Major Insect Pests
Thrips (Chaetanaphothrips signipennis)
Symptoms
- Distinctive reddish brown oval stains on the finger, which can extend the entire length.
- In severe cases peel splits and the exposed flesh quickly discolors.
Pest identification
- Egg: Kidney shaped, invisible to naked eye, laid just below the fruit or inside the pseudostem.
- Larva: They are wingless creamy white, smaller but have the same shape as the adult.
- Pupa: Pupae are white like the larvae, can crawl, 1 mm in length.
- Adult: They are slender, creamy yellow to golden brown with delicate feathery wings and 1.5 mm long. Their wings have dark, eye-like spots at the base and are fringed; when the wings are folded, the adult appears to have a black line down its back.
Biology of the pest
Adult banana rust thrips reproduce sexually. After mating, females lay eggs in plant tissues where the thrips feed and hatch in 6–9 days. The newly hatched yellow nymphs feed for a few days before moulting and after 8–10 days, mature nymphs move off the host plant into the soil and undergo pupation with the adult emerging in 6–10 days. The entire life cycle is completed in approximately 28 days.
Management practices
- At the time of shooting, cover the bunch firmly (without any space between polythene cover and bunch) with 100 gauge thickness polythene sleeve having 6 to 10% holes or polypropylene bunch leaves.
- Remove the male flower buds after opening of all hands.
- Verticillium lecanii (2 x 108 cfu/g) 3g/ lit + 1ml sticker or NSKE 5% (Neem Seed Kernel Extract) + sticker can be taken up as second spray.
Aphids (Pentalonia nigronervosa)
Symptoms
- Banana leaves are bunched into a rosette appearance with leaf margins becoming wavy and upward rolling thereby reducing the growth and vigour of plant. Severly infected plants do not produce bunches and act as a vector of bunchy top disease.
- Noticed in colonies on leaf axils and pseudostem.
Pest identification
- Eggs: Egg stage not present and young ones are born live.
- Nymph: Oval or slightly elongated, reddish brown with six segmented antennae.
- Adult: Reddish to dark brown/ almost black, shiny, small to medium sized.
Biology of the pest
It is a phloem feeder that uses its long stylet to pierce plant tissues to suck the sap directly from the vessels. Reproduction is entirely parthenogenetic (without mating). Females give birth directly to live young female. The life cycle from nymph to adult is completed in 9 to 16 days.
Management practices
- Adopt clean cultivation using healthy and pest free suckers.
- Remove the affected plants and do not take up ratoon and inter crops.
- Drench (നനയ്ക്കുക, കുതിര്ക്കുക) the petioles (ഇല ഞെട്ട്), furled (ചുരുണ്ട ) leaves, whorls (വാഴക്കുല) or young suckers with soapy water or insecticidal soap.
- Use of braconid* wasps, Lysiphlebius testaceipes as parasitoid.
- Release predators such as lady bird beetles and lace wings @ 5 insects/ plant.
- Apply bio control agent Beauveria bassiana (2 ml in 100 ml water) between the leaf sheath at the base.
braconid* : The Braconidae are a family of parasitoid wasps.
Host Plants: In the garden: Flowers
Where Found: Worldwide, wherever moths and butterflies are common
Description:
Small wasps with narrow waists, long antennae, and ant-like heads, usually less than ½ inch (1.2cm) long, with a long black ovipositor extending from their rear ends. Black is the apparent color at first glance, but many species have orange or reddish abdomens. Braconid wasps do not sting.
Beneficial Because:
Adults lay eggs on or in soft-bodied caterpillars including cabbage worms, tomato hornworms, and other garden pests. They are attracted by the smell of caterpillars munching on plant leaves. The braconid larvae feed inside their living hosts, weakening or killing them. A female braconid wasp can lay up to 200 eggs a day in warm summer weather.
Food and Habitat:
Flower nectar and pollen are major energy sources for braconid wasps. Flowers with small florets, including most herbs and carrot family cousins, are ideal for these small, fast-moving wasps. Braconids overwinter within the pupae or cocoons of the same pests they attack during the summer.
Attracting More:
When you see a caterpillar bearing rice-like cocoons, allow it to feed until the tips of the cocoons open and a new generation of braconid wasps emerges. Leaving a few broccoli stalks standing through winter can provide shelter for braconid species that attack cabbage worms.
Lysiphlebus testaceipes **
Lysiphlebus testaceipes is a species of small braconid parasitoid wasp in the subfamily Aphidiinae. L. testaceipes can utilize numerous species of aphids as hosts and has often been used as a biological control agent against aphid pests.
Corm weevil (Cosmopolites sordidus)
Cosmopolites sordidus, commonly known as the banana root borer, banana borer, or banana weevil, is a species of weevil in the family Curculionidae.
Symptoms
- The young grub tunnels into the base of suckers, roots and rhizome/ corm.
- Presence of larval tunnels on the entire length of corm rhizome.
- Yellowing and withering of leaves, reduced plant vigour, root destruction, reduced fruit production and are easily blown over by the wind.
