Difference between revisions of "Rice:Key"
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===BROWN=== | ===BROWN=== | ||
− | ==== | + | ====Aggregate Sheath Spot==== |
Oval lesions develop on the lower leaf sheaths at the waterline and have a gray-green to straw-colored center surrounded by a distinct brown margin; sclerotia are rectangular to globose and brown; leaves of diseased sheaths generally turn yellow and die | Oval lesions develop on the lower leaf sheaths at the waterline and have a gray-green to straw-colored center surrounded by a distinct brown margin; sclerotia are rectangular to globose and brown; leaves of diseased sheaths generally turn yellow and die | ||
====Bacterial Brown Stripe==== | ====Bacterial Brown Stripe==== |
Latest revision as of 02:31, 7 February 2016
KEY TO RICE PESTS AND NUTRITIONAL DISORDERS
Contents
- 1 Seed
- 2 Seedling
- 3 Root
- 4 Crown
- 5 Stem
- 6 Leaf
- 6.1 GRAY
- 6.2 BLACK
- 6.3 BLUE
- 6.4 BROWN
- 6.4.1 Aggregate Sheath Spot
- 6.4.2 Bacterial Brown Stripe
- 6.4.3 Bacterial Leaf Streak
- 6.4.4 Black Sheath Rot
- 6.4.5 Black-Streaked Dwarf
- 6.4.6 Brown Spot
- 6.4.7 Cercospora Sheath Spot
- 6.4.8 Collar Rot Blast
- 6.4.9 Crown Sheath Rot
- 6.4.10 Eyespot
- 6.4.11 Foot Rot
- 6.4.12 Grassy Stunt
- 6.4.13 Halo Blight
- 6.4.14 Leaf Blast
- 6.4.15 Leaf Scald
- 6.4.16 Myrothecium Blotch
- 6.4.17 Narrow Brown Leaf Spot
- 6.4.18 Ragged Stunt
- 6.4.19 Rice Blast
- 6.4.20 Sheath Blight
- 6.4.21 Sheath Blotch
- 6.4.22 Sheath Net Blotch
- 6.4.23 Sheath Rot
- 6.4.24 Spot
- 6.4.25 Stackburn
- 6.4.26 Stem Rot
- 6.4.27 White Leaf Streak
- 6.5 DARK
- 6.6 GRAY
- 6.7 GREEN
- 6.7.1 Aggregate Sheath Spot
- 6.7.2 Bacterial Leaf Streak
- 6.7.3 Black-Streaked Dwarf
- 6.7.4 Brown Spot
- 6.7.5 Eyespot
- 6.7.6 Gall Dwarf
- 6.7.7 Grassy Stunt
- 6.7.8 Halo Blight
- 6.7.9 Ragged Stunt
- 6.7.10 Sheath Blight
- 6.7.11 Sheath Spot
- 6.7.12 Straighthead
- 6.7.13 White Tip
- 6.7.14 Wrinkled Stunt and Witches' Broom
- 6.7.15 Yellow Dwarf
- 6.8 ORANGE
- 6.9 PURPLE
- 6.10 RED
- 6.11 RUST
- 6.12 SILVER
- 6.13 TAN
- 6.14 WHITE
- 6.14.1 Bacterial Blight
- 6.14.2 Bacterial Leaf Streak
- 6.14.3 Black-Streaked Dwarf
- 6.14.4 Downy Mildew
- 6.14.5 Eyespot
- 6.14.6 Gall Dwarf
- 6.14.7 Hoja Blanca
- 6.14.8 Leaf Blast
- 6.14.9 Rice Blast
- 6.14.10 Sheath Blight
- 6.14.11 Sheath Net Blotch
- 6.14.12 Sheath Spot
- 6.14.13 Stackburn
- 6.14.14 White Leaf Streak
- 6.14.15 White Tip
- 6.15 YELLOW
- 6.15.1 Crinkle
- 6.15.2 Aggregate Sheath Spot
- 6.15.3 Brown Spot
- 6.15.4 Cercospora Sheath Spot
- 6.15.5 Chlorotic Streak
- 6.15.6 Cyst Nematode
- 6.15.7 Downy Mildew
- 6.15.8 Dwarf
- 6.15.9 Eyespot
- 6.15.10 Foot Rot
- 6.15.11 Giallume
- 6.15.12 Grassy Stunt
- 6.15.13 Halo Blight
- 6.15.14 Hoja Blanca
- 6.15.15 Leaf Blast
- 6.15.16 Necrosis Mosaic
- 6.15.17 Orange Leaf
- 6.15.18 Ragged Stunt
- 6.15.19 Rice-Root Nematodes
- 6.15.20 Root-Knot Nematodes
- 6.15.21 Sheath Net Blotch
- 6.15.22 Stripe
- 6.15.23 Stripe Necrosis
- 6.15.24 Transitory Yellowing
- 6.15.25 Ufra
- 6.15.26 Yellow Dwarf
- 6.15.27 Yellow Mottle
- 6.16 No Distinct Discoloration
- 7 Flower
- 8 Fruit
Seed
Seed disorders are limited to disorders while in the ground and not to potential disorders inherent in the seed.
BROWN
Stackburn
Oval to circular spots develop on the leaves which are tan becoming gray to white and are surrounded by a narrow, dark brown border; small black dots are produced in the centers of older lesions; infection of the kernels produces discolored, shriveled, or brittle grains; dark brown lesions may also occur on the coleoptiles of germinating seeds or young seedlings
WHITE
Seed Rot
Seedlings fail to emerge; seed or germinated seed decay, often with white moldy growth
Seedling
BLACK
Black Kernel
A blackish discoloration may occur creating leaf spots or seedling blights; spores that develop are multicellular, strongly curved, and the center cells are larger and darker than the others
BROWN
Grain Rot
On seedlings, symptoms consist of a brown, water-soaked soft rot of the leaf sheaths accompanied by wilting or soft rot of the leaves; on the panicle, infected grains are shrunken and pale green, becoming dirty yellow to brown and dry; a brown margin between the infected and healthy parts of the grain is diagnostic
Seedling Blight
Seedlings with brown discoloration of growing point, leaf base, and/or roots; affected seedlings are stunted, yellowed, then killed; seedlings 1-4 inches tall dying in flood or after flushing field
Sheath Brown Rot
On seedlings, a systemic discoloration of the leaf sheath occurs, which may spread to the midrib or veins of the leaves; on the sheath, oblong to irregular dark green, water-soaked lesions occur, which become gray-brown or brown and may be surrounded by a dark brown margin; grains of infected panicles are discolored, deformed, or empty
Stackburn
Oval to circular spots develop on the leaves which are tan becoming gray to white and are surrounded by a narrow, dark brown border; small black dots are produced in the centers of older lesions; infection of the kernels produces discolored, shriveled, or brittle grains; dark brown lesions may also occur on the coleoptiles of germinating seeds or young seedlings
DARK
Southern Blight
Seedlings with dark rot on base of plants, white moldy growth on lower plant; tan to brown sclerotia near soil line may be present
GRAY
Sheath Brown Rot
On seedlings, a systemic discoloration of the leaf sheath occurs, which may spread to the midrib or veins of the leaves; on the sheath, oblong to irregular dark green, water-soaked lesions occur, which become gray-brown or brown and may be surrounded by a dark brown margin; grains of infected panicles are discolored, deformed, or empty
GREEN
Sheath Brown Rot
On seedlings, a systemic discoloration of the leaf sheath occurs, which may spread to the midrib or veins of the leaves; on the sheath, oblong to irregular dark green, water-soaked lesions occur, which become gray-brown or brown and may be surrounded by a dark brown margin; grains of infected panicles are discolored, deformed, or empty
Yellow Dwarf
Plants are stunted, tiller profusely, and show a general yellow of the tissues, producing pale green or yellow leaves; plants infected in the seedling stage usually die prematurely
ORANGE
Orange Leaf
Seedlings have short, malformed leaves that are serrated and yellow, and the leaf tips are twisted; leaves will turn yellow-orange beginning at the tip; eventually the leaves become entirely orange, roll inward, and dry out
WHITE
Seed Rot
Seedlings fail to emerge; seed or germinated seed decay, often with white moldy growth
YELLOW
Bakanae
Elongated, slender, pale seedlings may be stunted and yellow showing root and crown rot; leaf sheaths of infected plants may turn blue-black with the production of perithecia
Crinkle
Leaves of emerging seedlings are crinkled or distorted and may develop pale yellow, lens-shaped lesions; entire leaves may turn yellow, and roots become stubby and bushy
Orange Leaf
Seedlings have short, malformed leaves that are serrated and yellow, and the leaf tips are twisted; leaves will turn yellow-orange beginning at the tip; eventually the leaves become entirely orange, roll inward, and dry out
Seedling Blight
Seedlings with brown discoloration of growing point, leaf base, and/or roots; affected seedlings are stunted, yellowed, then killed; seedlings 1-4 inches tall dying in flood or after flushing field
Yellow Dwarf
Plants are stunted, tiller profusely, and show a general yellow of the tissues, producing pale green or yellow leaves; plants infected in the seedling stage usually die prematurely
Chlorotic Streak
Young leaves are stunted, have yellow streaks, and are spotted; other symptoms include poor emergence of panicles with sterile or discolored spikelets, leaf distortion, vein swelling, excess tillering, and formation of aerial roots
No Distinct Discoloration
Bacterial Brown Stripe
Water-soaked stripes develop on the leaves and leaf sheaths, which turn brown; stripes develop on the leaves along the midrib or leaf margins; disease attacks young, unfolded leaves causing stunting or the death of the seedling
Root
BROWN
Feeder Root Necrosis and Root Rot
Symptoms include an overall lack of fine feeder roots and there may be restricted, reddish brown lesions on the primary roots where the feeder roots were attached; plants may be slightly stunted and appear unthrifty
RED
Feeder Root Necrosis and Root Rot
Symptoms include an overall lack of fine feeder roots and there may be restricted, reddish brown lesions on the primary roots where the feeder roots were attached; plants may be slightly stunted and appear unthrifty
