Japanese maple pests

Today I took my first inspection through my stock plants to see what wood is going to be available for grafting this winter and was glad I hadn't left it any longer. Although I regularly inspect plants during the summer when aphid populations can build up quite quickly, some had obviously been overlooked. Several trees had infestations of juvenile aphids crawling all over them and action need to be taken fast.

To the casual observer, the sight of aphids in the autumn, whilst acting as a reminder that they need to be removed, won't engender any sense of urgency. It's a job that can be done when you've got some spare time next week or next month, if at all. You're thinking 'the only thing they seem to be doing is putting a sticky deposit on the leaves; they're going to fall off shortly and the upcoming cold weather will kill the aphids off so I'll leave it as I've got more important things to do in the garden'. Big Mistake!

What you can't see unless you get up very close and if you can see, it's too late, is the aphids are laying eggs. Initially, they're walking up and down leaf stalks and shoots, but gradually they will start congregating in specific ares, ready to unleash a time-bomb next spring. They will start laying their eggs in the leaf axils where next year's buds are developing. They're going to be in tiny cracks in the bark next to the buds and in the bud sheaths themselves. Once they've been laid, there is nothing you can do apart from wait for them to hatch next spring.

Unfortunately, next spring is going to be too late to minimise the extensive damage they can cause as, conveniently for them, they hatch just as the buds start expanding. But this time they're not going to be walking all over the leaf surface, at least not initially; they're going to be within the expanding buds. But it gets worse! They're not interested in the fully opened leaves where it's easy to get at them; they're going to be feasting om the most succulent part of the shoot, the growing tip and all you'll see is a mass of sticky distorted shoot tips covering the whole of your Japanese maple and severely weakening the growth of your plant.

When it gets to this stage, control is very difficult without causing extensive damage to the shoots. Repeated applications, because they won't go without putting up a fight, with garden chemicals can do almost as much damage as the aphids themselves. By spraying now with something like a soap solution or Neem oil, that works by suffocating them, you can quickly eliminate future problems. So today's tip is check for aphids, not just on your Japanese maples, but on all your trees and shrubs. That way you won't have any unpleasant surprises next spring!

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