Rice Diseases and Symptoms: Rice is the major food crop in Asia. It is the staple food in most states, particularly in India. Nevertheless, an IRRI report by the International Rice Research Institute shows an average worldwide loss of 37 percent of rice yield due to pests and diseases. Many paddy plant pests and diseases are caused by species like bacteria, pillows, and viruses. We will briefly describe the most commonly occurring rice pests and diseases pdf on the Asian continent. At the end of this tutorial, you will be able to learn about and treat different types of rice diseases.
Rice Disease Forms in India Rice Fungal Diseases Paddy Fungal Diseases: Over 40 fungal diseases occur in rice. They can be paddy disease ppt soil or air or seed-borne. Let’s pdf all the various types of rice diseases.
Blast Disease of Paddy
The blast is caused by the fungus Magnporthe grisea. The fungus infects the plant and causes lesions throughout the crop, including leaves, left neck, nodes, base, panicle, and grains. The Leaf Sheath and roots are usually left untouched. There are many rice blast disease symptoms. And the paddy disease in Hindi is the following on these symptoms and the location of the infection.
Leaf Blast: This takes place between the seedling stage and the late tillering stage. Initially, the young leaves when the fungus strikes. Afterward, the spots are transformed into spindles by the introduction of the yellow zone, from purple to brown borders. Brown spots occur only on the older leaves.
Neck Rot and Panicle Blast: They develop triangular lesions when the younger neck nodes get the infection. They stretch around the neck causing panicle damage.The panicles which are affected turn white in color. When the infection prolongs, the panicle may break and fall to the ground.
Collar Rot: Infection in the collars occurs at the blade and sheath junction contributing to brown lesion formation. In extreme cases, it is possible to kill the entire plant.
Node Blast: Lesions appear on the stem nodes changing the color of the rice tissue from brown to black. Culms and leaves at the infected Node turn straw-colored and finally fall off.
Rice Diseases Management Practices
Control Measures of Rice Diseases Blast:
- By segregating healthy seeds of diseased crops and sowing them as resistant varieties.
- By following recommended spaces during planting that is 20×20 cm to enhance aeration and light penetration.
- Applying recommended fertilizer levels can increase the intensity of blast infection due to excessive usage.
- By maintaining clean fields that can be the sources of infection.
- By burning or burying the diseased plants.
2. Sheath Blight Of Paddy Disease:
The causal organism of the Sheath Blight is Rhizoctonia Solani. This fungus is capable of surviving in the soil as Sclerotia or dominant mycelium during unfavorable conditions for over 2 years. Subsequently, the sclerotia in the soil trigger during land preparation or regular land irrigation. The Sclerotia bind to the seedling under favorable conditions and begin to germinate. The sheath blight disease may result in a significant loss of between 10 and 50%.
Symptoms of Sheath blight: initially, oval or initially oval or ellipsoidal greenish-grey lesions measuring 1-3 CM in length appears on the leaf sheath close to the soil or stagnant water. Later the lesions enlarge turning into great white centers surrounded by the dark brown margin. The lesions are gradually increasing and spreading to the upper part of the sheath and the leaves. Finally, the whole plant is filing. When they come into contact with the infected leaves, the infection easily spread to two neighboring Killers.
Sheath Blight of Rice Diseases
Control Measure of Sheath Blight:
- By growing more tolerant rice varieties.
- By avoiding the use of infected seeds.
- Treating the seeds with fungicide before sowing.
- By adopting cultural practices like wide space sowing, control of weed in and around Whitefield and burning of trouble.
- By avoiding the excessive use of Nitrogen fertilizer.
Practising the concept of green manuring during land preparation.
- By draining the water from the rice field early in the cropping season, that during the sheath formation so as to control the spread of an epidemic.
- Adopting crop rotation with dicot crops as the fungus read easily in monocot crops.
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3. False Smut Disease of Rice:
Ustilaginoidea virens is the causal fungal species of this disease. The structures are only evident in other phases of flowering. The fungus destroys an individual spikelet’s young ovary and turns it into big velvety balls or smut balls. During the flowering period, low-temperature high relative humidity and precipitation increase the frequency of viral infection.
Symptoms of False Smut: Initially, the smut ball is yellow in color and it has a membrane. After busting of the membrane the color changes to yellowish Green, Olive green and at the end turns greenish-black.
How to Control False Smut Disease:
- By avoiding the sowing of infected seeds.
- By scheduling the sowing date properly to avoid the damage caused during the time of moving.
- One has to spray of chlorothalonil 75 WP at the rate of 2 ML per liter during the flowering stage.
- By cleaning the bunds and fields regularly to avoid disease transmission through weed.
Upon processing, scrape the contaminated panicle and plant waste.
4. Brown spot of Paddy:
The Cochliobolus miyabeanus fungus causes it. Formerly referred to as Helminthosporium oryzae. In all stages of growth, the fungus affects the plant from seedling to the final stage. The spores join the coleoptile and the roots when a diseased seed is planted. The spores live on the leaf forming spots when the plant grows. The shape and size of the spots can vary. That’s large oval or circular spots from minute dark spots. This travels through the air to other leaves and panicles. The prevalence of the disease is higher in areas with temperatures ranging from 15 to 36 degrees Celsius and 86 to 100 percent relative humidity. During full tillering, the disease is crucial until the plant matures.
Symptoms of Brown spot:
- Yellow or brown lesions occur on the coleoptile at the seedling stage circular.
- The first small circular brown to purple-brown lesions occur on the leaves at the tillering point.
- The fully developed lesions are mostly circular to oval, light brown to gray clustered around the reddish-brown margin.
