Use Plant Covers for Insect, Disease Protection
This season, you may want to try a technique which will not only enable
you to have early production, but may be the difference between whether
you produce an abundant crop or no crop at all. This technique will also
enable you to grow a pest-free crop without applying pesticides.
Gardeners blame everything from vengeful neighbors to dishonest nurserymen
for stunted, nonproductive plants which are infected with a virus. No person
is to blame - thousands of insects, such as thrips, feed on a plant which
already has a virus and then transmit the virus to another plant. Not all
insects spread viruses. Insects which have been known to cause problems
include aphids, thrips, white flies and leaf-feeding beetles. Aphid mouth
parts puncture an infected plant and draw the virus particles and cell contents
into their body.
Some aphid-borne viruses are carried only on mouth parts, but others are
taken into the gut, circulatory system and eventually the salivary glands.
All the aphid has to do is "slobber" on a healthy plant to cause
infection. This is why virus prevention is so difficult - 100 percent insect
control is both impossible and impractical. Even if you could grow a plant
full of pesticide which would immediately kill any insect that damaged the
foliage, the virus is delivered the instant the plant tissue is penetrated.
Insect sprays are not the answer!
The remedy for insect damage and contamination is a physical barrier. Transplant
tomatoes and peppers into the garden. Immediately install concrete reinforcing
wire cages. Cages are nothing more than cylinders made of reinforcing wire,
hog wire or similar material to support the plant and keep the fruit off
Make the cylinder 18 to 20 inches in diameter and 2 1/2 (called half cages)
to 5 feet tall (the length of the roll of wire becomes the height of the
cage). Concrete reinforcing wire, generally considered to be the best, is
available in rolls of varying lengths. A 5-foot length makes a tomato cage
18 to 20 inches in diameter. Cages are held together by bending and crimping
the wire ends around one of the vertical wires.
To keep the cage supported and standing, snip off the bottom ring of the
cage and push the remaining prongs into the ground. Install cages around
and anchor all sides well with wire stakes in the soil. For a barrier, cover
the cages to the ground with clear plastic or a translucent, fabric-like
material known as spunweb (Grow-web). Adequate anchorage is essential for
cages covered with plastic or spunweb during windy periods.
Covered transplants will be protected from virus-carrying thrips and aphids
until the plant touches the sides of the cage and plastic has to be removed.
Plants covered with spunweb never have to be uncovered. Plastic covering
must be removed when foliage begins to touch the edges and bunch against
the sides of plastic. This will usually be about the time the plant has
marble-sized fruit. Because of excessive heat build-up, the plastic covering
must be removed when temperatures regularly begin to reach the high 80s.
Spunweb will never overheat plants since the temperature inside the fabric-like
material will not exceed 15°F above the daytime high temperature. Spunweb
can also be used for the fall crop, planted in July, since it will not overheat
plants and seems to act as a shading cloth. Plastic-covered cages need to
be closely monitored since temperatures will be 30°F warmer inside
the plastic. Ventilation from the bottom, by raising the plastic 4 to 6
inches, as well as opening the top, may be necessary when daytime temperatures
above 75°F occur.
The tops of these miniature greenhouses which are covered with plastic will
have to be left open during warm days to avoid excessive heat build up,
but most insects do not enter from the top. Most insects are blown in by
the wind. The covered plants are "hidden" from contaminating insects
and not as attractive to them as unprotected plants. Leave tops open when
daytime temperatures get above 75°F. On cold nights, tops should be
closed to provide extra protection. One of the advantages of the spunweb
is that it never requires ventilation. However, this web-like material does
not provide as much cold protection as plastic; each web-covered cage will
have to be artificially heated (with Christmas lights, etc.) if temperatures
fall below freezing.
One of the greatest benefits of this system will be protection from wind.
Findings indicate that winds as low as 15 mph can significantly slow plant
growth, delay harvest and decrease yields of vegetable crops. You may wonder
if plants will set fruit when covered with plastic or spunweb since no bees
or insects are able to enter. Tomatoes, peppers and eggplants are 85 percent
self-pollinated; that is, they don't need movement of pollen by insects.
If you want to insure adequate pollination, vigorously shake the covered
cages every day after bloom begins or thump bloom clusters daily with your
finger. You can also artificially set early blooms by spraying bloom clusters
with Blossom-Set, a plant hormone spray. Resulting fruit will have fewer
Protect tender transplants as soon as possible from virus-carrying insects
and environmental adversities with the covered cages. The larger a plant
is before infection occurs, the more productive it will be, and conversely.
To protect seedlings from birds or other varmints and vine crops (such as
broccoli and cole crops) from leaf-eating caterpillars, cover them with
spunweb. You can also use spunweb to "vine ripen" fruit. Spunweb
products can be found in local nurseries or ordered directly from the manufacturer
through the mail. One address is:
Indeco Products Incorporated, P.O. Box 865, San Marcos, Texas 78666 Telephone:
512-396-5814 or 1-888-246-3326; email email@example.com. ¶