Diseases of Rice

Diseases of Rice : A Farmer’s Guide to Keeping Crops Healthy

Imagine this—you wake up early, walk to your rice field, expecting to see lush green plants swaying in the breeze. Instead, you notice something’s wrong. The leaves look yellow and spotty, some plants are shriveling up, and worst of all, the grains are either missing or just plain bad. Rice farming isn’t just about planting and harvesting. It’s also about fighting off diseases that can wipe out your crop before you even get a chance to harvest it. Some diseases attack the leaves, some mess up the roots, and others make sure your grains never even form. It’s a real struggle. But don’t worry—I’ve got you covered. In this guide, we’ll go over the most common diseases of rice , what causes them, how to spot them early, and how to stop them before they ruin your season.

The Main Causes of Rice Diseases

Before we get into the actual diseases, let’s take a moment to understand why rice plants get sick in the first place.

1. Too much water or bad drainage – Rice loves water, but too much can lead to fungal and bacterial problems.
2. Crowded planting – If plants are too close together, air can’t circulate properly, making it easier for diseases to spread.
3. Poor-quality seeds – Starting with infected seeds means trouble from the beginning.
4. Insects – Some tiny bugs don’t just eat plants—they spread viruses too.
5. Over-fertilization – Adding too much nitrogen makes plants weak and more vulnerable to disease.

Alright, now that we know why diseases happen, let’s get into the actual troublemakers.

The Most Common Diseases of Rice and How to Deal With Them

1. Diseases of Rice: Rice Blast – The Deadly Leaf Killer

What it looks like:

If you’ve ever grown rice, there’s a disease you may have come across that turns your green, healthy field into something that looks like it caught fire. It’s called rice blast, and for many farmers across the world, it’s a name that brings real worry.

This isn’t a fancy science article. Just a straightforward talk about what rice blast is, how it shows up, and what you can realistically do about it—especially if you’re working hard with limited resources.

What Does Rice Blast Look Like?

It usually starts small.

You’ll see pale green or white spots on the leaves—almost like they’ve been dusted with ash. Then those spots grow longer, turning brown in the middle with dark edges. They sort of look like someone pressed a burning cigarette on the leaves.

As it spreads, the leaves dry up. In bad cases, the stem and even the grain head can be attacked. When that happens, the grains don’t form properly—or don’t form at all. That’s when real loss kicks in.

A farmer once said to me, “My plants looked tired, like they were sick. But by the time I noticed, the field was already half gone.”

When and Why Does It Show Up?

Rice blast loves:

• Warm weather
• Moist air
• Still air like in dense fields
• Too much nitrogen fertilizer

In short, it shows up when everything else looks perfect for rice growth. That’s the trick—it hides in ideal conditions. You think your crop is doing great, and then one rainy week changes everything.

The fungus behind rice blast is Magnaporthe oryzae. Sounds complicated, but all you need to know is that it spreads through tiny spores carried by wind and water. Once it’s in the air, it can land on leaves and start multiplying.

Why It’s So Dangerous

Here’s the scary part.

Rice blast doesn’t just nibble at your crop. It kills entire portions of the plant—sometimes the whole thing. In countries like Bangladesh, India, the Philippines, and Indonesia, farmers have lost up to 70% of their harvest in bad years.

And it’s not just big fields—small farmers with half-acre plots suffer the most. They don’t have the backup savings or tools to bounce back.

What Can You Actually Do?

Let’s skip the textbook advice and go to what really works in the field.

1. Grow Resistant Rice

Not all rice varieties get rice blast. Some were specially bred to handle it. If you can get seeds from your local agricultural office or seed supplier, ask for ones labeled “blast resistant.”

In Bangladesh, varieties like BRRI dhan66 or BRRI dhan28 show better resistance.

You won’t be 100% safe, but you’ll have a better chance.

2. Don’t Overfeed Your Crop

Many farmers add a lot of nitrogen like urea thinking more fertilizer = more grain.