No Distinct Discoloration
Bakanae
Elongated, slender, pale seedlings may be stunted and yellow showing root and crown rot; leaf sheaths of infected plants may turn blue-black with the production of perithecia
Chlorotic Streak
Young leaves are stunted, have yellow streaks, and are spotted; other symptoms include poor emergence of panicles with sterile or discolored spikelets, leaf distortion, vein swelling, excess tillering, and formation of aerial roots
Crinkle
Leaves of emerging seedlings are crinkled or distorted and may develop pale yellow, lens-shaped lesions; entire leaves may turn yellow, and roots become stubby and bushy
Cyst Nematode
Plants are stunted and have retarded growth; leaves are severely dry and yellow, and the number of tillers is reduced
Dwarf
Plants are stunted and produce small tillers or a reduced number of tillers; root growth is severely retarded and irregular yellow specks are formed on the leaves and sometimes on the leaf sheaths
Foot Rot
Leaf sheaths typically exhibit a dark brown decay, and the attached leaves turn yellow and wilt; infected culms and internodes turn black; roots attached to infected nodes decay and fall off; bacterial ooze may be present inside the culms and infected plants have an unpleasant odor
Hoja Blanca
Plants are stunted and the leaves have yellow stripes or are mottled turning the whole leaf blade white; the palea and lemma are distorted and turn brown; plants have fewer and smaller roots and the roots may be dry
Rice-Root Nematodes
Aboveground symptoms include retarded growth, reduction in the tiller number, stunted, yellowing, and late maturation
Root-Knot Nematodes
Aboveground symptoms include yellowing, wilting, retarded maturation, and reduction in growth and tillering which eventually develops into root galls
Seedling Blight
Seedlings with brown discoloration of growing point, leaf base, and/or roots; affected seedlings are stunted, yellowed, then killed; seedlings 1-4 inches tall dying in flood or after flushing field
Crown
No Distinct Discoloration
Bakanae
Elongated, slender, pale seedlings may be stunted and yellow showing root and crown rot; leaf sheaths of infected plants may turn blue-black with the production of perithecia
Crown Sheath Rot
Leaf sheaths become dark brown to black or develop a lesion that extends upward from the crown and the leaves of heavily infected sheaths die; the culm and crown are also infected causing inhibition of tillering and contributes to lodging, incomplete grain filling, and premature ripening of the panicle
Stem
BLACK
Ear Blight
Brown or black streaks create a discoloration and/or blight of the entire panicle or portions of the panicle, including the neck, branches, internodes, nodes, and spikelets
Foot Rot
Leaf sheaths typically exhibit a dark brown decay, and the attached leaves turn yellow and wilt; infected culms and internodes turn black; roots attached to infected nodes decay and fall off; bacterial ooze may be present inside the culms and infected plants have an unpleasant odor
Stem Rot
Small, black, linear lesions on lower leaf sheaths near the water line appear from tillering to internode movement; later, they appear as uniform dark brown to black discoloration of leaf sheaths; leaves of affected sheaths die and turn brown; black blotches are noted on the stem under rotted sheaths; internodal areas of stem rot break over; numerous small, black sclerotia are visible within sheaths and stems at maturity or after
BROWN
Black Sheath Rot
Gray or brown spots confined to lower leaf sheaths appear during internode movement; spots enlarge to cover entire leaf sheaths; spots are gray with a dark gray or brown to black upper and lower border; lower leaves of affected sheaths die and turn brown; reddish-brown, thread-like growth is observed on culm under rotted sheaths; black, pepper-like fruiting structures occur on rotted sheath during growing season; plants have a reduced number of tillers and frequently only one panicle per plant is produced; disease can cause lodging and incomplete emergence of the panicles
Ear Blight
Brown or black streaks create a discoloration and/or blight of the entire panicle or portions of the panicle, including the neck, branches, internodes, nodes, and spikelets
Southern Blight
Seedlings with dark rot on base of plants, white moldy growth on lower plant; tan to brown sclerotia near soil line may be present
Ufra
Plants show malformations and yellowing or mosaic discoloration of the upper leaves; later scattered dark stains appear on the leaves and parts of the upper internodes of the stem turn dark brown; disease is most evident on the panicles where the ufra may be swollen and ripe; the panicle coils and remains enclosed within the leaf sheath; the panicle may emerge but will be distorted, sterile or empty, and produce normal grains only near the tip
GRAY
Rotten Neck Blast
Brown discoloration of the panicle node and surrounding area; stem of panicle shrivels and breaks over; panicle turns white, and grain stops filling; node area may become gray as fungus grows and produces more spores
RED
Black Sheath Rot
Gray or brown spots confined to lower leaf sheaths appear during internode movement; spots enlarge to cover entire leaf sheaths; spots are gray with a dark gray or brown to black upper and lower border; lower leaves of affected sheaths die and turn brown; reddish-brown, thread-like growth is observed on culm under rotted sheaths; black, pepper-like fruiting structures occur on rotted sheath during growing season; plants have a reduced number of tillers and frequently only one panicle per plant is produced; disease can cause lodging and incomplete emergence of the panicles
TAN
Southern Blight
Seedlings with dark rot on base of plants, white moldy growth on lower plant; tan to brown sclerotia near soil line may be present
WHITE
Southern Blight
Seedlings with dark rot on base of plants, white moldy growth on lower plant; tan to brown sclerotia near soil line may be present
No Distinct Discoloration
Bunchy Stunt
Infected plants are stunted, tiller profusely, the leaves are short and narrow, and young leaves may show mottling; branches may form from the upper nodes and leaves may be produced in bunches in severe cases
Crown Sheath Rot
Leaf sheaths become dark brown to black or develop a lesion that extends upward from the crown and the leaves of heavily infected sheaths die; the culm and crown are also infected causing inhibition of tillering and contributes to lodging, incomplete grain filling, and premature ripening of the panicle
Necrosis Mosaic
Plants have elongate or spindle-shaped, yellow flecks and streaks on the lower leaves; dry flecks may develop on the basal portions of stems and sheaths; plants may be stunted, have a reduced number of tillers, and have a spreading growth habit
Rice-Root Nematodes
Aboveground symptoms include retarded growth, reduction in the tiller number, stunted, yellowing, and late maturation
Stripe
Early infection develops yellow leaves, which remain folded and wilt and droop as they elongate; later leaves develop yellow stripes or spotting and dry streaks; plants are stunted
Stripe Necrosis
Plants are stunted and have a reduced number of tillers; leaves have yellow stripes and exhibit drying
Leaf
GRAY
Sheath Blight
Gray-green, water-soaked spots appear on sheaths near water line from tillering to internode movement; oval spots develop with a gray center and dark gray border; when dry, spots are tan to white with reddish-brown to brown borders; white, thread-like growth spreads over healthy sheaths and leaves, forming new lesions; lesions commonly form a continuous pattern of wide, tan to gray, dead areas with narrow reddish-brown bands; brown sclerotia are loosely attached to blighted plant parts; panicle emerging from boot, fails to branch out, turns paper white with some brown discoloration, remains upright and fails to fill grain
BLACK
Bakanae
Elongated, slender, pale seedlings may be stunted and yellow showing root and crown rot; leaf sheaths of infected plants may turn blue-black with the production of perithecia
Black Kernel
A blackish discoloration may occur creating leaf spots or seedling blights; spores that develop are multicellular, strongly curved, and the center cells are larger and darker than the others
Crown Sheath Rot
Leaf sheaths become dark brown to black or develop a lesion that extends upward from the crown and the leaves of heavily infected sheaths die; the culm and crown are also infected causing inhibition of tillering and contributes to lodging, incomplete grain filling, and premature ripening of the panicle
