Diseases-Forage Grasses-Book.Rdo

Diseases of forage grasses in humid temperate zones

COVER PHOTOGRAPH: Red thread disease, Corticium fuciforme, on perennial ryegrass. Courtesy of C. J. O'Rourke. The United States Regional Pasture Research laboratory, U.S. Department of Agriculture, Agricultural Research Service, University Park, Pennsylvania

THE AUTHORS

S. W. BRAVERMAN is affiliate associate professor of plant .pathology and F. L. LUKEZic is professor of plant pathology at The Pennsylvania State Univer sity. K. E. ZEIDERS is research plant pathologist, Agri cultural Research Service, United States Department of Agriculture. J. B. WILSON is adjunct professor of plant pathology at The Pennsylvania State University and former director of the U.S. Regional Pasture Re search Laboratory, Agricultural Research Service, United States Department of Agriculture at Univer sity Park.

The authors wish to express their appreciation to the scientists and others who have provided photo graphs or otherwise contributed to the preparation of this publication. Dr. T. Tominaga, Sayama-Chi, Japan; Dr. T. Egli, CffiA-Geigy, Ltd., Basel, Switzerland; and Dr. D. Schmidt, Swiss Federal Re search Station for Agronomy, Nyon, Switzerland provided photographs of bacterial diseases. Dr. C. J. O'Rourke, The Agricultural Institute, Dublin, Ire land; and Dr. P. Weibull, Landskrona, Sweden, pro vided photographs of fungus diseases. Photographs of the virus diseases are courtesy of Dr. P. L. Catherall, Welsh Plant Breeding Station, Aberystwyth, Dyfed County, Wales. Mrs. Teri-Anne Jordan assisted in preparation of the manuscript for the authors and editors.

Research reported in this publication is supported by funds from the Pennsylvania State Legislature, the United States Congress, and other government and private sources. Published by The Pennsylvania State Agricultural Experiment Station in cooperation with the U.S. Regional Pasture Research Laboratory, Uni versity Park, Pennsylvania, and agricultural experi ment stations of the Northeast Region. Authorized for publication 21 November, 1985.

The Pennsylvania State University, in compliance with federal and state laws, is committed to the pol icy that all persons shall have equal access to pro grams, admission, and employment without regard to race, religion, sex, national origin, handicap, age, or status as a disabled or Vietnam-era veteran. Direct inquiries to the Affirmative Action Officer, Suzanne Brooks, 201 Willard Building, University Park, PA 16802; (814) 863-0471.

U.Ed. 86-445 FOREWORD

Continuing conversion of agricultural lands to non agricultural use dictates the need for continued im provement in the quality and production of forage grasses in grassland agriculture. The identification of forage grass diseases as they occur in the field is of paramount importance prior to the recommendation of adequate control measures or to the development of resistant cultivars through forage grass breeding programs. It is also important to develop improved techniques for expediting disease resistance and to facilitate the incorporation of disease resistant germplasm into forage grasses. The value of these improvement programs cannot be overestimated. This bulletin recognizes the fiftieth anniversary of the U.S. Regional Pasture Research Laboratory. The Laboratory is located on the campus of The Pennsyl vania State University, University Park. The Pasture Laboratory staff works in close cooperation with Pennsylvania Agricultural Experiment Station work ers on forage problems of mutual interest.

Charles R. Krueger Associate Dean for Research and Associate Director of the Pennsylvania Agricultural Experiment Station. OVERVIEW

Forage grasses are utilized as pasture and hay and are Gramineae has been reviewed by Braverman (1967, a basic foundation of United States agriculture. These 1986). grasses support the production of beef and dairy cat This bulletin describes control measures for com tle, each an annual multibillion dollar enterprise. The mon disease incitants on selected forage-, range-, and 1979 U.S. Department of Agriculture's Agricultural pasture-type grasses. The majority of the pathogens Statistics (1979), indicated that there were 110.9 mil discussed are common in the United States. How lion head of cattle worth $44.7 billion feeding on over ever, a few bacteria and viruses not known to occur 100 million acres of pastureland in the United States. in the United States are included because of their de Recent developments in grassland agriculture have structive potential, should the causal agents become focused on improved management practices which established. Host susceptibility, favorable tempera include planting warm-season forage grass species, ture and moisture, and suitable vectors for virus increasing yields, quality and nutrient content of the transmission are the major determinants of inci grasses, disease resistance, and other mechanisms of dence, rapidity, and severity of disease development. disease control. Resistant cultivars offer a prime means of control, The warm-season grasses include big bluestem and are most effective when used with good farm (Andropogon gerardi Vitman), little bluestem management and agricultural practices. Tillage, sani (Schizachrium scoparium (Michx.) Nash), indiangrass tation, crop rotation, fertilization, and proper time of (Sorghastrum nutans (L.) Nash) and switchgrass (Pani harvesting all influence development of diseases on cum virgatum L.). These major native grasses of North farm crops. America are distributed throughout the central and, Incitants discussed here are divided into the biotic to a lesser degree, the eastern United States. They are agents-bacterial, fungal pathogens, and viral agents, characterized by drought tolerance and relatively and then selected abiotic agents, including environ short growing season (mid-May to mid-September). mental factors and nutritional disorders. Publications Cool-season grasses grow from early April to Novem referenced for each disease are listed with the discus ber. The peak-production period for warm-season sion; a complete bibliography is presented on page 38. grasses is the hot, often dry, months of July and Au This publication has been written for growers, gust, a time when cool-season grasses produce little teachers, and researchers concerned with grassland forage. For this reason, they are important supple production. The biotic and abiotic diseases which af ments to the cool-season species for grazing and hay fect temperate forage grasses are described. Control production on many farms. measures are listed, if known. A glossary defines se Forage grasses are subject to a multitude of leaf, lected technical terminology. stem, floral, and root diseases. The leaf diseases in Nematodes damage fine turf. However, to the au clude rusts, smuts, and leafspots, and cause the ma thors' knowledge there are no reports of such dam jor reductions in yields, as harvested forage consists age to range and pasture grasses. primarily of leaf material. Grass diseases may limit ef Initially, the common name for each host species, fective utilization of the grass species and affect herb followed by the Latin binomial, is used. Thereafter, age quality, digestibility, tillering, and root growth. only the common name is listed. Binomials not ac Perennial grasses are usually prone to one or more companied by an appropriate common name indi diseases that, over an extended period, may weaken cates none was identified. the plant. A weakened plant is less likely to survive Diseases are listed according to hosts on page 43. winter-kill. Resistance in certain cultivars offers an efficient ap Literature: proach to control of several of the more serious fun Braverman, S. W. 1967. Disease resistance in cool gal, bacterial, and viral-caused diseases. Maintaining season forage, range and turf grasses. Bot. Rev. resistance in a cultivar may require continuous effort 33:329-378. because disease resistance often loses effectiveness. __ . 1986. Disease resistance in cool season forage, Loss of effective resistance may be due to the acquisi range and turf grasses n. Bot. Rev. 52:1-112. tion of new virulent genes in the pathogen. It be United States Department of Agriculture. 1979. Agri comes imperative to seek new and better sources of cultural Statistics, 1979. disease resistance from as broad a germplasm base as possible. Resistance to many of the diseases of the

