Lepidoptera larva that eat those leaves.

While I’m on Lepidoptera, there is one more which visits my
garden that can be controlled with Bt. This is a worm about
the size of a finger: the tomato horn worm. It is so named
because of a horn on its back end. It is usually first
noticed by its excrement also. These bugs should be picked
off, as even one can eat quite a bit. The horn can be
scary, even for an old bugpicker such as myself. When you
pull the worm off, it whips around causing you to think you
might be hurt. Not so, but still you might want to wear
gloves, or use pliers or something to do them in without
grasping them with bare fingers. I’m generally too lazy to
get gloves or pliers, so I just steel myself for the task.
(The moth of the tomato horn worm can be mistaken for a
hummingbird. It is that big and it acts like a hummingbird,
too.)

I have felt the presence of three other
Lepidoptera–European corn borer, corn earworm, and
cutworm. These creatures can be killed with Bt if you can
get them to eat it. The corn borer and earworm don’t hang
out on the surface of the plants. The borer bores a hole in
the stem and goes inside to eat. The earworm generally gets
inside the ear and eats the kernels. The cutworm lives
below ground. It cuts the stems of plants near the soil
line. Even if it were practical to spray the stems with Bt,
the nasty gray grub will have killed the entire plant
before the Bt takes effect.

Before I tell you what I do to avoid these problems, let me
tell you what I would do if I had them. There are a number
of good books dealing with garden insects. In them you will
find a variety of ways to control insects. What any
individual gardener uses is probably more a matter of
preference and what seems to work best for him or her.

Keep in mind that you won’t always know that your method of
control is effective in a given year. It is like the common
cold. You can take aspirin, vitamin C, lots of water, and
get plenty of rest and the cold will leave in seven days,
or you can do nothing and wait it out, in which case it
will be gone in about a week. If you feel proactive
measures need to be taken, you might consider doing nothing
on part of the patch, as I did with the cabbage.

Corn borers can be hand-picked. You need to be observant.
When you detect a hole in a corn stalk and perhaps some
sawdust outside, cut a slit below the hole and dig out the
worm. European corn earworms can be controlled by squirting
mineral oil on the silk where it emerges from the ear.
Cutworms can be controlled when you are transplanting by
putting a collar around each plant. Since the grub curls
around the stem when it is cutting it, a toothpick or other
small stick pushed into the ground next to the stem may
also work.

Those are the measures I would take if I were going to do
something. If every year were like last year in the corn
patch, I might consider those actions. Last year I had corn
earworm damage in just about every ear. I don’t consider
that a problem, as the part of the ear they damage can be
cut out leaving plenty to eat. But to go from virtually no
damage year after year to a year like the last one is
disconcerting. What happened?

Unfortunately, a lot of things happened, which is often the
case in gardening. That’s why it may take years of
observation and some experimentation to figure things out.
First, we had a winter that was unusually kind to life in
the soil. We got snow cover early and it stayed on the
ground insulating it all winter. The frost, which can go
four feet deep some winters, was only an inch deep in my
garden. Earworms and borers are usually killed in winters
north of New Jersey and fly into our fields and gardens
from the south. It is reasonable to think many survived
last winter. Second, there was a tropical storm that pumped
lots of warm air into Maine from the south at just the
right time to blow the moths of these caterpillars in our
direction. Third, I transplanted corn for the first time
ever to try to get an earlier crop. Fourth, I didn’t
fertilize my corn the way I usually do.

As you might guess, I don’t like the first two
possibilities. They indicate that my pest-free corn in
other years is just the luck of location. However, other
gardeners and farmers in the area in other years have had
to spray or take other measures to protect their corn,
which helps me keep faith in my methods.