But too much nitrogen makes the plant soft and juicy—perfect for the fungus. It’s like overfeeding a chicken until it can’t walk. Feed the plant right, not too much.

Use split applications, and balance nitrogen with potassium and phosphorus if you can.

3. Control Water and Air

If you plant too close together, the air can’t flow, and the leaves stay wet longer. Wet leaves = fungal party.

• Leave a bit more space while transplanting.
• Drain the field sometimes to allow leaves to dry.
• Avoid watering late in the day.

4. Remove Infected Plants

If you see leaves or panicles clearly affected, remove them gently and burn or bury them far from the field. Don’t compost them—they’ll just bring back the disease.

Also, clean up last season’s stubble after harvest. That’s often where the fungus sleeps and waits.

5. Fungicide – If You Can Afford It

Some farmers use Tricyclazole or Azoxystrobin to spray on infected crops. These can work well—but they cost money, and they need to be sprayed early, not after the disease has already taken over.

If you go this route:

• Don’t overuse the same chemical every time.
• Follow instructions exactly.
• Use safety measures—don’t spray bare-handed.

If you can’t afford fungicides, focus more on the resistant seed and spacing method. They cost less and still help.

A Farmer’s Small Experiment

In a village near Jessore, one farmer I met tried a small experiment. He planted half of his land with his usual local variety and half with BRRI dhan66. He used the same fertilizer, water, and schedule for both.

After a wet season, the local variety showed brown spots, and about 30% of the grains didn’t fill. But the BRRI dhan66 plot had only mild symptoms—and gave him a much better harvest.

It wasn’t magic. Just a smarter choice of seed.

Final Advice from One Farmer to Another

• Walk your field often. The earlier you spot it, the easier to control.
• Don’t panic. Even if it shows up, you can manage it with quick action.
• Talk to neighbors. If their fields have blast, yours might be next.
• Rotate your crop. Don’t plant rice over and over again in the same soil.
• Stay updated. Local agri-offices sometimes give out free advice or even seed samples.

2. Diseases of Rice: Bacterial Leaf Blight – The Silent Field Destroyer

What it looks like:

You won’t always notice it right away. The field looks green, the plants are standing tall, and everything seems fine. Then, almost quietly, the tips of the leaves begin to yellow. A few days later, the yellow moves downward, the edges dry up, and before you know it, the crop is suffering. That’s how Bacterial Leaf Blight creeps in—quietly, but dangerously.

In farming, not every disease announces itself loudly. This one often slips in under your nose.

What Farmers Usually See First

Most farmers say the same thing: “It started with the tips.”

You’ll spot it at the edges of the top leaves. The yellowing begins at the tip and slowly moves downward like a slow fire. After a while, those parts dry up and turn straw-colored. Sometimes, entire leaves look scorched, as if someone dragged a flame across them.

In young plants, it can be worse. They can wilt all at once. No yellowing. Just sudden collapse. That stage is called Kresek, and it’s hard to fix once it begins.

What’s Causing It?

The culprit is a bacterium called Xanthomonas oryzae. You don’t have to remember the name. Just know it’s a micro-organism that loves moisture, warm weather, and soft plants. It lives in infected water, soil, seeds—even leftover plant parts from last season.

When water splashes from one plant to another during rain or irrigation, the bacteria travel with it.

Why It’s So Dangerous

Bacterial Leaf Blight isn’t like a fungal disease that stays on the surface. It gets inside the plant and blocks the natural flow of water and nutrients. Once the system is blocked, the plant starts drying out from the inside—even if there’s enough water in the soil.

The result? Lower tillers, fewer grains, and often a field that looks far older than it is. In some places, BLB has caused yield losses up to 50%, especially when it shows up early.

What Makes It Worse?

