Q: I have a Japanese maple tree in a container on my porch. It has green leaves that turn a lovely cream and pink colour from midsummer until its leaves fall. But it has mealy bugs on it. An insecticide powder hasn't corrected the problem. I started to pick the bugs off the tree, but there are so many now I don't know what to do. I am an inexperienced gardener and I think I have over-watered the tree as well. I love this tree so much: can you help me?
A: It is possible to eradicate mealy bugs, but on a large, intricate tree this will take much hard work and a great deal of time. An onslaught with insecticide will only help when the mealy bugs are in the 'crawler' stage. At other times, their fluffy white coating protects them.
You'd find your tree much more manageable if you could prune it back. For this it might be best to seek the help of an experienced gardener, because shape and twig structure is an important part of the beauty of Japanese maples.
The generally rundown look of your maple could be over-watering. This can happen if its container doesn't drain freely or if it sits in water for long periods (inside a cache pot, perhaps). But its more likely your tree is sickening because a horde of mealy bugs are sucking its sap.
Some gardeners begin by blasting hose water over the infested plant to help remove the mealy bugs. It's definitely not a cure, but can remove some things you might otherwise have to pick off.
The remaining adults can be killed by pressing them with a cotton swab which has been dipped in alcohol. This is a tedious, boring and lengthy but important task.
The first vulnerable stage is the egg masses in the leaf axils. These look like tiny puffs of cotton wool. For every one of those you pick off, you are removing 300 to 600 embryo mealy bugs.
Eggs hatch into crawlers - the second vulnerable stage. These are tiny, greenish yellow insects which crawl over the plant for about ten days. Insecticidal soap spray kills them on contact but it's impossible to get each one. That's why you should repeat the spraying twice a week for at least four weeks, possibly longer.
The male creates its own white case and within it changes into a tiny fly which mates with the female. She can crawl a little, forms her own white case and settles down to lay eggs.
It's important to check all your other container plants. Mealy bugs can spread easily at the crawler stage and the adult male can fly over to the females and begin the infestation cycle on another plant.
Q: I recently acquired a lemon balm plant and I decided to separate it into smaller clumps, some with fine root attached but some with barely any. Will it survive and grow? Does it survive in any type of sunlight?
A: I'm quite sure your lemon balm will survive Clumps will enlarge and it will seed around as well. It will thrive in sun or shade. Sometimes it survives much too well and over-runs its neighbours.
Anne Marrison is happy to answer garden questions. Send them to her via email@example.com
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