Register with us or sign in
in Problem solving
Whilst spraying against blackfly on my Verbascums this afternoon I noticed something wrong on the underside of my hollyhock leaves. Is it rust? And any tips on treating it please? I've read to remove affected leaves, but this would leave the plant bare, would an insectisidal soap wash help or would that be pointless in this instance? Thanks.
You will have to cut all affected leaves off and destroy them, not compost heap, the plants should have been regularly sprayed with a fungal spray right from the beginning of growth, even if you dont see the rust then.
Thanks Lyn. That's quite annoying as up till a few days ago I just had the one plant and didn't even know rust existed. Since spotting some nice healthy looking ones on a garden centre discount shelf this week I now have five more, I'm tempted to pull up the infected one and plant the new ones there. If I do this what spray should I be using against rust in future?
Don't plant the new ones there, they'll get rust as well - the spores live in the soil, and infect the plant when splashed up by rain or watering.
If you have rust in your area (it likes clean, pollution-free air), you will never get rid of it, only control it. As well as spraying with a fungicide (take your pick from the garden centre - anything that says it treats rust will do), feed the plant well - you can often get the plants to grow vigorously enough so that the rust is less of a problem.
In autumn, once you've cut the plants down, mulch around them well to suppress as many spores as possible.
And no, a soap spray is no use at all - it's a fungus, not an insect problem.
Thanks Alina, that's most appreciated.