Farmer’s Guide

Banana Pests & Diseases

Contents

About this guide 3

Banana Bacterial Wilt 4

Fusarium Wilt/ Panama Disease 6

Banana Bunchy Top Disease 8

Leaf Spot Disease 10

Banana Streak/ Mosaic Disease 12

Fungal Diseases in Fruits 14

Banana Weevil 16

Nematodes 18

Lack of Nutrients 20

Good Banana Management 22

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Who are we?IITA or the International Institute for Tropical Agriculture is a research organization. Our scientists study crop production, pests and diseases around the world. We developed this booklet to pass on to you the most important information we have collected about banana pests and diseases. www.iita.org

About this guideThis booklet is all about banana pests and diseases. It tells you what they look like, how they spread, and how you can stop them. Sometimes diseases can be confused with lack of nutrients. Near the back of the book you’ll find information about nutrient deficiencies and how you can recognise them too.

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Banana Bacterial Wilt: Symptoms

Male bud wilts and fruits ripen early

Banana Bacterial Wilt or BBW causes the male bud to wilt. Then the fruits ripen when the bunch is still young.BBW affects all types of banana. It has caused 90% losses in some areas.

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Leaves brown and wilting

BBW causes the younger leaves to turn yellow and brown and wilt.

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Fruits with brown stains

BBW causes the fruits show brown stains when cut.

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Stem oozes yellow pus

BBW causes yellow pus to ooze from a cut stem and from the male bud after about 10 minutes.

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What is BBW? How is it spread?

BBW is caused by bacteria. The bacteria is spread from a sick plant to a healthy plant by:

Stingless bees going to • the male budTools like knives and hoes• Planting sick suckers in • new gardens

Stopping BBWRemove the male bud• Use a forked stick to remove the male bud after the last cluster formsDestroy sick plants• Chop and sun dry sick plants and suckersUse clean suckers and tools• Plant only clean suckers and disinfect tools with fire or bleach

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Fusarium Wilt: Symptoms

Yellow skirt around plants

The oldest leaves turn yellow. They collapse and look like a yellow skirt around the plant. The yellow spreads from the outside of the leaf. Infected plants fail to produce fruit. Young plants are stunted.

Red or brown stains

Red or brown stains are visible on the cut stem. The stain starts out pale red, turns darker and eventually becomes brown. It can be found in the stem, the base and roots of the plant.

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Stopping Fusarium WiltRemove infected plants and their suckers, even when • symptoms are not seen. Destroy themDo not move suckers from infected areas to clean areas• Fusarium Wilt spreads in the soil that is on tools and • shoes. Keep them clean to prevent it spreadingGrow resistant varieties. Try highland cooking and beer • banana varities, and Cavendish bananas. You can use FHIA 17, FHIA 23, and other hybrids from NARO and IITA.

What is Fusarium Wilt? 1. It is a fungus that lives in the soil and attacks the stem. It is also called Panama Disease. How does it spread? 2. It spreads through the soil and from mother plants to their suckers. The fungus lives in the soil for 30 years infecting new bananas when they are planted.Whatareit’seffects? 3. It affects many types of bananas including gonja, kisubi, kayinja, kamaramasenge and bogoya. It can cause yield losses of up to 100%

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Banana Bunchy Top Disease: Symptoms

Narrow upright leaves are bunched

Banana Bunchy Top Disease is easy to spot. The leaves are bunched together and the plants stunted on severely infected plants. The picture shows stunted mature plants with BBTD. They will not produce any fruit.

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Leaf edges yellow or bleached

BBTD causes the leaf edges to turn yellow and wilt when they are still young.

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Dots and dashes on leaves

If you look closely you will sometimes see dark dots and dashes on the leaves and stem.

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Where is BBTD?

What is it? How does it spread?

BBT is a virus, but it is usually transmitted by aphids. Where there is BBT you will usually find aphids in the stem.