Pest identification
- Egg: White colour, elongate to oval, about 2 to 3 mm long and present on upper surface and crevices of rhizome.
- Grub: Legless grubs, creamy white with red head having strong mouthparts, stout and distinctly curved.
- Pupa: They are white and found inside the rhizome tunnels.
Adult:
- Weevils newly emerged are reddish brown which turns almost black after a few days, hard-shelled having a long curved snout and about 10 to 16 mm long.
- They are active at night, may live up to two years but are very sensitive to dehydration and will die within 48 hours if kept in a dry substrate.
Biology of the pest
Females lay eggs singly in small cavities at the base of pseudostem, in the upper part of the corm, in roots near the soil surface and at the end of cut stems (stumps). They hatch after 6 to 8 days and pupation takes place in holes bored by the grubs and adults emerge from the pupae 5 to 7 days after pupation.
Management practices
- Practice clean cultivation with the suckers pruned periodically and infested clumps are removed and destroyed.
- Crop rotation with non host crops like paddy and sugarcane.
- Ensure proper fertilization and weed removal.
- Use of pheromone trap @ 16 traps /ha.
- Disc-on-stump traps can be used for trapping weevils.
- Application of bio control agents, Beauveria bassiana and Metarhizium anisopliae @ 3ml in 100 ml of water causes more than 90% mortality of the weevils.
Stem weevil / pseudostem borer (Odoiporus longicollis)
Odoiporus longicollis, commonly known as banana stem weevil or banana pseudostem borer, is a species of weevil found in South Asia and South East Asia.
Symptoms
- Presence of small pinhead-sized holes on the stem.
- Jelly exudation on the stem is the initial symptom of damage.
- Due to secondary infection of pathogens, rotting occurs and a foul odour is emitted.
- After flowering, when tunnelling occurs in the true stem and peduncle, the fruits do not develop properly.
Pest identification
- Egg: Creamy, cylindrical with rounded ends.
- Grub: They are fleshy, yellowish white dark brown head and apodous.
- Pupa: Pupate in fibrous cocoon, pale yellow colour and is exarate.
- Adult: Brownish black and measure 23-39 mm.
Biology of the pest
Gravid females lay eggs at random on cut ends of pseudostem.The incubation period ranges from 3 to 8 days. The larvae pass through five instars with the fifth instar larvae entering a non-feeding pre-pupal stage and after 15 days of pupation, adult emerges. The total life cycle completes about in 55-60 days
Management practices
- After harvesting the bunch, remove the pseudostem from ground level and destroy them in order to avoid it serving as a breeding site for the pest.
- Uproot and destroy infested plants.
- Use longitudinal pseudostem traps @ 100/ha for trapping weevils.
Other Pest
Burrowing nematode (Radopholus similis)
Symptoms
- Reddish-brown to black, elongated discoloured area seen parallel to the root axis which eventually blacken and die.
- Lack of vigour in infested plants and poor fruiting observed.
- Infested plants are readily toppled and the roots get exposed.
Biology of the pest
The nematode is a migratory endoparasite, which completes its life cycle in about 21 days at 25ºC in the root corm tissues. Females and juvenile stages both attack and enter host roots, especially near the tip of the roots. Males do not feed, as their stylets are weak. Females lay an average of 4-6 eggs each day.
Management practices
- Crop rotation with non host crops.
- Adopt soil solarization.
- Remove all the black or discolored spots on the corm and root tissue, leaving only clean white tissues.
- Grow marigold as repellent and trap crop in the inter space.
- Use of neem cake @ 500g/ plant along with anyone of the bioagents Trichoderma viride/ Paecilomyces lilacinus/ Pseudomonas fluorescens @ 20 g/ plant.
Major Diseases
Sigatoka leaf spot (Mycosphaerella eumusae)
Symptoms
- Small, pale spots on leaves that turn into elliptical shaped dark purplish black spots with grey centres.
- Disease more prevalent on shallow, poorly drained soil.
- Severity of symptoms depicts burnt appearance of leaves.
- Poor filling and quality of bunches.
- Fruits don’t mature uniformly.
Pathogen dissemination
- Wind, rain water and old dried infected leaves carrying conidiophores / ascosphores help to spread the disease.
Management practices
- The field must be kept weed free and clean. Follow either hand weeding/ harrowing till 5 months after planting or by intercropping with cowpea.
- While planting, optimum/ recommended spacing (1.6 m X 1.6 m) must be followed.
- Provide adequate drainage facility whenever it is required.
- Apply only the recommended dose of fertilizer - N, P, K g/ plant (200:40:400) as per the schedule + 25g azospirilium + 25 g phosphorus solublizing bacteria. Application of Neem cake @ 0.5 to 1 kg/plant may also be applied.
- Remove disease infected leaves or part of leaves & destroy it outside the orchard.
- No dried leaves should be hanging around the plant.
Anthracnose (Colletotrichum musae)
Symptoms
- Small, circular, black spots develop on the affected fruits.