Leaf Smut
Short, linear to elliptical black spots on both sides of leaves; spots become numerous but remain separated and are often slightly raised; occurs as rice approaches maturity
Stackburn
Oval to circular spots develop on the leaves which are tan becoming gray to white and are surrounded by a narrow, dark brown border; small black dots are produced in the centers of older lesions; infection of the kernels produces discolored, shriveled, or brittle grains; dark brown lesions may also occur on the coleoptiles of germinating seeds or young seedlings
Stem Rot
Small, black, linear lesions on lower leaf sheaths near the water line appear from tillering to internode movement; later, they appear as uniform dark brown to black discoloration of leaf sheaths; leaves of affected sheaths die and turn brown; black blotches are noted on the stem under rotted sheaths; internodal areas of stem rot break over; numerous small, black sclerotia are visible within sheaths and stems at maturity or after
BLUE
Bakanae
Elongated, slender, pale seedlings may be stunted and yellow showing root and crown rot; leaf sheaths of infected plants may turn blue-black with the production of perithecia
BROWN
Aggregate Sheath Spot
Oval lesions develop on the lower leaf sheaths at the waterline and have a gray-green to straw-colored center surrounded by a distinct brown margin; sclerotia are rectangular to globose and brown; leaves of diseased sheaths generally turn yellow and die
Bacterial Brown Stripe
Water-soaked stripes develop on the leaves and leaf sheaths, which turn brown; stripes develop on the leaves along the midrib or leaf margins; disease attacks young, unfolded leaves causing stunting or the death of the seedling
Bacterial Leaf Streak
Disease appears as small, interveinal, water-soaked streaks that are dark green and later become translucent and eventually become light brown; entire leaves turn brown and then grayish white and die
Black Sheath Rot
Gray or brown spots confined to lower leaf sheaths appear during internode movement; spots enlarge to cover entire leaf sheaths; spots are gray with a dark gray or brown to black upper and lower border; lower leaves of affected sheaths die and turn brown; reddish-brown, thread-like growth is observed on culm under rotted sheaths; black, pepper-like fruiting structures occur on rotted sheath during growing season; plants have a reduced number of tillers and frequently only one panicle per plant is produced; disease can cause lodging and incomplete emergence of the panicles
Black-Streaked Dwarf
Plants are stunted with dark green discoloration of the leaves, and occasional vein swellings on the sheath; leaf tips are twisted and may split at the leaf margins; dark brown streaks consist of white, swollen veins or galls that develop along the undersides of the leaves and on the sheaths and culms; dark brown blotches may form on the kernels
Brown Spot
Small, round, dark brown spots with a dull yellow margin enlarging to round spots with a gray center and a thick, dark brown border; spots are usually observed on pale green rice plants growing under stress; dark brown to black spots on grain hulls often large enough to cover entire grain; affected grain may be poorly filled and chalky
Cercospora Sheath Spot
Reddish or purple brown, netlike spot on sheaths of lower leaves; blades of affected leaves turn yellow and die
Collar Rot Blast
Collar portion of flag leaf becomes brown; flag leaf shrivels, dies, and may fall off
Crown Sheath Rot
Leaf sheaths become dark brown to black or develop a lesion that extends upward from the crown and the leaves of heavily infected sheaths die; the culm and crown are also infected causing inhibition of tillering and contributes to lodging, incomplete grain filling, and premature ripening of the panicle
Eyespot
Lesions appear on leaves as small, oval, water-soaked gray-green spots; a yellow halo frequently surrounds young lesions and as the disease progresses, the lesions enlarge and become white to straw-colored and delimited by a well-defined, brown margin; leaves turn yellow and wilt immediately after heading
Foot Rot
Leaf sheaths typically exhibit a dark brown decay, and the attached leaves turn yellow and wilt; infected culms and internodes turn black; roots attached to infected nodes decay and fall off; bacterial ooze may be present inside the culms and infected plants have an unpleasant odor
Grassy Stunt
Plants are stunted, show a proliferation of tiller, and have short, narrow, pale green to pale yellow leaves; leaves also may have numerous small, irregular, dark brown or rust-colored spots; infected plants produce no panicles or a few panicles with unfilled kernels
Halo Blight
Circular, pale green to yellowish brown lesions, 2-10 mm in diameter develop on leaf blades; the lesions are surrounded by a distinct halo and have a dark brown spot or stripe in the center
Leaf Blast
Lesions vary from round or oval spots with a gray or white center surrounded by a reddish brown border to elongated spots with pointed ends having a gray to white dead center; elongated lesions may have a bright yellow border, a narrow reddish-brown border, or both, with the outer margin being yellow
Leaf Scald
Zonate lesions beginning at the leaf tip or margin with alternating bands of tan to gray with reddish brown forming a V pattern
Myrothecium Blotch
Irregular to oblong lesions with dark brown centers and a lighter brown margin, occur on the flag leaf sheaths; brown lesions, sometimes with whitish centers, also occur on the glumes of affected plants
Narrow Brown Leaf Spot
Long, narrow, reddish-brown lesions parallel to leaf veins, usually confined to the area between veins
Ragged Stunt
Plants are stunted and develop short, dark green leaves that are serrated and twisted along one or both edges, giving them a ragged appearance; vein swellings or galls appear on the underside of the leaf blade and on the outer surface of the leaf sheath near the collar; the galls are pale yellow to sometimes brown
Rice Blast
Spots or lesions develop on leaves, nodes, and different parts of the panicles and grains, usually with no spots on the leaf sheaths; spots are often pointed or diamond shaped; the center of the spot is gray or whitish and the margin is brown or a reddish brown and the spots can elongate; leaf blast can attack at the tillering stage and completely kill some varieties
Sheath Blight
Gray-green, water-soaked spots appear on sheaths near water line from tillering to internode movement; oval spots develop with a gray center and dark gray border; when dry, spots are tan to white with reddish-brown to brown borders; white, thread-like growth spreads over healthy sheaths and leaves, forming new lesions; lesions commonly form a continuous pattern of wide, tan to gray, dead areas with narrow reddish-brown bands; brown sclerotia are loosely attached to blighted plant parts; panicle emerging from boot, fails to branch out, turns paper white with some brown discoloration, remains upright and fails to fill grain
Sheath Blotch
Large, brown oblong lesions, about 2.5-5 cm long occur on the leaf sheaths; lesions lengthen up to 10 cm and turn grayish at the center
Sheath Net Blotch
Small, yellow oval lesions 1-2 cm long develop on the leaf sheaths near the waterline; eventually the lesions expand becoming whitish, and are covered by a brown, netlike pattern formed from horizontal and longitudinal streaks
Sheath Rot
Reddish-brown discoloration of the flag leaf sheath with panicles emerging poorly; panicle may be twisted, covered with a white powdery mass, and has florets with brown discoloration; panicle may fail to emerge fully from boot, and grain may not fill
Spot
Spots on upper portion of leaf sheaths near the leaf blade, usually appearing midway in the rice canopy; spots are oval with white to pale green centers and a thick, dark, reddish-brown border; spots remain separated and do not progress extensively onto leaves
Stackburn
Oval to circular spots develop on the leaves which are tan becoming gray to white and are surrounded by a narrow, dark brown border; small black dots are produced in the centers of older lesions; infection of the kernels produces discolored, shriveled, or brittle grains; dark brown lesions may also occur on the coleoptiles of germinating seeds or young seedlings
Stem Rot
