Photo shows bizarre microwave method to kill pest 'quickly' taking over Aussie gardens

A Perth man was desperate to protect his lemon tree from the citrus gall wasp which is 'quickly' spreading across the country.

Left: Bowl full of off-cuts from pruned lemon tree. Right: Lemon tree in Australian backyard.
The Perth man pruned his lemon tree before placing the off-cuts, which contained the galls, in a bowl in the microwave to kill the wasps. Source: Charlie Hamzah

Residents in parts of Australia are being inundated with an invasive, serial pest in their gardens — one that's capable of "spreading very quickly and easily" and ruining some trees and plants.

But Aussies are getting creative with managing their citrus gall wasp infestation which targets citrus trees, mostly lemon and grapefruit, and are using appliances including home microwaves and barbeques to get rid of them for good.

One Perth man named Charlie was shocked to discover "bulges on the stems" of his lemon tree, telling Yahoo News Australia he had not noticed them before. The citrus gall wasp is an Australian native insect originally from northern NSW and Queensland but is now established in most Perth suburbs after spreading across the country.

The eggs are laid in new shoots of citrus trees and the tree reacts by producing distinctive galls around the developing larvae. Adult wasps then emerge from galls.

"Advice from people was to cut the infected stems, bag it and place it out in the sun to kill the gall wasp inside," he told Yahoo after taking to Facebook with his problem. "Another recommendation was to burn or microwave it.

"I chose the latter," he added. Previously another homeowner cooked the stems on the barbie.

Healthy lemons picked from man's lemon tree.
The man said he was still able to grow healthy, unharmed lemons. Source: Charlie Hamzah

A photo shared by Charlie shows a bowl full of off-cuts from his lemon tree with noticeable bulbs protruding from the stem which he "nuked in the microwave". And while burning or cooking them might seem odd, there is some logic behind it.

Pruning is said to be a suitable control method, and one homeowners can undertake easily. However, wasps can still emerge from offcuts if pruned too close to their usual emergence period — usually between September and December. So burning can be one way to mitigate any risk associated with wasp-infected off-cuts. Shredding and mulching or placing the branches in a sealed bag can help too.

"I did five mins [in the microwave]," Charlie said. "I think it’s more effective than bagging and sunning it. Especially when cloudy or raining. I reckon it kills the eggs or pupae in the stem."

Lifecycle of Citrus gall wasp.
Lifecycle of Citrus gall wasp. Source: WA Department of Primary Industries

If left untreated, the galls created to house the larvae are known to disrupt water and nutrient flow which can weaken trees and affect productivity. Heavy infestations will often reduce fruit size and quantity over time.

Thankfully Charlie said his lemon tree was unscathed in the end and has grown "lots of fruit". "But we just need to keep on top of the infestation," he added.

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