host, and is seed-borne, but will not survive in the soil. sistant to the strains of the pathogen tested: red top During the growing season, local spread is by wind (Agrostis alba L. = (A. gigantea Roth)), tall oatgrass, blown rain and contact. smooth bromegrass, Bromus marginatus, soft chess (B. mollis L.), tall fescue, meadow fescue, annual and Host Range: While the symptoms and pathogenic perennial ryegrasses, and Kentucky bluegrass. characteristics of the four X. campestris (Pammel) Dowson 1939 pathovars are similar, their host ranges X. campestris pv. vasculorum (Cobb 1893) Dye 1978. are different. The host range for each of the four Hosts: signal grass (Brachiaria mutica (Forsk.) Stapf), pathovars is presented here. The listings, except for Guinea grass (Panicum maximum Jacq.), and elephant that of X. campestris pv. translucens, are from grass (Pennisetum purpureum (Schum.). Bradbury (1984). Publications of Tominaga (1967, 1971) have been summarized for the host range of the Literature: Bradbury, J.F. 1984. Genus II. Xanthomonas Dawson latter: 1939, 187. In "Bergey's Manual of Systematic Bacte X. campestris pv. cerealis (Hagborg 1942) Dye 1978. riology." Vol. 1, p. 199-210, (Ed. N.R. Krieg and Hosts: Agropyron spp., Avena spp., Bromus spp., Hor J.G. Holt) Williams and Wilkins. Baltimore, deum spp., rye, and Triticum spp. Maryland. Tominaga, T. 1967. Bacterial blight of orchard grass X. campestris pv. hordei (Hagborg 1942) Dye 1978. f. Hosts: smooth bromegrass, Hordeum spp. caused by Xanthomonas translucens sp. hordei. Hagbord. Jap. J. Bact. 22:628-633. X. campestris pv. phleipratensis (Wallin & Reddy 1945) ___ . 1971. Studies on the diseases of forage Dye 1978. Host: timothy crops in Japan. Bull. Nat. Inst. Agric. Sci. (Jap.) Ser. C. No. 25. p. 205-306. X. campestris pv. translucens. Hosts: Japanese millet, Zillinsky, F.J. 1983. Common Diseases of Small Grain orchardgrass, smooth bromegrass and quackgrass. Cereals. A Guide to Identification. CIMMT. Investigations completed by Tominaga (1967, 1971) Mexico. 141 p. showed that the following pasture grasses were re-

7 yield, quality of forage, and seed production. The during late summer and autumn. Teliospores are fungus is heteroecious, alternating from grass to bar dark brown to black and are covered by the host's berry (Berberis vulgaris L.) or Mahonia spp. The disease epidermis. is most damaging in moderately humid areas. Etiology: The fungus overwinters as urediospores. Symptoms: The red rust, or uredial, stage is promi No aecial stage has been reported; teliospores germi nent on leaves and culms of grasses during the grow nate to produce basidiospores which subsequently ing season. As infection progresses, the epidermis is reinfect the same host and eventually form uredia of ruptured by uredial pustules containing orange-red this autoecious rust. spore masses (urediospores). These spores may be come wind-blown and spread to other plants, Host Range: The host range includes species of initiating infection. As the diseased plant matures, Agropyron, Agrostis, Festuca, Lolium, Phleum, Poa, and brown-black, oblong to elongated telia (black rust D. glomerata (Cummins, 1971). stage) develop in the uredia or in new sori on sheaths and culms. The telia give rise to black teliospores. Control: Braverman (1967, 1986) has summarized those genera and species in the Gramineae with re Etiology: The fungus overwinters as teliospores. In ported resistance to stripe rust. more mild climates, overwintering occurs as urediospores or teliospores on the host plant or as Literature: dormant mycelium. The teliospores germinate in the Braverman, S.W. 1967. Disease resistance in cool sea spring to produce basidiospores that become wind son forage, range and turf grasses. Bot. Rev. blown and infect leaves of barberry or Mahonia spp. 33:329-378. Pycniospores and aeciospores develop on the alter ___ . 1986. Disease resistance in cool season for nate host, and the latter spores infect the grass host. age, range and turf grasses II. Bot. Rev. 52:1-112. Subsequently, uredia are formed and the life cycle is Carr, A.J. 1971. Grasses. p. 286-295. In Diseases of completed. Crop Plants. J.H. Western Ed. Macmillan. London. 404p. Host Range: The host range includes species of Cummins, G.B. 1m. The Rust Fungi of Cereals, Agropyron, Agrostis, Andropogon, Dactylis, Festuca, Lo Grasses and Bamboo. Springer-Verlag. New York. lium, Phleum, and Poa (Cummins, 1971). 570p.

Control: Braverman (1967, 1986) listed numerous cultivars of several grass genera and species devel Yellow Leaf Rust caused by Puccinia poae-nemoralis oped for stem rust resistance. Otth.

Literature: Yellow leaf rust attacks several grass genera but does Braverman, S.W. 1967. Disease resistance in cool sea not infect cereals. P. poae-nemoralis has several spe son forage, range and turf grasses. Bot. Rev. cialized forms, but only the form that parasitizes tall 33:329-378. oatgrass has a pycnial and aecial stage on barberry. ___ . 1986. Disease resistance in cool season for age, range and turf grasses II. Bot. Rev. 52:1-112. Symptoms: The fungus produces round to oval, Cummins, G.B. 1971. The Rust Fungi of Cereals, yellow-brown to red-brown uredial sori on the upper Grasses and Bamboo. Springer-Verlag. New York. leaf surface and also on the leaf sheaths. The sori are 570p. covered by the epidermis and surrounded by chlo rotic leaf tissue, and may be arranged in dense groups (Weibull, 1983). Telia, rarely found, are Stripe Rust caused by Puccinia striiformis West. brown to black and covered by the epidermis. When present, they are found on the lower leaf surface. Stripe rust (yellow rust) occurs on many economically important grasses, particularly in the Northern hemi Etiology: The fungus overwinters as urediospores sphere. In Ireland, a heavy attack will render forage unless teliospores are produced. New infections in unpalatable and reduce seed production. In England, the spring result from wind-blown urediospores pro P. striiformis is very destructive on orchardgrass duced from overwintering mycelium. (Carr, 1971). Host Range: The host range includes species of Fes Symptoms: Uredia are lemon-yellow and amphige tuca and Poa (Cummins, 1971). nous and become more numerous toward the leaf tips. Telia develop, usually on the lower leaf surface, Control: Braverman (1986) has listed a number of re- 9 spot smut. Sori of these smuts are linear and form Literature: long or short stripes between the leaf veins. The leaf Braverman, S.W. 1986. Disease resistance in cool sea epidermis ruptures, discharging the spores and son forage, range and turf grasses H. Bot. Rev. shredding the leaves. Chlamydospores are formed 52:112. in the shredded tissue. Sori in leaf spot smuts are Fischer, G.W. 1953. Manual of the North American covered by the epidermis and are more permanent. smutfungi. Ronald Press Co. New York. 343p. In seedlings where crown tissue is invaded, Smiley, R.W. 1983. Compendium of turfgrass dis infection is followed by a systemic infection of the eases. American Phytopathological Society. 102 p. primordia. Spore formation occurs in the leaves as they become fully developed. In perennial grasses, Flag Smut caused by Urocystis agropyri (Preuss) the ~mut mycelium may persist in dormant buds and crown tissue for several years. In some strains Schroet. of stripe smut, infection of bud primordia occurs in established perennial plants. Seed infection occurs Flag smut infects a wide range of the Gramineae and in some grasses. is worldwide in distribution. The disease is usually not destructive.