Small, black, linear lesions on lower leaf sheaths near the water line appear from tillering to internode movement; later, they appear as uniform dark brown to black discoloration of leaf sheaths; leaves of affected sheaths die and turn brown; black blotches are noted on the stem under rotted sheaths; internodal areas of stem rot break over; numerous small, black sclerotia are visible within sheaths and stems at maturity or after
White Leaf Streak
Small, interveinal, oblong to linear lesions develop on both leaf surfaces; lesions are white to light gray and surrounded by a distinct, very narrow, brown margin; long, uninterrupted white streaks may develop on heavily infected plants; young lesions may be white on the leaf surface and brown on the underside
DARK
Ufra
Plants show malformations and yellowing or mosaic discoloration of the upper leaves; later scattered dark stains appear on the leaves and parts of the upper internodes of the stem turn dark brown; disease is most evident on the panicles where the ufra may be swollen and ripe; the panicle coils and remains enclosed within the leaf sheath; the panicle may emerge but will be distorted, sterile or empty, and produce normal grains only near the tip
Wrinkled Stunt and Witches' Broom
Symptoms include severe stunting with dark green, wrinkled, twisted leaves with pronounced tillering
GRAY
Aggregate Sheath Spot
Oval lesions develop on the lower leaf sheaths at the waterline and have a gray-green to straw-colored center surrounded by a distinct brown margin; sclerotia are rectangular to globose and brown; leaves of diseased sheaths generally turn yellow and die
Bacterial Blight
Lesions begin as water-soaked stripes near the leaf tip or margin; as lesions enlarge, the affected areas die and turn white to gray and have a wavy margin; active lesions maintain a water-soaked leading edge, and milky-colored droplets may appear during periods of high humidity
Bacterial Leaf Streak
Disease appears as small, interveinal, water-soaked streaks that are dark green and later become translucent and eventually become light brown; entire leaves turn brown and then grayish white and die
Black Sheath Rot
Gray or brown spots confined to lower leaf sheaths appear during internode movement; spots enlarge to cover entire leaf sheaths; spots are gray with a dark gray or brown to black upper and lower border; lower leaves of affected sheaths die and turn brown; reddish-brown, thread-like growth is observed on culm under rotted sheaths; black, pepper-like fruiting structures occur on rotted sheath during growing season; plants have a reduced number of tillers and frequently only one panicle per plant is produced; disease can cause lodging and incomplete emergence of the panicles
Brown Spot
Small, round, dark brown spots with a dull yellow margin enlarging to round spots with a gray center and a thick, dark brown border; spots are usually observed on pale green rice plants growing under stress; dark brown to black spots on grain hulls often large enough to cover entire grain; affected grain may be poorly filled and chalky
Eyespot
Lesions appear on leaves as small, oval, water-soaked gray-green spots; a yellow halo frequently surrounds young lesions and as the disease progresses, the lesions enlarge and become white to straw-colored and delimited by a well-defined, brown margin; leaves turn yellow and wilt immediately after heading
Leaf Blast
Lesions vary from round or oval spots with a gray or white center surrounded by a reddish brown border to elongated spots with pointed ends having a gray to white dead center; elongated lesions may have a bright yellow border, a narrow reddish-brown border, or both, with the outer margin being yellow
Leaf Scald
Zonate lesions beginning at the leaf tip or margin with alternating bands of tan to gray with reddish brown forming a V pattern
Rice Blast
Spots or lesions develop on leaves, nodes, and different parts of the panicles and grains, usually with no spots on the leaf sheaths; spots are often pointed or diamond shaped; the center of the spot is gray or whitish and the margin is brown or a reddish brown and the spots can elongate; leaf blast can attack at the tillering stage and completely kill some varieties
Sheath Blotch
Large, brown oblong lesions, about 2.5-5 cm long occur on the leaf sheaths; lesions lengthen up to 10 cm and turn grayish at the center
Stackburn
Oval to circular spots develop on the leaves which are tan becoming gray to white and are surrounded by a narrow, dark brown border; small black dots are produced in the centers of older lesions; infection of the kernels produces discolored, shriveled, or brittle grains; dark brown lesions may also occur on the coleoptiles of germinating seeds or young seedlings
White Leaf Streak
Small, interveinal, oblong to linear lesions develop on both leaf surfaces; lesions are white to light gray and surrounded by a distinct, very narrow, brown margin; long, uninterrupted white streaks may develop on heavily infected plants; young lesions may be white on the leaf surface and brown on the underside
GREEN
Aggregate Sheath Spot
Oval lesions develop on the lower leaf sheaths at the waterline and have a gray-green to straw-colored center surrounded by a distinct brown margin; sclerotia are rectangular to globose and brown; leaves of diseased sheaths generally turn yellow and die
Bacterial Leaf Streak
Disease appears as small, interveinal, water-soaked streaks that are dark green and later become translucent and eventually become light brown; entire leaves turn brown and then grayish white and die
Black-Streaked Dwarf
Plants are stunted with dark green discoloration of the leaves, and occasional vein swellings on the sheath; leaf tips are twisted and may split at the leaf margins; dark brown streaks consist of white, swollen veins or galls that develop along the undersides of the leaves and on the sheaths and culms; dark brown blotches may form on the kernels
Brown Spot
Small, round, dark brown spots with a dull yellow margin enlarging to round spots with a gray center and a thick, dark brown border; spots are usually observed on pale green rice plants growing under stress; dark brown to black spots on grain hulls often large enough to cover entire grain; affected grain may be poorly filled and chalky
Eyespot
Lesions appear on leaves as small, oval, water-soaked gray-green spots; a yellow halo frequently surrounds young lesions and as the disease progresses, the lesions enlarge and become white to straw-colored and delimited by a well-defined, brown margin; leaves turn yellow and wilt immediately after heading
Gall Dwarf
Typical symptoms include stunted dark green leaves, twisted of the leaf tips, and small galls on the underside of leaf blades and on the outer surface of leaf sheaths; the galls begin light green and somewhat translucent later turning white
Grassy Stunt
Plants are stunted, show a proliferation of tiller, and have short, narrow, pale green to pale yellow leaves; leaves also may have numerous small, irregular, dark brown or rust-colored spots; infected plants produce no panicles or a few panicles with unfilled kernels
Halo Blight
Circular, pale green to yellowish brown lesions, 2-10 mm in diameter develop on leaf blades; the lesions are surrounded by a distinct halo and have a dark brown spot or stripe in the center
Ragged Stunt
Plants are stunted and develop short, dark green leaves that are serrated and twisted along one or both edges, giving them a ragged appearance; vein swellings or galls appear on the underside of the leaf blade and on the outer surface of the leaf sheath near the collar; the galls are pale yellow to sometimes brown
Sheath Blight
Gray-green, water-soaked spots appear on sheaths near water line from tillering to internode movement; oval spots develop with a gray center and dark gray border; when dry, spots are tan to white with reddish-brown to brown borders; white, thread-like growth spreads over healthy sheaths and leaves, forming new lesions; lesions commonly form a continuous pattern of wide, tan to gray, dead areas with narrow reddish-brown bands; brown sclerotia are loosely attached to blighted plant parts; panicle emerging from boot, fails to branch out, turns paper white with some brown discoloration, remains upright and fails to fill grain
Sheath Spot
Spots on upper portion of leaf sheaths near the leaf blade, usually appearing midway in the rice canopy; spots are oval with white to pale green centers and a thick, dark, reddish-brown border; spots remain separated and do not progress extensively onto leaves
Straighthead
