• Banana is much more vulnerable to disease than to the insect pests. The diseases often occur in epidemic proportions and bring about catastrophic losses.
• Among the diseases, the banana wilt ranks first. In addition to fungal diseases, the bunchy top virus has created a situation of a dismal future for the banana industry.

Anthracnose:

Gloeosporium musarum

• Severe during June-September when temperatures are high accompanied by rain. Attack plants at any growth stage.
• Both green and ripe fruits are attacked, however, ripe fruits are more susceptible to the disease.

Symptoms

• Infection of green fruits, flowers and distal end of hands show circular black, sunken spots surrounded by yellow halos later convening the entire fruit resulting in premature ripening.

Black spots on Fruit

Ripe fruits develop symptoms from the tip as minute, circular dark brown sunken spots invading the entire tip which becomes black. A pinkish fungus sporulation is produced in the black, sunken areas of fruit.

Control

• Spraying Chlorothalonil 2 g/I at 15 days interval is effective in minimising later infections.
• Careful harvesting, clean packing, refrigeration at 10⁰C after harvest, fruit dip in aqueous solution of Benomyl at 1000 ppm or aureofungin 100 ppm help in reducing blemishes on fruits.

Symptoms

• The spot is black, sunken, diamond-shaped lesion, very much confusing with pitting disease.
• Diamond spot is prevalent after prolonged rainy season.

Control

• Plantation sanitation, good drainage and proper spacing reduce the incidence of this disease.
• To prevent spread of the disease, spraying of Captan or Dithane M-45 or Dithane Z-78 is effective.

Symptoms

• Brown spots occur on the rachis, and fingers. The spots are pale to dark brown with an irregular margin surrounded by a halo of water soaked tissue.

Control

• Plantation sanitation, good drainage and proper spacing reduce the incidence of this disease.
• To prevent spread of the disease, spraying of Captan or Dithane M-45 or Dithane Z-78 is effective.

Symptoms

• A black necrosis spread from the perianth into the tip of immature fingers. The corrugated necrotic tissues become covered with fungus and resemble the greyish ash of a cigar end.

Control

• The only best control was the removal of the pistil and perianth by hand as soon as the fingers emerged.
• Placing a polythene bag over the stem before the hands emerged was effective.

Mycosphaerella muscicola - sexual stage

Cercospora musai - asexual stage

• Sigatoka is the name of the valley where the disease first attracted attention. A monogrpah has reviewed information of leaf spot disease. It is a fungal disease.
• Causes severe economic losses. Spreads very fast during rainy season. Attacks mostly leaves.

Epidemiology

• Three components of weather, usually, determine the production and movement of sigatoka inoculum, rainfall, dew and temperature.
• Conditions favouring mass infection are most common during the rainy season with temperature above 21 C.
• Other factors, which influence the rate of disease developed and intensity of spotting, include amount of inoculum on the leaf, age and position of the leaf, plant growth, sun and shade effects on leaf tissue, etc.
• The major commercial cultivars of banana-Gros Michel and Cavendish group are all highly susceptible to leaf spot disease.
• All triploid AAA desert bananas of commerce are highly susceptible to sigatoka.

Symptoms

	Spots are concentrated towards the leaf edges.
Eye shaped spots	Streaks enlarge and form small spindle or eye shaped spots with greyish centre and dark brown or black borders and chlorotic halo around them.
Scorching appearance	Disease first appears as pale yellow or greenish yellow streaks running parallel to leaf veins on both the leaf surfaces.

• Leaves present a scorched appearance, petioles collapse and leaves hang down from pseudostem. if severe, bunch maturity is affected.
• Early diseased plant produces poor fruits.

Control

• Removal of infected leaves and burning.
• Proper drainage, spacing, weed management are very
• Spraying of Thiophanate methyl 1 g/l, or 1per cent Bordeaux mixture + 2% linseed oil, or Captan 2 g/l are some practices that can manage the disease.

• The first major disease which attacked banana was called Panama disease from the area where it first became serious.
• Banana wilt is a soil-borne fungal disease and gets entry in the plant body through roots and wounds caused by nematodes. It is most serious in poorly drained soil. Disease spreads through infected suckers.

Epidiomology

• Warm soil temperature and bad drainage favour the spread of the disease and also light soils and high soil moisture. Greater incidence of the disease has been noticed in poor soil with continuous cropping of banana.

Symptoms

Breaking of petiole

Splitting of Pseudostem

Vascular discoloration

• Dreaded disease of banana and is wide spread in Assam, Bihar, Karnataka, Kerala, Tamil Nadu, Andhra Pradesh,Telangana, Maharashtra and West Bengal where the cultivars of Rasthali group such as Rasbale, Amrutapani, Malbhog and Mariban are grown.
• Initial symptoms appear in older leaves as characteristic yellowing which ultimately wither, break at petiole and hang down along the pseudostem.
• Young leaves may not dry immediately but are erect and also get affected later. If severe, entire foliage wilt within 2-3 days
• Splitting of pseudostem , discoloured vascular region in rhizome are also seen.
• Individual strands appear yellow, in addition red or brown dots and streaks are also seen.
• Longitudinal splitting of pseudostem, emittance of rotten fish smell when cut, stunting of plants, wilting and death of suckers are other symptoms of the disease.