- At the initial stage dark brown patches on immature fruits.
- Severe infestation leads to shriveled and black coloured rotten fruits covered with pink spore masses, which gradually spreads and affects the whole bunch.
Pathogen dissemination
- Air-borne conidia and numerous insects visiting banana flowers spread the disease.
- High atmospheric temperature, humidity, wounds and bruises caused in the fruit favours disease development.
Management practices
- Adopt clean cultivation and maintain proper field sanitation.
- When all the hands are opened, the distal bud should be removed to prevent infection.
- Transported bunches should be stored carefully at 14ºC without causing any bruises.
- Avoid contamination in collecting places, during transport and in ripening rooms.
Banana bract mosaic virus (BBMV)
Symptoms
- Presence of spindle shaped pinkish to reddish streaks on pseudostem, petiole, midrib and peduncle.
- At emergence, suckers exhibit unusual reddish brown streaks and separation of leaf sheath from central axis.
- Crowding of leaves at crown which appears like palm leaf frill with elongated peduncle and half filled hands.
Pathogen dissemination
- Disease spread is mainly through suckers planting materials.
- Aphid vectors such as Aphis gossypii, Pentalonia nigronervosa and Rhopalosiphum maidis also transmit the disease.
Management practices
- Use disease free planting material.
- Avoid taking suckers for planting from the diseased plants.
- Practice clean cultivation and remove weeds which might harbour virus.
- Apply more amount of organic manures especially cakes and 25% more of recommended fertilizers.
Banana bunchy top virus (BBTV)
Symptoms
- Yellowing of leaf margin initially and dark green streaks on the leaves.
- New leaves emerge with difficulty, are narrower than normal, wavy rather than flat, and have yellow (chlorotic) leaf margins.
- Leaves form a bunch at the top.
- Usually fruiting doesn’t occur in severely infected banana plants but if produced, the banana hands and fingers are likely to be distorted and twisted.
Pathogen dissemination
- It is transmitted by infected suckers and banana aphid.
Management practices
- Use of virus free planting materials.
- Rouging and removal of infected banana plants.
- Practice clean cultivation.
Cigar end rot (Verticillium theobromae)
Symptoms
- Black necrosis from the perianth to the tip of immature fruits causing shrinkage and folding of the tissues.
- Fingers that appear rotten are full of grey conidia, which look like the ash of cigar.
Pathogen dissemination
- Warm and moist conditions favour the disease occurrence and the disease spread is high in old and badly maintained plantations.
Management practices
- Avoid overcrowding of plants ensuring enough aeration in plantations.
- Young bunches should be exposed to light and air and the stray bracts should be removed especially during wet weather.
- Improved sanitation helps in the reduction of the disease.
- Removal of pistil and perianth by hand immediately after the fruits are formed. Pistils should be removed 8 to 11 days after bunch emergence.
Erwinia rot (Erwinia carotovora)
Symptoms
- Affected young suckers show rotting and emits foul odour.
- The rot progresses up the pseudostem causing internal decay often with vascular discoloration.
- If affected plants are pulled, it comes out from the collar region leaving the corm with their roots in the soil.
- Infection at late stage shows splitting of pseudostem in some cultivars.
- Yellowish to reddish ooze seen when affected plants are cut open at collar region.
- Soft rotting may spread radially towards growing point through the cortical tissues.
Pathogen dissemination
- The pathogen being soil borne enters through wounds and also through leaf sheath of suckers.
- Hot and damp weather with plenty of rainfall trigger the disease development.
- Water is required for the bacteria to invade into the plant.
Management practices
- Use disease free suckers for planting.
- Removal and destruction of infected plants. Rainy season planting should be avoided.
- Grow sunnhemp or cowpea as intercrop to provide shade to the banana plants.
- Give regular irrigation only in either morning or evening hrs.
- Apply the plants with bleaching powder @ 8g/plant at 10 to 15 days interval for 2-3 times.
- Use healthy planting material.
Panama wilt (Fusarium oxysporum f. sp. cubense)
Symptoms
- Visual observations show yellowing of lower leaves, longitudinal splitting of pseudostem and wilting of plants.
- Advanced stages of disease shows plants with a spiky appearance due to prominent upright apical leaves.
- The xylem (water conducting) vessels turn reddishbrown as the fungus grows through the tissues.
Pathogen dissemination
- It is a soil borne disease and the fungus enters the roots through the fine laterals.
- Infected rhizomes or suckers, soil adhering to farm implements, irrigation water is responsible for the spread of the fungus.
Management practices
- Follow proper crop rotation.
- Grow wilt resistant cultivars in endemic areas and avoid susceptible varieties.
- Use pathogen free suckers.
- Use tissue cultured plants.
- Practice clean cultivation with proper fertilization, irrigation and weed control.
- Provide good drainage especially during rainy season and use organic soil amendments.
- Apply neem cake @ 250 Kg/ha.
- Application of bioagent Trichoderma viride and Pseudomonas fluorescens along with farmyard manure and neem cake.
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