Stripe Smut caused by Ustilago striiformis (West.) Symptoms: Symptoms induced by U. agropyri are NiessI. similar to those of stripe smut, but the disease is man ifest especially in the upper leaves of infected hosts. Stripe smut is common on many grasses and world According to O'Rourke (1976), diseased plants are wide in distribution. Physiologic races and varieties stunted, and production of total dry matter and inflo are distinguished on certain grasses. rescence is markedly reduced. Sori, which develop beneath the epidermal cells in the leaf, rupture and Symptoms: Stripe smut is systemic, and the patho release powdery masses of spore balls. Chlamydo gen is soil and seed-borne. Infection results in long, spores of flag smut may be distinguished from stripe yellow-green narrow streaks which extend the entire smut spores with a microscope; flag smut produces length of the leaf blade. The epidermis eventually spore balls in the smut sori. The spore balls consist of ruptures, exposing underlying black spore masses. one to four dark, smooth, spores surrounded by As the spore masses mature, the leaf blades curl smaller, hyaline to pale brown, sterile cells (Kreitlow down, turn brown, shred, and eventually die. Fungal et al., 1953). Leaf sheaths may also be infected. sori may also appear on the leaf sheath. In a heavy in fection, growth is retarded and inflorescence devel Etiology: The etiology of flag smut is similar to that of opment is inhibited. stripe smut. Infection occurs in coleoptiles of young seedlings or in underground lateral buds of mature Etiology: The pathogen overwinters as dormant my plants. The host is systemically colonized, and sori celium in plant debris or as chlamydospores in the eventually erupt through the epidermis and disperse soil or on the seed. In the spring, infection hyphae by wind and rain. develop from the chlamydospores and penetrate the coleoptiles of young seedlings or tillers in older Host Range: Flag smut infects species of Agropyron, grasses. The host is systemically colonized. Cool, Agrostis, Bromus, Elymus, Phleum, Poa, orchardgrass moist weather favors disease development. Masses and red fescue (Festuca rubra L.) (Fischer, 1953; of chlamydospores develop in the colonized foliage, Smiley, 1983). and these spores eventually rupture the epidermis and are dispersed by wind and rain. Control: Some systemic fungicides provide an effec tive control of flag smut in breeding stock nurseries Host Range: Stripe smut occurs on red top, creeping (O'Rourke, 1976). Several Kentucky bluegrass bentgrass (Agrostis alba Huds. ), colonial bentgrass (A. cultivars are noted by Braverman (1986) as resistant. tenuis Sibth.), orchardgrass, timothy, and Kentucky bluegrass. It is less widely distributed on species of Literature: Agropyron, Bromus, Elymus, Festuca, Lolium, and reed Braverman, S.W. 1986. Disease resistance in cool sea canarygrass (Fischer, 1953; Smiley, 1983). son forage, range and turf grasses H. Bot. Rev. 52:112. Control: Braverman (1986) listed several cultivars of Fischer, G.W. 1953. Manual of the North American grass genera and species developed for resistance to smut fungi. Ronald Press Co. New York. 343 p. stripe smut. Fungicide seed treatment and crop rota Kreitlow, K.W., J.H. Graham, and R.J. Garber. 1953. tion are useful control practices. Diseases of forage grasses and legumes in the northeastern states. Pa. Agric. Exp. Stn. Bull. 573. 11 O'Rourke, C.J. 1976. Diseases of forage grasses and Control: Some selections of crested wheatgrass (Agro legumes in Ireland. An Foras Taluntais. Oak Park pyron cristatum (L.) Beauv.) apparently are resistant Res. Centre. Carlow. 115p. (Dickson, 1956). Smiley, R.W. 1983. Compendium of turfgrass dis eases. American Phytopathological Society. 102 p. Literature: Dickson, J.G. 1956. Diseases of Field Crops. McGraw Hill. New York. 517p. Leaf Spot Smuts (Blister Smuts) caused by Entyloma spp. Head Smuts caused by species of Ustilago, Leaf spot smuts are the third category of the leaf Sorosporium, and Sphacelotheca. smuts. They are caused by Entyloma spp. and are common on many grasses. A representative smut of These smuts, most abundant in western North this group, E. dactylis (Pass.) Cif., is worldwide in dis America, form sori in grass inflorescences. Head tribution. These smuts are differentiated from Tilletia smuts (loose smuts) produce spores in the total infl~ and Urocystis in that sori of Entyloma in the leaf forms rescence, or just in the floral bracts and ovaries. They discolored spots that are frequently light in color, are differentiated from kernel smuts, in which sori hence the common name "white smuts." Aerial co form only in the ovaries. nidia may be formed on the surface of the spots, giv These three genera of the Ustilaginaceae are differ ing the spots an appearance similar to that of pow entiated by these characters: Ustilago-sori naked or dery mildew. without an enclosing membrane and forming black, dusty masses at maturity; Sorosporium-sori generally Symptoms: Sori are formed on the leaves and less fre dusty and without an enclosing membrane; Sphacelo quently in the floral bracts. Fruiting structures resem theca-sori generally in the inflorescence, replacing ble tar-like angular to oblong spots. The epidermis the kernels; and with a false external membrane. over the developing masses of chlamydospores re Ustilago bullata Berk. causes common head or ear mains intact. This gives a blister-like appearance. smut in a variety of grasses in the western United States and in drier climates; it has also been found in Etiology: Entyloma blister smuts are not systemic in the central and eastern United States. Sori form in the the host. According to Smiley (1983), most of the in spikelets, involving all or part of the floral bracts, and fection results from sporidia spreading on the leaves. are enclosed in the epidermal membranes of the floral Sporidia are disseminated by rain, leaf-t~leaf con structure. The loose to semi-covered spore mass is tact, and by movement of equipment and animals. dark brown to purple-black. The powdery mass of spores that replaces the kernels is usually covered by Host Range: The fungus occurs on species of Agrostis, the glume; glumes are rarely destroyed completely. Festuca, Phleum, andPoa (Smiley, 1983). Seedling infection occurs in perennial grasses, and the disease may survive in the host for years. Literature: Siniley, R.W. 1983. Compendium of turfgrass dis Host Range: Species of Agropyron, Bromus, Elymus, eases. American Phytopathological society. 102 p. and Festuca are common hosts (Fischer, 1953).

Control: Several rescuegrass cultivars resistant to Culm Smuts caused by Ustilago spp. head smut have been developed; mountain brome grass 'Bromar' is also resistant. These smuts, also called sheath smuts, are found in Ustilago avenae (Pers.) Rostr. causes a loose smut of western North America, South America, Europe, tall oatgrass, generally wherever the grass is grown. North Africa, and Asia. Dickson (1956) reports four The seeds are replaced by black, compact sori which species: U. spegazzinii (Hirschh.) Fischer ( = U. eventually become powdery. These sori replace the hypodytes Aucht.) appears to be the most ubiquitous. floral parts.

Symptoms: Smut sori are superficial on the inter Literature: nodes of the culms and occasionally on aborted inflo Fischer, G.W. 1953. Manual of the North American rescences. Naked linear dark brown to black sori are smut fungi. Ronald Press Co. New York. 343 p. covered by leaf sheaths. Infections also occur in the crown-bud primordia, and sori appear for two to three seasons following infection. Mycelium will also Kernel (Covered) Smuts caused by Tilletia spp. persist in stolons and crowns of perennial grasses. Some kernel smuts caused by species of Tilletia infect

these two genera exhibit a wide range of host speci Control: Resistant cultivars offer partial means of ficity, from D. poae (Baudys) Shoem., that incites controlling the disease (Braverman, 1986). Berget al. melting out of bluegrass, to H. sativum Pam., King & (1983) studied inheritance of leafspot resistance in Bakke ( = Bipolaris sorokinianum (Sacc. ex. Sorok.) smooth bromegrass and demonstrated that lesion Shoem. ), that causes leafspotlblotch on many grass size is regulated by multiple genes and that suscepti species. bility to the fungus may be dominant or epistatic to The perfect (sexual) stages of D. dactylidis Shoem. resistance. For these reasons, they concluded that it (Pleospora phaeocomes (Rab.) Wint.), D. bromi (Died.) will be difficult to develop populations with high lev Shoem., (Pyrenophora bromi (Died.) Drechs.), D. els of resistance to the pathogen. siccans (Drechs.) Shoem. (P. lolii Dovaston), and H. sativum (Cochiobolus sativus (Ito & Kurib.) Dastur.) Literature: have been described. Conidia of these and other spe Berg, C.C., R.T. Sherwood, K.E. Zeiders, and R.R. cies (for which a perfect stage has not yet been re Hill, Jr. 1983. Inheritance of brown leaf spot resis ported) serve as primary sources of inoculum. With tance in smooth bromegrass. Crop Sd. 23:138-140. the exception of D. catenaria (Drechs.) Ito, there is Braverman, S.W. 1986. Disease resistance in cool sea similarity in the etiology of diseases caused by son forage, range and turf grasses II. Bot. Rev. Drechslera spp. and H. sativum. This characteristic is 52:1-112. recognized in the discussions that follow. Conidia Kreitlow, K.W., J.H. Graham, and R.J. Garber. 1953. form on leaves and are disseminated by wind and Diseases of forage grasses and legumes in the water droplets, infecting nearby plants. Early spring northeastern states. Pa. Agric. Exp. Stn. Bull. 573. infections, particularly evident in D. catenaria, D. dictyoides, D. poae, D. siccans, and H. sativum, may be caused by planting infected seed. Brown leafspot Net Blotch caused by Drechslera dictyoides (Drechs.) caused by D. bromi is most prominent during cool, Shoem. Figure 17 wet weather of the spring and fall months. Descriptions, host range, and recommended con Net blotch, one of the most common foliar diseases of tall and meadow fescue, is prevalent in the eastern trol measures for seven Drechslera spp. and H. sativum and southeastern United States and widespread in follow. the Nordic countries. Literature: Shoemaker, R.A. 1959. Nomenclature of Drechslera Symptoms: Foliar lesions, present throughout the growing season, first appear as scattered, dark brown and Bipolaris, grass parasites segregated from spots on the upper and lower leaf surfaces. When the Helminthosporium. Can. J. Bot. 37:880-886. disease is severe, symptoms will be seen on the leaf ---· 1962. Drechslera Ito. Can. J. Bot. 40:809-843. sheath. Lesions expand to about 15 mm long and up to 10 mm wide. The larger lesions often develop into Brown Leafspot caused by Drechslera bromi. extensive lateral and transverse brown threads, Figure 16 creating the net-like total withering of the leaf. Le sions usually remain small when the host is growing Smooth bromegrass is very susceptible to brown rapidly. If grass growth is slow, lesions may spread leafspot. The fungus usually attacks this host wher across the leaf blade and cause an early senescence ever smooth bromegras~ is grown in the temperate and yellowing of the leaf tip. This yellowing is char areas of.the United States and in Canada. The fungus acteristic of a heavy infection (Weibull, 1978a). The apparently is restricted to species of Bromus. net blotch symptom is most evident from spring to autumn.

