ALABAMA A&M AND AUBURN UNIVERSITIES Diseases of Barley, Rye, and Triticale in Alabama ANR-903

Barley, rye, and triticale are cereal most susceptible, followed by barley, ment fungicides and “IPM For Small crops grown in Alabama either as a oats, triticale, and rye, which is least Grains.” Maintain proper soil fertility winter grain or as winter grazing. susceptible. Crop rotation is the best levels to promote vigorous root This publication summarizes the control for take-all root rot. Care growth. major diseases and control measures must be taken to eliminate all grass of these crops that are commonly species from the rotation, because found in the state. the fungus can survive on a variety Foliar Diseases of grass species. Other control mea- sures include the use of nitrogen fer- Scald Root And Crown tilizer in the ammoniacal form, par- Scald is caused by the fungus Diseases ticularly in areas where the soil pH is Rhynchosporium secalis; it is a dis- acidic, to lessen the disease. ease of both barley and rye. Yield Take-All Root Rot Nitrogen in the nitrate form may in- loss occurs primarily through re- duced kernel weight. In severe infec- Take-all root rot, caused by the crease the severity of the disease. tions, both the number of kernels fungus Gaeumannomyces gramminis per head and the number of heads var. tritici, is one of the most serious Common Root Rot And per plant may be reduced. The root rotting diseases of barley, Seedling Blight pathogen is carried from season to wheat, rye, and triticale. The fungus Common root rot is caused by season on infected plant debris and survives in crop stubble. one or more fungi. Depending on through infected seed. The disease Infections can occur anytime dur- the location, fungal pathogens asso- spreads within a crop by rain that ing a growing season. Early infection ciated with diseases of root and splashes spores from the lesions on causes the most damage, because crown tissue include Cochliobolus infected plants onto leaves of unin- both roots and culms are affected. sativus, Fusarium culmorum, and F. fected plants. Infections when the plant is ap- graminearum. In Alabama, C. Symptoms. Scald is easily recog- proaching maturity are usually con- sativus is frequently isolated from nized by the pale gray or bluish-gray fined to root tissue and cause only small grains. It survives as thick lesions on leaves. As the infection minor damage. Root infection is fa- walled conidia in the soil. advances, the centers of lesions dry vored by cool, moist soil conditions. Symptoms. Developing seedlings out and bleach, becoming light gray, Symptoms. The most obvious may be killed, or they may be stunt- tan, or white with dark brown edges. symptom of take-all root rot is the ed, with brownish roots and coleop- development of white heads during tiles. Older plants have small, oval, the grain filling period. Infection and brown lesions on roots, the usually attacks patches of plants that lower leaf sheath, or the subcrown become stunted. Roots of affected internode. plants are dark brown toARCHIVE black be- Control. Using clean, certified cause of fungal invasion. As the seed can reduce seedling infections. plant matures, its roots become rot- Fungicide seed treatments can also ten and brittle until the plant can be aid in controlling seedborne infec- easily pulled from the soil. tions. A fungicide with a broad spec- Control. Barley, triticale, and rye trum of activity appears to work are all susceptible to take-all root rot. best. Ask your county Extension of- In order of susceptibility, wheat is fice for information on seed treat- Scald on barley (courtesy T. Khan).

Visit our Web site at: www.aces.edu Control. Scald is controlled by Control. Spot blotch is best con- See Circular ANR-458, “IPM for Small rotation with nonhost crops such as trolled by resistant varieties. The use Grains,” for a listing of labeled seed a forage legume or plowing under of pathogen-free seed or a fungicide treatment fungicides. infected residue. No cultivar with a seed treatment can reduce seedborne high degree of resistance has been or soilborne inoculum. Leaf Rust found. Leaf rust is a common disease on Powdery Mildew many cereal crops. The disease is Net Blotch Powdery mildew is caused by the caused by the Puccinia fungus— Net blotch is caused by the fungus fungus Erysiphe graminis. The Puccinia hordei on barley, Puccinia Drechslera teres. It can cause disease pathogen attacks barley, rye, and trit- reconita on triticale and rye. Leaf in barley, rye, and triticale. The net icale. The fungus survives as cleis- rust is favored by moist weather and blotch fungus is carried from season tothecia (black fungal fruiting bod- temperatures ranging from 55° to 75°F. to season on infected crop residue ies) in plant debris. With fall rains, and seed. spores are released from cleistothe- cia, and they infect nearby plants. Spores produced on these plants may be carried by winds a long dis- tance and infect other plants.

