Keeping ahead of harlequin bugs

With a brief moment of warm weather on September 2 this year, the harlequin bugs are on the march again.

Many gardeners around Bacchus Marsh have encountered plagues of these sap-sucking critters. They are remarkably adaptable, feeding off hosts as widespread as mallow, pepper tree, citrus, tomatoes and rhubarb. Most insects that are leaf-chewers only feed off one or a few closely related species of plant, because they need to specialise their metabolism to overcome the chemical defenses of the plant. Sap-suckers bypass the leaf with its battery of noxious compounds, and tap straight into the sweet flow of the plant’s sap, which is relatively free of chemical defenses. Continue reading


DIY Native lawn redux

I posted in 2015 about how to establish a lawn with native grass seeds. But my results were fairly early. Here I report on how it’s going (well!) and re-summarise my (updated) DIY advice.

In a dry but otherwise mostly mild summer, the lawn browned off (that is, leaves died and it turned a straw-brown colour) until we got a good rainfall in early February. Then the summer-growing grasses (redleg grass* and windmill grass*) immediately put on lots of new, green growth. The winter-growing grasses (weeping grass* and wallaby grass*) put up a little new growth, and new seedheads, too. Continue reading

Native plants vs Agapanthus

Agapanthus. Not a native.

A while back I was in the largest chain of hardware/garden/etc stores’ local (Melton) outlet and saw a big selection of Agapanthus lilies for sale in the “Native Plants” section.

According to the informative article here, the “Black Pantha” variety produces few if any viable seed, which is a bonus. I don’t know about the other varieties that were on offer, though. The plant can become a weed in areas with a suitable climate. It’s native to South Africa, like a lot of our worst ecological weeds.

This is clearly not a native! I could leave it at that as a comment on the uselessness of big chain stores, but let’s explore this a bit more. Continue reading

Harlequin Bug Hell

The Harlequin Bug, Dindymus versicolor, is a native Australian insect that can become a pest in gardens and agriculture.

You can buy poison to kill it; I wouldn’t put poison in my garden if I can avoid it.

For ornamental plants, the commercial product Confidor is available; its active ingredient is Imidacloprid, a neonicotinoid – a class of chemicals now banned in some countries because of their suspected role in colony collapse disorder of bees.

Heidi, the blogger at A Year In A Gippsland Garden, relays the recipe from Gardening Australia’s Peter Cundall: a strong mixture of cheap (hopefully, biodegradable) detergent in water. Spray it on the bugs, or knock them into a bucket of it.

(photo from A Year In A Gippsland Garden – visit that blog for more excellent pics and discussion)

How to get it out of your garden by other means? I looked for scientific papers and there isn’t much, but here’s what I found.

Control of mallow/hibiscus species (like the weeds that commonly grow in my lawn here) seems sensible, based on a paper from Latrobe University, published in the Australian Journal of Ecology in 1981 (see table reproduced below). Continue reading

Why not weed mat?

Weeds are a pain, right? A weed is a plant that is growing where it shouldn’t – or more to the point, where you don’t want it to. In a garden, that could be any number of overenthusiastic “volunteer” garden plants, introduced exotic weeds, or natives making their way in.

Instead of spending your days pulling them out, hoeing, and mulching to suppress them, why not try something more permanent? After you rule out poison (because it’s poisonous! – more on that in another blog post) weed matting is a popular option.

Weed mat comes in many forms, one of the most popular being the old black plastic sheeting. Unfortunately, it does great damage to your nice garden soil. Really? It’s pretty inert isn’t it? Continue reading