Japenese Maple pests

Dominick Mejia
last year
last modified: last year

Hello guys

We bought a Japanese Maple a few months back.

About a month or so ago, we noticed that the leaves were "drying up". We thought that we had not been watering the plant enough so we made sure to water it more often. However this didn't help so put the plant indoors as we thought maybe it was getting blasted with sunlight while we were at work.

I was watering the plant today and checking its leaves to see if it was getting better, when I noticed strings of "web" on some of the leaves. On taking a closer look I found 7 of these caterpillar like things. They had cocooned themselves in the leaves.

I've now taken them out but we're concerned that they will come back. Does anyone have any tips on how to stop this from happening? If anyone knows of a specific brand of anti pest spray we should buy please let me know.

Also, we would appreciate any advice on any steps we can do to help the plant recover. I've attached some photos of the plant and the pests, to help anyone wanting to give any advice.

Thanks in advance.

Comments (4)

  • tamp75
    last year

    I’m not an expert but I would say the leaves drying up may have been due to too much wind (& poss sun). This has happened to our Acer before - they do like to have a sheltered spot. It will recover but probably not this year as we’re coming up to autumn. Consider moving it somewhere more sheltered next year & the leaves should come back fine in spring.

  • Ribena Drinker
    last year

    I've got about 14 different varieties of acers in various sizes and ages and I've never had any caterpillars in over 15 years. However, we had sawfly caterpillars on our Soloman Seal plants this year, which we've never had before, and also I found something similar to what you have on a bay tree this year - never had anything like it before. I just cut off the affected leaves and it seems to still be clear of them.

    The good thing is that it is nearly autumn and the acers will be dropping the leaves soon, so if you do cut off, it won't cause too much of a problem. And the leaves will just reappear next year as though nothing had happened.

    For future infestations, I always use Roseclear for all manner of bugs - chiefly because I grow a lot of roses and I always have it on hand. Your caterpillars were obviously laid as eggs at some point, so next year it may be worth, just keeping an eye open for any eggs on the underside of the leaves and treat/spray them immediately.

    The one consolation about caterpillars is that they're easy to deal with - you can just pick them off - and although they're a nuisance, providing they haven't done massive, overwhelming damage to the plant, the plant usually recovers well and will be fine.

    As for the "drying up", acer leaves are prone to sun scorch and can get quite damaged by the sun, so I keep all of mine in dappled shade/light shade all the time which they prefer. The red leaved ones appear to suffer worst. But again providing not too much of the plant is damaged, it should recover well, often growing new leaves if it's earlier enough in the season.

    A few other tips:- during the summer, our acers are watered once a day, the key for acers in pots is regular watering and occasional feeding.

    I cover my smaller acers with fleece over winter, from the first frosts and then removing it in about March/April.

    You may also need to look at re-potting yours into a slightly bigger pot in a couple of years as the current one is very narrow at the bottom. If you do re-pot it, mix in some ericaceous compost with normal compost as they like the soil a little on the acidic side.

  • Sonia
    last year

    I can reiterate that Acers hate two things - hot sun and strong winds. They are a woodland plant so dappled shade is best. They will suffer in any other conditions. I had a red one that shrivelled up completely so I replaced it with a Cornus, much more tolerant.

    I’m not sure what species the caterpillar‘s are, but I like to encourage wildlife into my garden so I never use pesticides, ever. That caterpillar provides essential food for birds, especially baby ones. Imagine you spray it then a bird eats it or feeds it to its young? I like a more holistic approach to gardening. Slugs? No problem, they are essential food for birds, frogs, hedgehogs and foxes. Yes my hostas were eaten but there you go. My plants have aphids, ants, caterpillars and slugs on them, but all these creatures are there for a reason. It’s the cycle of life and needs preserving.

  • Dominick Mejia
    Original Author
    last year

    Thank you for all your help guys! I was getting worried that the plant would end up just dying but it got a lot healthier in the past few days.

United Kingdom
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