Rice: Sheath blight, khaira and tungro
Rice (धान): Sheath blight, khaira and tungro:-
Sheath Blight (शीथ ब्लाइट):-
Introduction (परिचय):-
Rhizoctonia solani [Sexual stage (लैंगिक अवस्था): Thanetophorus cucumeris]
Symptoms (लक्षण):-
- The fungus affects the crop from tillering to heading stage.
(कवक पौधे को टिलरिंग से लेकर हेडिंग स्टेज तक प्रभावित करता है।)
- Initial symptoms are noticed on leaf sheaths near water level.
(प्रारंभिक लक्षण पानी के स्तर के पास पत्तियों की शीथ पर देखे जाते हैं।)
- On the leaf sheath oval or elliptical or irregular greenish grey spots are formed.
(पत्ती की शीथ पर अंडाकार, दीर्घवृत्ताकार या अनियमित हरे-भूरे धब्बे बनते हैं।)
- As the spots enlarge, the centre becomes greyish white with an irregular blackish brown or purple brown border.
(जैसे-जैसे धब्बे बढ़ते हैं, उनका केंद्र ग्रे-व्हाइट हो जाता है और सीमा अनियमित काले-भूरे या बैंगनी-भूरे रंग की हो जाती है।)
- Lesions on the upper parts of plants extend rapidly coalesing with each other to cover entire tillers from the water line to the flag leaf.
(पौधे के ऊपरी हिस्सों पर घाव तेजी से फैलते हैं और एक-दूसरे के साथ मिलकर पूरे टिलर को पानी की रेखा से ध्वज पर्ण तक ढक लेते हैं।)
- The presence of several large lesions on a leaf sheath usually causes death of the whole leaf, and in severe cases all the leaves of a plant may be blighted in this way.
(पत्ती की शीथ पर कई बड़े घावों की उपस्थिति से आमतौर पर पूरी पत्ती की मृत्यु हो जाती है, और गंभीर मामलों में इस तरह से पूरे पौधे की पत्तियाँ ब्लाइटेड हो सकती हैं।)
- The infection extends to the inner sheaths resulting in death of the entire plant.
(संक्रमण आंतरिक शीथों तक फैल जाता है, जिससे पूरे पौधे की मृत्यु हो जाती है।)
- Older plants are highly susceptible.
(पुराने पौधे अत्यधिक संवेदनशील होते हैं।)
- Five to six week old leaf sheaths are highly susceptible.
(पांच से छह सप्ताह पुरानी पत्तियों की शीथ अत्यधिक संवेदनशील होती है।)
- Plants heavily infected in the early heading and grain filling growth stages produce poorly filled grain, especially in the lower part of the panicle.
(शुरुआती हेडिंग और ग्रेन फिलिंग वृद्धि अवस्था में भारी संक्रमित पौधे खराब तरीके से भरे हुए दाने उत्पन्न करते हैं, विशेष रूप से पैनिकल के निचले हिस्से में।)
Etiology (रोगजनन):- The fungus produces usually long cells of septate mycelium which are hyaline when young, yellowish brown when old. It produces large number of globose sclerotia, which are initially white, later turn to brown or purplish brown.
(कवक आमतौर पर लंबी कोशिकाओं वाला विभाजित कवकजाल उत्पन्न करता है, जो तरुण होने पर पारदर्शी होता है और परिपक्व होने पर पीले-भूरे रंग का हो जाता है। यह गोलाकार स्क्लेरोशिया की बड़ी संख्या उत्पन्न करता है, जो प्रारंभ में सफेद होते हैं, बाद में भूरे या बैंगनी-भूरे रंग में बदल जाते हैं।)
Disease cycle (रोग चक्र):-
- The pathogen can survive as sclerotia or mycelium in dry soil for about 20 months but for 5-8 months in moist soil.
(रोगजनक शुष्क मिट्टी में स्क्लेरोशिया या कवकजाल के रूप में लगभग 20 महीने तक जीवित रह सकता है, लेकिन नम मिट्टी में 5-8 महीने तक।)
- It infects more than 188 crop species in 32 families.
