Yellow vein mosaic of okra: symptoms, spread and control

Photo at the top: An okra leaf with yellow vein mosaic. The yellow net of veins is the main sign, Photo: Srigayu1996, CC BY-SA 4.0

Quick answer

Yellow vein mosaic of okra is a virus disease spread by whitefly. The leaf veins turn yellow, then the whole leaf, and pods become pale, small and hard. No spray cures an infected plant. Grow a tolerant variety, pull out sick plants early, keep weeds down and control whitefly from the seedling stage.

How to identify yellow vein mosaic of okra

This disease is caused by a virus called bhendi yellow vein mosaic virus (often shortened to YVMV). In Hindi it is called bhindi ka peela shira mosaic (भिंडी का पीला शिरा मोज़ेक), and in Telugu benda pallaku tegulu (బెండ పల్లాకు తెగులు). It is one of the most serious problems of okra in India. The National Institute of Plant Health Management (NIPHM) calls it a very serious problem in bhindi growing all over the country.

Walk through the field and look at the young leaves near the top of the plant first. That is where the signs show up early.

• Early sign: the veins of the leaf turn yellow. You see a fine yellow net on a green leaf. This is called vein clearing.
• Later: the yellow spreads from the veins into the rest of the leaf. In a bad attack the leaf turns fully yellow or almost white.
• New leaves: come out yellow and smaller than normal.
• Whole plant: stays short and weak. It gives few flowers.
• Pods: pale yellow or white, small, hard and rough. Traders do not buy them.

The infection can start at any stage of the crop. The earlier a plant gets it, the less it gives. A plant infected in the first weeks may give almost no pods worth selling.

Look-alikes and how to tell them apart

• Iron deficiency: young leaves turn yellow but the veins stay green. In yellow vein mosaic it is the other way round: the veins turn yellow first. See iron deficiency in plants, where the veins stay green.
• Jassid damage: the edges of the leaf turn yellow, then red or brown, and the leaf curls. The veins do not form a yellow net. Turn the leaf over and you see small green insects that walk sideways. See how to identify and control jassids in okra, cotton and brinjal.
• Enation leaf curl: another okra virus spread by whitefly. Leaves curl and twist, and small raised growths (enations) form on the veins under the leaf. The leaf does not show the clear yellow net.
• Nitrogen shortage or waterlogging: older, lower leaves turn evenly pale yellow. There is no yellow vein pattern, and new leaves look normal.

How it spreads and when it attacks

The virus lives inside sick okra plants and in some weeds. NIPHM names weed hosts such as Hibiscus tetraphyllus (a wild hibiscus), Croton sparsiflorus and Ageratum. It cannot fly or move on its own. It needs a carrier.

That carrier is the whitefly (Bemisia tabaci), a tiny white insect that lives under the leaves. When a whitefly sucks sap from a sick plant or weed, it picks up the virus. It then flies to a healthy okra plant, feeds, and passes the virus on. A few whiteflies moving through the field can infect many plants.

So the disease follows the whitefly. Whitefly builds up in warm, dry weather and in long dry spells between rains. Heavy rain knocks its numbers down for a while.

In Telangana and Andhra Pradesh, okra is grown in kharif, rabi and summer. The summer crop and the dry gaps of kharif face the most whitefly. TNAU (Tamil Nadu Agricultural University) advises farmers not to grow susceptible varieties in summer, when whitefly activity is high.

Crops it attacks

Okra (bhindi, bhendi): this is the main crop. Plants can be infected at any stage, from seedling to fruiting. Early infection does the most harm, because the plant stops growing before it can set pods. NIPHM puts the loss in pod yield at 50 to 100 percent, depending on how many plants in the field are infected.

Weeds around the field: the weed hosts named above carry the virus between okra crops. Keep the field and bunds clean.

Chilli and tomato get a different whitefly-borne virus, leaf curl. Cotton gets cotton leaf curl virus. If you grow these crops too, see leaf curl virus in chilli and tomato and cotton leaf curl virus.

When to act

There is no spray threshold for a virus. Once a plant shows the yellow net, it stays infected. So act early, before the disease spreads.

• Check the crop twice a week from the seedling stage. Look at the top leaves for yellow veins.
• Pull out the first sick plants as soon as you see them. Each sick plant is a source of virus for the whitefly.
• Watch the whitefly: NIPHM advises 2 yellow sticky traps per acre for monitoring. Rising catches tell you whitefly is building up.

For a whitefly threshold in okra, we could not confirm a figure from a recognised public source, so we do not give one here. Our whitefly guide for cotton, brinjal and okra explains how to check for it under the leaves.

Yellow vein mosaic of okra: control without chemicals

Most of these steps come from TNAU and the NIPHM pest management package for okra. They work better together than alone.

