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Management Of Leaf Spot Disease In Banan

Starch and amylase variability in banana cultivars.

Globally, dessert bananas (Musa spp., AA, AB, and AAA genome), plantain (AAB) and cooking banana (ABB), constitute fourth most important commodity after rice, wheat and maize. It is grown in more than 130 countries across the world in an area of 4.8 million ha producing 93.39 million tonnes of banana and plantain. India is the largest producer of banana in the world, contributing 29 per cent to the global production of banana with a total production of 29.78 million tonnes from an area of 0.83 million ha (NHB 2013).Unripe banana fruit flour based products has a more beneficial effect on stomach related ailments in human beings due to the presence of more resistant starch (RS), which is strongly associated with amylose content. The present study was carried out to analyse sugars, starch and amylose content of mature unripened banana fruits of nine banana cultivars. Among tested cultivars, starch content varied in the range of 80.53–86.76 % and amylose content ranged from 24.41 to 36.87 %. Amylose content differentiates the dessert bananas from plantain and cooking bananas. The plantain and cooking bananas viz, Nendran, Monthan and Saba recorded 34 % of amylose and they have greater potential in food industries as raw material. Preparation of amylose rich banana fruit flour products reduces considerable post-harvest losses, especially in Nendran, thereby converting the rejected/culled banana fruits into flour based food products

Leaf Gas Exchange Characters of Musa AB ‘Ney Poovan’ and Musa ABB (Pisang awak) Karpuravalli

The differences in the photosynthetic capacity of banana genomes and leaf segment and position have been discussed.Ney Poovan (AB) and Karpuravalli (ABB) are indigenous and popular banana cultivars in south India for their unique taste, sweetness, and flavor. Leaf gas exchange traits for these cultivars are important for better management practices. Diploid cv. Ney Poovan recorded higher photosynthesis (12.49 µmol m-2s-1) than triploid cv. Karpuravalli (9.57 µmol m-2s-1) during the vegetative stage. Ney Poovan has erect and narrow leaves compared to Karpuravalli (broad and droopy leaves) and helps in intercepting radiation effectively during morning hours. Stomatal conductance (gs) could demarcate physiologically efficient leaves in both cultivars, as older and youngest leaves recorded lower stomatal conductance. The older leaves transpired on par with most active leaves with a lower assimilation rate in both cultivars. The gas exchange parameters recorded higher in the top 2-5 leaves, therefore these leaves can be used for any physiological and biochemical studies they reflect the active physiological state of the leaves. Ney Poovan manifested early vigour by increased Pn, gs than Karpuravalli. Therefore, nutrient scheduling and management practices must be worked out separately for each cultivar; thereby we can exploit the production potential of both cultivars.ICA

First Report on the Occurrence of a Virulent Strain of Fusarium Wilt Pathogen (Race-1) Infecting Cavendish (AAA) Group of Bananas in India

Banana wilt disease caused by Fusarium oxysporum f. sp. cubense is one of the most significant threats to banana production worldwide. Strains of F. oxysporum f. sp. cubense have been grouped into race-1, -2, or -4 on the basis of differential virulence among different genotypes of banana. In India, though the disease is reported among susceptible varieties of races 1 and 2, the disease is not reported from Cavendish cultivars, which are the differential host to race-4. Recent surveys of the Cumbum areas (Theni District, Tamil Nadu) revealed symptoms (e.g., yellowing and drooping of leaves around the pseudostem and longitudinal splitting of pseudostem) on cv. Grand Naine (Cavendish group -- AAA). F. oxysporum f. sp. cubense was recovered and single-spore isolates had characteristic white-to-purple aerial mycelia producing single-celled, oval microconidia in false heads on branched monophialides and sickle-shaped macroconidia with an attenuated apical cell and a foot-shaped basal cell. Pathogenicity was demonstrated on cv. Grand Naine by inoculation with sand maize meal inoculum (20 g per pot containing 106 spores per g). Vegetative compatibility, using 33 nit-M testers of all known vegetative compatibility groups (2), showed that nit-1 mutants generated from a wild strain of F. oxysporum f. sp. cubense isolated from cv. Grand Naine formed robust heterokaryons with nit-M tester 0124 of the Department of Employment, Economic Development and Innovation, Brisbane, Australia and also with nit-M tester obtained from an isolate of F. oxysporum f. sp. cubense from Karpuravalli (Pisang Awak-ABB). Further characterization of this new Cavendish strain was studied on the basis of volatile odor production (3) using VCGs 0125 for race-1 (‘inodoratum group’) and 0120 for race 4 (‘odoratum group’) as positive controls and sterile medium as a negative control. This new F. oxysporum f. sp. cubense strain of Cavendish belonged to ‘inodoratum’ group of F. oxysporum f. sp. cubense. Pathogenicity was demonstrated on potted plants (10 per cultivar) of cvs. Rasthali (Silk-AAB), Karpuravalli (Pisang Awak-ABB), Ney Poovan (AB), Poovan (Mysore-AAB), Red Banana (AAA), Nendran (French plantain-AAB), Monthan (ABB), and Grand Naine (Cavendish-AAA) by inoculation with sand maize meal inoculum (20 g per pot containing 106 spores per g) in three replicate experiments. Plants were uprooted 2 months postinoculation and disease severity was estimated by rating internal vascular discoloration in the corm (1). The result showed that all cultivars, except Red Banana and Nendran, had the highest rating for disease severity, 6. To our knowledge, this is the first report of a virulent strain of F. oxysporum f. sp. cubense VCG 0124 of race-1on Cavendish banana

