Although physical controls aren't always made of
organic materials, they do keep within the spirit and intent of Organic Gardening by not using
synthetic chemicals to manage unwanted pests. When used in conjunction with other methods of
organic pest management, they can create an effective tool towards controlling the infestation you
have or preventing one from taking root. Many of these methods are quite simple and quite old, but
Using Barriers to Bar Pests:
A physical barrier that keeps pests away from
your beloved plants can be your first line of defense in most cases. Insects have to be able to
reach them in order to eat them. There are some simple techniques that can help you to simply block
their path. Here are just a few.
These types of barriers can be effective depending on the size of the pest you're trying to keep
out.. Birds, rabbits and other plant eating rodents can easily be thwarted using this method. A
simple 2 foot high high chicken wire fence will keep out rabbits, but a more formidable barrier is
needed to keep out garden adversaries like like raccoons, deer, and woodchucks. Birds can can be
stopped from eating crops they are fond of by using netting above any of the fences described
Appearance and cost are considerations when
considering what materials you'd like to use. Picket style wood fences are more attractive than
staked chicken wire fences, but they are considerably more expensive, and may partially block the
sun from your plants. Although the latter may possibly benefit some varieties needing more shade,
these types of fences are also more difficult to install.
If you decide to use a chicken wire fence, get a
width that will allow you to bury a portion around the perimeter if you want to keep burrowing
pests out as well. Dig a trench and put about a foot below ground, six inches straight down, then
the last six bent 90 degrees so that it's flat against the trench. Fill it with dirt and
subterranean gophers and their cousins are out of luck. One inch mesh works best for excluding most
animal pests. You'll need some good sturdy stakes to attach the wire fencing to as well as to
define it's boundary and shape.
The expense of this type of fence can have an
impact on your budget as well if you are fencing in a large area. Keep in mind though, that you
don't always need to fence in the whole garden, but sometimes just those plants most vulnerable to
the pesky little guys. Fencing in melons and corn is a good idea if you have problems with
raccoons. You can also use chicken wire in a circular pattern around plants like tomatoes. Other
plants like peppers usually need not be fenced in because common pests will usually only make the
mistake to bite into them once.
Chicken wire can also be made into more elaborate
fence designs that allow for easy removal for regular garden chores. by making light rectangle wood
frames that will slide into posts with groves in their centers, you can easily slide up a few
panels for easy gardening access, and slide them back in to protect them when you're
Can be made out of cardboard easily and act as a barrier to prevent Cutworms from attacking the
stems of newly transplanted items. Just cut strips of lightweight cardboard to about 7 1/2 inches
long and about 3 inches wide, bend over and overlap the ends to form a wide short tube and fasten
with tape. You can also use preformed cardboard tubes like that from wrapping paper and cut similar
proportions. Those you'll have to slit up one side so you can slip the stem past it. Position them
around the base of the stem and press about 1 inch of the collar below the soil line. The cutworms
route has just been closed!
Strips of copper sheet metal make a excellent and permanent barrier against slugs and snails. Put
them around the trunks of trees and shrubs, wrap around legs or edges of greenhouse benches, or use
them to edge garden beds or particularly vulnerable sections of plants. Make sure you've barred
their path completely and there are no gaps in your copper barrier. Remove or cut back any
overhanging branches or plants that may give the slimy little guys an on ramp to your green jewels.
Make sure you eliminate the slugs inside the barrier with slug traps or by leaving ground barren
long before putting up your copper barrier.
Tar paper, cut into squares about six to eight inches across can be an effective barrier against
cabbage root flies wishing to lay their eggs around the roots of cabbage plants. Just cut an 'X'
shaped into each center, slide the square over the plant and flatten it against the soil. Press the
center flaps firmly around the stem and anchor the square with pebbles.
These are an effective way of barring pests unable to fly such as ants, snails, slugs and gypsy
moth caterpillars. Some will trap the pests while other simply prevent them from crossing. You can
make cloth tree bands from strips of heavy cotton cloth or burlap about 14 inches wide, that is
long enough to create a large overlap when they are wrapped around the tree's trunk. Fasten them
around the center with a piece of twine or string and pull the top portion of the cloth down over
the lower half to make a dead end for the creatures. Then check daily and destroy any pests caught
in the material.
When pests try to cross sticky bands, the get stuck on them and eventually die. You can paint a 4
inch band of a sticky compound all around the the trunk of matured trees. If trees are younger,
wrap a piece of fabric around their trunks, cover with plastic wrap and tie both down firmly. Then
just paint the compound on the plastic covered collar. Weather and dust will eventually reduce it's
effectiveness, so repeat as necessary.
Covers as Barriers:
Super light spunbonded polypropylene is often used by gardeners of all types as floating row
covers. The inexpensive, gauze like material keeps pests off plants while allowing light and
moisture to pass through it easily. To keep it from hindering or damaging your plants as they grow,
you'll need to support it over your row of plants. The most common way to do this is with thick
wires that can be bent into arches and anchored into the soil with a good push. Space them out
about two feet apart and pound a 1 1/2 foot stake at either end of the row. Hammer the end of a
string into one end and and begin to loop it around the very top of each wire arch once until
you've reached the other end where you'll then secure that string to the stake. This will give you
support sideways as well. If you stop here, you'll probably still have problems with pests as there
will be at least small gaps at the soil level. To take care of that, simply bury the edges of the
polypropylene into the soil and pat it down well. Make sure the soil beneath your row covers is
moist before you begin this process and water the row after you've completed.
Hanes will be happy to hear about this one. Old pantyhose need not be throw away anymore. They
actually make very effective pest barriers for crops like melons which you can cover the vulnerable
fruits when as they begin to grow. Their fine mesh will keep out most bugs, yet allow the plant to
breath and get light as well. Simply cut off the end and cover the melons like you would put on a
sock. You can tie the end or place a firm, but yielding rubber band near the stem to cut off the
bugs alternate route. This method can also be effectively used for vegetables like corn, cucumbers
squash, cabbage and brussel sprouts since as they grow the hose will expand with them as
Dust barriers like diatomaceous earth (DE) are primarily spread around the base of vulnerable
plants because they are actually made up of sharp particles that will cut up the delicate
underbellies of insects like snails and slugs. If they do cross the cuts on their pads will cause
them to get dehydrated and die. These are best effective when dry so should be reapplied after a
Cabbage root maggots can be deterred from laying
their larvae by spreading a six inch circle of talc, wood ashes, DE, or lime around the plants
Another idea call for a mixture of 1/4 pound DE,
1 teaspoon of soap and water to be thickly painted onto tree bark to repel ants and to hinder adult
borers from laying their eggs inside the bark.
The physical barriers described above can be
wonderful alternatives to chemical pesticides as they go directly towards the Organic Gardener's
goal of prevention and pest management. And the best reason to use them is that they are not
harmful to the environment in which you will be amongst and pull food from. Some are old ideas
using new technology to make them better, but to the serious organic gardener, they are all better
than chemical pesticides. This article is provided as
information to the world gardening community and the GreenWeb does not offer the items
mentioned above for sale.