Symptoms: The disease first appears as small, dark Host Range: The fungus is widespread on annual brown, oblong spots on the foliage which develops in and perennial ryegrasses, meadow fescue, and to a the spring. As the growing season progresses, the lesser extent on tall fescue. D. dictyoides f. sp. spots become dark purplish-brown, elongate, and are dictyoides (Braverman & Graham) Shoem. occurs pri surrounded by a yellow band or halo (Kreitlow et al., marily on meadow and tall fescues. D. dictyoides £. sp. 1953). Lesions may coalesce, forming large yellow to perenne (Braverman & Graham) Shoem. occurs brown areas. Lesions may envelop the entire leaf. mainly on annual and perennial ryegrass (Braverman and Graham, 1960). Host Range: The fungus is restricted to smooth bromegrass and several annual and perennial Bromus Control: Braverman (1967, 1986) has summarized the spp. reported resistance of meadow and tall fescues and annual and perennial ryegrasses to net blotch. 18 Literature: grass stands. Braverman, S. W. 1967. Disease resistance in cool sea son forage, range and turf grasses. Bot. Rev. Symptoms: The initial foliar symptoms appear as 33:329-378. tiny, dark green spots surrounded by a chlorotic ___ . 1986. Disease resistance in cool season for halo. Mature lesions are elongated and reddish age, range and turf grasses II. Bot. Rev. 52:1-112. brown, often with light-buff-colored centers. As le ___ , and J .H. Graham. 1960. Helminthosporium sions increase in size, they often coalesce to form dictyoides and related species on forage grasses. large areas of necrotic tissue on susceptible clones Phytopathology 50:691-695. (Zeiders, 1976). Weibull, Peter. 1978a. Descriptions of grass diseases No.1. Weibull's Gras-tips 21:3-4. Etiology: There is evidence suggesting that patho genesis by D. catenaria is accomplished primarily by secretion of a toxic substance(s) which precedes my Brown blight caused by Drechslera siccans. celial colonization of the tissue. The fungus over winters as mycelium in tissue infected the previous Brown blight is a common foliar disease on annual year. D. catenarium may also be seed-borne. and perennial ryegrasses in the eastern United States and in Europe. In Ireland, the disease is most preva Host Range: The fungus is common on reed lent on ryegrasses and meadow fescue. D. siccans is canarygrass, woodreed (Cinna arundinacea L.), and to fairly common in the Nordic countries. a lesser extent on orchardgrass and bentgrass.

Symptoms: Symptoms caused by D. siccans resemble Control: Reed canarygrass genotypes with good re those incited by D. dictyoides. However, characteristic sistance to D. catenaria exist (Zeiders, 1976). These net markings are either very faint or lacking on the clones could be used in breeding programs designed leaves. The fungus produces numerous dark brown to increase disease resistance. spots, of various shapes, which may coalesce to form large mottled discolored areas. More mature lesions Literature: show ash-gray centers and a yellowing of surround Zeiders, K.E. 1976. A new disease of reed canary ing tissue (O'Rourke, 1976). If the infection is severe, grass caused by Helminthosporium catenarium. Plant the leaves become yellow at the tip. The blade and Dis. Rep. 60:556-560. sheath gradually wither and die (I

Literature: Symptoms: The disease appears as well defined Graham, J.H. 1955a. A disease of orchardgrass purplish-black to reddish-brown oval leaf spots with caused by Pleospora phaeocomes. Phytopathology a chocolate-brown to purple-brown margin and a 45:633-634. light center (Weibull, 1979a). Lesions often form in Zeiders, K.E. 1980. A variable-spored isolate of rows along the margin of ·the leaf. Some lesions ex Drechslera dactylidis pathogenic on orchardgrass tend the width of the leaf blade, causing it to break and corn. Plant Dis. 64:211-213. over or wither from the tip downward to the lesion. The symptoms frequently extend to the inflores cence, and lesions may coalesce to form a large Drechslera Leaf Streak caused by Drechslera phlei necrotic area extending across the entire leaf to the (Graham) Shoem. sheath and stem base. This results in weakening and death of the plant. Frequently, the immature inflores This leaf streak disease of timothy was first observed cence in the boot is diseased, with the flower heads in central Pennsylvania and subsequently was re inside being attacked. ported to occur throughout the northeastern United States (Graham, 1955b). Host Range: D. poae is confined to species of Poa.

Symptoms: The disease is characterized by irregular Control: High clipping or mowing (1112 inches or light brown, necrotic streaks with conspicuous chlo more) reduces the incidence of melting out by main rotic borders. The necrotic areas, which are 1 to 5 mm taining the less susceptible older leaves without wide, are often marginal and may extend the entire stimulating succulent new shoots from the crown length of the leaf blade (Graham, 1955b). Often, le (Kreitlow et al., 1953). Several cultivars have been de sions may coalesce, thereby causing a browning of veloped for resistance to D. poae, as reviewed by most of the leaf. If the chlorotic symptom is lacking, Braverman (1986). the disease is difficult to distinguish from leaf streak. However, under moist conditions, the leaf streak dis Literature: ease is characterized by parallel rows of dark tufts of Braverman, S. W. 1986. Disease resistance in cool sea conidiophores of the causal fungus on infected son forage, range and turf grasses n. Bot. Rev. leaves. 52:1-112. Kreitlow, K.W., J.H. Graham, and R.J. Garber. 1953. Host Range: The fungus is limited to timothy and Diseases of forage grasses and legumes in the other Phleum spp. northeastern states. Pa. Agric. Exp. Stn. Bull. 573. Weibull, Peter. 1979a. Descriptions of grass diseases Control: Resistant cultivars offer a means of reducing No.7. Weibull'sGras-tips. 22:unpaginated. severity of Drechslera leaf streak of timothy (Braverman, 1986). Bipolaris Foot Rot, Leaf Blight, and Seedling Blight caused by Bipolaris sorokinianum (sexual stage: Literature: Braverman, S.W. 1986. Disease resistance in cool sea Cochliobolus sativus). son forage, range and turf grasses n. Bot. Rev. The disease incitant causes a foot rot, leaf blight, and 52:1-112. Graham, J.H. 1955b. Helminthosporium leaf streak of seedling blight on a wide range of grasses in North timothy. Phytopathology 45:227-228. America. While the pathogen is of significant eco nomic importance on wheat, barley, and oats, it is ca pable of causing moderate to severe damage on cool Melting Out, Leafspot, and Foot Rot caused by and warm-season grasses. Drechslera poae. Symptoms: The predominant symptom on grasses is This fungus causes a leafspot and foot rot of either a leafspot or leaf blight. Lesions caused by B. Kentucky bluegrass, and according to Kreitlow et al. sorokinianum are elongated, dark to purple, and mea (1953), melting out is probably the most prevalent sure 2 to 5 mm. Older lesions may become light and serious disease of the host in the northeastern colored in the center. As disease severity increases part of the United States. D. poae is also common on with time, lesions often coalesce, causing foliage to many Poa spp. in northern Europe and is considered become blighted. This reduces forage quality. The to be the most important pathogen on Kentucky disease is most severe on switchgrass during the 20

