Bacterial speck and spot

What you see

Tiny dark specks, barely 1-2 mm, often with a yellow halo, scattered over leaves, stems and green fruit. Unlike fungal spots the edges are angular where they hit a leaf vein. Fruit specks stay small, raised and scabby.

Conditions

Cool wet weather for speck, warm wet weather for spot. Both explode after a storm or after handling wet plants - bacteria need a water film and a wound or leaf pore to get in.

Treatment

Copper is the only real option and it only protects - it does not cure. Stop overhead watering completely. Remove badly spotted leaves. Never work among tomatoes while the foliage is wet; you spread it on your hands and sleeves.

Prevention

Buy clean seed or hot-water treat your own (50C for 25 minutes). Rotate three years. Space and stake so leaves dry fast. Clear all debris in autumn.

Months: April, May, June, September, October, November

Plants

Tomato, Sweet pepper, Chilli

Remedies

Bordeaux mixture (copper)

The thing people get wrong

The yellow halo is the giveaway that this is bacterial rather than fungal - and it matters, because sulphur, milk spray and bicarbonate do nothing at all against bacteria. Most of the spread is you: walking the row after rain moves it further in ten minutes than the weather does in a week.