When I harvested the transplanted corn and found the
earworm damage, I was convinced it was because the plants
had been weakened by transplanting. I was anxious to have
this confirmed by the later plantings of corn. You can
imagine my disappointment at finding all the plantings
damaged by caterpillars. That leads to the fourth anomaly.
I like to plant double rows of corn about six inches apart
with three-and-a-half feet between. I start by hoeing a
trench eight inches or so deep. I spread manure in the
bottom of the trench–even a hot, raw manure like
chicken. I then partially cover the manure by hoeing
another trench three inches deep on one side of the manure
trench. Seeds are planted in this trench, a pair every
foot. This is repeated on the other side of the manure
trench, the seeds covered, and, voila!, insect control in
the corn has been taken care of for another year. Last year
the manure I used was two-year-old horse manure that had
been stored outside. It was lovely humus but it didn’t have
much nitrogen, which corn needs in abundance. That’s what
I’m blaming my corn insect problem on. Hey, even if I had
that much of a problem every year, it would still be minor.
As proud as I am of harvesting insect-free corn year after
year, I can still live with a little damage and less pride.

There is another insect that may be found in corn. This
poor fellow suffers the slings and arrows of gardeners
though it is more beneficial than destructive. I refer to
earwigs. The earwig did not get its name from being
discovered in corn ears, though that is a frequent day-time
hangout. It was once believed that earwigs crawled into the
ears of sleeping persons. A nasty thought, especially since
they frequently do get into houses. They are not
particularly attractive, either. They are brown,
beetle-like insects, almost an inch long, with
menacing-looking pincers at the tail end that look like
forceps.

Earwigs eat a little bit of everything. Decaying matter and
other insects are helpful to us. If they eat corn silk, it
will cause the corn ears to be deformed. Did you realize
that every kernel of corn is attached to a strand of silk?
If the strand is damaged, that kernel will not develop. I
have never noticed much damage from earwigs so I leave them
alone. Anyone who wants to get rid of them can take heart
in the knowledge that they don’t fly worth a darn. Most
earwig movement is as hitch-hikers. You may bring some home
from the florist or the grocery store.

Now, to wrap up the caterpillars that I have come to know
in my garden. I think I read somewhere–but since I
can’t find it in any of my books right now perhaps I
dreamed it–that cutworms like wilting plants. No
matter if it isn’t a proven theo ry, my experience over the
years has supported it. I can only recall one time when
cutworms bothered any vegetables other than those that had
been transplanted. We had a very dry spring that year. I
had not built up the humus level very much at the time and
plants wilted in the draught. Cutworms damaged several
crops that had been planted from seed. I had never seen
anything like it before nor have I since. The damage seemed
significant in the spring, but as the garden matured what
once seemed like big spaces filled in.

I protect my seedlings from cutworms by making their
transition from seedling flat to garden as stress-free as
possible. First, the seedlings are hardened off by moving
them outside in the flats for an hour or two the first day
and increasing the time until, in a week, they stay out
around the clock. Second, I separate the seedling roots
from each other while sloshing them around in a bucket of
water and working the planting medium back and fourth
gently. This minimizes the amount of root damage. I put a
tablespoon or so of liquid seaweed in the bucket of water
just for good measure. When the transplants go in the
ground the soil is firmed around the roots and then the
ground is soaked so that the water will further put roots
in contact with soil. lust in case, I hold onto extra
plants either healed in at the end of the row or still in
flats as replacements. I seldom need a replacement.

I set out in this article to cover all the insects that
damage crops in my vegetable garden. They are such a small
part of gardening that I was sure I could cover the subject
adequately, but I have only covered caterpillars, earwigs,
and aphids. It was not my intention to slight the beetle
family known to my cucumbers, asparagus, beans, and, of
course, potatoes. Lets not forget the flea beetles that
have wiped out early plantings of broccoli and severely
stunted radishes. Then there are flies that lay eggs that
become root maggots and leaf miners. Squash bugs are always
good for a laugh, especially when you squash them and are
reminded that when you were younger you called them stink
bugs. All told there are 17 vegetable-eating insects with
which I have become familiar over the years, and so far I
only covered eight. Next issue I’ll finish the job.

Part II of our guide to “Low-Maintenance Pest Control” will
appear in April.

Related Articles:

Types of Pest Control