At times, minute gelatinous masses of conidia may be vored by cool, moist weather and high relative hu seen on the matted leaves. The dead tissue, after dry midity. Conidia and mycelia produced under these ing, forms a thick pink mat, providing the name climatic conditions invade healthy tissue. Perithecia "pink snow mold." The pink color distinguishes this of M. nivalis are abundant on cereals, but rarely ob disease from other low-temperature maladies, such served on grasses in the field and do not form in cul as those caused by Typhula spp. and Sclerotinia sp. tures of F. nivale isolated from grass. Chlamydo (Weibull, 1979b). spores are absent (Weibull, 1979b). Typhula blight or gray or speckled snow mold, The etiologies of the three diseases caused by caused by T. incarnata, is widespread and may se Typhula spp. are similar. Each fungus produces scle verely damage grasses. Although fungal attacks will rotia that remain dormant on the soil surface during occur on grasses without snow cover, damage is most the summer months. As temperatures become cooler severe after at least 90 days of cover. The disease first and moist conditions prevail, the sclerotia germinate appears as small patches, 2 to 5 em in diameter, and produce one to three sporophores that bear which at first light are yellowish-brown to a grayish basiodiospores. While the basid.iospores may cause white. Under snow, the diseased patches coalesce to infections, the most infections are from mycelial a considerable size. Initially, a white-grayish myce growth into weakened tissues. Sclerotia buried in the lium develops on the grass substrate. Pink to pinkish soil may survive for several years. orange followed by reddish-brown to dark brown Sclerotinia borealis produces sclerotia that are dor sub-globose sclerotia develop on or within infected mant during the summer months, and become a tissue (Weibull, 1979b). source of inoculum in autumn. Elongated asci, hav Gray or speckled snow mold, also called Typhula ing eight ascospores, develop during moderately low blight, is caused by T. ishikariensis and is a major dis temperatures and high moisture. Ascospores dis ease on overwintering grasses with prolonged snow charge onto surrounding foliage and are the main in cover. Much more virulent than T. incarnatum (Wei oculum source. Infection may also occur by direct bull, 1979b), r. ishikariensis becomes a major incitant mycelial growth in weakened host tissues. The scle of snow mold on grasses covered 150 days or longer. rotia may survive burial in the soil for years. Symptoms of this snow mold are bleached patches of dead or dying plants sparsely covered with a grayish Host Range: Snow molds occur on a wide variety of white mycelium. The decaying tissue is speckled grasses and are particularly prevalent on Agrostis with numerous dark, globose to slightly flattened spp., Festuca spp., and Poa spp. During periods of sclerotia. prolonged snow cover, Lolium spp., timothy, and A third causal agent of the Typhula speckled snow Agropyron spp. may be extensively damaged. mold or snow scald is T. itoana. The fungus is preva lent on grasses snow-covered during winter and Control: Good management practices offer a measure early spring. As the snow melts, those grasses at of control for snow mold-susceptible grass- species. tacked by the fungus appear as flattened mats of Cutting low in autumn to reduce excessive top bleached dead foliage and mycelium. Numerous growth, avoiding heavy top dressings or winter brown sclerotia develop on the dead leaves and grass mulches, and eliminating heavy or late nitrogen ap stems. T. itoana is apparently the most widely distrib plications may be effective. Abundant late-season ni uted of the three incitants of Typhula snow molds. trogen contributes to a dense host growth and creates Sclerotinia snow mold is also a major disease on a microclimate favorable to fungal development. overwintering grasses. It is restricted to those regions Good drainage is important and fungicide applica of extreme cold where snow cover lasts for at least tions may be advisable. 180 days. The disease causes severe damage to Resistant cultivars offer a good measure of snow grasses. Symptoms first appear, after snow melt, as mold resistance in forage grasses (Abe and Matsu bleached patches of dead and/or dying plants. Dis moto, 1981; Duich et al., 1972; Funk et al., 1969, 1973, eased areas are covered with grayish-white myce 1974; Jam.alanien, 1974; . O'Rourke, 1976; Schmidt, lium. Elongated and flattened grayish-white sclerotia 1976a, b; and summarized by Braverman, 1967, 1986). form on or within the infected tissue and blacken upon maturity. Literature: Abe, J., and N. Matsumoto. 1981. Resistance to snow Etiology: Fusarium patch disease may occur through mold disease caused by Typhula spp. in cocksfoot. out the year, while pink snow mold occurs only un J. Jap. Soc. Grassl. Sci. 27:152-158. (Abstr. Rev. der a snow cover or very shortly after a thaw. Both Appl. Plant Pathol. 61:148. 1982.) Fusarium patch and pink snow mold are favored by Braverman, S.W. 1967. Disease resistance in cool sea cool, moist conditions. The conidial stage of F. nivale son forage, range and turf grasses. Bot. Rev. is the primary inoculum source. The disease is fa- 33:329-378.

28 ___ . 1986. Disease resistance in cool season for and grasses to low temperature parasitic fungi. age, range and turf grasses II. Bot. Rev. 52:1-112. Ann. Rev. Phytopathol. 12:281-302. Duich, J.M., A.T. Perkins, and H. Cole. 1972. Regis O'Rourke, C.J. 1976. Diseases of grasses and forage tration of Pennfine perennial ryegrass (Reg. No. legumes in Ireland. An Foras Taluntais. Oak Park 26). Crop Sci. 12:257. Res. Centre. Carlow. 115 p. Funk, C.R., R.W. Duell, and P.M. Halisky. 1969. Schmidt, D. 1976a. Diseases affecting persistence in Registration of Manhattan perennial ryegrass (Reg. Italian ryegrass. Arbeiten aus dem Gebiete des No. 18). Crop Sci. 9:679-680. Futterbaues 20:50-59. ___ , R.E. Engle, G.W. Pepin, A.M. Radko, and ___ . 1976b. Observations sur la pourriture des R.J. Peterson. 1974. Registration of Bonnieblue neiges affectant les graminees. Revue Suisse Kentucky bluegrass (Reg. No. 10). Crop Sci. 14:906. d'Agriculture 8:8-14. ___ , R.E. Engle, G.W. Pepin, A.M. Radko, and Weibull, Peter. 1979b. Descriptions of grass diseases. A.R. Russell. 1973. Registration of Adelphi Weibull's Gras-tips 22:unpaginated. Kentucky bluegrass (Reg. No. 9). Crop Sci. 13:580. ___ . 1983. Descriptions of grass diseases No. 12. Jamalainen, E.A. 1974. Resistance in winter cereals Weibull's Gras-tips. p. 22-25, December 1983.

___ . 1970. Phleum :qtottle virus. Plant Pathol. Walters, H.J. 1969. Beetle transmission of plant 19:101-103. viruses. Adv. Vir. Res. 15:339-363.

34 MINERAL DEFICIENCIES

This section describes characteristic effects on plants Interveinal areas and older leaves are first to express of various mineral disorders but does not attempt to symptoms. Leaf bases and stems become red-purple. be comprehensive. For a more extensive coverage of minerals and their role in plant growth and composi Phosphorus. Symptoms of phosphorus deficiency tion, the reader is referred to the volumes edited by frequently resemble those of nitrogen deficiency. C. Bould, E.J. Hewitt, and P. Needham titled "Diag There is a diminutive or spindly habit, suppression of nosis of Mineral Disorders in Plants," Volume 1, tillering, acut~ leaf angles, decreased size and num "Principles," and Volume 2, ''Vegetables," published bers of flowers, prolonged dormancy, and early se by Chemical Publishing, N.Y., 1984, from which the nescence. The leaves lack luster; leaf color changes, following information has been summarized. but may be either paler or darker than normal. Again, depending on species, leaf color may range from Maaonutrient Deficiencies deep purple to red, or be absent.

