Frequently asked questions - Answers from NRCB

FAQs published by NRCB is reproduced here for the readers easy reference :

FAQs . . .

1. What are the commercial varieties of banana grown in India? Commercially, Robusta, Dwarf Cavendish, Poovan, Rasthali, Monthan, Karpuravalli, Nendran and Ney Poovan are cultivated in various states of India. The varieties like Matti, Rajapuri, Pacha Nadan, Virupakshi are some of the varieties of local significance. 2. How to select a planting material? There are two types of planting materials. The commonly used propagation material is sucker or corms. The sucker should be a sword sucker, with narrow leaves of 3 to 4 months old, weighing 1.5 to 2 Kgs. The suckers should be of uniform size, selected from disease free plantations. Recently tissue cultured plants are becoming popular due to its disease free nature and potential for high yield. An ideal tissue culture plant should be about 30 cm height with 5 to 6 developed leaves having proper orientation. The leaves should not exhibit any malformation and chlorotic streaks. 3. What are the precautions to be taken at the time of planting? If the planting material is a sucker, the roots should be trimmed and pared-off all tissues on the surface to make it free of nematode infestations. The pared corm should be dipped in a solution containing 0.5% Monocrotophos for 30 minutes. Alternatively application of 40g of Carbofuran in the soil at planting. For tissue culture plants, especially Robusta and Cavendish varieties should be applied with 10g Carbofuran and drenched with 0.1% Emisan to control nematodes and bacterial rot disease respectively in the polybag itself before planting. 4. Are tissue culture plants better than suckers? Yes, tissue culture plants are high yielding and healthy as they are multiplied from high yielding mother plants free from viruses. The plants are also free from soil borne pest and diseases like wilt, Erwinia rot and nematodes at the time of planting. 5. Can we go for ratooning of tissue culture plants? Yes, tissue culture plants can be ratooned for 2 crops economically. 6. Are suckers from tissue culture plants as good as original tissue culture plants? Yes, they are as good as original tissue culture plants in respect of high yielding ability. But they are not free from viruses and soil borne diseases and pests. 7. Can we get tissue culture plants for planting one acre or more from NRCB? No, at NRCB commercial multiplication is not being done. We supply only samples to interested growers at free of cost and mother cultures to institutions at nominal rates depending upon the availability and demand. 8.What is the reason for non flowering of the tissue culture plants, sometimes? The tissue culture plants may undergo mutation and result in off types, if sufficient care is not taken in the multiplication stage. The permissible limit for off types as per the DBT guidelines is 1%. So quality of planting materials should be important before planting and it should be from reputed companies. 9. Are there any new planting methods? Yes, there are two high density planting methods. One is planting three suckers per hill at a spacing of 1.8x3.6m (4500 plant/ha.) for Robusta and Nendran varieties planting at 2x4m for tall varieties like Poovan, Rasthali, Ney Poovan, etc. (3750 plant/ha.). Another method is called Paired row system, planting at a spacing of 1.2 X1.2X2 m with a population of 5200 plants/ha. 10. What is the advantage of new high density planting method? The advantage is 50-100% increase in population per unit area, 25-30% reduction in fertilizer and water consumption, 30-40 percent reduction in cost of cultivation and 30-40% increase in profit per unit area. 11. What is fertigation? Providing required quantity of fertilizers mainly  N and K either daily or weekly in small quantities through drip irrigation system is called fertigation. The high density planting coupled with drip irrigation/ fertigation would greatly reduce cost of cultivation and enhance productivity. 12. Is there any difference in fertilizer dosage for tissue culture plants? Due to its vigorous growth and more number of roots, the tissue culture plants require 50% more fertilizers than the conventional plants. The fertilizers should be applied in 5-7 splits at 30 to 45 days interval as against 3 splits in conventional planting method. 13. What is the frequency of fertigation? Banana plants require 16-20 lit. of water. The water soluble / conventional fertilizers are dissolved and applied through drip daily or at weekly intervals, so that the absorption and utilization are maximum. More number of split application of fertilizers at proper stage alongwith micronutrients  is possible in fertigation. 14. What kind of soil is suitable for banana cultivation? Loamy textured soil with at least 2 m. depth and proper drainage facilities is suitable for banana cultivation. The slope of the land should be <1%. There should not be subsurface hard pans and calcarious layers. The gravel content of the soil should not exceed 5%. 