(यह 32 कुलों की 188 से अधिक फसल प्रजातियों को संक्रमित करता है।)
- Sclerotia spread through irrigation water.
(स्क्लेरोशिया सिंचाई के पानी के माध्यम से फैलता है।)
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Management (प्रबंधन):-
- Avoid excess doses of fertilizers.
(उर्वरकों की अधिक मात्रा से बचें।)
- Adopt optimum spacing.
(उचित दूरी अपनाएं।)
- Eliminate weed hosts.
(खरपतवारों को नष्ट करें।)
- Apply organic amendments.
(जैविक संशोधनों का उपयोग करें।)
- Avoid flow of irrigation water from infected fields to healthy fields.
(संक्रमित खेतों से स्वस्थ खेतों में सिंचाई के पानी के प्रवाह से बचें।)
- Deep ploughing in summer and burning of stubbles.
(गर्मियों में गहरी जुताई करें और ठूंठ को जलाएं।)
- Grow disease tolerant varieties like Shiva (WGL 3943).
[शिवा (WGL 3943) जैसी रोग प्रतिरोधी किस्में उगाएं।]
- Spray Propiconazole@0.1% or Hexaconazole@0.2% or Validamycin@0.2%.
(प्रोपिकोनाज़ोल @0.1% या हेक्साकोनाज़ोल @0.2% या वेलिडामाइसीन @0.2% का छिड़काव करें।)
- Seed treatment with Pseudomonas fluorescens @ of 10g/kg of seed followed by seedling dip @ of 2.5 kg of product/ha dissolved in 100 litres and dipping for 30 minutes.
(स्यूडोमोनास फ्लोरेसेंस के साथ बीज उपचार @ 10 ग्राम/किलो बीज और फिर पौध डुबाना @ 2.5 किलो उत्पाद/हेक्टेयर को 100 लीटर में घोलकर 30 मिनट तक डुबाना।)
- Soil application of P. fluorescens @ of 2.5 kg/ha after 30 days of transplanting (This product should be mixed with 50 kg of FYM/Sand and then applied).
[30 दिनों के बाद स्यूडोमोनास फ्लोरेसेंस @ 2.5 किलो/हेक्टेयर मिट्टी में डालें (इस उत्पाद को 50 किलो FYM/रेत के साथ मिलाकर डाला जाना चाहिए)।]
- Foliar spray at 0.2% concentration commencing from 45 days after transplanting at 10 days interval for 3 times depending upon the intensity of disease.
(45 दिनों के बाद से 0.2% सांद्रता पर 10 दिनों के अंतराल पर 3 बार पत्तियों पर छिड़काव करें, रोग की तीव्रता के आधार पर।)
Introduction (परिचय):- Xanthomonas oryzae pv. oryzae
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Symptoms (लक्षण):-
- The bacterium induces either wilting of plants or leaf blight.
- Wilt syndrome known as Kresek is seen in seedlings within 3-4 weeks after transplanting of the crop.
- Kresek results either in the death of whole plant or wilting of only a few leaves.
- The bacterium enters through the hydathodes and cut wounds in the leaf tips, becomes systemic and cause death of entire seedling.
- The disease is usually noticed at the time of heading but in severe cases occur earlier also.
- In grown up plants water soaked, translucent lesions appear usually near the leaf margin.
- The lesions enlarge both in length and width with a wavy margin and turn straw yellow within a few days, covering the entire leaf. As the disease progresses, the lesions cover the entire leaf blade which may turn white or straw coloured.
- Lesions may also be seen on leaf sheaths in susceptible varieties.
- Milky or opaque dew drops containing bacterial masses are formed on young lesions in the early morning. They dry up on the surface leaving a white encrustation.
- If the cut end of leaf is dipped in water, bacterial ooze makes the water turbid.
Etiology (रोगजनन):-
- The bacterium is strict aerobe, gram negative, non spore forming, rod shaped with monotrichous polar flagellum of at one end.
