Loose smut

at heading, when heads push out of the boot, some heads come out not green and grain-filled but black — turned into a soft mass of black, powdery dust instead of grain.

that black powder (the spores) blows away in the wind within days, leaving behind only the bare central stalk of the head (the rachis) — a thin, naked spike like a little stick where a full head should be. Infected plants often head a few days earlier than the healthy ones around them, so the black heads show up first.

it shows up head by head, scattered through the field — one plant here, one there — not as a patch. Each affected plant usually has its whole head destroyed.

with common bunt (stinking smut), where the head stays whole and greenish but the grains are swapped for grey, greasy "balls" of dark powder that stay put and give off a rotten-fish smell — loose smut's dust is loose and blows away, leaving a bare stalk, and has no smell. It is also not ergot (hard, black, horn-like bodies sticking out of the head) or ordinary black sooty mould (a surface dirt you can rub off a still-healthy head).

watch at heading and flowering, near the end of the season (late season) — that is the only time loose smut shows itself, because it lives inside the plant until the head forms.

walk a big "W" across the field so you cross all four corners and the middle, not just the edge by the path. Make about 10 stops along the way.

at each stop, look across the heads for any that have turned to black powdery dust or a bare naked stalk — these stand out against the green healthy heads, especially early when they head first.

finding even a single smutted head tells you the seed that came off this field is carrying the fungus. Do not save any seed from a field with smutted heads for planting, and treat next season's seed before you sow it. The more black heads you count, the heavier the load your seed would carry into next year.

sow certified, disease-free seed and never re-sow seed saved from a crop that showed any smut — this is a seed problem, so clean seed is the whole battle. Where you can get it, grow a variety that resists loose smut; resistant varieties carry far less infection year to year.

if you spot just a few smutted heads, cut or bag them and carry them out before the black dust blows off — this stops those spores from landing on the open flowers of your healthy plants and cutting into next season's seed. It will not save this crop, but it protects the seed you keep.

because the fungus hides inside the seed, only a systemic fungicide — one that soaks into the seed and travels inside to kill the fungus hidden within, unlike a contact/surface dressing that only coats the outside — can reach it. Treat the seed before planting (the product class named for this is a systemic seed-treatment fungicide). Safety: wear gloves and cover your skin, nose and eyes when handling treated seed, mix in the open air with the wind behind you, never eat treated seed or feed it to animals or people, keep it away from food, water, children and animals, wash your hands and clothes after, and store leftover treated seed clearly marked and apart from grain. To keep the fungicide working over the years, rotate to a different chemical group rather than using the same one every season.

if you still see smutted heads season after season, stop saving your own seed altogether — buy fresh certified, treated seed each year and switch to a resistant variety. Any field that heads out with black smutted heads has already lost that grain, so harvest it for eating or feed only, save none of it for seed, and start the next crop clean.