Leaf rust on barley (courtesy T. Khan).

Net blotch on barley (courtesy T. Khan). Symptoms. Leaf rust symptoms appear as small, round, light orange- Symptoms. Net blotch symptoms brown pustules on the leaf blade appear as a distinctive dark brown and leaf sheath. They may also occur reticulate (netting) pattern that devel- on heads of very susceptible culti- ops in the otherwise light brown le- vars in the advanced stages of an sion. epidemic. Brown, oblong pustules Control. Resistant varieties offer appear later in the season. the best means of control. Use of Control. Resistant varieties are pathogen-free seed or seeds treated the most practical control measure. with a fungicide can prevent the in- Foliar fungicide—labeled only for troduction of the pathogen into clean barley and rye—can be effective fields. against leaf rust. But, because of the limited acreage of these crops, fungi- Spot Blotch cide use would be expensive. Spot blotch, caused by Cochlio- Powdery mildew on barley bolus sativus, is a common foliar dis- (courtesy T. Khan). Septoria Leaf And ease of small grains in Alabama. It is Glume Blotch favored by warm, humid weather. Symptoms. Symptoms appear as The septoria leaf and glume Yield losses can be as high as 36 pure white, fluffy growth on the sur- blotch disease complex is a common percent. face of the leaf. This growth enlarges disease of rye, barley, and triticale. Symptoms. Spots develop on rapidly and individual colonies coa- Septoria leaf blotch on barley is leaves and leaf sheaths ARCHIVEat all stages caused by the fungus Septoria ave- lesce, producing so many spores that of plant development. Lesions are the leaf appears powdery. Infection nae f. sp. triticea, and on rye and round to oblong, with a definite mar- leads to premature yellowing and triticale by S. tritici. Glume blotch of gin varying in size. The spots may later death of the leaf. rye, barley, and triticale is caused by continue to enlarge and coalesce to Control. The use of resistant vari- S. nodorum. Septoria diseases are fa- form blotches that cover large areas eties is the best method of disease vored by warm, wet weather. Spores of the leaf. Older lesions are olive- control. The fungicide seed treatment produced during wet weather are colored because of sporulation of the Baytan can offer early season protec- spread by splashing rain, and they fungus. tion for 8 to 10 weeks after planting. initiate infections throughout the year.

