Farmer s Guide Banana Pests & Diseases

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 2

About this guide This 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. 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 3

Banana Bacterial Wilt: Symptoms 1 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. 2 Leaves brown and wilting BBW causes the younger leaves to turn yellow and brown and wilt. 3 Fruits with brown stains BBW causes the fruits show brown stains when cut. 4

4 Stem oozes yellow pus BBW causes yellow pus to ooze from a cut stem and from the male bud after about 10 minutes. 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 bud Tools like knives and hoes Planting sick suckers in new gardens Stopping BBW Remove the male bud Use a forked stick to remove the male bud after the last cluster forms Destroy sick plants Chop and sun dry sick plants and suckers Use clean suckers and tools Plant only clean suckers and disinfect tools with fire or bleach 5

Fusarium Wilt: Symptoms 1 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. 2 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. 6

1. What is Fusarium Wilt? It is a fungus that lives in the soil and attacks the stem. It is also called Panama Disease. 2. How does it spread? 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. 3. What are it s effects? It affects many types of bananas including gonja, kisubi, kayinja, kamaramasenge and bogoya. It can cause yield losses of up to 100% Stopping Fusarium Wilt Remove infected plants and their suckers, even when symptoms are not seen. Destroy them Do 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 spreading Grow 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. 7

Banana Bunchy Top Disease: Symptoms 1 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. 2 Leaf edges yellow or bleached BBTD causes the leaf edges to turn yellow and wilt when they are still young. 3 Dots and dashes on leaves If you look closely you will sometimes see dark dots and dashes on the leaves and stem. 8

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. Where is BBTD? 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.? Stopping BBTD Destroy sick plants Dig up and bury infected plants and their suckers. Check the surrounding plants for symptoms Use 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 9

Leaf Spot Disease: Symptoms 1 Yellow or black streaks Small yellow or black streaks or spots. Older leaves dry. Infected plants fail to produce fruit. Grey marks in 2 centre of spot If you look closely you can see the streaks have a grey centre. 10

1. What is Leaf Spot disease? Leaf spot is a fungus that attacks leaves. It is sometimes called Sigatoka. 2. How does it spread? It lives in the air but only spreads in wet and warm conditions. 3. What are it s effects? It kills banana leaves Reduces the size of the bunch Makes fruits ripen early It encourages fruit flies Stopping Leaf Spot Remove diseased leaves and burn them to stop the fungus spreading A 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 11

Banana Streak/ Mosaic: Symptoms 1 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. 2 Brown streaks The yellow streaks can turn brown. You will find that the streaks disappear and re-appear now and then. 3 Black streaks Sometimes the streaks appear black. 12

Mealybug Aphid 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. What are it s effects? 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 Stopping Banana Streak/ Mosaic Mulch 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 healthy Use clean suckers Be careful to only plant suckers that are far away from sick plants 13

Fruit Fungus diseases 1 Cigar end rot The tips of the fruit become covered in a grey fungus. The ends of the fruits are dead. 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. 2 Fruit Peel Disease First, black spots appear on the peel. They enlarge into diamond shaped wounds and eventually cover the whole fruit. 14

Severe Fruit Peel Disease You can see how fruit peel disease can destroy a whole bunch. 1. How does fruit fungus spread? Fungus spreads in hot and humid conditions. 2. What are the effects? Grey and black rot on the peel of the fruit. Poor quality fruits, leading to death of bunch. Stopping Fruit Fungus Clean 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. 15

Banana Weevil: Symptoms 1 Weevils are black insects Weevils are easy to spot. They look like this. They lay their eggs near the collar of the plant. 2 Weevil larvae The eggs hatch into larvae like this one. The larvae dig into the plant causing damage. 3 Weevil damage to stem If you look closely you will see dark dots and dashes on the cut stem. 16

1. How do weevils spread? Weevils spread to suckers and other banana plants. They multiply in old plants after harvest. 2. What are the effects? The larvae are the most destructive Stunted growth Reduced and dieing suckers Snapping of stem just above the ground Stopping Weevils 1. 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 Where choppings around. is BBTD? 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. 1 2 17

Nematodes: Symptoms Clean root 1 Dead roots Nematodes feed on banana roots killing them. They stop roots taking water and nutrients to the plant. Dead root 2 Falling plants When nematodes are many, the roots will be destroyed, and the plants will fall over. 18

1. What are nematodes? They are microscopic worms that feed on roots. 2. How do they spread? They spread when infected suckers are planted in new fields. Stopping Nematodes 1. 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. 1 2 19

Lack of Nutrients 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. 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. Needs urine or poultry manure 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. Needs cow dung 20

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. Needs mulch, manure or fertilizer 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. Needs mulch or wood ash Stopping nutrient problems 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 damage Intercrop beans - adds N Urine/ woodash/ manure Add urine for N, manure for P and wood ash for K 21

Good Banana Management 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. Action Description Reason Mulching Weed regularly and Increases yields use as mulch Keeps moisture in soil Chop old banana plants Stops soil erosion and use as mulch Reduces banana mosaic and Use other plants as streak diseases mulch Reduces nematodes Clean your Pruning dead leaves Gives plants more light, shamba Chopping plants after space, and nutrients to grow harvesting bunch Reduces wet and warm Increase plant spacing areas where fungus can Reduce number of grow suckers to 2 Stops pests and diseases growing in old plants Use clean Use suckers from Reduces most pests and suckers clean shambas diseases Remove roots and peel base of sucker Boil suckers for 30 seconds Destroy Dig up, chop and sun Reduces most pests and sick plants dry sick plants diseases Clean Burn or clean tools Reduces Banana Bacterial tools with Jik routinely Wilt and Fusarium Wilt Remove Use a stick to remove Reduces Banana Bacterial male bud the male bud after fruit have formed Wilt 22

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