White mould

What you see

A soft watery rot at the stem base or on a fruit touching the ground, quickly covered in dense cotton-wool white mould. Cut the stem open and you find hard black objects the size and shape of rat droppings inside - the resting bodies.

Conditions

Cool and wet with a dense humid canopy. The resting bodies germinate in damp soil and produce tiny mushrooms that shoot spores onto dying petals - which is why infection so often starts where a flower fell and lodged.

Treatment

Remove and bin affected plants complete with the black resting bodies inside them. Do not compost - the bodies survive it. Improve airflow at the base of the remaining plants.

Prevention

Rotate away from its enormous host list for at least four years - cereals and sweetcorn are safe non-hosts. Avoid dense planting, mulch, and remove spent flowers and lower leaves.

Months: March, April, May, October, November

Plants

Green bean, Lettuce, Carrot, Cabbage, Sunflower, Tomato, Marrow / Courgette, Potato

Remedies

Mulch, Bacillus subtilis biofungicide

The thing people get wrong

Look for the black bodies inside the stem - it is the one certain identification, and it also explains why this comes back: those bodies sit in soil for five to eight years waiting. The other useful detail is that infection begins on dead petals, not living tissue. Tidying spent flowers out of a dense bean or courgette canopy removes the doorway the fungus uses.