Symptoms are not visible until the late boot to heading stages; affected plants may be darker green with more erect leaves than normal plants; the most common symptom is erect panicles that are partially to completely sterile and of insufficient weight to cause the panicle to tip over during the grain-filling stage as in normal rice
White Tip
Whitened leaf tips become dry and shred and the central part and the base of infected leaves are sometimes darker green; upper leaves are most infected with the flag leaf being twisted; other symptoms include reduction in the length of the panicle, reduction in the number of grains, sterile flower, misshapen grains, stunting, late ripening and maturation, and production of tillers from the upper nodes
Wrinkled Stunt and Witches' Broom
Symptoms include severe stunting with dark green, wrinkled, twisted leaves with pronounced tillering
Yellow Dwarf
Plants are stunted, tiller profusely, and show a general yellow of the tissues, producing pale green or yellow leaves; plants infected in the seedling stage usually die prematurely
ORANGE
Giallume
Leaves are yellow to orange, dry, small, erect and may have serrated margins; plants are stunted, have a reduced number of tillers and produce blasted florets; severely infected plants die
Orange Leaf
Seedlings have short, malformed leaves that are serrated and yellow, and the leaf tips are twisted; leaves will turn yellow-orange beginning at the tip; eventually the leaves become entirely orange, roll inward, and dry out
Transitory Yellowing
Plants are stunted and have a reduced number of tillers; lower leaves turn yellow to bright yellow or orange; at heading, plants are noticeable because they produce no panicles or poorly formed panicles
PURPLE
Cercospora Sheath Spot
Reddish or purple brown, netlike spot on sheaths of lower leaves; blades of affected leaves turn yellow and die
RED
Cercospora Sheath Spot
Reddish or purple brown, netlike spot on sheaths of lower leaves; blades of affected leaves turn yellow and die
Leaf Blast
Lesions vary from round or oval spots with a gray or white center surrounded by a reddish brown border to elongated spots with pointed ends having a gray to white dead center; elongated lesions may have a bright yellow border, a narrow reddish-brown border, or both, with the outer margin being yellow
Leaf Scald
Zonate lesions beginning at the leaf tip or margin with alternating bands of tan to gray with reddish brown forming a V pattern
Narrow Brown Leaf Spot
Long, narrow, reddish-brown lesions parallel to leaf veins, usually confined to the area between veins
Rice Blast
Spots or lesions develop on leaves, nodes, and different parts of the panicles and grains, usually with no spots on the leaf sheaths; spots are often pointed or diamond shaped; the center of the spot is gray or whitish and the margin is brown or a reddish brown and the spots can elongate; leaf blast can attack at the tillering stage and completely kill some varieties
Sheath Blight
Gray-green, water-soaked spots appear on sheaths near water line from tillering to internode movement; oval spots develop with a gray center and dark gray border; when dry, spots are tan to white with reddish-brown to brown borders; white, thread-like growth spreads over healthy sheaths and leaves, forming new lesions; lesions commonly form a continuous pattern of wide, tan to gray, dead areas with narrow reddish-brown bands; brown sclerotia are loosely attached to blighted plant parts; panicle emerging from boot, fails to branch out, turns paper white with some brown discoloration, remains upright and fails to fill grain
Sheath Rot
Reddish-brown discoloration of the flag leaf sheath with panicles emerging poorly; panicle may be twisted, covered with a white powdery mass, and has florets with brown discoloration; panicle may fail to emerge fully from boot, and grain may not fill
Sheath Spot
Spots on upper portion of leaf sheaths near the leaf blade, usually appearing midway in the rice canopy; spots are oval with white to pale green centers and a thick, dark, reddish-brown border; spots remain separated and do not progress extensively onto leaves
RUST
Grassy Stunt
Plants are stunted, show a proliferation of tiller, and have short, narrow, pale green to pale yellow leaves; leaves also may have numerous small, irregular, dark brown or rust-colored spots; infected plants produce no panicles or a few panicles with unfilled kernels
SILVER
Udbatta
Erect spikes develop at heading that are covered by white mycelium; the flag leaf and sheath of infected tillers are slightly distorted and the flag leaf and upper leaves may appear silvery; infected plants may also be stunted
TAN
Leaf Scald
Zonate lesions beginning at the leaf tip or margin with alternating bands of tan to gray with reddish brown forming a V pattern
Sheath Blight
Gray-green, water-soaked spots appear on sheaths near water line from tillering to internode movement; oval spots develop with a gray center and dark gray border; when dry, spots are tan to white with reddish-brown to brown borders; white, thread-like growth spreads over healthy sheaths and leaves, forming new lesions; lesions commonly form a continuous pattern of wide, tan to gray, dead areas with narrow reddish-brown bands; brown sclerotia are loosely attached to blighted plant parts; panicle emerging from boot, fails to branch out, turns paper white with some brown discoloration, remains upright and fails to fill grain
Stackburn
Oval to circular spots develop on the leaves which are tan becoming gray to white and are surrounded by a narrow, dark brown border; small black dots are produced in the centers of older lesions; infection of the kernels produces discolored, shriveled, or brittle grains; dark brown lesions may also occur on the coleoptiles of germinating seeds or young seedlings
WHITE
Bacterial Blight
Lesions begin as water-soaked stripes near the leaf tip or margin; as lesions enlarge, the affected areas die and turn white to gray and have a wavy margin; active lesions maintain a water-soaked leading edge, and milky-colored droplets may appear during periods of high humidity
Bacterial Leaf Streak
Disease appears as small, interveinal, water-soaked streaks that are dark green and later become translucent and eventually become light brown; entire leaves turn brown and then grayish white and die
Black-Streaked Dwarf
Plants are stunted with dark green discoloration of the leaves, and occasional vein swellings on the sheath; leaf tips are twisted and may split at the leaf margins; dark brown streaks consist of white, swollen veins or galls that develop along the undersides of the leaves and on the sheaths and culms; dark brown blotches may form on the kernels
Downy Mildew
Leaves may have yellow to white spots or patches and the flag leaf and upper leaves may be curled, bent, or twisted; the panicle fails to emerge completely and is contorted and fails to produce any grain, but remains green
Eyespot
Lesions appear on leaves as small, oval, water-soaked gray-green spots; a yellow halo frequently surrounds young lesions and as the disease progresses, the lesions enlarge and become white to straw-colored and delimited by a well-defined, brown margin; leaves turn yellow and wilt immediately after heading
Gall Dwarf
Typical symptoms include stunted dark green leaves, twisted of the leaf tips, and small galls on the underside of leaf blades and on the outer surface of leaf sheaths; the galls begin light green and somewhat translucent later turning white
Hoja Blanca
Plants are stunted and the leaves have yellow stripes or are mottled turning the whole leaf blade white; the palea and lemma are distorted and turn brown; plants have fewer and smaller roots and the roots may be dry
Leaf Blast
Lesions vary from round or oval spots with a gray or white center surrounded by a reddish brown border to elongated spots with pointed ends having a gray to white dead center; elongated lesions may have a bright yellow border, a narrow reddish-brown border, or both, with the outer margin being yellow
Rice Blast
Spots or lesions develop on leaves, nodes, and different parts of the panicles and grains, usually with no spots on the leaf sheaths; spots are often pointed or diamond shaped; the center of the spot is gray or whitish and the margin is brown or a reddish brown and the spots can elongate; leaf blast can attack at the tillering stage and completely kill some varieties
Sheath Blight
