The Itsy Bitsy Spider....Mite that is!
Edit: I originally started writing this last fall but didn’t have time to finish the research so I’ve left parts of the original article in but have now been able to do more research to address this issue and have finished the post.
If I had a fiver for every email/question I’ve gotten about spider mites (and broad mites and cyclamen mites) this summer- well let’s just say I’d have lots of cash for some pricy unicorn tubers this winter ;)
It’s been a really rough year for them. Most years, I see small localized outbreaks of them but usually the damage is minimal and easily contained. But this year, it’s been at the ‘fatal damage to plants level’ for some of you.
So while, it’s not a sexy topic, it’s a necessary one if we want luscious blooms!
Let’s talk about how to address pest issues in general first:
1. Scout your plants regularly. Grab your favorite beverage and walk your plants on at least a weekly basis, more if you have a lot of plants.
2. Use your phone camera to take pics of anything that looks suspicious.
3. Record your findings- date, what you found, add a pic if you can. This information is helpful when it comes to prevention methods in future years.
4. Employ prevention methods. But - fully realizing that sometimes it takes a few years to figure out the timing so give yourself a bit of grace.
Most of the time when I receive an email, the plant is already very damaged. Try using these methods to catch issues before they get really bad.
Next: Make sure you diagnose the problem correctly.
— Also remember you can have more than one issue at a time.
Knowing the lifecycle of pests is important. Some insecticides will only kill the pest at a certain stage. You can find the average lifecycle of most pests by simply searching online. Remember that unless you know the timing of when the pests begins to appear in your garden, there will most likely be all stages of the pest happening at once. This often means the need for multiple applications of an insecticide.
— Also verify your diagnosis in multiple places. There are a lot of ID apps and good research out there to use but a lot of these are based on AI which can be faulty so just use good common sense and verify it in a few places.
Research Findings:
*I’m not going to re-invent the wheel and re-write everything I read but I’ll summarize to give you an idea if the research may fit your situation.
Coping With Spider Mites- from The American Dahlia Society. This article talks a lot about different types of mites and specific insecticides to address them. It’s almost 20 years old, would love to see an update but I think there’s still some really good info here. I found the information about the use of pyrethrin’s and how they can actually encourage the spread of mites particularly interesting.
Dahlia: Plant Health Problems- This page is not specific to mites but to pests in general that bother dahlias (also fungal diseases). Some good photos for id help (wish there were more though).
Managing Spider Mites in the Garden and at Home- This article speaks generally of spider mites but they used dahlias as their example plant throughout. Good photos for diagnosis
Know Your Mites- Good article on the differences between broad mites and spider mites
Management of Broad Mite & Cyclamen Mite in Production Nurseries- long but good photos and in depth descriptions of different types of mites
Experience Based Findings: (For Prevention)
Several years ago I began using a sprinkler to cool my dahlias during the hottest days of summer. Turns out that it’s also a great method for preventing powdery mildew and spider mites. Both of those come on when we go hot and dry. But by increasing the amount of water my plants are getting, bringing the temperature down and keeping the air moisture levels higher, it’s creating an atmosphere around my plants that is not conducive to spider mites/powdery mildew.
Second - Keep your plants as healthy as possible. This means staying on top of feeding and watering and monitoring for pests. Stressed plants attract more bugs!
I sincerely hope this year is better- but when they do inevitably come, there’s a lot of good information here to help answer questions and help you formulate a plan of attack.
