Jassids (leafhoppers)

the edges of the leaves turn yellow, then red-brown or bronze, and curl and cup downward. This is called hopperburn. Badly hit leaves go brittle and dry from the rim inward, and young plants stay short and stunted. The give-away is that the burning always starts at the leaf margin (the edge) and works inward — never in the middle of the leaf first.

turn a leaf over and look at the underside. Jassids are tiny, wedge-shaped, pale-green insects, smaller than a grain of rice (the adults are only about 2–3 mm long). The young ones — the nymphs (the wingless babies) — are even smaller and paler. Both give themselves away by how they move: they run sideways, crab-fashion, and the winged adults hop or flit off the instant you disturb the leaf. They shelter on the lower and middle leaves and thrive in warm, dry weather.

aphids also sit under the leaf but are slow, soft and pear-shaped, packed together in clusters, and they leave a sticky, shiny film (honeydew) — jassids are fast, green, wedge-shaped and dart sideways. Whiteflies are snow-white and fly up in a little cloud, like tiny moths, when you shake the plant. Plain hunger (a nutrient shortage) or drought yellows the whole leaf, or the strips between the veins, with no insects underneath — whereas hopperburn bites the leaf edge, curls it under, and hides small green hoppers beneath.

start at the seedling stage and keep checking right through the growing and mid-season stages — young plants are hit the hardest, and jassid numbers build up fastest in warm, dry weather (about 25–35 °C). During a hot, dry spell, check at least twice a week.

walk a big "W" shape so you cover all four corners and the middle of the field, not just the row nearest the path. Make about 10 stops as you go.

turn over the lower and middle leaves and look on the underside for the small, pale-green nymphs, and run your eye along the leaf edges for the first signs of yellowing and downward cupping.

across your stops — or the first leaf-edge yellowing and downward cupping (hopperburn) on young plants. On tender seedlings, don't even wait for the count: the first patch of hopperburn is your signal to act, because a seedling has the least leaf to spare and is set back the worst.

in cotton and okra, choose the hairy-leaved (fuzzy) tolerant varieties. The tiny hairs on the leaf physically stop the small jassids from settling, feeding and laying their eggs, so this is your strongest single defence — and it needs no spraying at all. For beans, brinjal (eggplant) and groundnut, ask your extension officer or seed dealer for the tolerant varieties recommended for your area.

don't over-use nitrogen fertiliser — lush, soft, dark-green growth is exactly what jassids love; balanced feeding grows a tougher, less attractive plant. And pull out the weeds in and around the field, because weeds and other host plants are where jassids breed and carry over between crops.

ladybird beetles (ladybugs), lacewings, spiders and predatory bugs already in your field eat jassid nymphs and eggs for free. Don't reach for a strong, kill-everything spray the moment you see one hopper — wiping out these natural enemies makes the jassids come back even worse (this is called a resurgence). Let the predators do the early work while you keep scouting, and act firmly only once you hit the threshold.

if you reach 2 or more nymphs per lower leaf, or the first hopperburn on young plants, and the natural enemies clearly aren't coping, use a registered systemic insecticide. Systemic means the chemical travels inside the plant's sap, so it reaches the jassids hiding and sucking under the leaves — unlike a contact spray, which only kills what it directly lands on and mostly misses insects tucked underneath. A seed treatment (insecticide coated onto the seed at planting) is another good option, protecting the plant from the inside through the risky seedling stage. Safety every single time: cover your skin, eyes, nose and mouth; spray in the cool of the morning or evening, with the wind at your back; aim at the leaf underside where they hide; keep it well away from food, drinking water, children and bees; wait out the pre-harvest interval (the number of days the label tells you to leave between spraying and picking) before you harvest; and wash yourself and your clothes afterwards. To stop the jassids becoming resistant (no longer killed by the chemical), rotate to a different chemical group each time rather than using the same product over and over.

don't just re-spray the same product — switch to a different chemical group, and re-check your two biggest levers, variety and nitrogen, for next time. When it's already too late — a young crop burnt brown and stunted right across the field will not recover, because the poison damage is permanent — so protect the healthy plants that remain, cut your losses on the worst patches, and plan next season around a hairy-leaved tolerant variety, balanced feeding, and clean, weed-free field margins.