Control

• Basrai is immune and Poovan or Champa is resistant, while Sonkel, Rasthali Malbhog, Alpan, Morthaman, Kanthali, Sirumalai, Monthan, Virupakshi are susceptible. Other resistant cultivars include Cavendish group, Moongil, Peyladen Rajabale, Vamanakeli.
• Selection of healthy suckers, avoiding injury to roots
• The diseased plants should be uprooted and burnt.
• Highly infected soil should not be replanted with banana at least for 3-4 years.
• Use of disease-free planting material and resistant cultivar are recommended.
• Other measures include use of quicklime near the base of the plant and soaking with water.
• Application of lime to infested pits, dipping suckers in carbendazim 1 gl/I before planting followed by bimonthly drenching starting 6 months after planting are effective management practices
• However, once soil is generally infested, there is no economic method of reducing the pathogen population to a level where more than two or three crops of a susceptible cultivar can be obtained.

• This is a minor bacterial disease, but causing concern in West Bengal.

Symptoms

• It is characterised by a massive soft odorous rot of the centre or a portion of the rhizome. The rot progresses up the pseudostem destroying the growing point and causing internal decay often with vascular discolouration.
• Externally, the symptoms sometimes resemble those of fusariam wilt.
• Yellowing and wilting of the leaves are the characteristic symptoms.

Control

• Soil drenching with bleaching powder was found beneficial. Soil and plant drenching with bleaching powder at 2 g/l water at an interval of 10-15 days was found effective in controlling the disease.

Symptoms

Affected sucker	Affected plants show more or less rapid- wilting and collapse of leaves with a characteristic discolouration of vascular bundles, wilting and blackening of suckers.
Affected young plant	If pseudostem and rhizomes are cut, a characteristic bacterial oozing as shiny drops can be noticed for besides vascular discolouration. In Cavendish varieties, lower leaves develop a yellowish tinge which soon spreads to other leaves of the plant, which subsequently droop and petioles break at the junction of lamina or pseudostem.

• Production of yellow fingers, discoloured vascular bundles of fruit stalks and internal dry rot of fruits can also be noticed.
• Bacterium is soil born. Spreads through use of diseased suckers for planting.
• In field disease spreads through irrigation water, implements and insects. Infection is favoured by root injury.

Control

• Disease can be minimised by exposing soil to sunlight.
• Selection of healthy planting material, eradication of infected plants. Disinfecting cutting knives and providing better drainage.
• Flower visiting insects are main agents for transmitting the disease and this is a good reason for following the practice of removing the bud from the male axis before the bunch matures.
• Herbicides, e.g., 2, 4-D and 2, 4, 5-T, can be used to kill infected plants in situ and dieldrin sprayed onto a chopped down mat will prevent insects transmitting the disease to the unaffected plants.

• The disease is covered by domestic quarantine regulations. Losses were estimated to be Rs.4 crores every year and 100% loss occurs if infected suckers are planted.

Symptoms

Dark green streaks

Stunting of plant

Aphid

• Symptoms appear at stage of growth associated with occurrence of prominent dark green streaks on petioles and along leaf veins.
• In badly diseased plants leaves bunch together, margins of lamina become wavy and slightly roll upwards.
• In case of secondary infections, irregular, dark green streaks occur along the secondary veins from series of dark green dots to a continuous dark green line.
• Severe stunting, non-elongation of leaf stalks, more erect leaves, non production of bunches are other external symptoms.
• The virus spreads through infected suckers and by banana aphid Pentalonia nigronervosa.

Control

• Adoption of strict quarantine measures. The diseased plants along with rhizomes should be destroyed as soon as they are detected.
• Planting materials should not be collected from places affected by this disease.
• The aphid should be controlled to check spread of the disease by spraying with an effective insecticide (Metasystox 0.1 to 0.5%, Dimecron or Parathion).
• Injection of Monocrotphos solution diluted with water at 1:4 ratio at 30-day interval twice or thrice at 2-3 months after planting has been found effective.
• Injection of Fernoxone, 4 ml mixed with water at 1:8 ratio into the corm or insertion of capsules containing 200-400 mg of the chemical into the pseudostem after making a slanting hole are also suggested for effective killing of the infected plants.
• Regular inspection, roguing of diseased plants, and planting virus-free corms have reduced bunchy top disease in Australia.
• Field trials with Dwarf Cavendish banana revealed that phytosanitary measures help in minimising the disease to a great extent.

• Infectious chlorosis or heart rot of banana is caused by Cucumber Mosaic Virus (CMV) has recently become serious, the disease has been recorded from 20 to 80 per cent in Poovan cultivar.

Symptoms

• The disease manifests itself in all stages of crop growth. Due to repeated use of suckers from infected plants the disease spreads and resulting in the gradual decrease in yield and quality.
• The disease is known to occur in all banana-growing states.

Yellow streaks on leaf

Light yellow streaks run parallel to leaf veins giving the leaf a striped appearance. The streaks run usually from mid rib to edge of the blade. Outer leaf sheath may separate from pseudostem and the emerging heart leaf may be necrotic. Diseased plants may not produce bunches or only a few fruits are produced.

Rolling of leaves

Mosaic plants are easily recognized by their dwarf growth and mottled, distorted leaves. Young leaves show loss of green colour in patches leading to typical mosaic pattern. Leaves are reduced in size, narrow, chlorotic. Virus is disseminated by suckers and Aphis gossypi.

Control

• Adoption of strict quarantine measures.
• Systematic destruction of diseased plants.
• Use of disease free suckers.
• Treating suckers at 40°C with dry heat for 1 day followed by treatment with 120 ppm aureofungin.
• Cultivation of varieties such as Kuru Bale are recommended