Prune them out and immerse the galls in water to drown the lavae of the wasp, is the latest method advocated by Kaye Roberts Palmer of Melbourne's Save our Citrus Campaign Group, to actually kill the lavae by drowning.
Kaye Roberts Palmer and Kylie Johnston, of the Save Our Citrus Campaign are calling on all of us this, to check our lemon, orange, lime and other citrus trees this first weekend of September, coinciding with Father's Day, for citrus gall wasp, which is fatal to citrus trees if left unchecked. This weekend is the last opportunity to act before this year's lavae hatch, with the onset of warmer weather.
They suggest buying dad a pair of secateurs for Father's Day for the purpose.
If dad is not into gardening, or not around, simply get out your favourite secateurs and loppers and go for it. Citrus should be pruned and opened up to a nice vase shape, with good airflow and kept to a height for easy picking. In any case, they love nothing better than a good prune, this time of the year and will flourish as a result.
Citrus have shallow roots and are heavy feeders, so now is also the time to dress your citrus with a good layer of aged cow manure, lots of lovely compost and a dose of iron chelates if their leaves are on the yellow side, indicating iron deficiency.
Absolutely all gall wasps should be cut from your tree, no matter how drastic this seems.
From my own experience in Pascoe Vale, I once had to reduce my Eureka Lemon to a mere skeleton of main branches. Everyone else expected my lemon to die, except me. Lemons are vigourous growers, when in good health and several months later my lemon had shot on and was looking as glorious as ever.
In areas where citrus grow in every backyard, trees with gall wasp left unchecked have the potential to infest the entire neighbourhood, as the tiny lavae are readily blown across a wide area on the wind.
It's up to all of us to work to erradicate this nasty and potentially fatal citrus pest from our citrus trees!
For photos of the citrus galls and lavae and more information about the Save Our Citrus Campaign, follow this link.