Bangladesh Rice Research Institute has so far detected a total of 32 diseases in different areas and varieties of rice in Bangladesh at different times. Out of these 10 are major diseases and the remaining 22 are minor. These diseases reduce the yield of rice by 10-15 percent. Among the diseases, 2 are
viral, 3 are bacterial, 22 are fungal, 5 are helminthic. Below are the descriptions of 9 rice diseases and disease control management [diseases of rice cultivation ]
1. Name of the disease: Brown spot disease
Cause of the disease: Bipolaris oryzae is caused by the fungus.
This disease can occur in rice plants of any age from the seedling stage. However, if the age of the seedling is high, the incidence of the disease is high. Lack of nutrients or lack of water in the soil increases the level of disease.
Symptoms
of the disease are small spots like sesame seeds on the leaves. The spots enlarge and become white in the center and brown at the edges.
Multiple spots can form large spots and kill the leaf. The disease is more common in the seed than in the leaf. Diseased plants produce malnourished seeds and turn brown.
Remedies: Sow healthy seeds; Seeds should be soaked in hot water (soaked at 50°C for 30 minutes); Treat with Carbendazim (Autostin) or Carboxin + Thiram (Provax 200 WP) at the rate of 2.5 g per kg of seed; Organic fertilizers should be used; Application of proper amount of nitrogen and potash fertilizers in the land reduces the disease; Proper water management must be done; Carbendazim (Autostin) should be sprayed at the rate of 1.5 grams per liter of water if the disease occurs.
2. Name of the disease: Blast disease . The disease attacks 3 parts of the rice plant. Based on the affected part of the tree, this disease is known by three names such as- 1. Leaf blast, 2. Git Blast and 3. Neck/Head Blast
The disease is caused
by a fungus called Pyricularia grisea This disease can occur in both Aman and Boro seasons. This disease can occur at any time from the seedling stage of rice to the time of ripening. Spread by seeds, wind, insects and weather. The disease spreads quickly when it is cold at night, hot during the day and thin dew accumulates in the morning. Light soils or sandy soils with low water holding capacity are more likely to develop the disease. The attack of this disease is more if the land is given excessive urea fertilizer and less potash fertilizer than required. Even if the land is dry for a long time, this disease can attack.
Symptoms of the disease :
leaf blast
First, small oval-shaped gray or white spots appear on the leaves. The edges of the spots are dark brown in color. Later, this scar gradually grows and takes the shape of an eye. Many spots can coalesce and kill the entire leaf. If the disease is heavily affected, the land sometimes looks like burning. In many cases black spots are formed at the junction of the bark and leaves. Which later rots and the leaves collapse and the yield is destroyed.
Knot or node blast
This disease is seen after the emergence of the stem of the rice plant. Black spots are formed on the knots. Gradually this spot increases and the knot rots, as a result the rice plant breaks along the knot.
If neck or seed blast
is a disease, the base of the seed or the base of the branch of the seed becomes black spots and rots. The seed or branch of the seed is broken. Paddy is crushed.
Disease Remedies
Disease resistant varieties should be used.
All types of fertilizers including organic fertilizers should be used in balanced amounts in the soil. The straw of the affected land should be burnt and the ash should be mixed with the land. Seeds should be collected from healthy plants, damaged or malnourished seeds should be discarded and healthy seeds should be used. In case of disease attack, application of urea fertilizer should be stopped. Water should always be kept in the land. At the beginning of the disease, 40 kg per hectare (5 kg per bigha) of potash fertilizer should be applied. Tricyclazole (Trooper 75 WP) or tebuconazole + trifloxystrobin (Native 75 WP) mixed at the rate of 1 gram per liter of water should be sprayed 2-3 times after 10-15 days.
3. Disease Name: Sheath rot is caused by the fungus Sarocladium oryzae .
Disease spread: It is seed borne. Positions diseased animals and substitutes. The prevalence of this disease is high in trees affected by maggots and tungro disease. This disease increases in hot and humid weather. This disease spreads during rain showers. Kholpacha disease is seen in all seasons. Generally, the disease is favorable for this disease when the tree is in cold condition.
Disease Symptoms The
disease never occurs on the leaves. Blister disease can occur on any pod, but damage occurs only when the leaf pods are affected. The attack of this disease can be seen when the paddy is infected. First there are round or irregular long spots on the sheath of the last leaf. The center of the spot is gray and the edges are brown or grayish brown. The spots may grow together and spread completely open. The face or head of the pod rots and powdery mildew abounds in the shell. If the attack of the disease is more, sometimes the grain is partially or not able to come out and the rice becomes black and shriveled.
