Holes in Leaves

By Christine Freeburn, Master Gardener

Several years ago I heard a wonderful talk by Martin Galloway on “Holes in Leaves.” His philosophy was that you can never totally eradicate pests from your gardens, so you should enjoy the beautiful lacing they do to your leaves. At the time, I was skeptical about how I could love holes in leaves and the pests that put them there. However as a Master Gardener, I now understand his perspective and I do try for a balance using safe methods to control pests. Integrated Pest Management (IPM) is a practice where pests are controlled using environmentally safe and economically sound values. Biological controls like BTK or parasitic nematodes can be used. Barriers such as diatomaceous earth, wood ashes or sticky boards are mechanical control methods as well as hand picking. Cultural methods include plant nutrition, sanitation, planting pest resistant varieties and plant rotation (in the case of vegetables).

Although we don’t want bad bugs in our garden, we do want the beneficial bugs that are predators and parasites. These include dragonflies and damselflies, lady bugs, lacewings, spiders, wasps and some types of flies.

Aphids or plant lice are one of the most common pests to attack your plants. They are tiny soft bodied creatures that can be black, red or green in colour. They suck the sap from your leaves, and leave a sticky substance behind. You will often see them in a long line on your stems. Red aphids are common on garden phlox. You can use an insecticidal soap for aphids. Or use a blast of hose water to knock them off your plants.

Beetles are hard bodied insects that are generally easy to find on your plants. There are many types and they are often named after their plant of choice, like scarlet lily beetle. The most effective method for controlling beetles is hand picking. Look for the striped cucumber beetle inside the blossoms. When handpicking, place a hand under where the beetle is to catch it as they tend to jump when you touch them.

Caterpillars are another garden pest that are easily spotted. In spring you may find your Hydrangea arborescens has closed, puckered leaves which are holding the common leaftier. You can gently open the leaf and remove and destroy the caterpillar inside or pluck of the entire leaf and squish.

Slugs and snails are sometimes difficult to find as they like dark damp places and feed at night. But you will know you have them when they are munching on your hosta leaves. Check out Gardens Plus for Dawn’s formula for slugs.

As we enter the dog days of summer, we are all battling voracious bugs eating our beautiful flowers and vegetables. The healthier your plants are, the less they will suffer from a deluge of bad bugs. That is why it is important that you give your plants the water and nutrients they need to be their best. Good soil health and good fertilizing methods will give you healthier plants.

Remember that anything you apply to your plants to kill those pests can also hurt pollinators and will be on the vegetables and fruit that you ingest.

To make your garden less inviting to pests

  1. plant the right plant in the right spot to keep it happy and not stressed
  2. do not overcrowd plants which encourages dampness and pests
  3. diversity in your garden will help with pest control – if there are a variety of plants, specific pests will not take over
  4. keep nitrogen levels moderate as many pests like aphids thrive on plants with high levels of N.
  5. Remove garden litter; if pests are present as they can overwinter there.

My favourite method of hand picking beetles and slugs and hosing down aphids is no cost and gets you out into your gardens….where you can enjoy your own “Holes in Leaves.”

For more information on garden pests go to https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems.aspx

or try https://cdn.dal.ca/content/dam/dalhousie/pdf/agriculture/ExtendedLearning/gardenbox/Managing%20Vegetable%20Pests_Garden%20Box_Online.pdf

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