- The bacterial cells are capsulated and are joined to form an aggregate mass. Colonies are circular, convex with entire margins, whitish yellow to straw yellow and opaque.
- The bacterium has many strains that differ in ability to infect rice plants.
- Strains in tropical countries are usually more virulent than those in temperate areas like Japan.
Disease cycle (रोग चक्र):-
- The bacterium enters the plant through water pores (hydathodes) along the edges of the leaf and through injuries in roots or leaves.
- It does not enter through stomata.
- BLB is primarily a vascular or systemic disease.
- Bacterial cells move along the vascular tissues causing wilting.
- Rain storms and typhoons help in the spread of the disease.
- Irrigation water also carries the organism from field to field.
- The primary source of infection is through bacterium overwintering in seed (husk and endosperm).
- Bacteria may survive in soil, plant stubbles and debris.
- The pathogen also survives on collateral hosts like Leersia hexandra, Leersia oryzoides, Zizania latifolia, Cyprus rotundus, Cyprus deformis, Phalaris arundinacea, Cyanodon dactylon, etc.
-The bacterial ooze serves as secondary inoculum and cause secondary infection.
Management (प्रबंधन):-
- Grow resistant cultivars like MTU 9992, Swarna, Ajaya, IR 20, IR 42, IR 50, IR 54, TKM 6, Mashuri, IET 4141, IET 1444, IET 2508, Chinsura Boro, etc.
- Resistant donors: Tetep, Tadukan, Zenith, etc.
- Affected stubbles are to be destroyed by burning or through ploughing.
- Judicious use of nitrogenous fertilizers.
- Avoid clipping of tip of seedling at the time of transplanting.
- Avoid flooded conditions or drying of the field (not at the time of flowering).
- Avoid flow of irrigation water from infected to healthy field.
- Seed treatment with Streptocycline (100ppm) along with foliar spray in combination with COC (100 ppm + 500 ppm) gave the best result against bacterial blight.
Introduction (परिचय):- Penyakitmerah which has been known in Malaysia since 1938 was identified as Tungro in 1965. The mentak disease of Indonesia is also identified as Tungro. Tungro is commonly found in Bangladesh and India. In India, it is seen in states of West Bengal, Kerala and other parts of India.
Symptoms (लक्षण):-
- Infection occurs both in the nursery and in the main field. Plants are markedly stunted.
- Stunting is more severe on susceptible varieties and slight on more resistant varieties.
- Leaves show yellow to orange discoloration and interveinal chlorosis.
- Yellow discoloration is commonly seen in “Japonica” varieties, while “Indica” varieties show orange discoloration.
- Yellowing starts from the tip of the leaf and may extend to the lower part of the leaf blade.
- Young leaves are often mottled with pale green to whitish interveinal stripes and the old leaves may have rusty streaks of various sizes.
- The plants may be killed if infected early.
- Tillering is reduced with poor root system.
- The infected plants have few spikelets and panicles are small with discoloured grains.
- Tungro infected plants can be chemically identified by lodine Test. Ten cm long leaf tip is cut in the early morning before 6 A.M. and dipped in a solution containing 2g Iodine and 6 g Potassium Iodide in 100 ml of water for 30 minutes. Tungro infected leaves show dark blue streaks.
Etiology (रोगजनन):-
- It is a composite disease caused by two morphologically unrelated viruses: rice tungro bacilliform virus (RTBV) and rice tungro spherical virus (RTSV). Virus can multiply only in living cells, so all viruses are always obligate endoparasites.
- Two types of virus particles are associated with the disease. Bacilliform particles cause majority of the symptoms of the disease. Spherical particles help in the transmission of bacilliform virus by the green leaf-hoppers.
- If the bacilliform virus particles are alone present in the rice plant they will not be transmitted by the leafhopper vector.
Disease cycle (रोग चक्र):-
- The virus causes severe damage only in area where the host plants and the insect vector multiply the year round. In the areas where the rice is not grown continuously, collateral hosts, especially wild rice are probable sources of inoculum.