Gray-green, water-soaked spots appear on sheaths near water line from tillering to internode movement; oval spots develop with a gray center and dark gray border; when dry, spots are tan to white with reddish-brown to brown borders; white, thread-like growth spreads over healthy sheaths and leaves, forming new lesions; lesions commonly form a continuous pattern of wide, tan to gray, dead areas with narrow reddish-brown bands; brown sclerotia are loosely attached to blighted plant parts; panicle emerging from boot, fails to branch out, turns paper white with some brown discoloration, remains upright and fails to fill grain
Sheath Net Blotch
Small, yellow oval lesions 1-2 cm long develop on the leaf sheaths near the waterline; eventually the lesions expand becoming whitish, and are covered by a brown, netlike pattern formed from horizontal and longitudinal streaks
Sheath Spot
Spots on upper portion of leaf sheaths near the leaf blade, usually appearing midway in the rice canopy; spots are oval with white to pale green centers and a thick, dark, reddish-brown border; spots remain separated and do not progress extensively onto leaves
Stackburn
Oval to circular spots develop on the leaves which are tan becoming gray to white and are surrounded by a narrow, dark brown border; small black dots are produced in the centers of older lesions; infection of the kernels produces discolored, shriveled, or brittle grains; dark brown lesions may also occur on the coleoptiles of germinating seeds or young seedlings
White Leaf Streak
Small, interveinal, oblong to linear lesions develop on both leaf surfaces; lesions are white to light gray and surrounded by a distinct, very narrow, brown margin; long, uninterrupted white streaks may develop on heavily infected plants; young lesions may be white on the leaf surface and brown on the underside
White Tip
Whitened leaf tips become dry and shred and the central part and the base of infected leaves are sometimes darker green; upper leaves are most infected with the flag leaf being twisted; other symptoms include reduction in the length of the panicle, reduction in the number of grains, sterile flower, misshapen grains, stunting, late ripening and maturation, and production of tillers from the upper nodes
YELLOW
Crinkle
Leaves of emerging seedlings are crinkled or distorted and may develop pale yellow, lens-shaped lesions; entire leaves may turn yellow, and roots become stubby and bushy
Aggregate Sheath Spot
Oval lesions develop on the lower leaf sheaths at the waterline and have a gray-green to straw-colored center surrounded by a distinct brown margin; sclerotia are rectangular to globose and brown; leaves of diseased sheaths generally turn yellow and die
Brown Spot
Small, round, dark brown spots with a dull yellow margin enlarging to round spots with a gray center and a thick, dark brown border; spots are usually observed on pale green rice plants growing under stress; dark brown to black spots on grain hulls often large enough to cover entire grain; affected grain may be poorly filled and chalky
Cercospora Sheath Spot
Reddish or purple brown, netlike spot on sheaths of lower leaves; blades of affected leaves turn yellow and die
Chlorotic Streak
Young leaves are stunted, have yellow streaks, and are spotted; other symptoms include poor emergence of panicles with sterile or discolored spikelets, leaf distortion, vein swelling, excess tillering, and formation of aerial roots
Cyst Nematode
Plants are stunted and have retarded growth; leaves are severely dry and yellow, and the number of tillers is reduced
Downy Mildew
Leaves may have yellow to white spots or patches and the flag leaf and upper leaves may be curled, bent, or twisted; the panicle fails to emerge completely and is contorted and fails to produce any grain, but remains green
Dwarf
Plants are stunted and produce small tillers or a reduced number of tillers; root growth is severely retarded and irregular yellow specks are formed on the leaves and sometimes on the leaf sheaths
Eyespot
Lesions appear on leaves as small, oval, water-soaked gray-green spots; a yellow halo frequently surrounds young lesions and as the disease progresses, the lesions enlarge and become white to straw-colored and delimited by a well-defined, brown margin; leaves turn yellow and wilt immediately after heading
Foot Rot
Leaf sheaths typically exhibit a dark brown decay, and the attached leaves turn yellow and wilt; infected culms and internodes turn black; roots attached to infected nodes decay and fall off; bacterial ooze may be present inside the culms and infected plants have an unpleasant odor
Giallume
Leaves are yellow to orange, dry, small, erect and may have serrated margins; plants are stunted, have a reduced number of tillers and produce blasted florets; severely infected plants die
Grassy Stunt
Plants are stunted, show a proliferation of tiller, and have short, narrow, pale green to pale yellow leaves; leaves also may have numerous small, irregular, dark brown or rust-colored spots; infected plants produce no panicles or a few panicles with unfilled kernels
Halo Blight
Circular, pale green to yellowish brown lesions, 2-10 mm in diameter develop on leaf blades; the lesions are surrounded by a distinct halo and have a dark brown spot or stripe in the center
Hoja Blanca
Plants are stunted and the leaves have yellow stripes or are mottled turning the whole leaf blade white; the palea and lemma are distorted and turn brown; plants have fewer and smaller roots and the roots may be dry
Leaf Blast
Lesions vary from round or oval spots with a gray or white center surrounded by a reddish brown border to elongated spots with pointed ends having a gray to white dead center; elongated lesions may have a bright yellow border, a narrow reddish-brown border, or both, with the outer margin being yellow
Necrosis Mosaic
Plants have elongate or spindle-shaped, yellow flecks and streaks on the lower leaves; dry flecks may develop on the basal portions of stems and sheaths; plants may be stunted, have a reduced number of tillers, and have a spreading growth habit
Orange Leaf
Seedlings have short, malformed leaves that are serrated and yellow, and the leaf tips are twisted; leaves will turn yellow-orange beginning at the tip; eventually the leaves become entirely orange, roll inward, and dry out
Ragged Stunt
Plants are stunted and develop short, dark green leaves that are serrated and twisted along one or both edges, giving them a ragged appearance; vein swellings or galls appear on the underside of the leaf blade and on the outer surface of the leaf sheath near the collar; the galls are pale yellow to sometimes brown
Rice-Root Nematodes
Aboveground symptoms include retarded growth, reduction in the tiller number, stunted, yellowing, and late maturation
Root-Knot Nematodes
Aboveground symptoms include yellowing, wilting, retarded maturation, and reduction in growth and tillering which eventually develops into root galls
Sheath Net Blotch
Small, yellow oval lesions 1-2 cm long develop on the leaf sheaths near the waterline; eventually the lesions expand becoming whitish, and are covered by a brown, netlike pattern formed from horizontal and longitudinal streaks
Stripe
Early infection develops yellow leaves, which remain folded and wilt and droop as they elongate; later leaves develop yellow stripes or spotting and dry streaks; plants are stunted
Stripe Necrosis
Plants are stunted and have a reduced number of tillers; leaves have yellow stripes and exhibit drying
Transitory Yellowing
Plants are stunted and have a reduced number of tillers; lower leaves turn yellow to bright yellow or orange; at heading, plants are noticeable because they produce no panicles or poorly formed panicles
Ufra
Plants show malformations and yellowing or mosaic discoloration of the upper leaves; later scattered dark stains appear on the leaves and parts of the upper internodes of the stem turn dark brown; disease is most evident on the panicles where the ufra may be swollen and ripe; the panicle coils and remains enclosed within the leaf sheath; the panicle may emerge but will be distorted, sterile or empty, and produce normal grains only near the tip
Yellow Dwarf
Plants are stunted, tiller profusely, and show a general yellow of the tissues, producing pale green or yellow leaves; plants infected in the seedling stage usually die prematurely
Yellow Mottle
Plants are stunted and produce few tillers; leaves are mottled or have yellowish streaks and are often twisted or crinkled; panicles of infected plants show incomplete emergence and sterile kernels
No Distinct Discoloration
Bunchy Stunt
Infected plants are stunted, tiller profusely, the leaves are short and narrow, and young leaves may show mottling; branches may form from the upper nodes and leaves may be produced in bunches in severe cases
Seedling Blight