Calcium. In plant tissue, the concentration of calcium Potassium. Potassium deficiency frequently iiippears is important to growing points and young leaves and as short telescoped shoots, caused by a shortening of is usually related to the distribution of specific symp stem internodes. Apical dominance of the viable ter toms, but does not entirely explain the appearance of minal bud is sometimes suppressed, causing exces others. In cereals and grasses, emerging young sive basal shoots or tillers. Severe deficiency causes leaves remain trapped in subtending leaves. Leaves' death of the terminal bud and a typical dieback. which have emerged remain rolled, chlorotic, and Strong light intensity accentuates and weak light of have circular constrictions a few centimeters behind ten reduces or eliminates these conditions. Leaf the apex. The distal portion wilts and withers. Death scorch, preceded by irregular marginal or interveinal of the stem apex occurs in calcium-deficient plants, chlorosis, appears first in the oldest leaves. Scorching but multiple apical shoots or axillary nodal shoots may be pale brown to almost black. Chlorosis almost may follow to fill the void. always occurs and first appears in oldest leaves, which often curve downwards or become convex. Magnesium. Magnesium is very important in the makeup of chlorophyll. Therefore, magnesium defi Sulphur. Decreased leaf size, red or purple pigmen ciency is most frequently indicated first by the loss of tation, and general chlorosis - symptoms of sulphur chlorophyll. As a rule, the chlorosis usually appears deficiency- resemble those of nitrogen. However, first in the oldest leaves and is progressive. In several there are important differences. Usually young leaves species, the chlorosis is generally interveinal within a are more sensitive to sulphur deficiency than older persistent green margin of the leaf. ones. In sulphur deficient soils, new leaves are fre Symptoms of magnesium deficiency may be diffi quently uniform golden yellow and stiff and erect. cult to distinguish from the symptoms of potassium deficiencies at certain stages of plant growth. The Micronutrient Deficiencies principal distinction is that magnesium deficiency af fects first the oldest leaves, while potassium defi Chlorine. Little has been reported in the literature as ciency usually is first noticed in younger leaves. to the effect of chlorine deficiency on plants in the Gramineae. Chlorine deficiency has been reported to Nitrogen. Nitrogen-deficient plants are much smaller limit growth and cause wilt, chlorosis, and promi than normal, but the root growth can be extensive nent raised veins and dubbed tips of roots in dicoty and root length may increase to compensate for the ledons. Deficiency will keep barley leaves rolled, as absence of N. The angle between petioles and stems does copper deficiency. is more acute. Tillering is suppressed, bud produc tion or expansion is decreased, and flowering is de Copper. In many plant species, the young leaves are layed. Bud dormancy can be prolonged. Foliage is most severely affected. Leaves are often rolled or pale green and leaf senescence is accelerated. De curled, and may be coiled in a spiral which may re pending upon species, leaves can develop purple, verse direction along its length. These leaves are of red, or orange anthocyanin tints in addition to the ten white. The emerging leaves may be trapped in yellowishness caused by the loss of chlorophyll. the subtending leaf, producing symptoms known as 35 white tip or wither tip. Floral meristems are sensitive form of chlorosis) are produced by manganese defi to copper deficiency. Head formation is suppressed, ciency. Older leaves are usually affected first. Chloro and the grains are shriveled or the glumes do not fill. sis is usually interveinal and produces a bold pattern Often the pollen cells are sterile. of dark green major veins which contrasts with the fine reticulate pattern observed with iron deficiency. Iron. Iron deficiency is first apparent as chlorosis of Manganese deficiency is also distinguished from iron rapidly expanding leaves. Chlorosis is usually inter deficiency symptoms in leaves by the appearance of veinal and produces a contrasting tramline effect in varied but characteristic necrotic spotting or lesions. the leaves. The glumes may be more chlorotic than In the Gramineae, these lesions vary in appearance the flag leaf. In cereals and grasses, bleached or from dark brown spots along interveinal areas to brown lesions develop more frequently in the chlorotic beading. In oats, the necrotic lesions are interveinal areas and leaves collapse transversely. elongated, generally ivory to pale brown with "blue green or grey'' halo areas, and -often coalesce into Manganese. A variety of symptoms (including some broad lesions that may collapse leaves transversely.

nomenclature and classification for plant patho Plant Viruses No. 107. genic bacteria. N.Z. J. Agric. Res. 21:153-177. Jamalainen, E.A. 1974. Resistance in winter cereals ___ , J.F. Bradbury, M. Goto, A.C. Hayward, and grasses to low temperature parasitic fungi. R.A. Lelliott, and M.N. Schroth. 1980. Interna Ann. Rev. Phytopathol. 12:281-302. tional standards for naming pathovars of phyto Kendrick, J.B. 1926. Holcus bacterial spot of Zea mays pathogenic bacteria and a list of pathovar names and Holcus species. Iowa Agric. Exp. Res. Bull. 100. and pathotype strains. Rev. Plant Pathol. Kreitlow, K.W., J.H. Graham, and R.J. Garber. 1953. 59:153-168. Diseases of forage grasses and legumes in the Egli, T., M. Goto, and D. Schmidt. 1975. Bacterial northeastern states. Pa. Agric. Exp. Stn. Bull. 573. wilt, a new forage grass disease. Phytopathol. Z. Lane, L.C. 1974. The bromeviruses. Advances in 82:111-121. Virus Research 19:151-220. ___ , and D. Schmidt. 1982. Pathogenic variation Latch, G.C.M. 1%6. Fungus diseases of ryegrass in among the causal agents of bacterial wilt of forage New Zealand. I. Foliar diseases. N .Z. J. Agric. Res. grasses. Phytopathol. Z. 104:138-150. 9:394-409. Elliott, E.S. 1%2. Disease damage in forage grasses. Luttrell, E.S. 1%2. Rhizoctonia blight of tall fescue Phytopathology 52:448-451. grass. Plant Dis. Rep. 46:661-664. Fischer, G.W. 1953. Manual of the North American Makela, K. 1970. The genus Mastigosporium Reiss. in smut fungi. Ronald Press Co. New York. 343 p. Finland. Karstenia 11:5-22. Funk, C.R., R.W. Duell, and P.M. Halisky. 1969. McKinney, H.H. 1953. Virus diseases of cereal crops. Registration of Manhattan perennial ryegrass (Reg. p. 350-360. In USDA Yearbook of Agriculture- No. 18). Crop sci. 9:679-680. 1953. Funk, C.R., R.E. Engle, G.W. Pepin, A.M. Radko, Mulligan, T.E. 1960. The transmission by mites, host and R.J. Peterson. 1974. Registration of Bonnieblue range and properties of ryegrass mosaic virus. Kentucky bluegrass (Reg. No. 10). Crop Sci. 14:906. Ann. Appl. Bioi. 48:575-579. ---, , , and A.R. Russell. 1973. Nilsson, H.E. 1%9. Studies on the foot and foot rot Registration of Adelphi Kentucky bluegrass (Reg. diseases of cereals and grasses I. On the resistance No. 9). Crop Sci. 13:580. to Ophiobolus graminis Sacc. Ann. Agric. Col. Swe. Gibson, R.W., and R.H. Kenten. 1978. The occur 35:275-807. rence of brome mosaic virus in Britain. Plant O'Rourke, C.J. 1976. Diseases of grasses and forage Pathol. 27:66-67. · legumes in Ireland. An Foras Taluntais. Oak Park Goto, M. 1964. Nomenclature of the bacteria causing Res. Centre. Carlow. 115 p. bacterial leaf streak and bacterial stripe of rice. Rep .. Panayotou, P.C. 1982. Some aspects on barley yellow Fac. Agric. Shizwoka Univ. 14:3-10. dwarf virus host range. Zeitschrift fur Pflanzen Graham, J.H. 1955a. A disease of orchardgrass caused drankkheiten und Pflanzenschultz 39:595-603. by Pleospora phaeocomes. Phytopathology 45:633-634. Roberts, D.A., R.T. Sherwood, K.D. Fezer, and c.s: ___ . 1955b. Helminthosporium leaf streak of Ramamurthi. 1955. Diseases of Forage Crops in timothy. Phytopathology 45:227-228. New York, 1954. Plant Dis. Rep. 39:316-317. ___ , K.E. Zeiders, and S.W. Braverman. 1963. Rochow, W.F. 1970. Barley yellow dwarf virus. Com Sporulation and pathogenicity of Scolecotrichum monwealth Mycological Institute/Association of graminis from orchardgrass and tall oatgrass. Plant Applied Biologists. Descriptions of Plant Viruses Dis. Rep. 47:255-256. No. 32. Gross, D.F., C.J. Martin, and J.G. Ross. 1975. Effect Sabet, K.A. 1954. On the host range and systematic of diseases on in vitro digestibility of smooth position of the bacteria responsible for the yellow bromegrass. Crop Sci. 15:273-275. slime diseases of wheat (Triticum vulgare Vill.) and Hanson, A.A. 1972. Grass varieties in the United cocksfoot grass (Dactylis glomerata L.). Ann. Appl. States. USDA Agric. Handb. No. 170. 124 p. Bioi. 41:606-611. Hayward, A.C. 1983. The Non-Fluorescent Pseudo Sakuma, T., and T. Marita. 1961. Heterosporium leaf monads. In "Plant Bacterial Disease, A Diagnostic spot of timothy and its causal fungus, Guide." p. 107, (Ed. P.C. Fahy and G.J. Persley). Heterosporium phlei Gregory. Bull. Hokkaido Agric. Academic Press. Exp. Stn. 7:77-90. Heard, A.J., J.A. Brook, E.T. Roberts, and R.J. Cook. Schaad, N.W., and B.W. Cunfer. 1979. Synonymy of 1974. The incidence of ryegrass mosaic virus in Pseudomonas coronafaciens, Pseudomonas coronafaciens crops of ryegrass grown for seed in some southern pathovar zeae, Pseudomonas coronafaciens subsp. counties of England. Plant Pathol. 23:119-127. atropurpurea and Pseudomonas striafaciens. Int. J. Huth, W., and H.L. Paul. 1972. Cocksfoot mild mo Syst. Bact. 29:213-221. saic virus. Commonwealth Mycological Institute/ ---, C.I. Kado, and D.R. Sumner. 1975. Synon Association of Applied Biologists. Descriptions of ymy of Pseudomonas avenae Manns 1905 and