- Stubbles of infected plants from the previous season also serve as a source of inoculum.
- Grassy weeds such as Eleusine indica, Echinochloa colonum, Echinochloa crusgalli may be infected
occasionally.
- The leafhoppers viz, Nephotettix virescens, N. nigropictus, N. parvus,N.malayanus and Recilia dorsalis transmit the virus in a non-persistent manner.
- Summer deep ploughing and burning of stubbles.
(गर्मियों में गहरी जुताई करें और ठूंठ को जलाएं।)
- Destroy weed hosts of the virus and vectors.
(वायरस और वाहकों के खरपतवार मेज़बानों को नष्ट करें।)
- Grow disease tolerant cultivars like MTU 9992, 1002, 1003, 1005, Suraksha, Vikramarya, Bharani, IR 36, IET 2508, RP 4-14, IET 1444, IR50 and Co45.
(रोग प्रतिरोधी किस्मों जैसे MTU 9992, 1002, 1003, 1005, सुरक्षा, विक्रमार्य, भरानी, IR 36, IET 2508, RP 4-14, IET 1444, IR50 और Co45 को उगाएँ।)
- Control the vectors in the nursery by application of carbofuran granules @170 g/cent, 10 days after sowing and @10kg/ac in main filed.
(नर्सरी में पत्ती हॉपर्स को नियंत्रित करने के लिए कार्बोफुरान ग्रैन्यूल्स @170 ग्राम/सेंट, बुवाई के 10 दिन बाद और मुख्य खेत में @10 किलो/एकड़ का अनुप्रयोग करें।)
- Spray Monochrotophos@2.2 ml/lt or Phosphamidan @1ml/lt or Ethophenphos@1.5ml/lt or Neem oil @3 per cent in the main field 15 and 30 days after transplanting to control leaf hoppers.
(मुख्य खेत में 15 और 30 दिन बाद पत्ती हॉपर्स को नियंत्रित करने के लिए मोनोक्रोटोफॉस @2.2 मिली/लीटर या फॉस्फामिडान @1 मिली/लीटर या एथोफेनफॉस @1.5 मिली/लीटर या नीम तेल @3% का छिड़काव करें।)
Introduction (परिचय):-
- It is micro-nutritional (Zn) deficiency characterized by the presence of dusty brown patches on leaves which ultimately undergo necrosis. Necrosis is browning or blackening of areas on a plant indicative of the death of plant cells.
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Symptoms (लक्षण):- There are many symptoms seen different parts of rice plant in khaira disease of rice. If these symptoms are identified at early stage-then khaira disease can be easily controlled minimising our loss. Most common symptoms seen on rice during the infestation of Khaira Disease are:-
- The symptoms of khaira disease is shown after 2-3 weeks of transplantation of rice.
- The peculiar symptom is-Yellowing of leaf at start and dusty brown patches are seen on leaf of rice. Later-These dusty patches covers whole leaf lamina. These patches looks like rust in iron.
- Chlorosis (Lack of Chlorophyll) is seen in affected leaves especially on lower leaves. Chlorosis occurs from basal part of leaf. This is because Zinc is responsible for the formation of chlorophyll.
- Stunted growth of plant. Rice cannot attain good height.
- There is no proper development of roots. Sometimes-Roots of rice plant also turns brown and fibrers are totally destroyed.
- The formation of ear (Grain Bearing Tip) is greatly reduced.
Management (प्रबंधन):- The disease should be controlled as soon as the symptoms are seen to minimize our production loss.
- khaira disease of rice can be controlled by spraying ZnSo4 in nursery bed of rice before transplanting in main field.
- During transplantation-ZnSo4 should be applied at the rate of (25-30)kg per hector of land.
- Seed priming i.e Dipping of seed on ZnO solution before sowing in field helps to reduce Zn deficiency.
- As high pH reduces the availability of Zinc. We should give priority to use fertilizers which reduces pH of soil like-We can use ammonium sulphate instead of Urea for N.
- Water logging should be avoided and there should be proper management of drainage in field.