Status of Fusarium wilt in India.

Banana (including plantain) is the world largest fruit crop with an annual production of 93.71 million tonnes (FAO, 2008). It is a staple food for nearly 400 million people worldwide. India produces 27 million tonnes annually, with average productivity levels ranging from 20 to 36 tonnes per hectare (IHD, 2009). Poor soil health, nutrients imbalance, diseases and nematodes are major production constraints affecting productivity. Among the diseases, Fusarium wilt caused by Fusarium oxysporum f. sp. cubense (Foc) is recognised as one of the most widespread and destructive banana diseases, and a major production constraint to banana worldwide. In Asia, the disease was first recorded in 1911 in West Bengal, India, and the disease now is widespread and destructive in almost all the banana-growing states in India, causing disease incidence of 30% in the plant crop and up to 85% in the ratoon crop.With an annual production of 27 million tonnes, India is the world largest producer of banana. Many pests and diseases cause huge economic losses to the farmers. Among these, Fusarium wilt caused by Fusarium oxysporum f. sp. cubense (Foc) is one of the most important production constraints. The disease is widespread in almost all banana-growing states of India, with disease severity as high as 80-90% in some states where susceptible cultivars are grown on large areas. The important groups of banana severely affected by this disease are: ‘Silk’ (AAB), ‘Ney Poovan’ (AB), ‘Pisang Awak’ (ABB), ‘Pome’ (AAB), ‘Bluggoe’ (ABB) and ‘Monthan’ (ABB). Recently, a virulent strain of Foc affecting Cavendish types has been identified. In addition, ‘Mysore’ (AAB) which was hitherto tolerant to Foc has recently been found infected by Foc vegetative compatibility group (VCG) 0124/0125. A diversity analysis was carried out on 200 Foc isolates collected from different parts of India, to find out the various pathotypes in Foc by VCG analysis. The analysis indicated the presence of six different VCG groups. Ddiversity analyses of Foc, pathogen-host resistance, biological control using endophytes, standardisation of a diagnostic kit for the identification of the pathogen present in the soil and in the plant are the major areas of Foc research in India. Recently, molecular markers for the identification of pathogenic Fusarium present in the soil as well as in planting material have been developed. No effective control measures are available except growing of resistant cultivars. Recently, the National Research Centre for Banana (NRCB) has identified an effective fungal antagonist, Trichoderma viride, which has effectively controlled the soil-borne inoculum of the Fusarium pathogen. A massproduction protocol at farm level using banana farm waste has been developed for the cost-effective management of the disease. Activities for the effective management of this disease are discussed

First report of corm rot disease caused by Sclerotium rolfsii in banana.

Bananas (Musa spp.) are the world’s fourth most important global food crop grown in more than 120 countries (Molina and Valmayor 1999) and are the staple food for more than 400 million people (Swennen et al. 1995). India is the world’s largest banana producer and 26 million tonnes are produced annually from 709 000 ha. However, various pests and disease problems, particularly Fusarium wilt, cause significant losses (Ploetz 2005)A corm rot disease was observed for the first time in banana. The disease was found to occur in the majority of commercial cultivars grown in different banana-growing states of India. The incidence of the disease was up to 50% and found to occur at an altitude up to 3000 m asl. The pathogen was identified as Sclerotium rolfsii based on morphological characters and rDNA internal transcribed spacer sequence data