Agro- advisory for diagnosis and management of banana blast and pitting disease
Banana blast and pitting disease (caused by fungus Pyricularia angulata) was observed in varying level of incidence with moderate intensity during 2014-15 in a survey carried out in some banana growing districts of Odisha viz., Khorda, Sundergarh, Boudh and Khandamal. They appear as unusual small pit like symptoms on maturing unripe banana fruits especially in cv. Grand Naine. Further study revealed the occurrence of blast spots on young tissue culture derived banana plantlets also.
On young tissue culture derived plantlets, numerous minute tan brownish spindle shaped blast spots develop on leaf lamina, which later widen into small oval spots (Fig 1). The disease causes blighting of leaves and death of whole plantlets, in case of severe infection. Under field condition, when rainy season coincides with susceptible fruit stage (usually more than 50 % matured fruits or more than 60 days old fruit), if the pathogen is present, pitting disease occurs. The incidence usually starts in the months of July and continues up to October when monsoon period coincides with fruit maturity stage. Symptoms on fruit start as minute black points usually surrounded by brown or blackish ring or circle. The peel within the circle becomes sunken dark pit of 3-7 mm dia. (Fig.2). Centre splitting of pits also occurs at later stage. Pitting symptom on maturing bunches leads to significant quality loss. Further, spindly shape blast lesions also appear on young leaves, mid rib, petioles, peduncle and crown.
Suitable management strategies should involve cultural practices like altering the time of planting in such a way that fruit maturity period does not coincide with rainy season. Bunch covering with perforated polythene bags will also be an efficient practice to avoid the contact with disease inoculum. Removal of drying transitory leaves or flag leaves will help in reducing inoculum level flowing into bunches along with rain water. Prophylactic spray with fungicides like Hexaconazole @ 0.05 % or Thiophanate methyl @ 0.1% along with sticker (1 ml /litre of water) may be taken up if there was disease occurrence during previous season and fruit maturity period is likely to coincide with ensuing rains. Supply of disease free tissue culture derived banana plantlets and awareness on use of healthy planting material among the stakeholders needs to be ensured to avoid losses to banana cultivation.
Blast disease on young plantlets
Pitting symptom on unripe fruits
For further information contact : Head, CHES, Bhubaneswar
Updated on 08.08.2016