Seedling blight or Damping-off

• Seedlings with a rotted appearance
• Seedlings are easily pulled from the soil because of rotted roots

Phytophthora root rot

• Seed rot and pre-emergence damping-off
• root and stem rot of older seedlings
• Chlorosis and wilting of leaves with dark brown discoloration on lower stem starting at soil line in more mature plants
• Root rot of older plants
• Affected plants will occur in clusters in fields

Rhizoctonia root rot

• Pre-emergence or post-emergence damping off
• Brown or reddish brown lesions on larger seedlings and young plant stems near soil line and on taproot
• Stems showing infection may break at the area of lesions

Anthracnose

• Necrosis of veins
• Leaf rolling
• Cankers develop on petiole
• Premature defoliation of plant

Asian soybean rust

• Fungal spores (spores are nearly undetectable with the human eye at first infection)
• Yellow areas appear on leaves and look nearly translucent
• Advanced disease produces spots normally clustered alongside veins
• Pustules (pimple-like structures) found on underside of the leaf
• Premature defoliation of plant

Soybean mosaic virus

• Stunting, mottling and curling of leaves
• leaves may be puckered and misshapen
• Diseased pods may be stunted and curved
• Seeds from diseased pods may be discolored

Soybean cyst nematode

• Slight to severe stunting and chlorosis
• Decreased nodulation
• Slow closing canopy
• Some root decay
• Cysts on roots first appear as white lemon- shaped females on root surface
• Cysts turn dark brown with age
• Foliar symptoms are similar to nitrogen and/or potassium deficiency

Bacterial blight

• Small Angular water soaked spots on leaves.
• Lesions with centers that dry out and turn brown to black.
• Affected tissue may drop off, causing the leaf to look tattered.

Brown spot

• Irregular light-brown lesions that range in size from a small speck to a few mm in diameter
• Lesions will eventually turn to a brownish black
• Lesions normally appear on leaves but they can occur on the stems, petioles and pods

Downy mildew

• Pale green to yellow spots on upper leaf surface
• Lesions will turn to a grayish brown to dark brown color with a yellow or light green margin.
• Gray tufts of fungal growth may form on lower leaf surface
• Leaves with a sever affection can turn brown and drop off
• Where pods are present a whitish fungal growth may develop on the interior of the pods and seed coats

Sudden death syndrome

• Yellow interveinal blotches
• Blotches become necrotic leaving green tissue along the veins
• Leaf blades will drop off leaving petioles attached to stem
• Foliar symptoms similar to brown stem rot
• Internal taproot tissue will turn light brown to gray
• Pith of stem remains white

Charcoal rot

• Loss of vigor in mature plants
• Leaves turn yellow and wilt but do not drop off
• Taproot and lower stem will develop a light gray or silver color after flowering
• Small black fungal structures form in taproot and stem tissues

Stem canker

• Slightly sunken brown lesions at the base of leaf nodes
• Lesions can expand into elongated reddish-brown sunken cankers
• Plant parts above cankers may die

Brown stem rot

• Sudden discoloration of leaves
• Brown tissue between leaf veins with green tissue along veins
• Leaves remain attached
• Infected plants display a browning of the pith inside the stem

Pod and stem blight

• No definite leaf or stem lesions
• Fungal spore-bearing structures appear as black specks in linear rows on dead stems and poorly-developed pods.