15. What is the NPK requirement of banana? Banana plant requires 200 g of nitrogen (N), 30-50 g of phosphorus (P) and 300-450 g of potassium (K) applied in 3-5 split doses. 16. What are the suitable fertilizers for banana? Urea, ammonium sulphate, super phosphate, diammonium phosphate, potassium chloride (muriate of potash) and potassium sulphate (sulphate of potash). 17. What is the requirement of micro nutrients in banana? The banana plants commonly exhibit micro nutrient deficiency symptoms for zinc and boran. To correct these deficiencies soil application of 25 g zinc sulphate/plant and 5 g of borax is recommended. Foliar spraying of 0.5% zinc sulphate and 0.05% boran is recommended between 3-5th month after planting. 18. Any banana micronutrient mixture is available at NRCB? Yes. ‘Banana Shakti’, a micronutrient mixture is available at NRCB for sale (Rs.100/kg). 19. What are the content of Banana Shakti? Banana Shakti contains all the essential micronutrients like iron, copper, zing, manganese and boron in optimum concentrations and in proper proportions.  20. How much quantity of Banana Shakti should be applied per plant? Banana Shakti mixture should be applied at the rate of 10 g/plant. It indirectly increases the macronutrient use efficiency. 21. Whether application of Banana Shakti mixture increases the yield? Yes, it increases the yield by 10-15% with an additional profit of Rs.10000 to Rs.15000 per hectare. 22.Whether Banana Shakti mixture can be applied as a foliar spray? Yes, the mixture is suitable for both soil and foliar application. Two percent foliar spray of this mixture in high pH soil avoids fixation of micronutrients in the soil. 23. Whether micronutrient deficiency occurs in banana growing soils? Yes, Micronutrient deficiency generally occurs in sandy soils, which lacks micronutrient elements. High pH clay soils rich in micronutrients, have less micronutrient supplying power. In such types of soils, micronutrient deficiency is very common. 24. How to rectify the micronutrient deficiency? In general, soil application of micronutrient is recommended, where the soil pH is less than 8.5 and foliar spraying of micronutrients is recommended where the soil pH is more than 8.5. In case of soil application, 10 g of ‘Banana Shakti’ (micronutrient mixture developed at NRCB) per plant at 4th month after planting (MAP) is recommended. In case of foliar spray, 2% Banana Shakti solution along with suitable adjuvant (sticking agent) at 4 MAP, 5 MAP and 6 MAP to correct the symptoms and increases the growth and yield. 25. How to grow banana in alkali or sodic soils? In alkali or sodic soil, apply more quantity of organic manures (15 to 20 kg/plant). Generally, banana roots have the capacity to eliminate or avoid sodium ion entry into the plant system from soil. This capacity could be enhanced by the presence of sufficient potassium ions in the soil. So, application of  20 to 30 per cent more potassic fertilizers is recommended. 26. How to manage sodicity and alkalinity problem in banana cultivation? Before planting of banana, first apply 5 to 7 tonnes of gypsum (calcium sulphate) per hectare, incorporate thoroughly in to the soil by proper ploughing, then stagnate water in the field and after one week, drain it and improve the drainage facilities. Apply 2 kg of gypsum per plant in the 60th day after planting, drain it with affluent water before application of fertilizers. The soil K:Na ratio should be maintained as 2½ : 1  at any time during banana growth period. 27. How to avoid marginal scorching of banana leaves in saline and sodic soils? Marginal scorching of banana leaves is observed in high pH soils and is due to accumulation of sodium ions in the leaves which lead to marginal chlorosis and subsequent necrosis. To rectify this problem, application of  2 kg of gypsum/plant along with good irrigation. Increase the quantity of potassium application in the fertilizer schedule by 20 percent. Give foliar spray of 2% potassium sulphate solution along with sticking agent. 28. How to manage acid soils in banana cultivation? In banana cultivation under acid soils, apply 100 g CaCO3 (Calcite) or 100 g Dolomite (calcium-magnesium carbonate) per plant and avoid acid forming fertilizers like ammonium chloride, ammonium sulphate etc. Prefer single super phosphate and rock phosphate as phosphatic sources.  Apply silicon rich, easily available materials like fly ash or rich husk ash or composted sugarcane trashes or paddy straw at the rate of 10 kg per plant, for better release of phosphate ions for banana growth.  29.  