Caterpillars defoliating Maple

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Richtko

Caterpillars defoliating Maple

Post by Richtko »

hope you all are having a good week,

I grew a few trees from seed for my daughter when she was born, the main one is a sugar or hard maple Acer saccharum I kept it on the balcony for a few years then moved it to a small plot we have next to my in-laws house. Its 5 years old now and mostly healthy.

The last few years its been getting hit hard by caterpillars, which often defoliate most if not the whole tree. usually it happens around mid summer. I don't think it will kill the tree but it certainly stunts it and makes it a bit unsightly.

Any ideas on how to mitigate or stop this from happening?

heres a few pics, first year and before it gets defoliated. 3rd pic is this year after it got eaten.
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Zasso Nouka
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Caterpillars defoliating Maple

Post by Zasso Nouka »

Nice trees.

I'd go with a BT spray, it's organic and harmless to anything other than caterpillars. There are plenty to choose from but my personal favourite would be Bashi Rex and Zentari comes a close second.

Richtko

Caterpillars defoliating Maple

Post by Richtko »

Zasso Nouka wrote:
Tue Nov 21, 2023 12:38 pm
Nice trees.

I'd go with a BT spray, it's organic and harmless to anything other than caterpillars. There are plenty to choose from but my personal favourite would be Bashi Rex and Zentari comes a close second.
Thank you, actually all the same tree.

I've seen BT being mentioned before. Can I apply this once early in the season, apply a couple times throughout the year? or do I need to wait till I start seeing damage?
Usually when I start seeing these guys, there's little to no leaves left in 24h.

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Caterpillars defoliating Maple

Post by Zasso Nouka »

If you know roughly when the caterpillars appear you can start spraying then or maybe a week before. Then a couple of follow up sprays one to two weeks apart and you should be golden.

Monitor the trees after that and if another outbreak occurs give them another spray.

As Bacillus Thuringiensis is a soil dwelling bacteria it doesn't last long in harsh sunlight but if you spray the undersides of the leaves as well then it can last a bit longer.

Richtko

Caterpillars defoliating Maple

Post by Richtko »

Zasso Nouka wrote:
Tue Nov 21, 2023 3:29 pm
If you know roughly when the caterpillars appear you can start spraying then or maybe a week before. Then a couple of follow up sprays one to two weeks apart and you should be golden.

Monitor the trees after that and if another outbreak occurs give them another spray.

As Bacillus Thuringiensis is a soil dwelling bacteria it doesn't last long in harsh sunlight but if you spray the undersides of the leaves as well then it can last a bit longer.
Thanks for advice.

I'll be down there in January so was hoping to put some preventative measures in place. I've heard you can use barriers or traps on the trunk of the tree that can help keep them from crawling up.

We are planning to be there for a month next summer also, so I'll try spraying it while I'm there. Hopefully I can get these buggers under control. The mother in-law freaks out about it, so want to keep her from stressing out to much.

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Caterpillars defoliating Maple

Post by Zasso Nouka »

Yes you can put traps or smear somehing like vaseline on the trunks if the caterpillars are coming from elsewhere but that won't stop any that were laid as eggs on the tree itself. If you aren't there when the caterpillars are around to respray the tree then you would need a long lasting spray containing something a bit more toxic like a neonicotinoid. That would persist in the leaves for several months once sprayed but is obviously not an organic solution but then you aren't likely to eat the maple leaves so might not be a concern.