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Pigeonpea sterility mosaic viruses (PPSMV-1 and PPSMV-2) Emaravirus cajani (PPSMV-1) and a second emaravirus (PPSMV-2), transmitted by the eriophyid mite Aceria cajani Channabasavanna, 1966 · formerly or also: SMD
Sterility mosaic makes pigeon pea plants pale green, bushy and stunted, with small leaves showing a mosaic pattern, and partly or completely stops them from flowering and setting pods, which is why it is called 'sterility' mosaic or 'green plague'. It is caused by viruses spread by a tiny eriophyid mite, Aceria cajani, and is one of the most important diseases of pigeon pea in South Asia. Infected plants that stay green and leafy are often mistaken for healthy ones.
Sterility mosaic of pigeon pea is caused by Pigeonpea sterility mosaic viruses (PPSMV-1 and PPSMV-2) Emaravirus cajani (PPSMV-1) and a second emaravirus (PPSMV-2), transmitted by the eriophyid mite Aceria cajani Channabasavanna, 1966, a virus (emaraviruses with RNA genomes), spread by an eriophyid mite (order Bunyavirales (Elliovirales), family Fimoviridae).
Older or alternative scientific names: SMD.
Found in India, Nepal, Bangladesh, Sri Lanka, Myanmar and Thailand; most important in South Asia, where pigeon pea is grown widely.
| Region | Status |
|---|---|
| South Asia | Widespread; major disease |
| South-East Asia | Present |
The viruses are emaraviruses with segmented RNA genomes, detected by RT-PCR or serological tests. The mite vector, Aceria cajani, is a tiny worm-like eriophyid mite, about 0.2 mm long, invisible without a microscope, living on the undersides of young leaves. Mites acquire and transmit the viruses within minutes to hours and carry them for some days; the viruses are not seed-transmitted. Mites are found mostly on the undersides of young leaves at the tips of branches.
| Crop stage | What you see |
|---|---|
| Early infection | Pale green or yellowish mosaic and ring spots on young leaves; leaves smaller. |
| Established infection | Plants bushy and stunted with many small, pale, mottled leaves; shortened internodes. |
| Flowering | Few or no flowers and pods on infected branches or whole plants (partial or complete sterility); plants stay green while healthy ones mature. |
The viruses and mites survive between seasons on perennial, ratoon and volunteer pigeon pea and on wild relatives. Mites are carried by wind to new crops and transmit the viruses while feeding on young leaves. Infected plants support more mites, so disease spreads from early-infected plants to their neighbours.
| Stage | Duration | Notes |
|---|---|---|
| Survival on perennial and volunteer plants | Between seasons | Main reservoir. |
| Wind dispersal of mites | Throughout the season | Mites are tiny and drift on air currents. |
| Transmission by mite feeding | Minutes to hours | On young leaves. |
| Symptom development | About 1-3 weeks | Early infection causes most loss. |
Mite populations build up in mild, humid weather; disease is most severe when plants are infected young.
Mites breed continuously, completing a generation in about two weeks.
Ratoon and perennial pigeon pea nearby, volunteer plants, susceptible varieties, early infection of young crops, and conditions that favour mite build-up.
There is no economic threshold; management is preventive, mainly through resistant varieties and removing sources of infection.
Thresholds are local. They depend on crop price, control cost, variety and natural-enemy activity, so use the figure your local extension service publishes where one exists.
Plants infected within the first one to two months may produce almost no pods, giving yield losses of up to 95-100% on those plants; field losses depend on how many plants are infected early.
Control works best as a sequence: prevent, monitor, then act only when a threshold or a risk forecast says so, using the least disruptive option that works.
Miticides applied early can reduce mite populations and spread in high-risk fields; they do not cure infected plants. What is registered differs by country and changes over time; follow the label and your local plant-protection authority.
| Scheme | Group | Mode of action | Notes |
|---|---|---|---|
| IRAC | 6 | Glutamate-gated chloride channel allosteric modulators | Acts on mites; translaminar. |
| IRAC | 23 | Inhibitors of acetyl CoA carboxylase | Acts on mites where registered. |
Pigeon pea and wild relatives such as Cajanus scarabaeoides; some other plants support the viruses in tests.
How to grow the crop well is the first line of defence. Laisha's free grow guides cover each crop from sowing to harvest:
Written by Laisha from the sources above, in its own words. This page is general reference, not a prescription: confirm identification locally and follow the label and your plant-protection authority.