Remedies for disease
should use healthy seeds. Treat with Carbendazim (Autostin) or Carboxin + Thiram (Provax 200 WP) at the rate of 2.5 g per kg of seed. The area around the land should be kept clean. Balanced fertilizer should be used and less urea should be applied. Potash fertilizer should be applied. If shell rot occurs, the water of the land should be dried and irrigation water should be given again after a few days. Propiconazole (Tilt 250 EC) should be mixed at the rate of 1 ml in 1 liter of water and sprayed 2-3 times after 10 days.
4. Disease name: Sheath blight Disease cause: Rhizoctonia solani is caused by the fungus.
Disease prevalence
This disease is more common during Aush and Aman seasons. Fungi are present in soil and abandoned straw. The prevalence of this disease is high in high temperature and humidity. If excess amount of urea fertilizer is used and frequent rainfall and waterlogging of the land also increases the attack of this disease.
Symptoms of the disease: Water-soaked green spots appear on the shell along the water level. The spots are gray in the center and brown at the edges. The spots coalesce and spread on the leaf sheaths and leaves, which look like rattlesnakes. If the attack is heavy, the fields sometimes look like they are on fire.
Disease control: Disease tolerant varieties should be used. Seedlings should be planted at proper distance (20-25 cm apart) and the stubble of the affected land should be burnt on the land. Use of balanced fertilizers and avoidance of excessive use of urea fertilizers. After the appearance of the disease, top application of 5 kg of potash fertilizer per bigha and Propiconazole (Tilt 250 EC) or Tebuconazole (Folicur 250 EC) or Hexaconazole (Contaf 5 EC) at the rate of 1 ml per liter of water should be sprayed 3-4 times after 10 days.
5. Disease Name: Foot rot and Bakanae Disease Cause: Caused by the fungus Fusarium moniliforme . This fungus secretes a type of hormone called gibberellin which helps in rapid growth of plant organs. Up to 30% crop damage can occur due to bakani attack.
Disease spread: Seed is one of the carriers of the disease. The germs of this disease spread from one land to another through soil, water, and air. If the germs of this disease are already present in the soil, this disease occurs in rice plants. The attack of this disease increases with the application of excess urea fertilizer. Disease attack is more at high temperature (30-35 degree Celsius).
Disease symptoms
Bakani disease can occur at any time from seedling stage to tillering. However, the most damage is done in the seedling stage. Infested rice seedlings are twice as tall as normal seedlings and become pale. Leaves of affected plants are pale green in color and appear weak. Affected skin becomes slimy and licky. Sometimes roots are seen emerging from the knots at the base of the tree. The root of the plant rots and gradually the affected plant dries up and dies. If infected with this disease at the seedling stage or soon after planting, the affected plants do not produce any fruit. However, if this disease occurs during pregnancy, there is more cheetah and malnourished rice and the grain is much smaller
Remedies
for disease Disease tolerant varieties of rice should be cultivated. Use healthy seeds. The straw should be burnt on the ground. Diseased seedlings should be selected and discarded while transplanting from the seed bed. The affected plant should be removed before flowering. If this disease occurs after planting, the affected trees should be removed and destroyed. The incidence of this disease can also be reduced by using urea fertilizers in moderate doses. As soon as root rot disease appears, the water of the land should be dried up. The fungicide Carbendazim (Autostin, Noin, Evazim) should be mixed at the rate of 2.5 grams per liter of water and the seeds should be soaked for 12 hours.
6. Disease Name: False Smut Disease Cause: Ustilaginoidea virens is caused by a fungus.
Disease spread: The disease can be seen at any time from the milk stage of the rice to the time of ripening of the rice. Drizzling rains at the time of flowering of rice and excessive application of urea fertilizers in the field increase the incidence of the disease.
Symptoms of the disease: Large blisters can be seen on some of the rice in the paddy field. The inside of the bead is yellow-orange in color and the outside is green in color. The outer coat later gradually turns black. The small beads are 1 cm. and may be larger in maturity. Chlamydospore-like organisms are not easily released from the beads due to the presence of a sticky substance. Usually no more than a few grains are attacked in any one grain.
Remedy: Urea fertilizer should be used in proper amount. Land drainage system should be improved. The best way to control this disease is to remove the infected plants or seeds. However, it should be picked in the morning by carefully wrapping the affected seeds in a polybag so that the spores cannot spread. If the disease occurs in the land, Carbendazim group fungicides such as Autostin or Noin at the rate of 1.5 gm/litre or Propiconazole (Tilt 250 EC) at the rate of 1 ml/litre should be sprayed in water.
7. Disease Name:
Bacterial Blight
Cause of disease: Xanthomonas oryzae pv oryzae (Xanthomonas oryzae pv.oryzae) is caused by a type of bacteria.
Distribution of the disease : The disease is prevalent in all three seasons of Aush, Aman and Boro. High temperature (26-30°C), relative humidity above 70%, stormy weather, planting of susceptible varieties, wounding of roots or plants during planting, application of high doses of urea fertilizers etc. increase the incidence of the disease. Leaf blight is spread from one field to another through paddy straw, soil, insects, wind and irrigation water.