BLB usually shows up more during:

• Heavy rains
• Windstorms
• Flooded or over-irrigated fields
• Fields with too much nitrogen like urea
• Tightly planted seedlings

Anything that injures the leaves—like insects or rough handling—gives the bacteria a way in. Once they enter, they multiply quickly.

What You Can Do to Protect Your Field

No fancy tricks here. Just practical things that real farmers have used and shared.

1. Start with the Right Seed

Some rice varieties are naturally stronger against BLB. Not immune, but stronger.

If you’re in Bangladesh, varieties like BRRI dhan71 and BRRI dhan47 have shown good resistance. Ask your local seed dealer or agriculture officer what varieties are doing well in your area.

2. Don’t Overfeed

Urea is like sugar for rice plants. But too much of it makes the leaves soft and juicy—perfect for bacterial attack.

Split your nitrogen doses. Give less in the early stages, and avoid applying just before or after heavy rains.

3. Mind the Water

If your field is connected to others, make sure water isn’t flowing freely from a sick field to yours.

Also, avoid letting water stand too long. Alternate wet and dry cycles if you can. It helps more than you’d think.

4. Don’t Handle Wet Plants

It might sound silly, but even walking through a wet, infected field can spread BLB.

Try not to do field work early in the morning or right after rain when the plants are still wet.

5. Remove Bad Plants

If a plant looks badly infected—especially during the early stages—it’s better to remove and destroy it than risk the whole patch.

Don’t throw it near the canal or compost pile. Burn or bury it away from the field.

6. Keep Insects in Check

Insects can create small wounds on the leaves, which is where bacteria enter. Managing leaf folders, stem borers, and hoppers can help reduce infection chances.

A Real-World Story

In a village near Rajshahi, a small farmer named Harun used to lose part of his field to BLB every year. He tried different fertilizers, changed his transplanting dates—but nothing worked. Then he attended a training from the local agri office and learned three things: plant resistant variety, reduce urea early on, and avoid field work when leaves are wet.

He didn’t change everything overnight. Just those three. The next season, his crop looked healthier, and by harvest, his field had almost no signs of BLB.

“Didn’t need chemicals,” he said. “Just needed better habits.”

What Research Says

• According to a study published in Plant Disease Journal (2006), managing nitrogen levels properly can reduce BLB by up to 40%.
• BRRI (2022) recommends resistant varieties as the most cost-effective method for small farmers.
• The International Rice Research Institute (IRRI) found that water management combined with good seed selection can protect over 60% of potential yield even during outbreak years.

3. Diseases of Rice: Sheath Blight – The Fungus That Won’t Quit

What it looks like:

Sometimes in farming, it’s not the big disasters that hurt the most—it’s the slow, silent ones. Sheath blight is one of those. It creeps in, sits low in the rice plant, and before you realize, it’s eating away your harvest from the bottom up.

It’s not loud. It doesn’t kill your crop overnight. But it sticks around—and comes back year after year if you don’t deal with it right.

So, What Is Sheath Blight?

Let’s keep it simple. Sheath blight is a disease in rice caused by a fungus. Its name is long and hard to pronounce—Rhizoctonia solani—but the problem it causes is easy to spot.

The fungus usually lives in soil and in old plant parts like straw, roots, and stubble. Once it’s in the field, it just waits for the right time: warm, wet weather and lots of green rice plants packed together.

What You See in the Field

It starts small. You walk into your paddy one day and notice gray-green patches near the bottom of the plant where the leaf wraps around the stem. You might think it’s nothing.

But over time:

• The patch spreads up the leaf.
• The spot turns brown with a darker edge.
• The leaf starts drying, curling, and bending down.

It’s worst in the middle of the season, especially in wet conditions. And the trouble is, the fungus spreads sideways, from one plant to the next, riding on moisture and air movement.

Why It Won’t Go Away Easily

Here’s the thing: sheath blight is a tough survivor.

• It stays in the field after harvest—on leftover straw and roots.
• It doesn’t need seeds to spread—it just lives in the soil and waits.
• It spreads quickly if plants are close together and the air is damp.
• And there’s no magic spray to kill it for good.