Stopping BBTDDestroy sick plants• Dig up and bury infected plants and their suckers. Check the surrounding plants for symptomsUse healthy planting materials• Never use suckers from sick fields, even if they appear healthy. They may be infected but will not show symptoms until later

BBTD has not yet been found • in Uganda. But it is already in Rwanda and DR Congo. If you see BBT symptoms • contact your local agricultural extension officer.

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Leaf Spot Disease: Symptoms

Yellow or black streaks

Small yellow or black streaks or spots. Older leaves dry.Infected plants fail to produce fruit.

Grey marks in centre of spot

If you look closely you can see the streaks have a grey centre.

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Stopping Leaf SpotRemove diseased leaves and burn them to stop the • fungus spreadingA good banana shamba should not be wet and warm.• Keep air flowing through the shamba. Prune trees, • remove suckers, and increase plant spacing. Avoid planting in watery areas• Weed the shamba regularly• Use resistant varieties of banana eg. Kayinja, Saba, • Mysore, Pelipita, Yangambi Km 5, and FHIA 01, 03, 17, 21, 23 and 25 from NARO and IITA.Apply fungicide eg. Benomoyl•

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What is Leaf Spot disease?1. Leaf spot is a fungus that attacks leaves. It is sometimes called Sigatoka. How does it spread?2. It lives in the air but only spreads in wet and warm conditions.Whatareit’seffects?3.

It kills banana leaves• Reduces the size of the bunch• Makes fruits ripen early• It encourages fruit flies•

Banana Streak/ Mosaic: Symptoms

Golden yellow streaks on leaves

Banana streak and banana mosaic are two different viruses with the same symptoms.They cause yellow streaks to appear on the leaf.

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Brown streaks

The yellow streaks can turn brown. You will find that the streaks disappear and re-appear now and then.

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Black streaks

Sometimes the streaks appear black.

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What is it? How does it spread?

Banana streak is a virus that is transmitted by mealybugs. Banana mosaic is actually caused by a Cucumber Mosaic Virus, which is transmitted by aphids.Both are spread when infected suckers are planted in new fields.

Stopping Banana Streak/ MosaicMulch and weed• Bananas can tolerate these diseases if they are regularly mulched and weeded. Mulching and weeding reduces yield losses below 20%Destroy sick plants• Dig up sick plants and their suckers, even if they seem healthyUse clean suckers• Be careful to only plant suckers that are far away from sick plants

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Aphid

Mealybug

Whatareit’seffects?Reduces plant growth• Reduces the size of the bunch• Severe infection causes the cigar leaf and the centre • of the plant to turn brown and die

Fruit Fungus diseases

Cigar end rot

The tips of the fruit become covered in a grey fungus. The ends of the fruits are dead.

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Bananas or cigars?

You can see here how bananas with cigar rot die at the tip. The tips look like the burnt end of a cigar.

Fruit Peel Disease

First, black spots appear on the peel. They enlarge into diamond shaped wounds and eventually cover the whole fruit.

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Severe Fruit Peel Disease

You can see how fruit peel disease can destroy a whole bunch.

How does fruit fungus spread?1. Fungus spreads in hot and humid conditions.What are the effects?2. Grey and black rot on the peel of the fruit. • Poor quality fruits, leading to death of bunch. •

Stopping Fruit FungusClean your shamba• Prune dying leaves and remove the male bud where the fungus can start. Keep air flowing in the field.Destroy sick plants• Remove the source of the infection by destroying the bunches and plants that are infected.

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Banana Weevil: Symptoms

Weevils are black insects

Weevils are easy to spot. They look like this. They lay their eggs near the collar of the plant.

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Weevil larvae

The eggs hatch into larvae like this one. The larvae dig into the plant causing damage.

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Weevil damage to stem

If you look closely you will see dark dots and dashes on the cut stem.

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Where is BBTD?

Stopping Weevils1. Make a trap Split a stem and cut it into 1 foot pieces, and put by infected plants. Weevils will be attracted and hide under the trap. Collect and kill them after 2 or 3 days.2. Clean your shamba After harvesting a bunch chop the plant and spread choppings around. This stops the weevils multiplying in old stems, and acts as a mulch.3. Use a pesticide You can apply a pesticide like Dursban or Furadan during the rainy season.

