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Disease Management in Rye
Tom Kucharek
Anthracnose
Cause: Fungus ( Colletotrichum graminicola )
Symptoms: If present, Anthracnose is likely to
be found in lower part of plant during the first two
weeks of March. Stem bases become bleached and later turn
brown. Purplish-brown, water- soaked blotches are formed
at or near nodes. Toward maturity of rye plant,
elongated, black, raised, spore bearing pustules, smaller
than a pinhead appear on stems and leaf sheaths and
blades or even floral parts. Root rot, culm
deterioration, lodging, sterility and premature ripening
occur.
Host Range: Rye, oats, barley, timothy, red
top, certain wheats, corn, sorghum, Johnson grass, sudan
barnyard grass, quack grass, cheat (chess), and wild
barley.
Control: Crop rotation with non-grasses. This
disease is associated with low pH and low phosphorus
soils. The presence of broom sedge is an indicator of
such soils.
Helminthosporium Leaf Spot
Cause: Fungus ( Helminthosporium sativum Syn:
Bipolaris sorokiniana )
Symptoms: This fungus is seedborne, causing
discolored shriveled seed. If such seed is planted,
germination may be low with pre- and post-emergence
damping-off (seedling blight). It may cause root and
crown rot. Crown rot will appear as a low vigor plant
with dark brown-green-black lesions on leaf sheaths.
Lesions in leaves and leaf sheaths are usually elongated,
football-shaped, reddish-brown in color and often
accompanied by a yellow halo. When sporulation occurs,
the lesion will have a greenish cast. Flower and head
parts (glumes, etc.) are also susceptible.
Host Range: Wheat, barley, rye and numerous
other crop and weed species.
Control: Use disease free seed. Treat seed with
fungicide. Such a treatment has increased germination of
infected seed. Use crop rotation. Use a fungicide spray
program with Mancozeb (e.g. Dithane M-45, Manzate 200,
etc) as described for use on wheat.
Leaf Rust
Cause: Puccinia rubigovera f. sp. secalis
Symptoms: Similar to leaf rust of wheat: a) 1
to 2 mm round or oblong raised, orange-red pustules
(uredia) on leaf blades, leaf sheaths and sometimes on
glumes and awns. They are found beginning in late winter
to early spring up though the heading stage. b) Black
pustules (telia) covered by leaf surface. This stage is
usually formed around heading time.
Host Range: Anchusa sp., Secale sp.,
possibly other small grain crops.
Control: None necessary at this time.
Pythium Root Rot
Cause: Fungus ( Pythium spp.)
Symptoms: Preemergence damping-off.
Post-emergence damping-off. Plants that emerge
successfully are stunted, and rot at base of stem. Root
tips appear water-soaked. Occurs most frequently in the
fall. Lower leaves become yellow. Laboratory diagnosis
should be used for this disease. Can be confused with or
occur with nitrogen deficiency.
Host Range: Wheat, rye, barley, oats, ryegrass,
peanuts, corn, sorghum, soybeans, tobacco, rice,
bermudagrass, and many other plant species.
Control: Seed treatment aids in control up to
emergence. Avoid planting before the first of October
with wheat, barley and rye and first of September with
oats. For crops intended for grain production, planting
should be done after October. Cool temperatures will
reduce the activity of this fungus. Serious losses may
require replanting. Seed treatment with Apron may be
beneficial.
Seedling Blight
Cause: Fungi ( Pythium spp., Rhizoctonia
spp., Helminthosporium sp., Fusarium sp.)
Symptoms: Pre or postemergence stunting,
distortion or death of seedling. Rotting of young roots
and culms present. Water-soaking of roots, reddish or
brown lesions in young plant parts. May mimic nitrogen
deficiency (yellowing of lower leaves).
Host Range: Wheat, rye, barley, oats, corn and
many crop and weed species.
Control: Avoid deep planting of seed. Crop
rotation with non-cereal crops. Bury stubble. Seed
treatment. Avoid planting before the first of November
for crops intended for grain production. Cool soil
temperatures reduce Pythium seedling blight in Florida.
Common Root Rot
Cause: Several fungi ( Helminthosporium spp.,
Fusarium spp., Rhizoctonia spp.)
Symptoms: Stunted plants which may be
accompanied by purpled leaves. Purplish coloration of
leaves may also occur due to cold damage or some other
stress factor. It may occur in patches or where small
grains have been grown on same land for several years, it
may be more general in field. Tan-brown lesions in roots
and basal leaf sheaths. Inner tissues of crown may be
brown. May follow drought, nematode or insect damage.
Host Range: Wheat, barley, rye, oats, corn and
many crop and weed species.
Control: Crop rotation with non-cereal crops.
Bury stubble. Use seed treatment.
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