Eliminating Allergenic Mold Spores in Your GardensSunlight and Molds
Bright light and fresh air are the enemies of mold. Many landscapes have huge trees overhead that let in little light. Consider hiring a tree trimmer to thin out some of the branches overhead. Open the trees up so that the sunlight can come through. Perhaps it would be a good idea to actually remove a tree or two if they're growing too close. Let the light shine!
When planting any new tree, consider the shade that it will cast when it is full-grown. Certain trees always develop very thick canopies while others will be light and airy. Watering and Irrigation
Perhaps as important as any other single mold factor is the watering. Too little water makes for weak plants that attract insects. Too much water will also always produce weak plants.
Automatic irrigation systems, on clocks, are responsible for a great deal of mold growth. Allergists in desert areas often find very high mold spore counts, in the middle of the summer! Much of this is being directly caused by irrigation systems that are not being monitored closely enough. Often they are set to irrigate lawns that are already still soggy from the last watering. Over-watered lawns will quickly become mold factories and will shower everyone near them with an abundance of mold spores.Plant Diseases and Spores
Many pests of our plants are not insects but are fungal type diseases such as mildew, rust, black spot, scab, and leaf blight. These organisms also produce allergenic airborne spores. The very best way to avoid these diseases and their spores is by planting disease resistant plants. The second most valuable approach is to keep plants growing cleanly and strongly.
Insect-attacked plants will often later be attacked by fungus diseases, and visa-versa. Healthy plants go a long way to keeping our air clean.
Certain plants if grown in the wrong area can almost be counted on to harbor disease. Evergreen viburnum growing in the shade will certainly get moldy and full of mildew.
Crape Myrtle trees grown in an area that doesn't have hot summers will always have mildew.
A cold, wet spring frequently brings out a huge flush of both mildew and anthracnose on the leaves of California Sycamore trees.
In areas with cool, foggy nights and warm days, rust will surely grow on any roses, hollyhocks, or snapdragons that are not rust-resistant.
Most roses grown in too much shade will quickly mildew. Actually almost any plant that thrives in full sun will run into problems in too much shade. Insecticides and Fungicides
When you see a plant covered with insects or fungus, fight the urge to go get out the chemical sprays. Many chemical sprays will themselves trigger allergies. They may also weaken your immune system.
A shrub full of insects can often be helped immensely by just blasting off the bugs with a strong jet of water from the garden hose. Spider mites on plants can also often be brought under control with this same stiff spray of water.
Many insect pests can be killed with a simple, non-toxic homemade spray of vegetable oil, water, and liquid dish soap. For a gallon of water add two tablespoons of vegetable oil and two to four tablespoons of soap. I like Ivory Liquid.
For fungus diseases spay them with a mix of baking soda and water. I use from two to six tablespoons of baking soda per gallon of water, depending on how bad the infestation of disease is. This often needs to be repeated all summer long. The baking soda will also kill some aphids. If you like you can just add some baking soda to the insecticide mix of soap and oil and have an all-around insecticide-fungicide spray mix.
Do not expect these homemade sprays to be just as effective as the most powerful chemical killers. Often they're not. But they do work and they are much safer and a whole lot less likely to cause allergies. IPM
This stands for Integrated Pest Management and one of the basic themes of IPM is that we are not looking to eliminate insect pests, just to control them. Using beneficial insects such as ladybugs, mealy bug destroyers, tiny parasitic wasps, and green lacewings is always worth a try. It would be worthwhile for any gardener interested in allergy control to read a book or two on organic pest control.Ants, Aphids and Scale
Ants will farm out aphids and scale and will protect them from their natural predators. When the aphids and scale have ruined one part of a plant, the ants will move them to another fresh spot.
Frequently we can't seem to get rid of the insects because there are so many ants on the trees and to kill the ants I use a slow-acting but effective mix of powdered sugar and borax. Look for the borax in a box in the grocery store where they sell laundry products. Mix the sugar and borax fifty-fifty. Sometimes I like to flood the area under where the ants are thick with a hose and then when they're all over the place, I sprinkle the sugar and borax mix.
A few types of ants don't much care for sugar and for these try mixing corn meal and borax. This bait mix will also kill some other garden pests such as slugs, earwigs and roaches. I have also had good luck killing ants with a mix of non-dairy creamer and borax. Cockroaches by the way, inside the house cause plenty of allergies and the best way to kill them is with a mix of boric acid and powdered sugar as a bait. Sprinkle this powder down where the roaches will walk through it. You can buy boric acid in almost any drug store. These baits are cheap, safer than other poisons, and they work.
Out in the yard don't put these baits where the dog will eat them. Sometimes it works well to hide them under old boards or flat rocks.A Note about Ferns
Ferns don't produce mold spores but they sure can produce fern spores. Often these spores from the ferns can be just as allergenic as the mold spores. Fern spores usually shoot out and land fairly close to the fern. Small ferns growing in a shady part of the garden rarely trigger much allergy. But people love to grow ferns in hanging baskets and then they often hang these over patio chairs, tables, right where someone will be sitting.
When these overhead ferns cast off their miniscule spores, they will land directly on the unsuspecting victim underneath. Hanging basket ferns are fine, but watch where you hang them!
Tree ferns are handsome creatures but again we need to watch where we plant them. All too often they are planted right next to front doors where with their added height, they can shower spores on the people coming and going. Another consideration with tree ferns is that they have millions of tiny reddish-brown colored, needle-sharp hairs on their trunks. These little fern hairs can make you itch and they can also cause plenty of irritation of the throat and nose when they're inhaled. Plant tree ferns back away from most human traffic.
By Thomas Leo Ogren MSc Agr.
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