Picture it: something's gone wrong on a leaf, you snap a photo, and thirty seconds later an app tells you exactly what it is and exactly what to spray. No ringing around, no waiting for someone at the garden centre to squint at a picture on your phone. Job done before your tea's gone cold. That's the pitch, anyway. And to be fair, plant ID and pest-and-disease apps have come a long way — I've used a few myself, out of curiosity as much as anything. The question worth answerin

Aphids, those tiny, sap-sucking insects, can be a persistent nuisance for gardeners and growers alike. Their voracious appetite for...