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How do weevils spread?1. Weevils spread to suckers and other banana plants. They multiply in old plants after harvest.What are the effects?2. The larvae are the most destructive• Stunted growth • Reduced and dieing suckers• Snapping of stem just above the ground•

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Nematodes: Symptoms

Dead roots

Nematodes feed on banana roots killing them. They stop roots taking water and nutrients to the plant.

Falling plants

When nematodes are many, the roots will be destroyed, and the plants will fall over.

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Dead root

Clean root

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What are nematodes?1. They are microscopic worms that feed on roots.How do they spread?2. They spread when infected suckers are planted in new fields.

Stopping Nematodes1. Peel the base of suckers First remove all roots and peel the base of suckers. Burn the roots and peelings to kill nematodes.2. Boil suckers Boil suckers for 30 seconds to kill nematodes. Don’t boil for longer or you may kill the sucker as well!3. Mulch Mulched plants cope better with nematodes.4. Rotate Plant cassava or sweet potatoes for 2 years instead of bananas as nematodes will not eat them. 5. Plant tolerant bananas Some bananas are quite tolerant of nematodes.

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Lack of Nutrients

Lack of Nitrogen (N)Nitrogen is good for the general health of the plant. Lack of nitrogen causes the leaves to turn light green. Then yellow patches appear. The mid-rib often turns pink.

Lack of Phosphorus (P)Phosphorus is important for the roots and flowers of a plant.When it is lacking the leaf edges turn a burnt brown, with a little yellowing.

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Disease or just lack of nutrients?Healthy soil contains nutrients like Nitrogen (N), Phosphorus (P), Potassium (K), and Magnesium (Mg). When the soil is tired, these nutrients get finished.Plants in tired soil become sick because they lack nutrients. It is easy to confuse the symptoms of pests and diseases with those of lack of nutrients.

Needs urine or poultry manure

Needs cow dung

Lack of Potassium (K)Potassium helps a plant stay healthy and fight diseases. Lack of potassium causes the leaf edges and tip to turn yellow, then burnt brown.

Lack of Magnesium (Mg)Magnesium is also good for the general health of the plant.Lack of magnesium causes a light yellow band to appear in the middle of the leaf.

Mulch - • Conserves water, stopping weeds, preventing soil erosion, and adds K and Mg Desucker - • Many suckers take many nutrients. Each mother banana should have just one daughter and one grand-daughter

Zero tillage - • Banana roots are shallow, so don’t dig up soil around bananas to stop root damageIntercrop beans• - adds NUrine/ woodash/ manure •Add urine for N, manure for P and wood ash for K

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Needs mulch, manure or fertilizer

Needs mulch or wood ash

Stopping nutrient problems

Good Banana Management

Action Description ReasonMulching Weed regularly and •

use as mulchChop old banana plants • and use as mulchUse other plants as • mulch

Increases yields • Keeps moisture in soil• Stops soil erosion• Reduces banana mosaic and • streak diseasesReduces nematodes•

Clean your shamba

Pruning dead leaves• Chopping plants after • harvesting bunchIncrease plant spacing• Reduce number of • suckers to 2

Gives plants more light, • space, and nutrients to growReduces wet and warm • areas where fungus can grow Stops pests and diseases • growing in old plants

Use clean suckers

Use suckers from • clean shambasRemove roots and peel • base of suckerBoil suckers for 30 • seconds

Reduces most pests and • diseases

Destroy sick plants

Dig up, chop and sun • dry sick plants

Reduces most pests and • diseases

Clean tools

Burn or clean tools • with Jik routinely

Reduces Banana Bacterial • Wilt and Fusarium Wilt

Remove male bud

Use a stick to remove • the male bud after fruit have formed

Reduces Banana Bacterial • Wilt

The cheapest and most effective way to stop pests and diseases is to practice good banana management. Cleaning your shamba, mulching, and using clean suckers will increase yields and stop pests and diseases.

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