by Darlene Markey, Sweetland Garden Supply
Oh no, the aphids are eating my brassicas! And wait, what are those little two spotted, nearly microscopic creatures under my leaf? What is leaving holes in my green bean sprouts!
You may have said one, or more of the above sentences at some time in your gardening career. I have said all three and can add, “Aw, cute little caterpillar…”
As our garden grows, so do these pesky little arthropods and larva of arthropods. How can we minimize the blooms of non-beneficial insects in our garden? And then how can we get rid of these pests?
There are ways to create gardens that make it difficult for problematic insects to thrive. Gardens are ecosystems, right? We naturally provide food for leaf eaters by planting cabbage and tomatoes. So, if we provide habitat and food for predator insects we help create balance.
Our first, and often necessary, reaction to problematic bugs is to spray something. Most insecticides are non-discriminatory, killing beneficial insects as well as the bad guys. Then, our garden ecosystem gets a little out of whack. Leaf eaters return first and often with a vengeance because there are no predators to eat them. For example, a tomato russet mite can reproduce two days after it is hatched, and females can lay up to 50 eggs, which then hatch in two days. In an exponential fashion a plant can be infested with russet mites within 2-4 days.
So, the trick is to somehow keep balance in your garden. How?
Add flowers that attract bees and ladybugs. Parsnips, carrots, chamomile, lavender, rosemary, basil, and mint attract good guys, but are not liked much by leaf eaters. Plant pyrethrum and marigolds, which leaf eaters do not like.
Add predators. Yes, some will eat some. But in a few weeks you will have a bunch of juicy leaves for aphids and spider mites, so it is important to have predators ready to eat them. Praying mantis and ladybugs eat aphids. Trichogramma wasps lay eggs in caterpillar eggs. Andersoni mites eat russet and thrips. Predatory nematodes eat soil larva.
Sprinkle diatomaceous earth on the soil under plants to slow down the march of soil dwelling leaf eaters. Sprinkle it on your leaves if need be. Excellent way to help keep down the grasshopper population.
Use bio pesticides, like naturally occurring bacteria, Bacillus Thurengiensis, which stops caterpillars from eating. Bacillus Thurengiensis Israelensis to reduces fungal gnat larva in the soil-as well as mosquitos.
Put chitosan in your soil. Frass is bug detritus and bugs don’t like to be around it. Chitosan is also in crab meal, shrimp meal, and feather meal. Add chitosan to a tea to foliar spray to deter insects.
Keep your garden clean. Anaerobic soils-compost piles- can attract fly larva and fungus gnats.
Sometime though, things just get out of hand. So chose an insecticide that targets whatever species you want to get rid of. Some insecticides kill, some just deter. Most need to be sprayed on the leaf surface and UNDER the leaf surface to work. Often just the act of spraying repels the unwanted insect. Always follow the manufacturer’s directions. Below are a few you can find commercially.
· Neem a favorite one, repels insects, often coats them, smothers them and inhibits movement. Neem also has a compound in it called azadirachtin that inhibits the insect’s ability to reproduce. Neem seed meal can be added to the soil as an insect deterrent and also as a fertilizer. Azadirachtin can be purchased separately.
· Azadirachtin solely, just
· Fish oil is a very strong, broad-spectrum insecticide and fungicide.
· Horticultural oils smother and repel.
· Diatomaceous earth, either as a fine dust or a flowable powder, kills insects when chards of glass like diatoms get into the belly of the insect. It also provides plants with silica.
· Soap kills and deters insects. There are commercially available insecticidal soaps.
· Nicotine and sugars kills on spider mites.
· A variety of herbs rosemary, lavender, eucalyptus, cloves, garlic, cinnamon, peppermint and coriander deter and often kill insects.
· Exoskeletons of other insects deter insects, (Is this like being in an insect graveyard to an insect?) This includes anything with chitosan: frass, crab meal, shrimp meal, etc.
· Pyrethrin, made from the flowers of chrysanthramum and pyrethrum kill many insects.
· Compost tea has also been known to reduce insect populations in two ways. One it increases the plants immune system and provides a coating on leaf surfaces that are not attractive to insects. There are microorganisms that attack insects!
· Bacillus Thurengiensis will kill caterpillars.
· Spinosad-the by-product of making Streptomyces-is non discriminate and is harmful to beneficial bees-more so than other products.
· Grandevo, a microbial based insecticide repels, stops feeding of leaf chewing insects.
So, if you need to spray, just be mindful that if you want a healthy garden you then need to reinstate a balanced ecosystem. It is always a give and take. For me, it is okay when the grasshoppers start taking nibbles out of plants. I can shake a few earwigs out of my corn. But those white flies on my cabbage..…..
Save the Date! Upcoming Classes at Sweetland Garden Supply
Compost Tea Demystified: Understand what compost tea is and learn how to make a back yard brewer. June 16th, 10 am-12 pm & July 11th, 6-8 pm.
Problem Solving: Discuss organic problem gardening methods with other gardeners and Sweetland Staff. Discussions will include spider mites, powdery mildew, termites and nutrient deficiencies.
For more info on classes, contact Sweetland Garden Supply at 292.9000.