Grow a tolerant okra variety

This is the most useful single step. TNAU names Arka Anamika, Arka Abhay, Parbhani Kranti and Varsha Uphar as varieties that hold up against yellow vein mosaic, and NIPHM lists more, such as Pusa Sawani and Hisar Unnat. Tolerant means the plant gets less disease, not that it never gets it. The virus can change over the years, so a variety that did well before may not do well now. Ask your Krishi Vigyan Kendra (KVK) or state agricultural university which varieties or hybrids hold up in your area.

Remove sick plants and weeds

• Pull out plants with yellow veins early. Put them in a bag and destroy them away from the field. NIPHM calls this roguing.
• Remove weed hosts from the field and bunds before sowing and during the crop.
• After the last picking, pull out the old okra plants. Do not leave them standing next to a new crop.

Block and trap the whitefly

• Border crop: NIPHM advises 4 rows of a tall crop such as maize, sorghum or pearl millet (bajra) around the okra field. It slows whitefly coming in from outside.
• Yellow sticky traps: whitefly is drawn to yellow. Use them to watch numbers and catch adults.
• Sowing time: avoid sowing a susceptible variety when whitefly is at its peak, as TNAU advises for summer.
• Nursery and young plants: protect seedlings in the first weeks. This is when infection hurts most.
• Do not overdo nitrogen and water. A soft, lush crop draws more whitefly.

Protect natural enemies

Ladybird beetles, lacewings, spiders and small parasitic wasps such as Encarsia feed on whitefly. NIPHM advises conserving them. Avoid sprays that are not needed, so these friends survive. NIPHM also lists neem-based sprays as a biological option against whitefly. Ask your KVK how to prepare and use them.

Can a spray cure yellow vein mosaic?

No. No spray, fungicide, insecticide or tonic cures a plant that already has the virus. Be careful of anyone who sells a "virus cure" for okra.

Sprays can only control the whitefly that carries the virus. That protects the healthy plants, not the sick ones. None of the products in our store lists yellow vein mosaic on its label, so we do not suggest one here. For whitefly on okra, see our whitefly insecticide guide, which shows what is label-approved for whitefly on okra, with dose and waiting period. Or ask your local agriculture officer or KVK for a product labelled for your crop.

If you do spray for whitefly, keep these points in mind:

• Spray the underside of the leaves, where whitefly lives.
• Do not use the same insecticide group again and again. Whitefly builds resistance fast. Change the group from one spray to the next. The whitefly guide shows the groups.
• TNAU warns against synthetic pyrethroids on okra for this problem, because they can make the whitefly problem worse.
• Use one product at a time. Do not mix products in one tank.

Safety and waiting period

• Okra is picked every few days. Before any spray, check the waiting period before harvest (PHI, pre-harvest interval) on the label. Choose a product whose waiting period fits your picking days.
• Wear gloves, a mask, full-sleeve clothes and boots while mixing and spraying. Do not eat, drink or smoke while you work. Wash well afterwards.
• Spray in the morning or evening, not in strong wind or hot sun. Do not spray on open flowers when bees are working.
• Keep sprays and washings away from ponds, canals and wells.
• Read the label and leaflet before use.

Frequently asked questions

Can yellow vein mosaic of okra be cured?

No. Once a plant has the virus, it stays infected for life. Pull it out early so whitefly does not spread the virus from it. Protect the rest of the crop by controlling whitefly and keeping weeds down.

Why are my bhindi leaves turning yellow with a net of veins?

A bright yellow net of veins on young leaves is the typical sign of yellow vein mosaic. If the veins stay green and the space between them turns yellow, it is more likely a nutrient problem such as iron deficiency.

Which okra variety is resistant to yellow vein mosaic?

No variety is fully resistant. TNAU names tolerant varieties such as Arka Anamika, Arka Abhay, Parbhani Kranti and Varsha Uphar, and NIPHM lists more. How well they hold up changes by area and year, so ask your KVK which ones do well near you.

Should I pull out okra plants with yellow vein mosaic?

Yes, and the earlier the better. A sick plant gives poor pods and acts as a source of virus for the healthy plants. Bag it and destroy it away from the field.

Does spraying for whitefly stop the disease?

It can slow the spread to healthy plants, but it does not cure sick ones. It works better with a tolerant variety, early removal of sick plants and clean bunds. Start whitefly control early, because young plants suffer the most.

Related reading

• Whitefly insecticide guide: control whitefly in cotton, brinjal and okra
• Jassids in cotton, okra and brinjal: identify and control leafhoppers
• Leaf curl virus in chilli and tomato
• Iron deficiency in plants: symptoms and how to correct it
• All insecticides

Sources

• Tamil Nadu Agricultural University, TNAU Agritech Portal: Vein clearing / yellow vein mosaic of bhendi
• National Institute of Plant Health Management (NIPHM), Government of India: AESA based IPM package for okra