- One of the most destructive fungal diseases of banana .
- Infects all stages of crop growth
- Characteristic yellowing of older leaves accompanied by vascular discolouration in the outer leaf sheath
- The yellowing develops as a band along the margin and spreads towards the midrib . The leaves wilt, the petiole buckles and the leaf hangs between the pseudostem and the middle of lamina, while the leaf is still green.(Image1
- The spindle leaf often stands green and erect while all other leaves wither, become yellowish-orange, collapse around the pseudostem and die.(Image2)
- Outer leaf sheaths of pseudostem above the soil level split longitudinally and pseudostem becomes hard.(Image3).
- Finally, the top leaf withers and dies.(Image4)
- The pseudostem soon gets surrounded by a number of daughter suckers, which are often not infected.
- Dwarfing and stunting of young and old plants.
- When an affected rhizome is cut transversely, reddish vascular strands appear as yellow, red or brown dots and streaks.(Image5).
- The diseased vascular strands become numerous and get deeply stained to form a reddish brown ring.(Image6)
- Typical vascular bundle discolouration is noticed in pseudostem and leaf sheath.
- Yellow colour develops in the innermost or youngest leaf sheath and dark red to brown colour in the older or outer leaf sheaths.
- Roots show reddish discolouration and rot .
- The infected pseudostem and rhizome emits a characteristic foul odour and the plant dies.
Randomly select five lines from the garden. From the selected lines record the plants showing typical symptoms.
The fungus is soil borne and survives as chlamydospores which remain for long periods in the field. It enters through the roots and entry is facilitated by root injury due to soil dwellers and the burrowing nematode, Rhadopholus similis.
- This disease can be controlled effectively only by the use of resistant varieties and by exclusion- by enforcing strict quarantine regulation. Once soils become infested, there is no economic method of reducing the pathogen population. As a result, resistant Cavendish varieties have replaced the susceptible Gros Michel in world commerce.
- Dip planting material in 2 % Pseudomonas before planting.
- Dip the suckers in 0.1-0.2 % carbendazim before planting.
- TNAU has recommended corm injection with 2% carbendazim for the management of the disease. The method involves corm injection with 2% carbendazim (@3ml/corm) or embedding into the corm 50mg of carbendazim in a capsule at the 5th, 7th and 9th month after planting.
- Under Kerala conditions the use of tolerant types like Nendran, Red banana, Palayankodan, etc are suitable in areas prone to the disease along with the avoidance of susceptible types like Poovan and Njalipoovan.
- Remove and destroy affected plants at first sight of disease incidence followed by liming of infected pits @ 500g/ per pit . Drench the pit and neighbouring plants with 0.1% carbendazim to prevent spread of the disease
- Apply of soil based inoculum of AMF @500 g/pit ; 50 g of Trichoderma harzianum or Pseudomonas fluorescens or PGPR Mix 1 per pit.