Introduction

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.

Fungal Diseases of Post-Harvest-Fruits

1-Anthracnose:

The causal organism       Gloeosporium musarum

Severe during June-September when temperatures are high . The pathogen 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.
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.


2-Diamond Spot
The causal organism       Fusarium spp

Symptoms

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


3- Brown Spot

The causal organism       Cercospora musae

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.



4- Cigar End/ Tip Rot

The causal organism       Verticillium theobromae

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.

5- Leaf spot: sigatoka Disease
The causal organism       Mycosphaerella muscicola

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 leave.

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.

Symptoms
Spots are concentrated towards the leaf edges.
Streaks enlarge and form small spindle or eye shaped spots with greyish centre and dark brown or black borders and chlorotic halo around them.
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.

6-Panama Disease Or Banana Wilt
The causal organism       Fusarium oxysporum f.sp. Cubense

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.
Epidemiology

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

Dreaded is wide spread all over banana plantation areas
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 wilts within 2-3 days
Splitting of pseudostem , discoloured vascular region in rhizome are also see
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.

Bacterial Disease

1- Bacterial Wilt Or Moko Disease

The causal organism       Pseudomonas solanacearum

Symptoms

Affected plants show more or less rapid- wilting and collapse of leaves with a characteristic discoloration of vascular bundles, wilting and blackening of suckers.
If pseudo stem and rhizomes are cut, a characteristic bacterial oozing as shiny drops can be noticed for besides vascular discoloration.
Some 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 pseudo stem.
Production of yellow fingers, discolored 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 favored by root injury.

Virus Diseases
Bunchy Top

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

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.

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.

Control
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).
Aphox              50G / 100 L.W

Banana Mosaic Or Infectious Chlorosis

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.

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.

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, and chlorotic.

Virus is disseminated by suckers and Aphis gossypi.

- 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

Insect on Banana

1- Banana Aphid

The causal organism       Pentalonia nigronervosa

The insect, Pentalonia nigronervosa is particularly important, as it is the vector of the virus causing bunchy top disease.

Minor pest in south India, nymphs and adults suck sap from tender leaves and trasmit bunchy top disease.
Control : Nudrin         75 G / 100 L.W

2- Banana Rust Thrips

The causal organism       Chaetanaphothrips signipennis

It has yellowish shaded wings; The damage done by thrips is by oviposition on the young fruits.

Nature of damage

It causes smoky or red discoloration between individual fingers.

The skin becomes reddish brown, roughened and dull in appearance, superficial cracks appear in discolored skin. The fruits may also split.

Control
Aphox              50G / 100 L.W

Tissue culture of banana

Introduction

- Biotechnology is an area with a tremendous potential in solving basic problems of food, fibre, fuel and medicine, particularly in developing Asian countries.

- It can become versatile tool for Mass multiplication of elite clones, Elimination of disease in planting material, Creation of Super genotypes of agricultural crops, Which hither to it was not possible through conventional plant breeding methods.

- Tissue culture propagation can greatly enhance our ability to produce consistently uniform superior planting material for export and domestic market.

- Advantages of tissue culture raised plants against the conventionally propagated (by suckers) plants were clearly demonstrated in banana Field trials.

- Superiority of Tissue Cultured quality plants in terms of developed root system, greater functional leaf area leading to high photosynthetic rate and higher yields in now well established.

Technology

- The technology can improve continuously, the productivity, profitability, stability and sustainability of the farming system.

- Each plant cell has the potential to generate into a single plant. This is called Totipotency and when this character is involved into rapid and mass multiplication of propagules at optimum levels is called Micropropagation. This is an alternate to slow vegetative plant propagation.

- In Tissue Culture when a group of undifferentiated and meristamatically active cell called Tissue is aseptically disserted out and put into a medium containing nutrient and incubated under conducive controlled conditions of light and temperature, it establish it self and starts growth. This is called Culture and the concept of 'tissue culture' was thus conceived.

Tissue culture involved following stages
Preparation of Stock plant

- The selected plants are chosen and maintained under healthy conditions (by spraying fungicide, bactericide and insecticide) and then the plant parts are taken for initiation.

Initiation (Stage-1):

- The innermost tissue of surface sterilized plant in dissected aseptically and put and to the medium of growth, Medium contains major and miner elements, same vitamins. Amino acids and growth promoting hormones, solidified by agar.

Multiplication (Stage II):

- When the tissue starts growth in stage I and forms a shoot it is carefully transferred to another medium containing growth promoting hormones (enhancing cell division).

- The growing shoot multiplies and forms a dump of 3-4 shoots. Those are transferred to another medium for shooting and rooting after optimum growth.

- The growing shoot multiplies and forms a dump of 3-4 shoots. Those are transferred to another medium for shooting and rooting after optimum growth.

- After multiplication, the single shoots are separated and placed into a shooting are rooting medium. At this stage the hormones may or may not be required.

- The shoot elongates and new root came up. Rooting takes place within 3-5 weeks.

- It involves acclimatization of bottle grown plants to the natural environment in Green House.

- The plants are taken out of the bottle and the media adhering to the root system in washed fully.

- After wards the plants are graded as per their size and then transferred singly to wells of portrays containing sterile medium (a mixture of peat moss and perlite1:1).

- The whole portray with plants is maintained under high humidity conditions for a couple of weeks and there after the new plants are kept in open in the Green House under controlled temperature and humidity.

- This hardening taken 6 weeks and is called primary hardening - Regular sprays of plant protection chemicals are sprayed to achieve good healthy condition of the plants.