Gardening Tips: Friends & Foes

Editor’s Note: This column last appeared on 27 May 2020.


What to do this week

Having got the early spring planting well underway, it is time for me to turn my attention to orchard chores. The trees are budding out and many are already at the green tip stage. It only takes a few days of warm weather for things to start speeding up! Every location will have a slightly different response to the weather, and different soil types as well. Sandy soils will hasten bloom and cold clay soils will delay it. It is important to keep an eye on the changes happening with your trees in your garden. The stage the blossoms are at will let you know what to do and when.

Foe: Lygus lineolaris (tarnished plant bug). US Department of Agriculture, Public Domain, via Wikimedia Commons.)

At half-inch green – which is literally when the green leaf tips are half an inch long – it may be time to spray horticultural oil on the trees to control scale. Regular readers will know that I would never recommend spraying broad-spectrum insecticides. This goes for organic pesticides as well, like pyrethrins or rotenone. I like the balance I have achieved with the pests and the beneficial insects and pollinators.

Horticultural oil sprayed at half-inch green will suffocate the scale larvae just when their hard outer case is softening to allow them to increase their infestation. It will not affect your beneficials at all. Most trees can handle a bit of scale, but some varieties are more susceptible than others and a bad infestation can kill off whole branches and really set the tree back. If you intend to use a fungicide later on like sulphur or Bordeaux mixture be aware that you should wait at least thirty days after using oil.

I prefer to ensure that there is good air circulation in the orchard to reduce the incidence of scab and leaf blights, but the weather in some years will be worse than others for these things. The latest thinking on controlling scab is to let the grass grow long in the orchard until the end of June when the risk of serious scab infection has passed. The cover will keep the spores low to the ground and off the leaves and fruit. When the weather dries out in July, you can safely mow again. I need hardly say it’s a win to me to reduce the amount of mowing and the incidence of scab at the same time!

Some pests are starting to be on the move and now is your chance to get ahead of them. Examine your trees for the egg masses of tent caterpillars and peel them off and burn them. Don’t try to burn the nests with a torch later – the caterpillars will only drop to the ground and re-infest the tree. If you are careful, you can sometimes get the whole nest and drop it into soapy water or kerosene when it is still small but it is better to get the eggs before you have a problem at all.

Different insects are attracted to different wavelengths of light and can be controlled at different stages of their life cycle. If you have a larger orchard you may even want to purchase pheromone lures to trap the pests you are targeting. Pheromones mimic the chemicals the female insects use to attract males and the traps are placed according to the manufacturer’s instructions for maximum effectiveness. But even without chemical pheromones there are many visual traps that you can purchase or make to do much the same thing in your home garden.

Friend: A quarter-inch-long parasitic wasp, Peristenus digoneutis, prepares to lay an egg in a tarnished plant bug nymph. (Photo by Scott Bauer, US Dept of Agriculture, Public Domain, via Wikimedia Commons)

Tarnished plant bug (TPB) and sawfly larvae feed on buds and developing fruit but they can be controlled by hanging sticky white 15 cm x 20cm rectangles when the trees are at pink bud stage. For sawflies, place them at eye level or a little higher on the south side of the trees. For TPB, place them at thigh-height on perimeter trees. These traps will catch other emerging insects so you will get a good idea of what else is going on in your orchard.

One common pest I struggle with is apple maggot, but it is one of the easiest to control through trapping. The emerging flies are attracted to sticky yellow rectangles, which mimic the wavelength of foliage the flies feed on before mating and laying eggs in the fruit. If that level of control is not enough, hanging red plastic spheres covered in Tangletrap is a good way to trap the females as they jump from fruit to fruit to lay their eggs. The trap should be placed at eye-level close to clusters of fruit but with 12 to 16 inches of clearance between it and the foliage. Special attention should be paid to perimeter trees. For monitoring, use one or two traps for a full size tree. For serious control, use three to four traps per tree. The effectiveness of these traps can also be enhanced with the use of scent and pheromone lures, available at orchard supply houses.

Codling moth is not much of a problem in Cape Breton orchards, at least not yet, but good control is possible through the use of trapezoidal pheromone traps.

And don’t forget to stop worrying about the bad bugs and spend some time making things cosy for the good guys. Like the trichogramma wasps that parasitize over 200 insect pests like codling moth and fruit worms. Or lady bugs that munch their way through aphids like nobody’s business. They are a gardener’s friends!

Make sure you have plenty of diverse habitat to welcome these pals. Don’t forget to provide plenty of pollen and nectar sources for your pollinator friends as well to keep them fed and happy in between their work among your trees and fruit bushes. If you must control the pests yourself, rather than rely on the natural cycles, use the targeted methods I have just described to minimize the collateral damage.


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.