39 Pseudomonas alboprecipitans Rosen 1922. Int. J. Syst. Weibull, Peter. 1978a. Descriptions of grass diseases Bact. 25:133-137. No. 1. Weibull's Gras-tips 21:3-4. Schmidt, D. 1976a. Diseases affecting persistence in ---. 1978b. Descriptions of grass diseases No. 2. Italian ryegrass. Arbeiten aus dem Gebiete des Weibull's Gras-tips 21:5-6. Futterbaues 20:50-59. ___ . 197&. Descriptions of grass diseases No. 3. ___ . 1976b. Observations sur la pourriture des Weibull's Gras-tips 21:7-8. neiges affectant les graminees. Revue Suisse Weibull, Peter. 1979a. Descriptions of grass diseases d'Agriculture 8:8-14. No. 7. Weibull's Gras-tips 22:unpaginated. Schmidt, H., R. Fritzsche, and W. Lehmann. 1963. . 1979b. Descriptions of grass diseases. Die Ubertragung des W eidelgrasmosaik-Virus Weibull's Gras-tips 22:unpaginated. Nematoden durch Nematoden. Die Natur ___ . 1979c. Descriptions of grass diseases No. wissenschaften 50:386. 11. Ice and water damage. Weibull' s Gras-tips Serjeant, E.P. 1964. Cocksfoot mottle virus. Plant 22:unpaginated. Pathol. 13:23-24. ___ . 1983. Descriptions of grass diseases No. 12. ___ . 1967. Some properties of cocksfoot mottle Weibull's Gras-tips. p. 22-25, December 1983. virus. Ann. Appl. Bioi. 59:31-38. Wilkins, P.W. 1977. Herbage viruses. p. 176-177. In Shoemaker, R.A. 1959. Nomenclature of Drechslera Welsh Plant Breeding Station Report for 1977. and Bipolaris, grass parasites segregated from Aberysthwyth. Helminthosporium. Can. J. Bot. 37:880-886. Wright, C.E. 1%7. Blind seed disease of ryegrass. ___ . 1962. Drechslera Ito. Can. J. Bot. 40:809-843. Euphytica 16:122-130. Slykhuis, J.T. 1972. Ryegrass mosaic virus. Common ___ ,and E.L. Breese. 1966. The genetic control wealth Mycological Institute/Association of Ap of blind seed disease resistance in Lolium perenne in plied Biologists. Descriptions of Plant Viruses No. relation to breeding practice. Proc. lOth Int. Grassl. 86. Congr. p. 737-741. ___ . 1973. Agropyron mosaic virus. Common Zeiders, K.E. 1975. Stagonospora foliicola, a pathogen wealth Mycological Institute/Association of Ap of reed canarygrass spray-irrigated with municipal plied Biologists. Descriptions of Plant Viruses No. sewage effluent. Plant Dis. Rep. 59:779-783. 118. ___ . 1976. A new disease of reed canarygrass ___ . 1976. Virus and virus-like diseases of cereal caused by Helminthosporium catenarium. Plant Dis. crops. Annu. Rev. Phytopathol. 14:189-210. Rep. 60:556-560. Smiley, R.W. 1983. Compendium of turfgrass dis --- . 1979. A Septoria disease of reed canary eases. American Phytopathological Society. 102 p. grass in Pennsylvania. Plant Dis. Rep. 63:796-800. Smith, J.D. 1970. Resistance of timothy cultivars to ---. 1980. A variable-spored isolate of Drechslera Heterosporium phlei, Drechslera phlei and frost injury. dactylidis pathogenic on orchardgrass and corn. Can. J. Plant Dis. Sur. 50:95-98. Plant Dis. 64:211-213. Sprague, R. 1950. Diseases of Cereals and Grasses in ___ . 1982. Leaf spots of big bluestem, little North America. Ronald Press. New York. 538 p. bluestem, and indiangrass caused by Ascochyta Tominaga, T. 1%7. Bacterial blight of orchard grass brachypodii. Plant Dis. 66:502-505. caused by Xanthomonas translucens f. sp. hordei. Zeiders, K.E. 1984. Helminthosporium spot blotch of Hagbord. Jap. J. Bact. 22:628-633. switchgrass in Pennsylvania. Plant Dis. 68:120-122. ___ . 1968a. Brown stripe of bromegrass and ___ , C.C. Berg, and R.T. Sherwood. 1984. Effect wheatgrass caused by Pseudomonas setariae (Okabe) of recurrent phenotypic selection on resistance to Savulescu. Jap. J. Bact. 23:176-183. purple leafspot in orchardgrass. Crop Sci. 1968b. Halo blight of ryegrass, 24:182-185. bromegrasses and fescues. Ann. Phytopathol. Soc. ___ ,and J.H. Graham. 1%2. Stagonospora bromi Jap. 34:242-249. on Bromus inermis. Plant Dis. Rep. 46:729-731. ___ . 1971. Studies on the diseases of forage ___ , and R. T. Sherwood. 1977a. Effect of irriga crops in Japan. Bull. Nat. Inst. Agric. Sci. Gap.) tion with sewage wastewater, cutting manage Ser. C. No. 25. p. 205-306. ment, and genotype on tawny blotch of reed United States Department of Agriculture. 1979. Agri canarygrass. Crop Sci. 17:594-596 .. cultural Statistics, 1979. ___ , andR.T. Sherwood.1977b. Reaction of reed Walker, J. 1975. Take-all diseases of Gramineae: Are canarygrass genotypes to the leafspot pathogens view of recent work. Rev. Plant Pathol. 54:113-144. Stagonospora foliicola and Helminthosporium Walker, J.C. 1970. Plant Pathology. McGraw-Hill catenarium. Crop Sci. 17:651-653. Book Co. New York. 819 p. Zillinsky, F .J. 1983. Common Diseases of Small Grain Walters, H.J. 1%9. Beetle transmission of plant Cereals. A Guide to Identification. CIMMT. viruses. Adv. Vir. Res. 15:339-363. Mexico. 141 p.

