Plant Doctor Archive

Red-brown patches on lawn

Question OUR lawn has been getting lots (5–10 cm across) of small brown patches which develop quite bright red pigmentation after a while. Our lawn is really strong and healthy; I fertilise it in spring and autumn with a general lawn fertiliser and have recently sprayed (3 weeks ago) with Versatil to kill weeds. A couple of months ago I treated a few larger brown patches on the lawn for grass grub. Do you have any ideas on what might be causing this and how we could remedy it?

Answer FROM your description it sounds as if your lawn has a fungal disease, likely to be ‘Red Thread’. Spray your lawn with either Fungus Fighter or Greenguard. Fertilise your lawn with a specially blended lawn fertiliser in spring and autumn (as you have done) and avoid mowing your lawn too closely.

Having sprayed with Versatil, do not use your lawn clippings in your compost or as a mulch around the garden for six months, as the spray has a residual effect and will harm susceptible plants. Mulch clippings back into the lawn or discard.