PEST AND DISEASE CONTROL FOR ROSES
Don Trotter
Hello Fellow Earthlings and welcome to the second of our five part series
on rose care. This discussion will be focusing on pest and disease control.
Let's get a look at those roses.
It is widely known that roses can be a real pain in the --------- if they
want to be or are in any way not attended to. This is not so of a rose
that is allowed to grow under natural condition without nitrogen fortified
chemical fertilizers and harmful insecticides and fungicides. The truth of
the matter is that roses can be very easy to tend to if they are cared for
with a light hand during the growing season. The fewer things that a
gardener does to shock a natural balance of things the fewer problems will
arise as a result of that shock.
Chemical insecticides are only effective until the target pest develops a
resistance to that chemical. Then it becomes necessary to alternate harmful
substances to control an insect population that continually gets worse
because of lack of competition and natural predators due to high
concentrations of chemicals. The major rose pests that we encounter here in
your rose garden can be controlled by establishing populations of two
beneficial insects and periodic treatments with a bacteria and a tree sap
extract. The two beneficial insects are the Green Lacewing and Trichogramma
Wasps. These two insects will guard your roses against everything from
Aphids to some Scales and Spider Mites. Lacewings are very active and
voracious feeders who's host or target prey are aphids, mealybugs,
whiteflies of some species, juvenile scale insects, and some spider mites.
The tiny Trichogramma wasp is a parasite of caterpillars some species of
budworm and will antagonize a number of other butterfly and moth species.
These parasites do not have a stinger (no need to fear them), they have an
ovipositor that lays her eggs inside the host. As the wasp larvae develop
they use the host as a food supply.
The bacteria that I spoke of is Bacillus thuringiensis variety Kurstaki or
Berliner. This product is often referred to as BT and is a paralyzing
bacteria that affects many species of worm and caterpillar including the
leaf skeletonizer worm. By paralyzing the stomach of its host this bacteria
is very useful against its target pests.
The tree sap that I was referring to is Oil of the Neem Tree of India. The
active substance in this sap (seed oil) has been named Azidirachtin after
the botanical name of the tree. The extracted oils from the tissue and sap
of this tree are very effective at repelling and keeping your rose bushes
free of any sign of insects. Although it smells like hazelnuts to us it has
the most repellent affect on pest insects. Neem oil is sold under the name
Bio-Neem under the Safer label and Rose Defense under the Green Light
label. These two products can be found at any garden supply store.
Controlling diseases in your rose garden is really not very difficult at
all. There is no need for harmful fungicides that can cause severe physical
problems or have a negative affect on outdoor pets and bees as well as wipe
out entire earthworm populations from a single spraying. Balanced nutrition
and a couple of minerals can keep your garden disease free without weekly
exposure to chemicals.
Most diseases of plants will leave a healthy plant alone. It is the same
with us, if we're healthy we don't get sick. Plants also have immune
systems. This is where a balanced diet that contains the proper amount of
copper, sulfur, potassium, magnesium and calcium will ensure that certain
very commonplace and damaging fungi don't get a foothold in your garden.
Potassium is very important for resistance against powdery mildew and rust
on roses. Not in some crazy amount that is available to the plant in five
seconds after application but instead long lasting natural sources from
mineral deposits or from other natural source. When potassium is broken
down in the soil by a healthy soil it will actually help to prevent the
onset and spreading of powdery mildew and rust, which are tough problems
for most chemical gardeners to control. High calcium levels along with an
abundance of naturally available magnesium will cause your roses to produce
thick healthy canes without problems with of slow root development in our
heavy soils. Copper and sulfur are the two elements, which I use as a spray
fungicide if absolutely necessary. Other than dormant spraying minimal
spraying should be necessary to prevent fungus and disease if the roses are
fed naturally.
Don Trotter's natural gardening columns appear nationally in environmentally sensitive publications.
Look for Don's book Natural Gardening A-Z from Hay House at bookstores everywhere and at all online booksellers and check out Don's columns in Hearst's Healthy Living Magazine coming soon.
Enjoy some of Dr. Curly's past gardening articles from our growers archive.
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