Fusarium patch

What you see

Small round patches of water-soaked, then orange-brown, then bleached dead grass, 5-30 cm across, which run together into larger areas. In damp conditions a white-pink cobwebby mould rings the patch edge in the early morning.

Conditions

Cool, wet, still weather in autumn, winter and early spring, particularly on lush growth from a late nitrogen feed, and worst where leaves or debris lie on the grass.

Treatment

Improve air movement and light by clearing leaves and cutting back overhanging growth. Brush off dew in the morning. Avoid feeding nitrogen while it is active.

Prevention

Stop nitrogen feeding by late summer and switch to autumn feeds high in potassium. Aerate and scarify to reduce thatch. Rake leaves off the lawn promptly.

Months: October, November, December, January, February, March

Plants

Lawn

Remedies

Wood ash, Seaweed extract

The thing people get wrong

This is the one lawn disease actively caused by good intentions - a generous autumn feed of ordinary lawn fertiliser pushes soft lush growth into exactly the cold damp months when the fungus is active. Autumn feeds are formulated low in nitrogen and high in potassium for this precise reason, and using the summer bag in October is what starts most outbreaks.