Maize streak virus

shows on the youngest leaves: broken, pale-yellow to near-white streaks and dots running the length of the leaf, along the veins. At first they look like scattered dashes, like someone flicked pale paint down the leaf.

, the dashes join into long continuous cream or white stripes so the whole leaf looks striped yellow-and-green. The streaks are dry and flat, not wet, not fuzzy, and not raised — the leaf just loses its green in narrow lines.

, growth stalls: the plant stays short and bunched, leaves are narrow, and it makes a small cob or no cob at all. Plants infected later are less stunted but still striped.

turn over young leaves and open the whorl to find leafhoppers — pale green to grey jumping insects, smaller than a grain of rice, that hop or fly off quickly when disturbed. They gather most on the newest growth.

Streaks that are straight, fine and run only along the veins point to streak virus. Yellowing between the veins with the veins staying green is usually a nutrient shortage (like nitrogen or zinc), not this virus. Pale blotches that spread from the leaf edge or a whole yellow older leaf are more likely hunger or drought. And a striped seedling that is also stunted and bunched is streak, not a feeding scar.

this virus does its worst damage at the seedling and young-plant stage (the crop's vulnerable window). Start checking from the day of emergence and keep going every week until the plants are knee-to-waist high — the earlier a plant is infected, the more it loses.

cross the field in a large "W" so you cover all four corners and the middle, not just the edge by the path or near grassland — leafhoppers move in from field margins first.

make about 10 stops, and at each stop check 10 young plants — look down into the whorl and at the newest leaves for pale vein-streaks, and watch for leafhoppers hopping off.

as soon as you find streak symptoms on young plants, OR leafhoppers settling on your seedlings — even a few striped plants in your first walk — treat the field as at risk and act. Waiting lets the leafhoppers carry it plant to plant.

scout hardest when your crop is young next to grassland, next to older or volunteer maize, or planted late while nearby fields are already up — that is where the leafhoppers come from.

As soon as you spot striped, stunted seedlings, pull them out and remove them (this is roguing — taking out infected plants so they can't feed more leafhoppers). It won't cure the field but it lowers the source while plants are still young.

No spray cures an infected plant. The only chemical option is protecting seedlings from the leafhopper with an insecticide seed treatment / vector-control product — a systemic treatment (one that is taken up inside the plant, so it protects the seedling from the inside) used only in high-risk situations such as late planting beside infected fields. Safety: treated seed is poison — never eat it, feed it to animals, or mix it by hand without gloves; keep it away from food, water, children and animals. If you spray a vector insecticide, cover your skin, eyes and nose, spray in the cool of the day with the wind behind you, keep off food, water, children and bees, respect the pre-harvest interval (the wait between spraying and harvest printed on the label), wash well afterwards, and rotate to a different chemical group each time so the leafhoppers don't build resistance.

don't waste money spraying a field that is already badly striped — the virus is inside the plants and won't come out. Instead switch your plan for next season: buy certified streak-resistant seed, plant earlier and all at once, and keep the grass weeds and volunteer maize cleared. When a field is already mostly stunted and won't make cobs, cut your losses — remove the worst plants or the crop early, feed healthy green material to livestock if it is safe, and put your effort into a clean, resistant, early-planted crop next time.