Gardening Tips: Put Down the Pesticide!

What to do this week

There may not be any garden insect pests in view just yet but they are still there. They’re slumbering in the soil or the half-rotten dropped fruit you didn’t get a chance to rake up last fall — all waiting for that first warm day to hatch and wreak havoc. With climate change, many pests may be changing their range and their behavior as they adapt, so gardeners must be nimble to adapt along with them.

Since the first defense is understanding the life cycle of those pesky predators, this week’s column will help you put down the can of Raid in favor of more benign – and more effective – measures. No, this isn’t merely an ideological stance to promote organic methods. It is based on sound ecological principles. Here is an example:

Aphids attack plants and reproduce alarmingly quickly. Heck, those aphid females are often born pregnant (it’s called parthenogenesis), sidestepping the bother of insemination altogether. Ladybugs eat aphids, and in large quantities, but reproduce normally and more slowly. If you reach for that spray can of broad-spectrum insecticide, you will knock out both populations almost completely. Trouble is, the aphids that are left will repopulate a lot faster than the ladybugs that eat them.

By Greyson Orlando - File:Ladybug aphids.JPG, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=35279712

A ladybug, (Coccinella sp., probably C. septempunctata) with aphids on a weed. Photo by Greyson Orlando CC BY-SA 3.0, via Wikimedia Commons)

Not only that, the aphids that are doing the reproducing are also the ones most resistant to insecticide. It’s a race the ladybugs can’t win and it means you’ll be tempted to keep using more and stronger sprays to keep the aphids in check. Stepping back a bit, you’ll find that encouraging diverse habitat also encourages ladybugs. Keep them happy and they’ll gleefully keep munching critters on your behalf.

Ants tend aphids and milk them for their sugary secretions, so discouraging ant hills will also help. They like dry, sandy soil, so making sure your garden has good organic matter is key, as is dousing the hill with strong manure or compost tea.

A reasonable aphid population will do only cosmetic damage to plants, but if you still can’t stand it or they are attacking young plants that are more vulnerable, you can use physical methods of control like spraying with insecticidal soap, which dries out their skin so they dehydrate, or simply knocking them off the plant with a jet of water. If your garden or your neighbor’s has been sprayed with broad-spectrum insecticides for a few years, it may take a while to bring everything back into balance, but the results are worth the effort.

 

Wider application

These principles apply to more than aphids and ladybugs. If you know the life cycle of your pests, you are better able to combat them. The middle of gardening season is too hectic to study up on remedial biology, which is why we’re talking about it now to get ahead of the game.

In the orchard, it is very important to hold off spraying dormant oil until half-inch green if you are trying to control scale and other pests. Half-inch green is when the leaf buds are just that, half an inch long, no more. Before that, the scale insects on the branches are dormant in their hard-shelled cases and impervious to the smothering effect of the oil. Too much after that and they have already spread their infestation. There is no need to spray unless you have seen their crescent-shaped casings on the bark of young twigs.

Likewise, if you had a problem with cankerworms last year it will soon be time to band the trees to prevent the flightless females from crawling up from the ground where they pupated and laying eggs. I wrap a band of sill gasket or heavy paper around the trunk and tape it rather tightly. I then spread Tanglefoot on the tape, making sure I don’t leave any blank spots. Renew this again in June, as well after the hard frosts in the fall to help control codling and other moths.

As you go through pruning your orchard, keep your eye out for the egg masses of tent caterpillars. Peel them off and dispose of them in the woodstove – one fellow forgot to take them out of his pocket only to find they had hatched in the warmth of his laundry room!

If you want to control for things like apple maggot or tarnished plant bug, there are a couple of tricks. They don’t come into play until May but it is best to be ahead with your orchard supplies if you need to order them from a supply house. Around green-tip stage, hang white or yellow plastic rectangles covered with Tanglefoot in the trees. They also come already sticky in different sizes or you can make your own from reusable corrugated plastic. These will look like a big delicious leaf to the insects and invite them to land. You will trap some beneficials as well, so don’t leave them hanging past the middle to the end of June. You can then use them to catch the first emergence of the squash borers in your garden beds. Again, don’t leave them out after the squashes have started to flower or you’ll capture the insects you need for pollination.

For additional control of apple maggot, I hang red plastic spheres, also covered in Tanglefoot, on branches at the south-facing, outside edges of the trees, especially around the perimeter of the orchard. Three or four traps per mature tree are recommended for control – only one per tree for monitoring. Early-maturing trees are best for this as they are the most attractive to the maggots. There are some traps that combine the yellow card with the red sphere – they can even come with a volatile lure to attract those egg-laying females. It all depends on how badly your trees are suffering. This level is not generally necessary for the home garden or small orchard. Orcharding supplies, including pheromone lures for other pests, can be found either by mail-order or from the better garden centers. I use Great Lakes IPM in Michigan, but for small quantities of this sort of thing, the Co-op Country Store on Keltic Drive is good.

While you’re waiting for spring to hustle along, it pays to spend a bit of time learning about the small rascally creatures that threaten your garden. You can’t and shouldn’t get rid of them altogether, but you can make sure they don’t come to anything but an annoyance.

 

 

Market gardener, farmer, workshop leader, seed-saver, political candidate and mother, Michelle Smith has spent over 30 years coping with the challenges of our bioregion and in the process has built a store of practical and technical knowledge. The Inverness resident has served on the board of Seeds of Diversity Canada and represented Alternative Producers with the Federation of Agriculture but can do nothing about her hair. She is pictured with a head of Club Wheat, a seed that shares her approach to hairdressing.

 

 

 

 

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