Phytophthora blight

a plant that wilts and does not stand back up — even after you water it, even in the cool of the morning. Healthy plants droop in the midday heat and recover by evening; a blighted plant stays collapsed and dies within a few days.

You will find a dark brown-to-black, wet, water-soaked band that wraps all the way around the stem (a girdling lesion). Above it the plant is choked off and dying. The roots and crown underneath turn brown and mushy — this is the crown and root rot.

dark green, greasy, water-soaked blotches on leaves that dry to brown dead patches. Fruit touching or near the wet ground turns soft and rotten and is often coated in a fuzzy white mould (the mould's spores).

always start looking in the low, wet spots — the bottom of the slope, the ends of furrows, anywhere water pools after rain or irrigation. It shows up there first and marches outward with the water.

Bacterial wilt also makes plants collapse, but the stem stays firm with no dark girdling band at the soil line (cut a wilted stem and dip it in clear water — bacterial wilt bleeds a milky thread, this blight does not). Simple drought wilt recovers overnight after watering; blight wilt never does. Cutworm damage cuts the stem clean through at the base — there is no dark, wet, spreading rot.

watch hardest from when the plants are growing and bushing out through fruiting and right up to harvest (the development, mid-season and late-season stages) — the whole time the crop is in the wet field. Warm weather between 24 and 30 °C with soaked soil is the danger zone.

The day after water sits in the field, go and check — that is exactly when this mould moves.

cross the field in a big "W" so you cover all four corners and the middle. Make about 10 stops, and at each stop deliberately swing through the low, wet patches where water collects — do not just check the dry high ground.

any plant that is wilting and not recovering; the stem base at the soil line for a dark, wet, girdling band; and any fruit lying on or near wet soil for soft rot or white mould.

this mould spreads too fast in water to wait for a big count — even ONE plant with sudden un-recovering wilt or a dark stem-base lesion after rain or irrigation is your threshold. One sick plant → act today.

Plant on raised beds or ridges so water drains away and never sits around the stem. Do not over-water and never flood-irrigate onto soaked ground. Rotate peppers, chillies, tomatoes, eggplants and cucurbits away from any bed that has had this blight — go 3–4 seasons into non-host crops (like cereals) before coming back. Start with clean, healthy transplants from disease-free ground.

Ask your seed supplier or extension officer for tolerant/resistant varieties or grafted plants on resistant rootstocks of your crop. They will not be perfect, but they slow the disease down and buy you time — combine them with good drainage, never rely on them alone.

As soon as you spot a wilted or stem-rotted plant, pull it out with the soil around the roots and carry it right out of the field — bury it deep or burn it, never toss it on the field edge where water washes back. Do not let water run from the sick patch to healthy plants, and wash the soil off your tools, boots and hands before working clean beds, because you carry the spores in mud.

Ordinary fungicides do NOT work on this water mould; you need an oomycete-specific fungicide (the phosphonate or metalaxyl group — ask your agro-dealer for one labelled for Phytophthora). Sprays protect healthy plants and cannot save rotted ones, so drench the beds around a sick spot preventively. Safety: cover your skin, eyes, nose and mouth; spray in the cool of morning or evening with the wind at your back; keep it off food, drinking water, children, and bees; respect the pre-harvest interval (the number of days on the label you must wait between spraying and picking fruit); and wash yourself and your clothes afterwards. Resistance: metalaxyl especially fails fast if over-used, so rotate to a different chemical group each time and never spray the same one over and over.

double down on drainage — cut channels to drain the wet spots, stop irrigating that block, and keep pulling and removing every new sick plant daily to save the rest. When a patch is lost, cut your losses: rope it off, harvest any clean fruit from healthy plants nearby, and after the season rotate that ground out of peppers, tomatoes, eggplants and cucurbits for several years — the spores survive in the soil, so replanting a host there just feeds the disease again.