Is there any need of application of biofertilizers for rectifying the acidic soils? Yes, application of 25g of vesicular arbuscular micorhiza (VAM) and 25g of phosphobacteria per plant to increase the availability of insoluble phosphorus to plants in such soil conditions. The recommended dose of potassic fertilizers like KCl or K2SO4 should be applied in splits, in small quantities at a time.  The optimum soil Ca:Mg:K ratio for banana cultivation is 10:5:1. This ratio should be maintained through regular soil testing. 30. Is it possible to grow banana organically? A technology for growing banana organically by using organic fertilizers, bio pesticides and fungicides has been developed at this Centre. For organic bananas, there is a great demand for export and in domestic market. Successful organic farming is possible if the soil is highly fertile and rich in organic matter. 31. Application of vermicompost in banana – economical or not? Application of vermicompost to banana is recommended and good for improving soil health. The farmers can produce the required vermicompost from their farm waste, it is more economical 32. What are the suitable organic manures for banana? Farm yard manure, vermicompost, poultry manure, pig manure, press mud, composted coir pith, goat manure, bone meal, blood meal, horn and hoof meal etc. are suitable organic manures for banana. 33. Is there any serious pest in banana? Pseudostem stem borer is becoming a serious pest affecting varieties like Nendran, Karpuravalli, Robusta and Rasthali. The incidence is observed after 5th month. This pest can be monitored and controlled by keeping the longitudinal split of pseudostem of 90 cm length or disc on stump trap @100 per ha. 34. How to identify banana stem weevil damage initially? Jelly exudation on the stem is the initial symptom of the stem weevil damage. 35. Is there any chemical control for banana stem weevil? Chlorpyripos 2.5ml/l with adjuvant 1ml/l swabbing on the stem prevents infestation of banana stem weevil. Once jelly exudation is noticed, inject 2ml monocrotophos solution (350ml in 150ml water). Two injections per plant at 2 and 4 feet above the ground level till flowering. The injection needle should enter only two or three leaf sheaths and should not touch the central core. 36.  Where the biocontrol agents for insect control is available? The, National Research Centre for Banana (NRCB), Trichy is selling the mother inoculums of biocontrol agents for farmers which can be mass multiplied under farm house conditions by the farmers themselves. 37. How to prepare banana stem trap for weevil control? Cut the stem into 90 cm length bits and split the same into two halves. Each piece will be used as a trap. These traps are to be placed @100/ha near the base of banana plants. The trapped weevils have to be collected manually and killed. 38.  Is there any biocontrol method available for stem weevil control? Yes, entomopathogenic fungus Beauveria bassiana and Heterorhabditis indica can be swabbed on the stem trap and kept in the garden. The weevils attracted to the  traps will get infected and killed. This will avoid manual collection and killing of weevils. 39. How to prepare  banana stem trap with biocontrol agents? The longitudinal split traps can be swabbed on the cut surface with entomopathogenic fungus Beauveria bassiana @ 25g containing 1X109 CFU/gm or the entomopathogenic nematode  Heterorhabditis indica @25ml/trap containg 1x108 IJs/ml. Keep the traps near the base of the plants. 40. Where to get stem injector? Banana stem injector can be purchased from Tamil Nadu Agricultural University, Coimbatore or Secretary,  Vanoli Uzhavar Sevai Maiyam, Chatram Bus Stand, Trichy 620 002. 41. What are the control measures for banana leaf eating caterpillar? Spray Bacillus thuringiensis (2 gm/l with 1 ml adjuvant/l).  Pheromone traps were also available which can be tied @ 10/ha at about 3 feet above ground level. Chemical control measure is spraying of chlorpyrifos @ 2.5 ml/l with adjuvant. 42. What are the insects which cause problem during dry or drought weather conditions? Thrips (Helionothrips kadaliphilus) and foliar mite (Tetranychus sp.) and Eutetranychus orientalis infestation is more during dry weather. It can be controlled with spray of Dimethoate 1.5 ml/l with 1 ml adjuvant/l. 43. What are the reasons for the banana plants being toppled down? The sudden toppling down of banana plants is due to heavy incidence of nematodes, resulting in poor anchorage. There are five major nematodes infesting banana and causing economical damage to the plants. This can be controlled by application of carbofuran 40g at time of planting and at 5th month after planting. 44. What is Nematode?  How do I see Nematodes? Nematodes are worms like structure feeding on the roots and damaging the plants. Nematodes cannot be seen through naked eye. It can be seen   only through microscopes. 45. How can such tiny organisms do serious damage? Nematodes attack the roots by piercing the tissues with their spear-like stylet and feeding on the cell contents. More damage occurs after nematodes invasion due to the infection by other organisms present in the soil, such as fungi and bacteria and some carried by the nematodes. 