Rice Disease Management

Management of major diseases according to rice crop stages



• Sheath Blight

• Blast

Leaf Blast



Node Blast



Panicle Blast

Seeding

Tillering

Panicle Initiation

Heading/Flowering

- apply right amount of nitrogen fertilizer - remove sclerotial bodies in the field to reduce inoculum potential and spread of disease - practice sanitation in the field by removing weeds and infected plant debris - use recommended fungicide only as last resort but avoid application when 50-70% reached heading

Ripening/Maturity - plow infesed field after harvest to reduce disease inoculum

- raise seedlings on wetbed - avoid dry condition as it increases susceptibility to blast - use resistant varieties - avoid thick crop stand; a 20x20 cm spacing is recommended - avoid excessive application of nitrogen; applying more than 120kg N per hectare favors blast development





• Bakanae

• Panicle Blight

- employ proper water management in the field that reduce water stress to plant - use fungicide only as last resort; timing of fungicide application is critical, if leaf blast is observed apply at early heading and during panicle emergence to avoid panicle blast - burn infested rice straw and stubbles to reduce inoculum potential and spread of airborne spores in the field

• Rice Tungro

• Bacterial Blight

Kresek



Leaf Blight

- use of resistant varieties/cultivars - employ seed treatment; use bleach powder at 100ug/ml or 2% zinc sulfate to ensure clean seeds - avoid flooding in seedbed, provide good drainage - avoid thick stand in the seedbed or in the field - apply moderate level of nitrogen and required level of potassium - maintain 2-3 cm water level - provide good drainage in case severe flooding occurs - practice field sanitation by removal and burning of infected plant/stubbles or weeds - plow under infected stubbles and straw - allow fallow period to reduce inoculum in the field and hence disease severity - susceptible stage of the plant

Seeding

Tillering

Panicle Initiation

Heading/Flowering

Ripening/Maturity

- use certified seeds or clean seeds - use resistant varieties such as PSB Rc54 and NSIC Rc130 in areas where the disease always occur - employ seed treatment using fungicide - practice field sanitation by removing infected seedlings and weeds at once and dispose properly - use fungicides only as last resort - avoid excessive nitrogen application in the field - eradicate source of pathogen by removing infected plant or plant parts as and weeds that serve as alternate host - practice regular planting as late planted rice are more susceptible to the disease - use chemicals only as last resort; antibiotics, copper and copper-containing compounds may be used - practice synchronous planting where epidemics occur - practice rotation of varieties; use matatag lines in endemic areas during wet season plantings or use vector resistant cultivars - practice sanitation by immediate removal of infected plants - practice fallow period after each cropping season

Resistant Rice Varieties for Major Pest and Diseases of Rice

General Recommendations:

1. Use resistant variety (refer to list of recommended rice varieties) • plant locally adapted resistant varieties • rotation of different varieties with different genes for resistance every 2 years to avoid breakdown of resistance by the pathogen 2. Use certified seeds or clean seeds • plant certified seeds from accredited seed growers • use salt water as floatation method to separate lightweigt from infected seeds 3. Seed treatment • hot water treatment of seeds at 57oC for 10 minutes is recommended • use fungicide as seed treatment • surface sterilization using 300 ppm chlorine solution helps prevent seedborne disease especially bakanae 4. Practice synchronous planting • planting within a month in a community helps reduce pest buildup 5. Adequate land preparation • plow under crop debris/volunteer crops/weeds to reduce inoculum potential in the field • level the field properly before transplanting for easy water management, minimize golden apple snail damage and weed control 6. Time of sowing and transplanting • adjust time of planting to evade peak periods of rains during tillering and maximum tillering of the plant during wet season • late planted crops increases the risk for disease epidemic 7. Follow recommended plant spacing/avoid thick stand in the field or seedbed • use 40-60 kg seeding rate in 400 sq.m. seed bed of inbred varieties • use 20 X 20 cm spacing

8. Practice sanitation in the field and nursery • plow under infected field right after harvest to eliminate disease and reduce source of inoculum 9. Fertilizer application • employ need base application of Nitrogen fertilizer through the use of leaf color chart (LCC) to determine the right time and dosage of application • split application of N during the crop growth stages • applying more than 120 kg N/ha favors blast development • form of N applied also affecgts blast severity; NO3-increases susceptibility of rice to blast infection • balance application of P and N reduces disease incidence 10. Water management • avoid water logging condition in the seedbed or in the field; maintain 2-3 cm water level during high water requirement stage of the plant • drought increases susceptibility to blast infection 11. Practice fallow period after each cropping season and/or practice crop rotation 12. Use available biological control agent 13. Use appropriate pesticide with proper timing and dosage of application • check for the list of appropriate pesticide • employ as a last resort in controlling disease problem in the field

DISEASES Rice Blast Irrigated Lowland Rainfed Lowland Rainfed Dry Seeded

Recommended Rice Varieties

Bacterial Blight Irrigated Lowland Irrigated Lowland (glutinous) Saline Prone Irrigated

PSB Rc32 (Jaro) PSB Rc34 (Burdagol) PSB Rc58 (Mayapa) PSB Rc66(Agusan) PSB Rc78(Pampanga) BPI R1 IR65 PSB Rc50 (Bicol)

Tungro Irrigated Lowland

PSB Rc2 (Nahalin) IR73885-1-4-3-2-1-6 (Matatag 9) NSIC Rc120 (Matatag 6)

PSB Rc4 (Molawin) PSB Rc10 (Pagsanjan) PSB Rc26H (Magat) PSB Rc28 (Agno) PSB Rc34 (Burdagol) PSB Rc54 (Abra) PSB Rc76 (Panay) PSB Rc82 (Peñaranda) NSIC Rc122 (Angelica) NSIC Rc124(Mestizo4) NSIC Rc 126H (Mestizo5) NSIC Rc132H (Mestizo 6) PSB Rc40 (Chayong) PSB Rc42 (Baliwag) PSB Rc62 (Naguilian) PSB Rc70 (Bamban)

INSECT Brown Planthopper Irrigated Lowland (BPH) Rainfed Lowland Transplanted Green Leafhopper (GLH)

Irrigated Lowland Irrgigated Lowland (glutinous)

Stemborer Irrigated Lowland Rainfed Lowland Transplanted Cool Elevated Saline Prone Irrigated

Recommended Rice Varieties PSB RC10 (Pagsanjan) PSB Rc32 (Jaro) PSB Rc 34 (Burdagol) PSB Rc98 (Lian) PSB Rc74 (Aklan) IR65 PSB Rc76H (Panay) NSIC Rc122(Angelica) NSIC Rc128 (Mabango1) PSB Rc100 (Santiago) PSB Rc44 (Gohang) PSB Rc50 (Bicol)

Source: Philippine Seed Board (PSB)/NSIC Rice Variety List as of June 2005