Whether you’re in the city or the country, you have to wage a constant war on weeds. Many are hard to kill, some are poisonous.

Others, however, are hard to identify. And if you don’t know what it is, how do you know whether to pull it out (and how)?

When down at the recent Small Farm Field Day, I visited the stand manned by the Department of Agriculture. They pointed me to an excellent phone app, called NSW WeedWise.

This contains a comprehensive collection of weeds, including photos and descriptions. It also indicates how serious a weed is, and whether you’re required to destroy it.

A lot of the weeds I already knew about, but I was pleased to learn about Moth vine. This looks quite like choko, and it’s growing on the back fence of the convent.

Far from being edible, however, it has sap that’s poisonous, and it spreads itself liberally when the seed pod bursts open.

Another day, another weed. Download the app from the Apple Store or Google Play.