46. What are the important nematode problems in banana? How much damage is caused by nematodes on banana? The most damaging and widespread nematodes attacking banana are : the burrowing nematode, Radopholus similis, root-lesion nematode, Pratylenchus coffeae, spiral nematode, Helicotylenchus multicinctus, root-knot nematode, Meloidogyne incognita and cyst nematode, Heterodera oryzicola. Nematodes form a major pest on banana and crop losses caused by nematodes is estimated about 20%. 47. How to know, the banana plants are affeted by nematodes? Nematode infested banana plants have poor growth with lanky pseudostems, foliar necrosis and produce very small bunches. However symptoms on roots and corms are more specific. Lesion-nematode produces small cuticular sunken lesions on the creamy white to light orange coloured portion of the main tender roots of banana. Whereas, on older roots surface cracks appear. This shows extensive reddish-brown lesions in cortex when cut longitudinally. These cause decay and death of distal cells. In heavily nematode infested field, banana plants topple over easily during wet and windy weather because of inadequate anchorage. 48. Is there any nematode-fungal disease complex in banana? Yes. Incidence and losses due to banana wilt disease caused by Fusarium oxysporum f.sp.cubense is enhanced in association with major nematode pathogens viz. Radopholus similis, Pratylenchus coffeae or Meloidogyne incognita. Infection of nematodes prior to fungus or in combination resulted in the early onset and increased severity of the Fusarium wilt symptoms incidence. 49. Can a banana plant attacked by different nematodes be saved? Yes. Lesion nematodes can be effectively managed by applying Carbofuran 50g/plant, one at the time of planting and two applications after planting at 3 months interval. Plant recovery and yield increase was observed  in the plants applied with Carbofuran. 50. Is there any other non-chemical control method for nematodes? Nowadays, non-chemical methods are receiving greater attention in view of the chemical residual toxicity and the pollution of soil and environment. Marigold (Tagetes spp.) grown as an inter crop reduced the root lesion nematode population with 25 per cent yield increase. Crop rotation with paddy, sugarcane, green gram, sunnhemp (Crotolaria juncea) followed by banana are recommended. Cultivation of sunnhemp is generally recommended prior to planting in order to manage the nematode population. 51. How to get nematode free planting material? Select the suckers from nematode free banana field. Otherwise, collect the planting material after paring immerse the suckers in hot water at 50-55°C for 20 minutes or dip the suckers in 0.1 per cent Monocrotophos solution for 30 minutes to get nematode free planting material. 52. Which is the best and cheapest control method for nematode? Newer nematicides Rugby 10G applied at 5g per plant during 3 and 5th month reduced the nematode population and increased the yield. The cost is much cheaper.           Among different neem formulations, Econeem formulations was found to be very effective in reducing the nematode populations and enhanced plant growth. 53. What are the biocontrol agents available to control nematode infesting banana? Biocontrol agents like Paecilomyces lilacinus, Verticillium chlamydosporium, V.lecanii, Pasteuria penetrans, Bacillus subtilis and VAM Glomus mosseae  were found very effective in reducing the nematode population and increase the plant growth. 54. How to identify and manage viral diseases? Based on characteristic symptoms induced by individual virus, it can be identified. Virus indexing using diagnosis kit can be used to detect viruses. 55. Which varieties are susceptible to wilt pathogens? Cultivars like Ney Poovan, Rasthali, Virupakshi, Sakkia, Monthan, Red Banana and Nadan are susceptible to wilt pathogens. 56. How to manage leaf spot diseases? Spray 0.1%  Propicanazole at 20 days interval. Remove old diseased, infected hanging leaves before spray. 3-4 sprays may be given. The same fungicides should not be repeated and different fungicides like Carbendazim (0.1%), Calixin (0.2%) Mancozeb or Copper oxychloride (0.25%) may be sprayed with any wetting agent (5ml/10 l water) on the under side of the leaf gives very good control of leaf spot diseases. 57. Pseudostem split symptom, is it caused by wilt pathogen? Yes, the FOC can cause pseudostem split symptoms. Similar symptoms are also noticed with Erwinia rot disease. 58. How to manage wilt in banana? Use pathogen free suckers, pairing and pralinage of suckers, application of Furadon and dipping in 1% Bavistin is necessary before planting. Use tissue culture plants Drenching and injection with 2% Bavistin (3ml/plant) can minimize the spread.