Leaf Galls

There’s always something interesting or unusual happening in the yard throughout the year. If it’s not the birds or animals up to something, then it’s the trees and plants. This Spring, something perhaps not overly unusual but most certainly on a huge scale has happened to all the Messmate gums in our yard, our neighbours and, as far as I can tell, elsewhere in the neighbourhood. For some reason, leaf galls have appeared in massive quantities and caused leaves to drop in vast numbers. Our yard is full of such leaves and when I took our hound for a walk one morning, I noticed similarly large numbers on the road, with most squashed by car tyres or feet. These leaf galls were everywhere. I’ve seen these most years, but never in such quantities and our neighbour is also perplexed as he hasn’t seen such a mass event in all of his years living in the area.

Leaf Gall

Leaf Gall

After a bit of research, it confirmed what I remembered and that these galls are usually caused by some insect or organism. They happen anywhere in the world and there’s nothing uncommon about the occurrence. In Australia, galls are quite common on gums and wattles and are formed by a invasion of ‘wasps, flies, beetles, psyllids, coccids, thrips, moths and aphids, as well as by nematodes, mites, bacteria or fungi.’ The only thing left out was global warming. You could possibly call the galls a defence response to the attack, but in doing so, it offers refuge for the attacker. The galls that were showing up in our yard were not quite as terrifying looking as some that appear from time to time in other places, but the sheer number is quite a sight in itself. Some leaves were completely engulfed by these galls.

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

The galls attached to the leaves that have fallen are fairly rapidly drying up, even though it’s been quite wet, so if they do contain the larvae of some bug or whatnot, then I wonder whether they will survive, especially with some hot days predicted. The mass of galls on each leaf has made it very difficult for the leaves to sustain not just the weight but also the nutrient demands of the leaves, or their inhabitants, such that they appear to have given up. This would be very similar to how gums react to drought by simply dropping leaves so that less leaves have to be provided with scare water. This is something that we experienced when we first moved to Mirboo North, our yard was constantly littered with dry leaves to the point that we had to keep raking them up on an almost daily basis. It’s been quite different over the last few years and we’ve had to collect very few leaves by comparison.

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

But it’s not just the gums that are affected by these galls. On our recent morning walks I’ve seen other plants also hosting small to large growths of a similar nature. The other plants that these galls are growing on have much finer leaves and the galls are growing on the branches or stems of the plants, rather than on the leaves. These galls tend to look more like berries and are not anywhere near as ugly looking as those found on the gum leaves and they are also much larger than the ones on the leaves of the gums. Nor do they seem to be all over the ground as with the gums, I guess because they have firmer purchase on the stems and can’t shed as easily as with the gums. Again, the plants don’t appear to be affected in any detrimental way by these galls, so I guess they are used to getting them from time to time.

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

Leaf Gall

How long this event will last is anyone’s guess, but I suspect that the main event is over and with Summer now afoot (though it’s hard to tell because of the horrid weather), these will soon be just more rotting leaf litter around the garden. Thankfully it’s nothing to be concerned about and the trees are quite safe despite the onslaught, but if nothing else, it’s given us another display of nature working in its mysterious ways.

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