Diseased Blueberry plant – scale?


Hi Can you help me here. I believe I have some sort of stem scale on my Blueberry plants. If so should i cut it back now or wait until winter. How do i prevent it in the future. How is the best way to test the soil pH. I bought a meter to test moisture, pH and light but the pH readings do not work well if at all.


It’s not possible from your photo to see what is affecting your plant. I suggest that you take clear photos (with closeups of the affected stems) to your local nursery to see if someone can positively identify the problem as scale.   For the purposes of my response below, I’ve assumed it is indeed scale.

If the scale infestation is not severe, simply rub the scale off the plants with a toothbrush or a glove.  If you have a major infestation on any branches, prune these off and discard in the garbage (don’t compost).

For future care of the plants, as scale insects overwinter on old, woody canes – prune these off regularly, especially at the end of the season.  Next spring, apply dormant oil in March or April, when the plants are still dormant but temperatures are above freezing, ensuring that you cover the plant thoroughly with the oil.

It may also be helpful to make sure that the environment in which your blueberry plants are growing is as ideal as possible, so they can thrive in the containers.   See our previous posting Blueberries , which discusses ideal sunlight needs, best soil type, and fertilizer. Note too that too much nitrogen in fertilizers can promote an increase in the scale outbreak.  This post also discusses how to create a more acidic soil environment  (e.g., mixes for acid-loving plants, use of pine needle mulch). You may also be interested in Wisconsin Horticulture’s Growing blueberries in containers.  The link in our post for the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) has expired – see the Ministry’s current Fact Sheet – Blueberries for home garden.

OMAFRA’s Check for signs of scale insects on blueberry  has significant helpful information. This article mentions insecticides – we don’t recommend the use of these chemicals unless absolutely necessary, as they can have unwanted effects on other insects like pollinators (e.g., bees).

I’m sorry to hear that your moisture/pH/light meter is not working well for you. I’d suggest contacting the manufacturer or someone in the store where you purchased this item to go over instructions on how to use it – sometimes these meters are quite complicated and difficult to use.   To test soil pH, you could purchase (a different) pH meter – reliability is often a concern with these meters, which can range from cheap and cheerful to very costly.  Another option is to send a soil sample to a lab.  See the City of Toronto’s Guide for testing in urban gardens, which advises how to find qualified labs – this can be costly, always confirm the price of testing your sample before using a lab.

May 30 2021