Gardening Tips Week 17: Spray It, Don’t Say It

What to do this week

This week is a good time to talk about spraying fruit trees because now is the time to do that. There are a couple of reasons that even an organic grower might want to spray.

McIntosh apple 1/2-inch green (Source: Healthy Fruit Vol. 24, 2016, UMass Extension

McIntosh apple 1/2-inch green (Source: Healthy Fruit Vol. 24, 2016, UMass Extension)

One would be to rid the trees of pests before they get ahead of you. People often use dormant oil for this, or horticultural oil. I prefer the latter. It is a little lighter. You would spray oil to control things like scale on your apple trees. Scale is a little pest that lays its eggs on the branches of your trees in what look like silver crescents. That kind of infestation can really knock back the tree, zapping its vitality. Scale rarely kills a tree but it makes it very unhealthy and unable to resist other problems.

The correct time to spray for scale is when the buds are half inch green (or centimeter green). That is a technical term. It applies to apple trees that have about 1/2 inch of green leaf tissue emerging out of their fruit buds. At that point, the encasings of the little parasites that got laid on the branches over the previous summer start to soften. When the cases are soft, the pests will be smothered by the dormant oil. Prior to that, it won’t really have much effect and will be washed off by the rain before it can be of use.

Another reason you might want to spray is for leaf blight and all the fungal diseases like peach leaf curl or apple scab. There are a few different mixes that you can use for that. Some people suggest using a dormant oil mixed with lime sulfur but I recommend that you do these two treatments, if you need them, separately. Lime sulfur or Bordeaux mixture, which is copper sulfate, are your best options. You can buy these at the Farmers’ Co-op.

If you had a problem with leaf curl last year, you should apply your first spray when the branches are still dormant. Wait for a mild, dry, windless day. If you can find a day when there is no rain expected for a few days following, that would be best. You should spray every couple of weeks, avoiding the period of blossoming, until the really hot weather arrives in July. Any of these sprays will damage the blossoms, and later the heat will dry the humidity that these pests like, so this is an early spring to mid-summer activity. If you get on top of it in the spring, the tree itself will fight the disease during the hot weather of the summer.

There is a school of thought that says you can avoid apple scab by not mowing the grass around your trees until the end of June. In fact, I don’t spray for scab because I don’t mow. The theory is that this stops the spores from being disturbed and getting to your tree. There is some current research from the United States to support this claim, and anecdotally, I can say that it seems to work in my case. It can look a little scruffy so you may have to make your decision with consideration for your neighbors. I am fine where I am, and I don’t have much trouble with apple scab.

If you do decide to spray, follow the instructions on the product container. Mix in the recommended proportions, wear protective gloves and long sleeves and be mindful of your eyes and lungs. These products are natural, but they can still be corrosive to your skin. They are not toxic, but that doesn’t mean you want to breathe them in if you can help it. If you have just one or a few trees, all you need is a domestic spray bottle. Do the best you can to reach all the branches safely. I have a backpack sprayer with a long rod, but only because I have so many trees. You could consider height when you are pruning in the fall, remembering that you are going to want to reach most of the tree next spring.

Featured image: McIntosh apple, half-inch green. (Source: UMass Amherst Center for Agriculture, Food and the Environment)





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.




Backyard food gardener Madeline Yakimchuk caught the food-security bug in the early ’90s through Cuba’s Urban Agriculture Department, taking her first permaculture course and planting her first garden. She can often be found discussing food security, nurturing a plant-based lifestyle or trying to give away vegetables. Professionally, she is GRYPHON media productions but sometimes uses la bruja in her volunteer work, most notably in managing the garden column, which begins life as a telephone interview.





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