Once it’s in the field, it keeps showing up—year after year—unless you change the way you manage things.

What Makes It Worse?

From what farmers have seen and what research backs up, these things help sheath blight spread faster:

• Too much nitrogen fertilizer especially urea
• Closely spaced seedlings
• No cleaning after harvest
• Warm, rainy days with poor drainage

Basically, if the lower parts of your rice plants stay wet and crowded, you’re giving sheath blight a warm bed to sleep in.

A Real Farmer’s Words

Last season, I visited a farmer named Robiul in Kushtia. He had beautiful rice at first—BRRI dhan28, nice and tall. But halfway through the season, the leaves started drying from the bottom.

He said, “I thought it was just heat. But then I looked closely—big brown marks, like someone had dipped the leaves in tea.”

He had seen it before. It was sheath blight, and he had used no fungicide, hadn’t cleaned last year’s stubble, and planted a bit too close.

What Can You Do?

No disease can be avoided 100%, but sheath blight can be managed. Here are things that have worked for real farmers—not just lab ideas.

1. Give Space Between Plants

Too many seedlings crammed together means the lower leaves stay wet. Just leaving a bit more space during transplanting can make a difference. Aim for 20×20 cm if you can manage.

2. Don’t Overuse Urea

More urea doesn’t mean more rice. Too much nitrogen makes soft, leafy plants that sheath blight loves. Try split doses instead of dumping it all at once.

3. Clean Up After Harvest

This one is key. If you leave behind stubble, straw, and roots, the fungus stays and waits for the next crop. Try to burn, bury, or remove infected materials.

4. Use a Tolerant Variety

There’s no “immune” variety yet, but some handle sheath blight better.

Farmers in Bangladesh often prefer:

• BRRI dhan56
• BRRI dhan57
• IR64

Ask your local agri officer what works in your area.

5. Spray Only If You Need To

Fungicides like Validamycin or Hexaconazole can help if the infection is starting—but they won’t solve the whole problem. Use them early, not after the disease has spread all over.

And don’t rely only on chemicals—use them along with other methods.

What the Research Says

• IRRI (International Rice Research Institute) notes that short, dense rice is more vulnerable to sheath blight because it stays humid near the ground.
• BRRI found that balanced fertilizer and resistant varieties reduced disease severity by up to 30–40% in field trials.
• A study by Savary et al. (2000) reported yield losses of up to 50% in untreated, dense-planted fields affected by sheath blight.

Final Words – Keep It Clean and Balanced

Sheath blight may not scream for attention like some other rice diseases, but it slowly eats away your yield. It needs a bit of discipline to manage—good spacing, balanced fertilizer, clean fields, and early observation.

No single fix will wipe it out, but small changes can make a big difference. If you’ve got healthy lower leaves, you’ve got a stronger plant. And in farming, strong plants usually mean fuller grains and better harvests.

4. Diseases of Rice: Tungro Virus – The Invisible Yield Killer

What it looks like:

Rice farmers deal with a lot—floods, drought, pests, and sometimes things that are hard to even notice at first. Tungro is one of those quiet problems. It sneaks in, doesn’t shout, doesn’t kill the plant right away. But by harvest time, you realize your field gave you much less than you expected.

That’s why farmers call it the invisible yield killer.

How It Shows Up in the Field

At first, everything might look fine. But slowly, you notice some plants aren’t growing right. The leaves start to turn a bit yellowish-orange, not like the usual healthy green. The plants seem shorter, and the leaves look stiff, almost plastic-like.

You think maybe the soil is lacking something, or maybe it’s just heat stress. But then the color spreads. New tillers stop coming. And that’s when it hits—Tungro virus has made itself at home.

One farmer in Tangail told me, “I thought it was just bad fertilizer. But by the time I understood, I had already lost half my field.”

What Causes Tungro?