Seedlings with brown discoloration of growing point, leaf base, and/or roots; affected seedlings are stunted, yellowed, then killed; seedlings 1-4 inches tall dying in flood or after flushing field
Flower
BROWN
Panicle Blast
Panicle branches and small branches holding florets with brown discoloration, later turning gray; portions of branch above these lesions turn white, and grains stop filling
Rotten Neck Blast
Brown discoloration of the panicle node and surrounding area; stem of panicle shrivels and breaks over; panicle turns white, and grain stops filling; node area may become gray as fungus grows and produces more spores
Sheath Rot
Reddish-brown discoloration of the flag leaf sheath with panicles emerging poorly; panicle may be twisted, covered with a white powdery mass, and has florets with brown discoloration; panicle may fail to emerge fully from boot, and grain may not fill
GRAY
Panicle Blast
Panicle branches and small branches holding florets with brown discoloration, later turning gray; portions of branch above these lesions turn white, and grains stop filling
WHITE
Panicle Blast
Panicle branches and small branches holding florets with brown discoloration, later turning gray; portions of branch above these lesions turn white, and grains stop filling
Rotten Neck Blast
Brown discoloration of the panicle node and surrounding area; stem of panicle shrivels and breaks over; panicle turns white, and grain stops filling; node area may become gray as fungus grows and produces more spores
No Distinct Discoloration
Bacterial Palea Browning
Symptoms usually first appear at early flowering as light brown, water-soaked lesions on the lemma or palea that eventually turn dark brown
Giallume
Leaves are yellow to orange, dry, small, erect and may have serrated margins; plants are stunted, have a reduced number of tillers and produce blasted florets; severely infected plants die
Rice Blast
Spots or lesions develop on leaves, nodes, and different parts of the panicles and grains, usually with no spots on the leaf sheaths; spots are often pointed or diamond shaped; the center of the spot is gray or whitish and the margin is brown or a reddish brown and the spots can elongate; leaf blast can attack at the tillering stage and completely kill some varieties
Straighthead
Symptoms are not visible until the late boot to heading stages; affected plants may be darker green with more erect leaves than normal plants; the most common symptom is erect panicles that are partially to completely sterile and of insufficient weight to cause the panicle to tip over during the grain-filling stage as in normal rice
White Tip
Whitened leaf tips become dry and shred and the central part and the base of infected leaves are sometimes darker green; upper leaves are most infected with the flag leaf being twisted; other symptoms include reduction in the length of the panicle, reduction in the number of grains, sterile flower, misshapen grains, stunting, late ripening and maturation, and production of tillers from the upper nodes
Fruit
No Distinct Discoloration
Stackburn
Oval to circular spots develop on the leaves which are tan becoming gray to white and are surrounded by a narrow, dark brown border; small black dots are produced in the centers of older lesions; infection of the kernels produces discolored, shriveled, or brittle grains; dark brown lesions may also occur on the coleoptiles of germinating seeds or young seedlings
BLACK
Black Sheath Rot
Gray or brown spots confined to lower leaf sheaths appear during internode movement; spots enlarge to cover entire leaf sheaths; spots are gray with a dark gray or brown to black upper and lower border; lower leaves of affected sheaths die and turn brown; reddish-brown, thread-like growth is observed on culm under rotted sheaths; black, pepper-like fruiting structures occur on rotted sheath during growing season; plants have a reduced number of tillers and frequently only one panicle per plant is produced; disease can cause lodging and incomplete emergence of the panicles
Brown Spot
Dark brown to black spots develop on grain hulls often large enough to cover entire grain; affected grain may be poorly filled and chalky
Ear Blight
Brown or black streaks create a discoloration and/or blight of the entire panicle or portions of the panicle, including the neck, branches, internodes, nodes, and spikelets
False Smut
Rice kernels are replaced by globose, velvety spore balls up to 1 cm in diameter, which burst out from between the glumes; the balls consist of three spore-producing layers surrounding a hard core of tightly woven mycelium; the innermost and middle layers contain immature spores and are pale yellow and orange yellow, and the outer layer, which consists of mature spores, is olive to black in color
Grain Spotting or Pecky Rice
Hulls of developing or maturing rice grain develop dark spots or areas creating a general grain darkening; individual kernels have small black spots to large white spots with a brown margin; affected kernels may be chalky and break during milling
Kernel Smut
Grain is poorly filled and covered with and/or partially filled with a black, powdery mass that rubs off easily
BROWN
Bacterial Palea Browning
Symptoms usually first appear at early flowering as light brown, water-soaked lesions on the lemma or palea that eventually turn dark brown
Black-Streaked Dwarf
Plants are stunted with dark green discoloration of the leaves, and occasional vein swellings on the sheath; leaf tips are twisted and may split at the leaf margins; dark brown streaks consist of white, swollen veins or galls that develop along the undersides of the leaves and on the sheaths and culms; dark brown blotches may form on the kernels
Brown Spot
Dark brown to black spots develop on grain hulls often large enough to cover entire grain; affected grain may be poorly filled and chalky
Ear Blight
Brown or black streaks create a discoloration and/or blight of the entire panicle or portions of the panicle, including the neck, branches, internodes, nodes, and spikelets
Glume Blight
Appears as brown, pinhead-sized lesions or as lens-shaped lesions with bleached centers and brown margins on the panicles; when the panicle becomes extremely wet, reddish brown blotches appear on the glumes
Grain Rot
On seedlings, symptoms consist of a brown, water-soaked soft rot of the leaf sheaths accompanied by wilting or soft rot of the leaves; on the panicle, infected grains are shrunken and pale green, becoming dirty yellow to brown and dry; a brown margin between the infected and healthy parts of the grain is diagnostic
Grain Spotting or Pecky Rice
Hulls of developing or maturing rice grain develop dark spots or areas creating a general grain darkening; individual kernels have small black spots to large white spots with a brown margin; affected kernels may be chalky and break during milling
Hoja Blanca
Plants are stunted and the leaves have yellow stripes or are mottled turning the whole leaf blade white; the palea and lemma are distorted and turn brown; plants have fewer and smaller roots and the roots may be dry
Myrothecium Blotch
Irregular to oblong lesions with dark brown centers and a lighter brown margin, occur on the flag leaf sheaths; brown lesions, sometimes with whitish centers, also occur on the glumes of affected plants
Rice Blast
Spots or lesions develop on leaves, nodes, and different parts of the panicles and grains, usually with no spots on the leaf sheaths; spots are often pointed or diamond shaped; the center of the spot is gray or whitish and the margin is brown or a reddish brown and the spots can elongate; leaf blast can attack at the tillering stage and completely kill some varieties
Water Mold
Ball of fungal strands surrounding seed under water; copper brown or green spot on soil surface surrounding seed when field is drained
COPPER
Water Mold
Ball of fungal strands surrounding seed under water; copper brown or green spot on soil surface surrounding seed when field is drained
DARK
Grain Spotting or Pecky Rice
Hulls of developing or maturing rice grain develop dark spots or areas creating a general grain darkening; individual kernels have small black spots to large white spots with a brown margin; affected kernels may be chalky and break during milling
GRAY
Rice Blast
Spots or lesions develop on leaves, nodes, and different parts of the panicles and grains, usually with no spots on the leaf sheaths; spots are often pointed or diamond shaped; the center of the spot is gray or whitish and the margin is brown or a reddish brown and the spots can elongate; leaf blast can attack at the tillering stage and completely kill some varieties