Symptoms of the disease:First, bluish water-sucking spots appear on the tips or edges of the leaves. The spots gradually take on a light yellow color and grow downwards from the tip of the leaf. Eventually the leaves become partially or completely scorched and take on a gray or dry straw color. As a result, the tree first falls and slowly the whole tree dies. Krysek symptoms usually appear in seedlings and pods. As a result of this disease, the tree first falls and slowly the whole tree dies. Bacterial cells often precede the symptoms of the disease and the cells coalesce to form yellow bead-like granules in the early morning which dry and harden on the leaves. Subsequently, the water droplets on the leaves dissolve the droplets, allowing the disease germs to spread easily. A foul-smelling pus-like liquid oozes out when the affected plant is pressed. The temperature difference between night and day is high (8-10 degrees Celsius).
Remedies
for diseases Disease resistant varieties should be cultivated. After harvesting the diseased paddy, threshing and straw should be burnt. Be careful not to break the roots while lifting the seedlings. Fertilizer should be used in balanced amount and urea fertilizer should be applied in 3/4 installments. But after seeing the disease, application of urea fertilizer should be stopped. After 5-10 days dry the affected land should be watered again. After seeing the disease, additional 5 kg of potash fertilizer per bigha should be sprinkled and applied in water. Spraying of chelated zinc at the rate of 1 gram per liter of water reduces the severity of the disease.
8. Disease name : Tungro . In many areas this disease is referred to as salinity, sitting, redness etc.
Cause of the disease: This disease is caused by a type of microbe called Rice Tungro Virus .
Disease prevalence: This disease is more common during Aush and Aman seasons. Tungro is spread by transplanting infected seedlings. The virus is spread by green leafhoppers (Nephoteticus virescens), diseased plants that grow freely in the vicinity, bawa rice or grasses. The carrier insect can collect the virus by sucking sap from an infected plant for 2-3 minutes and transmit it to a healthy plant during the next 2-3 minutes. As a result, disease symptoms appear within 2-3 weeks even in healthy plants.
Disease Symptoms
Tungro affected leaves initially show light green and light yellow streaks along the veins. Later all the leaves gradually turn yellow or orange-yellow. Affected young leaves are pale in color and curl. Affected plants are shorter than healthy plants when infected at the seedling/bud stage but not as much as in older plants. Affected plants become weak, buds are reduced and roots become weak. Affected leaves fall to the ground. Infected plants may survive until the rice is ripe, but if the infestation is severe, the plants may wither and die. Mildly affected plants survive, but flower somewhat late and yield much less.
Disease Remedy: Disease resistant varieties should be cultivated. Green leafhoppers should be caught and killed with hand nets. Planting of seeds around tungro affected land should be avoided. Diseased trees, weeds and weeds should be controlled. Green leafhoppers should be killed using light traps. Perching should be done by burying bamboo cones in the ground. Imidachloropid (Admir/Emitaf) 0.5 ml/litre or Diazinon (60 liquid) 1.5 ml/litre should be sprayed in water for control of vector insects.
9. Name of the disease: Ufra disease (post burn) (Ufra) . In different areas, this disease is known as urba, dakpora, burning, burning, salinity etc. Usually 40-100% of the yield can be lost. Cause of disease: Ditylenchus angustus (Ditylenchus angustus) is caused by a type of worm.
Spread of the disease: The disease is spread by irrigation water, frequent rainfall, soil, diseased seedlings, straw and straw. Initially this disease was in Jolly Aman rice but now it is seen in all seasons. They attack from one tree to another by floating in irrigation water. This worm can survive up to 6-8 months after ripening in the abandoned paddy, straw, part of the grain or fallen paddy and soil without any food in the affected land.
Symptoms of the disease: The worm attacks the junction of young leaves and pods of rice plants. As the worms absorb the sap, white spots first appear on the base of the leaves. The white spot gradually turns brown and later the spot grows and dries up the entire leaf. Many times the rhyme cannot come out from thodha or even if it comes out, it comes out half or partially. If the rhyme does not come out, it remains twisted inside. The tree is cut down a bit. Paddy is very dirty and malnourished. When the attack begins during the growing season, no yield of that rice is obtained.
Remedy of diseases: after harvesting the diseased crop, the straw and straw should be burnt in the field; Weeds and weeds must be destroyed; After the first rain of the year the land should be plowed and dried for 15-20 days; Instead of planting rice in succession, other crops should be cultivated alternately; Avoid planting seeds on or near affected land; In the first stage of attack, the agar part of the rice should be cut and burned; 12-20 hours before planting the seedlings should be removed from the seedbed and the roots should be soaked in 1.5% deworming solution such as Furadan 5g or Curator 5g and planted in the ground; Carbofuran (Furadan 5g or Curator 5g) should be applied at the rate of 2.5-3.0 kg per hectare when the disease occurs in the field
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