- The lesions are 5 to 14 mm long in some cases, causing the leaves to wax.
- On infected glumes and panicles, the dark brown to black oval spots are evident.
- The grain value decreases as a result of incomplete grain filling when the florets are contaminated.
- The fungi that penetrate the grains and cause grain spotting and discoloration, a condition known as pecky rice.
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Management of Brown Spots:
- By improving the soil fertility through regular monitoring of soil nutrients and by applying fertilizers.
- Sowing the seeds of resistant varieties so as to reduce the loss caused by infection.
By treating the seeds with fungicides such as propiconazole, trifloxystrobin,
- Carbendazim, Prodione by treating the seats for 10 to 12 minutes in hot water at 53 to 54 degrees Celsius before planting to control the primary infection that may occur at the seedling stage.
5. Grain Discoloration of Paddy:
Rice grain discoloration is a serious disease by a wide range of microorganisms such as Drechslera oryzae, Curvularia lunata, Sarocladium, Phoma species, Microdochium Species, Nigrospora species, and Fusarium species. When the grains are attacked by this virus, either after milk or after harvest or during the storage cycle. The infection may affect externally on the groom or internally on the kernels resulting in discoloration of the glumes or Kernels.
Symptoms of Brain Discolouration:
- Darkening of glumes or spikelet to brown or black in color.
- The appearance of dark brown or black spots on the grains.
- Management Practices of Grain Discoloration:
- By spraying Carbendazim, Thiram, Mancozeb at 1:1:1 ratio during the middle of the flowering stage.
Bacterial Diseases of Rice in India and Their Management:
We’ve heard about the fungal infections right now let’s move on to the bacterial infections. In rice cultivation, bacterial diseases pose a major threat to sustainable productivity. In Asian countries, particularly in India, they are the root cause of many problems. Here we’re going to discuss one of the major bacterial diseases that cause a major productivity loss.
Bacterial Blight in Paddy:
The causative agent of this disorder is Xanthomonas oryzae pathovar (PV). The species reach through the leaves and roots pores into the plant. They grow within the plant and penetrate the veins of the leaf as well as block the roots ‘ water-conducting tissues. After the initial lesions emerge, the bacteria ooze and spread by rain or wind to other crops. And the 25 to 34-degree Celsius atmospheric temperature and relative humidity above 70% are perfect conditions for these bacteria’s growth. The yield loss usually exceeds 50 percent when the paddy crop is affected by Bacterial Blight.
At the initial stage of inferior operation, water socked streaks appear near the tip and margins of the leaf. Gradually it transforms into yellow and straw-colored stripes with wavy edges. At the creek phase, the leaves turn greyish green, wilt, role up and later wither. Finally, the entire plant will dry or die.
Management of Bacterial Blight in Paddy:
- By developing resistant varieties that are able to withstand bacteria infection.
- Through harvesting seeds from disease-free crops and before sowing, disinfecting seeds.
- Adjusting the time of sowing and transplantation to avoid rainfall during tillering.
- By avoiding transplantation of saplings in waterlogged areas that are susceptible to flooding.
- Also, by employing shallow irrigation which can help in minimizing the spread of bacteria.
- By using the appropriate dosage of fertilizers containing nitrogen and potassium.
- Maintaining field sanitation through the removal of infected straw that acts as careers of disease.
- Burning the crop residue that was previously contaminated without leaving it in the ground.
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3. Viral Disease in Rice and Their Management:
The viral disease is yet again a serious threat to write cultivation in Southeast Asia. Here we shall focus on one of the most virulent types, the Rice Tungro Disease.
Rice tungro Disease in Paddy:
There are two viruses that cause this Rice Tungro Disease in Paddy. We are spherical virus Rice Tungro Bacilliform and spherical virus Rice tungro. The green leafhopper transmits this virus from an infected plant to a healthy plant. This virus is acquired by a truck that feeds on an infected person scheduled for 30 minutes. The transmission of the virus occurs in the healthy plant causing infection when the same feeds occur on the healthy plant for 15 minutes. The virus can be transmitted instantly in 2 hours or within 5 days after the hopper has been acquired. Essentially, after 5 days, this virus will no longer be virulent unless the insect gets the virus back.
Rice Tungro Disease of Rice Diseases
Symptoms of Rice Tungro Disease:
The infected plant shows stunted or reduced tillering. The leaves turn Yellow or Orange Yellowish in color and also may develop rust-colored spots. The discoloration starts from the leaf tip and extends to the blade and to the lower portion of the leaf. Delays in flowering in plants with the infection. While the panicles are small and unfilled or may have discolored grains.
Management Practices of Rice Tungro Disease:
These viruses can affect the rice plant, particularly during the vegetative stage, at any stage of growth. Rice Tungro Disease management practices are easy to grow by growing resistant varieties that are resistant to Tungro virus or leafhopper.
- For example IR36, IR50, etc.
- By observing the fallow period for one month that is leaving the land and unseeded after
plowing and tillering to monitor the spread of vectors in that area.
- By pursuing the field’s crop rotation that is susceptible to infection.
- Settling light traps to draw and reduce the population of the Hoppers seed.
- With the application of insecticides and fertilizers.
- By clearing after harvest the polluted stubbles to kill leafhoppers ‘ nests.
- Summary of Rice Diseases in India:
- Bacterial leaf blight is rice’s most common bacterial disease.
- Tungro-caused rice disease is commonly found in various agro-climatic regions.
- Cultivating resistant varieties of rice can help control diseases that typically affect rice cultivation.
We hope you’ve got enough ideas in India about Rice Diseases. You can keep rice plantation in your region with this guide on Rice Diseases.