Tuesday, August 08, 2006

Aphids Are Among Us

Gardeners are all familiar with these tiny creatures, even if they only grow a rose bush or two. The soft squishy things can reproduce like wild fire and if left unchecked they can wilt tender rose buds before the sun reaches high noon. And roses are not their only targets. They like all sorts of delectable garden fare. Aphids suck. Yes they do. In fact that is how they make their living.

These little creatures have a longish proboscis, kind of like a mosquito. They use this, first to pierce tender plant parts, and then like a straw, to slurp up carbohydrate rich plant juice. Aphids are like natural born diabetics. What they excrete is actually sweeter than what they slurp up. Aphids exude a thick syrup of concentrated minerals and sugar. Ants are often attracted to aphid colonies, collecting their “honey dew” and using it for food. When the honey dew is not consumed, but rather collects in abundance on plant leaves it can lead to mildew, rust, and fungus, which are definitely not good news. However, honey dew is not all bad news. Azotobacter, a free living nitrogen fixing bacteria that inhabits the soil, thrives on the stuff aphids excrete. Also, keep in mind that slight to moderate pest damage increases the nutrient value of produce. Plants under some insect stress produce more anti-oxidants and phytochemicals to protect their health, and those nutrients also help protect our health.

Aphids offer damage and danger to our plants, while at the same time they can be symbiotic and beneficial. What’s a gardener to do? Diversity, balance, and attention are key. Planting to attract beneficial insects goes along way towards encouraging the diversity necessary to keep aphids in check By encouraging a balance between predator and prey, the gardener may need do nothing more than watch the laws of nature at work in the garden.

Aphids are harried by a number of tiny wasps who lay their eggs right inside the aphids body. Then there are the hover flies whose caterpillar like larva devour tender aphids like they are the tastiest treat on the planet. Ladybugs and lace wings, as well as their larva, happily dine on the squishy sticky creatures. Except for the lace wings, all of these creatures are hard at work in my garden, and I have never ordered or purchased a single bug. (If you missed the article on Beneficial Insects please see: http://harvestsgardeningsecrets.blogspot.com/2006/05/beneficial-insects.html You will find all the info you need to attract these hard working insects into your yard and garden.)

Even with the beneficial bugs hard at work in my garden, there are times I take matters into my own hands. Just before my Evening Primrose started to bloom, I noticed lots of aphids colonizing the buds. I studied these aphids up for a while. There were no tale-tale “mummies” that signal busy parasitic wasps. (I have a photo of the mumies, but I am having problems with blogger uploading my photos lately. If you need to see the photo, leave a comment and I will try again.) No hungry hover fly larva, no ladybugs at any stage. The remedy was quite simple. I hosed off the flower buds with a gentle steady stream. In the spots that the buggers were holding on tightly, I used my fingers to gently dislodge them, and hosed some more. Now that the Primroses are blooming, I find there are a few aphids, but they never came back in force.

Simply washing aphids from your plants is the least toxic and least disruptive way to deal with populations that are out of control. There are additional strategies that are considered organic. Insecticidal soap and Neem oil may provide longer protection as they actually kill the aphids rather than just displace them. These products are available at many garden supply outlets, through catalogs, and are often found at natural food supper-markets. Follow the directions on the labels and spray at dusk to minimize damage to beneficial insects. While you will need to thoroughly wet the infested surfaces, try to minimize the amount of your solution that drips on to your soil. Small amounts of Neem and Insecticidal soap will not harm earthworms or soil microorganisms. Just be careful not to over do.

If you happen to have food or agriculture grade diatomaceous earth laying around, it also makes quick work of aphids. Diatomaceous Earth often called DE is non toxic to fish, amphibians, and to you and your pets. It is made up of fossilized bodies of microscopic sea creatures called Diatoms. When prepared as a food preservative or as an insecticide it is ground in such a way that preserves the sharp edges of these tiny ancient creature’s shells. These sharp edges pierce the bodies of insects, both beneficial and pests, and the insects die of dehydration as their body fluids leak and evaporate.

I hate to use DE because it is death to beneficials, but I gave it a try as an experiment for the sake of this article. I sprinkled some on some squash leaves that were infested with aphids. By morning there were no more aphids in sight and after a week they haven’t returned. DE looks like dust or powder on the plant, and as long as it remains it is lethal. Small amounts can be ingested by earthworms, pets, and people without harm. (In fact, it is sometimes used internally to kill intestinal parasites. But do your own research or ask your doc or vet before trying this yourself.) Make sure not to breathe the DE dust or get it in your eyes. It is high in silica which is not good for your lungs and the sharp edges can irritate delicate eye membranes. (If you think this is scary, read the labels on any commercial pesticide, most of them are known to cause cancer, respiratory distress, and more.) DE can be found in most of the same places as Neem Oil and Insecticidal Soap.

Tobacco tea is a totally free ‘natural’ pesticide that you can grow and use on aphids. Be aware, natural does not always mean safe and non toxic. It is advised not to pick produce sprayed with tobacco for at least two weeks after the last application. I only use tobacco tea when my tiny seedlings in cell packs are under heavy attack. That way my produce and the garden ecosystem are not poisoned. For more information see:

While aphids may not exactly be gardeners best friends, they do have their good points. And even when they are being naughty they are generally not as harmful as people think. Tolerating some aphids in the garden while growing plants that encourage beneficial insects provides great tools for teaching children about nature, ecosystems, balance and diversity. Gardens that nurture life, nourish much more than just our bodies, they teach us lessons about life and nourish our souls.

Stay tuned, next time we will be looking at garden fresh chives which offer reliable hot weather flavor. In the meantime you can probably find me in the garden, Digging the Dirt.

Copyright 2006 Harvest McCampbell, from my column "Digging the Dirt," published in The Hoopa Valley People Newspaper, July 18, 2006. Posted here with permission.

(Also, chapter 4 of my novel in progress, Spirit House, is up at: http://360.yahoo.com/harvest95546 Look for the Blog section - near the top of the page.)