My citrus are under attack, I have found the dreaded lumps on my Eureka Lemon, Meyer Lemon, Orange and Lime. Unlike many of Australia’s pests citrus gall wasp is actually a native annoyance. Having lived for years in our native limes it is now more likely to make its home in backyard lemons and limes along Australia’s East Coast. It has so far ignored my finger lime in favour of its imported cousins. Citrus gall wasp is a tiny wasp which lays it eggs in the new growth of citrus trees and as the larvae grow bumps appear on the branches of the trees.
When the larvae emerge in early Spring they leave small tell tale holes in the bumps. Citrus gall wasp has the ability to severely limit the growth of trees, so my understanding is that it is best to do something about it. With my lemon, which is in the ground, and has been for a couple of years, I pruned off the affected branches and placed them in the garbage. With my dwarf potted citrus – the Meyer lemon, Tahitian Lime and the Navel Orange to prune off the affected branches would be to decimate the tree completely. With these I have tried a different tact. I have taken a slice out of each bump which although it is damaging the tree it is also killing the larvae. As you can see below – the larvae have fallen out of the little holes in each bump. Whether this will have gotten all the larvae in each lump remains to be seen but I felt it was more likely to save the tree than radical pruning would.
Whether this will be a completely successful method of getting rid of citrus gall wasp remains to be seen. At the very least it should limit the number of larvae hatching. I will isolate the affected plants in late winter (you should act against the wasp by late August as they hatch soon after) to try and stop it spreading to my other potted citrus. I do hope I get rid of it as I love my citrus and they aren’t cheap to replace. Its always the tinniest creatures that seem to do the most damage, as my black aphid eaten garlic chives will attest.