GREEN
False Smut
Rice kernels are replaced by globose, velvety spore balls up to 1 cm in diameter, which burst out from between the glumes; the balls consist of three spore-producing layers surrounding a hard core of tightly woven mycelium; the innermost and middle layers contain immature spores and are pale yellow and orange yellow, and the outer layer, which consists of mature spores, is olive to black in color
Grain Rot
On seedlings, symptoms consist of a brown, water-soaked soft rot of the leaf sheaths accompanied by wilting or soft rot of the leaves; on the panicle, infected grains are shrunken and pale green, becoming dirty yellow to brown and dry; a brown margin between the infected and healthy parts of the grain is diagnostic
Water Mold
Ball of fungal strands surrounding seed under water; copper brown or green spot on soil surface surrounding seed when field is drained
LIGHT
Glume Blight
Appears as brown, pinhead-sized lesions or as lens-shaped lesions with bleached centers and brown margins on the panicles; when the panicle becomes extremely wet, reddish brown blotches appear on the glumes
Scab
Bleached lesions or a bleached discoloration develops on the glumes; affected areas become yellow to salmon with the production of spores; infected grains are light, shrunken, and brittle and may be sterile
ORANGE
False Smut
Rice kernels are replaced by globose, velvety spore balls up to 1 cm in diameter, which burst out from between the glumes; the balls consist of three spore-producing layers surrounding a hard core of tightly woven mycelium; the innermost and middle layers contain immature spores and are pale yellow and orange yellow, and the outer layer, which consists of mature spores, is olive to black in color
Scab
Bleached lesions or a bleached discoloration develops on the glumes; affected areas become yellow to salmon with the production of spores; infected grains are light, shrunken, and brittle and may be sterile
RED
Glume Blight
Appears as brown, pinhead-sized lesions or as lens-shaped lesions with bleached centers and brown margins on the panicles; when the panicle becomes extremely wet, reddish brown blotches appear on the glumes
Rice Blast
Spots or lesions develop on leaves, nodes, and different parts of the panicles and grains, usually with no spots on the leaf sheaths; spots are often pointed or diamond shaped; the center of the spot is gray or whitish and the margin is brown or a reddish brown and the spots can elongate; leaf blast can attack at the tillering stage and completely kill some varieties
WHITE
Grain Spotting or Pecky Rice
Hulls of developing or maturing rice grain develop dark spots or areas creating a general grain darkening; individual kernels have small black spots to large white spots with a brown margin; affected kernels may be chalky and break during milling
Myrothecium Blotch
Irregular to oblong lesions with dark brown centers and a lighter brown margin, occur on the flag leaf sheaths; brown lesions, sometimes with whitish centers, also occur on the glumes of affected plants
Rice Blast
Spots or lesions develop on leaves, nodes, and different parts of the panicles and grains, usually with no spots on the leaf sheaths; spots are often pointed or diamond shaped; the center of the spot is gray or whitish and the margin is brown or a reddish brown and the spots can elongate; leaf blast can attack at the tillering stage and completely kill some varieties
Sheath Rot
Reddish-brown discoloration of the flag leaf sheath with panicles emerging poorly; panicle may be twisted, covered with a white powdery mass, and has florets with brown discoloration; panicle may fail to emerge fully from boot, and grain may not fill
Udbatta
Erect spikes develop at heading that are covered by white mycelium; the flag leaf and sheath of infected tillers are slightly distorted and the flag leaf and upper leaves may appear silvery; infected plants may also be stunted
YELLOW
False Smut
Rice kernels are replaced by globose, velvety spore balls up to 1 cm in diameter, which burst out from between the glumes; the balls consist of three spore-producing layers surrounding a hard core of tightly woven mycelium; the innermost and middle layers contain immature spores and are pale yellow and orange yellow, and the outer layer, which consists of mature spores, is olive to black in color
Grain Rot
On seedlings, symptoms consist of a brown, water-soaked soft rot of the leaf sheaths accompanied by wilting or soft rot of the leaves; on the panicle, infected grains are shrunken and pale green, becoming dirty yellow to brown and dry; a brown margin between the infected and healthy parts of the grain is diagnostic
Scab
Bleached lesions or a bleached discoloration develops on the glumes; affected areas become yellow to salmon with the production of spores; infected grains are light, shrunken, and brittle and may be sterile
No Distinct Discoloration
Chlorotic Streak
Young leaves are stunted, have yellow streaks, and are spotted; other symptoms include poor emergence of panicles with sterile or discolored spikelets, leaf distortion, vein swelling, excess tillering, and formation of aerial roots
Downy Mildew
Leaves may have yellow to white spots or patches and the flag leaf and upper leaves may be curled, bent, or twisted; the panicle fails to emerge completely and is contorted and fails to produce any grain, but remains green
Grassy Stunt
Plants are stunted, show a proliferation of tiller, and have short, narrow, pale green to pale yellow leaves; leaves also may have numerous small, irregular, dark brown or rust-colored spots; infected plants produce no panicles or a few panicles with unfilled kernels
Rotten Neck Blast
Brown discoloration of the panicle node and surrounding area; stem of panicle shrivels and breaks over; panicle turns white, and grain stops filling; node area may become gray as fungus grows and produces more spores
Sheath Blight
Gray-green, water-soaked spots appear on sheaths near water line from tillering to internode movement; oval spots develop with a gray center and dark gray border; when dry, spots are tan to white with reddish-brown to brown borders; white, thread-like growth spreads over healthy sheaths and leaves, forming new lesions; lesions commonly form a continuous pattern of wide, tan to gray, dead areas with narrow reddish-brown bands; brown sclerotia are loosely attached to blighted plant parts; panicle emerging from boot, fails to branch out, turns paper white with some brown discoloration, remains upright and fails to fill grain
Sheath Brown Rot
On seedlings, a systemic discoloration of the leaf sheath occurs, which may spread to the midrib or veins of the leaves; on the sheath, oblong to irregular dark green, water-soaked lesions occur, which become gray-brown or brown and may be surrounded by a dark brown margin; grains of infected panicles are discolored, deformed, or empty
Straighthead
Symptoms are not visible until the late boot to heading stages; affected plants may be darker green with more erect leaves than normal plants; the most common symptom is erect panicles that are partially to completely sterile and of insufficient weight to cause the panicle to tip over during the grain-filling stage as in normal rice
Transitory Yellowing
Plants are stunted and have a reduced number of tillers; lower leaves turn yellow to bright yellow or orange; at heading, plants are noticeable because they produce no panicles or poorly formed panicles
Ufra
Plants show malformations and yellowing or mosaic discoloration of the upper leaves; later scattered dark stains appear on the leaves and parts of the upper internodes of the stem turn dark brown; disease is most evident on the panicles where the ufra may be swollen and ripe; the panicle coils and remains enclosed within the leaf sheath; the panicle may emerge but will be distorted, sterile or empty, and produce normal grains only near the tip
White Tip
Whitened leaf tips become dry and shred and the central part and the base of infected leaves are sometimes darker green; upper leaves are most infected with the flag leaf being twisted; other symptoms include reduction in the length of the panicle, reduction in the number of grains, sterile flower, misshapen grains, stunting, late ripening and maturation, and production of tillers from the upper nodes
Yellow Mottle
Plants are stunted and produce few tillers; leaves are mottled or have yellowish streaks and are often twisted or crinkled; panicles of infected plants show incomplete emergence and sterile kernels