Tungro isn’t caused by a single thing. It’s actually a combination of two viruses working together, and they get carried around by a small insect called the green leafhopper.

The leafhopper sucks juice from infected plants and then flies over to healthy plants and infects them too. So, the virus doesn’t come from seeds or soil—it moves through insects.

Why It’s So Hard to Catch

The tricky part with Tungro is that it doesn’t kill plants outright. It just weakens them, slows them down, and makes them poor grain producers.

So unless you’re paying close attention, it might be weeks before you notice something’s wrong. And by then, it’s usually too late to fix completely.

What the Experts Found

Researchers from IRRI (International Rice Research Institute) and BRRI (Bangladesh Rice Research Institute) have studied Tungro for decades.

They found:

• If Tungro hits within the first 20–30 days after transplanting, it can cause up to 100% grain loss in affected plants.
• The green leafhopper is the main carrier, and its population increases during dry, warm weather.
• Fields with leftover ratoon crops or volunteer rice plants are more likely to host the virus.

(Source: Hibino, 1996; BRRI field reports)

What Can You Do?

You don’t need to panic. Tungro can be managed, especially if you catch it early and use a few simple tricks.

1. Use Resistant Varieties

There are several rice types that resist Tungro or at least handle it better.

Some known ones in Bangladesh include:

• BRRI dhan47
• BRRI dhan29
• IR64

If you’re not sure which ones suit your region, ask your local agriculture office. It’s worth planting a variety with some resistance.

2. Get Rid of Infected Plants Early

If you spot a plant showing yellow leaves and stunted growth early in the season—pull it out right away. That one plant could be the source of infection for dozens more.

Don’t leave it lying around. Burn it or bury it outside the field.

3. Control Leafhoppers

The leafhoppers are small but mighty. Stopping them early can make a big difference.

• Use light traps in the early evening to catch them.
• Spray a mild insecticide only if needed—when you see leafhoppers moving in groups.
• Try neem-based organic sprays if you prefer a natural method.

Don’t spray randomly—too many chemicals kill good insects too.

4. Don’t Leave Old Crops Standing

Tungro virus hides in leftover rice plants—especially ratoon growth and volunteer seedlings that sprout after harvest.

Clean the field properly. Plough under or remove any green rice plant left behind.

5. Sow Together with Neighbors

This one might surprise you. If your whole village plants rice at the same time, there’s less chance for leafhoppers to jump from one field to another and carry Tungro.

It’s a community-level protection method—and it works.

A Farmer’s Story

Abdur Rahman from Dinajpur faced Tungro two seasons back. He noticed a patch of yellow plants early on but thought they’d recover. By the time he acted, the virus had spread across 40% of his land.

Last season, he changed a few things—used BRRI dhan47, cleaned his field properly after harvest, and planted the same week as his neighbors. He also checked for leafhoppers every few days during the early stage.

This time, no Tungro. He smiled and said, “The difference was not money—it was timing and watching closely.”

How to Prevent Rice Diseases

If you don’t want to deal with sick rice plants, follow these golden rules:

1. Use good-quality seeds – If your seeds are bad, your season is doomed from the start.
2. Give your plants space – Avoid overcrowding, or diseases will spread like gossip in a small village.
3. Don’t over-fertilize – Too much nitrogen makes plants weak and disease-prone.
4. Manage water properly – Avoid standing water in the field.
5. Rotate crops – Don’t plant rice in the same field every season.
6. Keep an eye out – If you notice something weird early on, take action .

Final Thoughts

Rice farming isn’t just about planting and harvesting—it’s about fighting off diseases before they ruin everything. Some diseases are easy to manage, while others are merciless crop killers.

The key? Prevention and quick action. If you stay one step ahead, your rice crop will stay healthy and productive.

References

1. IRRI (International Rice Research Institute) – Managing Rice Diseases
2. FAO – Rice Disease Control Strategies
3. USDA – Common Rice Diseases