2 Alabama Cooperative Extension System come dry. Pycnidia (fungal fruiting Symptoms. Infected seed appear bodies) appear as small, black normal. However, when it germi- specks within the lesions. The symp- nates, the fungus becomes active and toms of glume blotch start out as grows slowly in the growing point of brown or grayish spots on the leaf the plant. Diseased plants appear blade and leaf sheath. Later in the normal until heading but may be season oval or lens-shaped, red- taller and mature earlier than sur- brown spots develop along the leaf rounding healthy plants. The fungus blade and sheath and affect the en- then grows rapidly and forms a com- tire leaf. Spots may develop on the pact spore mass to replace the cereal glumes and awns after heading. If head. The black powdery spores seed is infected, pycnidia may devel- blow away to leave a bare stalk. The op on the seed surface. spores are released as the rest of the Control. Control measures in- crop is flowering, and they infect the clude use of pathogen-free seed; use developing grains of healthy heads, of seed protectant fungicide; and de- remaining dormant in the grain until struction of infected host residue that seed is sown the next season. through deep plowing, or crop rota- Control. Loose smut is controlled tion, preferably with a nongrass by treating seed with a systemic crop. There are no known cultivars fungicide that penetrates the devel- resistant to the septoria disease com- oping seedling to kill the internal in- plex. Some varieties may differ in fection. For information on fungicide Septoria blotch on triticale. susceptibility. See the Alabama seed treatments, see “IPM For Small Performance Comparison of Small Grains” for appropriate seed treat- Grain Varieties (Alabama Agricultural ment fungicides. Experiment Station) for the disease reactions of small grain varieties in your area. Virus Diseases Loose Smut Barley Yellow Dwarf Barley Yellow Dwarf Virus Smut diseases are caused by fungi (BYDV) can infect barley, wheat, that live as parasites on the host oats, triticale, and rye as well as sev- plant and produce soot-like spores in eral grasses. It is transmitted by grains or ears. Smut fungi may be aphid species that have fed on in- borne either on the inside or outside fected plants. The occurrence of of the seed. On barley and rye, loose BYDV therefore depends on condi- smut is caused by the fungus tions favorable for aphid build-up Ustilago tritici. Triticale is thought to and movement, such as cool, moist be resistant to loose smut. weather that favors grass and cereal growth as well as aphid multiplica- tion and migration. Symptoms. BYDV normally in- fects scattered single plants in a crop or causes small, circular patches of stunted plants. The disease begins as Septoria on glumes of triticale. yellowing, which starts at the tip of ARCHIVEthe leaf and progresses down. Infection of young plants may cause Symptoms. The symptoms of stunting, reduced grain formation, septoria leaf blotch are lesions on and grain filling. Late infection may leaves and leaf sheaths that are gray- not cause stunting but it may still re- ish green and turn light tan with age. duce yield. Lesions vary in size. Eventually, the lesions merge and may cover the whole area of the leaf. The leaf mar- gins often pinch and roll and be- Loose smut on barley (courtesy T. Khan).

Diseases Of Barley, Rye, And Triticale In Alabama 3 Wheat Soilborne Mosaic Wheat soilborne mosaic was first reported on wheat in Alabama around 1988. Wheat soilborne mosa- ic attacks wheat, rye, and barley. The virus is transmitted by the soilborne fungus Polymyxa graminis. The dis- ease is most often found in low- lying, wet areas of fields. Symptoms. Symptoms of wheat soilborne mosaic range from mild green to prominent yellow leaf mo- saics. Stunting as well as rosetting may occur to some extent with some strains. Warming spring temperatures slow and eventually stop disease de- velopment, thus confining symptoms to lower leaves. Control. Losses to barley seem to be minor. There is no information on Barley yellow dwarf on barley (courtesy T. Khan). resistance of barley and rye to this disease. Control. There are no known weighed, because BYDV may be BYDV-resistant cultivars. Controlling spread by insects that escape treat- the aphids in the field with insecti- ment or that emigrate from untreated cides can reduce the incidence of areas. BYDV is best controlled by barley yellow dwarf and increase late-fall planting so that the small yields. However, the economics of grain seedling avoids periods of high this practice must be carefully aphid activity.

Daniel J. Collins, Extension Plant Pathologist, Assistant Professor, Plant Pathology Use pesticides only according to the directions on the label. Follow all directions, precautions, and restrictions that are list- ed. Do not use pesticides on plants that are not listed on the label. The pesticide rates in this publication are recommended only if they are registered with the Environmental Protection Agency and the Alabama Department of Agriculture and Industries. If a registration is changed or cancelled, the rate listed here is no longer recommended. Before you apply any pesticide, check with your county Extension agent for the latest in- formation. ARCHIVETrade names are used only to give specific information. The Alabama Cooperative Extension System does not endorse or guarantee any product and does not recommend one product instead of another that might be similar. For more information, call your county Extension office. Look in your telephone directory under your county’s name to find the number. Issued in furtherance of Cooperative Extension work in agriculture and home economics, Acts of May 8 and June 30, 1914, and other related acts, in cooperation with the U.S. Department of Agriculture. The Alabama Cooperative Extension System (Alabama A&M University and Auburn University) offers educational programs, materials, and equal opportunity employment to all people without regard to race, color, national origin, religion, sex, age, veteran status, or disability. ANR-903 UPS, 3M50, New April 1995, ANR-903