Rice:Key

KEY TO RICE PESTS AND NUTRITIONAL DISORDERS

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