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Tackle blackspot on roses11 July 2014
Tackle blackspot on roses as soon as you notice the ugly black lesions begin to spread across leaves. This nasty and very persistent fungal disease often takes hold in summer, particularly after long spells of damp weather, and it'll defoliate and seriously weaken your plants if you let it.
Spray early on, before the disease gets a hold, and you'll keep on top of the problem from the start. In your garden centre you'll find a range of products to help you blitz the blotch: it's a good idea to switch between several formulations so you tackle all the various blackspot strains. Spray every three to four weeks and you'll be covered (always follow manufacturers' instructions).
You can prevent infection next year with good hygiene. Blackspot overwinters on fallen leaves, so clear up rose leaves this autumn and bin or burn them - the fungus will survive a compost heap. Some rose varieties, like 'The Mayflower' or the species rose Rosa rugosa, are able to resist blackspot. And another good trick is to plant clumps of chives under roses: their roots exude a pungent white liquid which acts as a fungicide, building up in the rose's system and after a couple of years helping keep blackspot at bay.