40 GLOSSARY

Morphological definitions are based in part on CUTICLE. The outermost layer of leaf tissue. .Kreitlow, J.W., et al., 1953, and O'Rourke, C.J., 1976. DISEASE. An interaction between a causal agent and host which alters the morphological and physiolog ABIOTIC [A disease] not caused by a biological agent. ical development of the host. ACERVULUS (1). A small, open fruiting body that has DISEASE DEVELOPMENT. The sequence of events from ruptured the host epidermis and consists of a mass time of infection to symptom expression. of hyphae bearing conidiophores and conidia. DISEASE IN CIT ANT. An abiotic or biotic entity which AECIOSPORE. A spore formed in chains within the ae may cause disease. cium of a rust. ENDEMIC. The occurrence of a disease from year to AEciUM (A). A cup-shaped fruiting structure charac year in moderate to severe form. teristic of the rusts in which aeciospores are borne. EPIPHYTIC. A large-scale disease outbreak in plants. ALTERNATE HOST. Either of two unrelated plant spe FORMA (AE) SPECIAUS (ES). A subdivision within a cies necessary for certain rust fungi to complete species, distinguished by physiological traits rather their life cycle. than by morphological characteristics. AMPHIGENOUS. Making growth all around or on two GERMINATION. The process by which a hypha sides. emerges from a spore. APOTHEciUM (A). An open cup or saucer-shaped GUTTATION. The process of the escape of liquid water fruiting body whose concave surface is lined with from uninjured plants. asci. HAusTORIUM (A). A specialized mycelial branch, es AsaGERous. Having asci. pecially one within a living cell of a host. AscocARP. The ascus-bearing structure of the HETEROECious. Referring to a parasite that completes Ascomycetes. its life cycle on unrelated hosts. AscosPORE. One of normally eight spores borne in an HosT PLANT. A plant morphologically and physiolog ascus. ically altered by a disease incitant. Ascus (I). A sac-like structure in which normally HoST RANGE. Those plant species known to be sus eight ascospores are formed as a result of the sex ceptible to a pathogenic organism. ual process. HYDATHODE. A pore-like structure in a plant leaf ASEXUAL REPRODUCTION Reproduction without fu through which guttation occurs. sion of gametes. HYPHA (AE). A single strand or strands of mycelium. AUTOECious. Referring to a parasite which completes INFECTION. The establishment of a disease incitant its life cycle on one host. within a host. BACTERIUM (A). A single-celled microscopic organism LESION. An area of tissue showing disease lacking a well-defined nucleus or nuclear symptoms. membrane. LIFE CYCLE. A sequential series of forms and relation BASIDIOSPORE. A spore produced at the apex of a ships assumed by an organism from a primary basidium. stage to a resumption of that stage. BASIDIUM. A fruiting structure which bears the MACROCONIDIUM (A). The larger conidium of a fun basidiospores. gus which also has Inicroconidia. BIOTIC. [A disease] caused by a biological agent. MICROCONIDIUM (A). The smaller conidium of a fun BLIND SEED. Sterile seed. gus which also has macroconidia. CHLAMYDOSPORE. A thick-walled asexual resting MoRPHOLOGY. A study dealing with the form and body formed by the rounding up of a mycelial structure of organisms. segment. MYCELIUM (A). The vegetative body of the fungus CHLOROTIC. Deficient in chlorophyll. comprising a mass of hyphae. CLEISTOTHECIUM (A). A fungal fruiting body, con NECROTIC. Dead or dying. taining asci, which has no specific opening (e.g., in OBLIGATE PARASITE. An organism that grows only on Erysiphaceae). its host and which usually cannot be cultured on CONIDIUM (A). An asexual spore. artificial media. CONIDIOPHORE. A specialized branch of the myce OsTIOLB. An opening from which spores extrude lium bearing cells from which conidia are borne. from an ascigerous or pycnial fruiting body. CULM. The stem of a grass. PARASITE. An organism which derives its nourish- 41 ment from another organism, the host. rupturing the epidermis of the host. PATHOGEN. A disease-causing organism. SPoRE. A specialized cell(s) adapted for dissemina PATHOVAR. A specialized variety of a pathogenic or tion and capable of germinating to perpetuate the ganism based on host range or its characteristic species. growth on a specific culture medium. SPORIDIUM (A). One of several spores borne on a spe PENETRATION. An initial invasion of a host by a dis cialized hypha (promycelium) which develop from ease incitant. teliospores of rusts and smuts. PERITHECIUM (A). A round-oval, flask-shaped fruiting SPORDOCHIUM. A compact conidial body; mass of structure containing asci and an apical aperture. sporophores. PHYSIOLOGIC RACE. A pathogen similar in morpholog STRAIN. An organism with similar morphologic char ical characteristics but differing in ability to parasi acteristics to another but with different physiologic tize certain varieties of the host. characters. PoLYGENIC. Having more than one gene. STROMATIC BODY (STROMA). A mass of vegetative hy PRIMARY INOCULUM. The initial infective disease phae in or on which fruiting structures develop. inciting agent (pathogen) causing infection in the SuBSTRATE. The base upon which an organism de host plant. rives its nourishment. PYCNIDWM (A). A small globose or flask-shaped fruit SYMPTOM. The expression by the host resulting from ing body containing asexual spores. the host-pathogen disease-incitant interaction. PYcNIDIOSPORE(s). A spore or spores developed in a SYSTEMIC. Spread throughout the host tissues; not lo pycnidium. calized or confined within specific boundaries. SAPROPHYTE. An organism which derives its nourish TELIOSPORE. A spore produced by rusts and smuts ment from dead organic matter. which germinates to form a hypha (promycelium) SCLEROTIUM (A). A firm-bodied resting structure on which sporidia are abstricted. formed by certain fungi consisting of a mass of hy TELIUM (A). A spore-bearing body or sorus in which phae surrounded by a darker outer ring. teliospores are produced. SECONDARY INOCULUM. Spores or infective bodies TussoCK. A compact tuft (clump) of a grass. produced after the host has been colonized. UREDIUM (A). A spore-bearing body or sorus in which SECONDARY INFECTION. An infection resulting from urediospores are produced. inoculum produced by the pathogen during pri UREDIOSPORE (s). A spore characteristic of the rust mary infection or during the production of second fungi capable of initiating secondary infection by ary inoculum. reinfecting the same host. SETA (AE). A small, slender, usually rigid bristle or VECTOR. A living organism capable of transmitting a hair. disease incitant. SEXUAL REPRODUCTION. Reproduction requiring nu VIRUS. A submicroscopic infective entity which can clear fusion and meiosis. reproduce only in living cells. SoRus (1). A spore-containing body of rusts and YELLOWS. A foliage condition caused by destruction smuts which become exposed at maturity upon of the chlorophyll.

42 DISEASES INDEXED BY HOST

Bentgrass and Red Top Yellow leaf rust 9 Flag smut (red fescue) 11 Anthracnose 23 Crested wheatgrass Halo blight/brown spot 5 Ascochyta leafspot (A. sorghi) 24 Agropyron mosaic 32 Leaf blotch (Rhynchosporium) 16 Bipolaris foot rot 20 Anthracnose 23 Leaf rust 10 Blister smuts (leafspot smuts) 12 Ascochyta leafspot (A. sorghi) 24 Leaf scald 16 Cocksfoot mottle 31 Bacterial brown stripe 3 Leafspot smuts (blister smuts) 12 Covered smuts (kernel smuts) 12 Bacterial stripe 3 Leaf streak (Rhynchosporium) 16 Crownrust8 Bipolaris foot rot 20 Leaf streak (Scolecotrichum) 15 Drechslera leafspot 20 Ergot 14 Net blotch 18 Ergot 14 Flag smut 11 Phleum mottle 33 Kernel smuts (covered smuts) 12 Head smuts (loose smuts) 12 Powdery mildew 13 Leaf rust 10 Loose smuts (head smuts) 12 Red thread (red fescue) 27 Leafspot smuts (blister smuts) 12 Powdery mildew 13 Rhizoctonia blight 26 Mastigosporium leaf fleck 16 Rhizoctonia blight 26 Ryegrass mosaic 30 Phleum mottle 33 Snow molds 27 Snow molds 27 Powdery mildew 13 Take-all26 Stem rust (black stem rust) 8 Red thread 27 Stem rust (black stem rust) 8 Stripe rust (yellow rust) 9 Rhizoctonia blight 26 Stripe rust (yellow rust) 9 Take-all (red fescue) 26 Stem rust (black stem rust) 8 Uromyces leaf rust 10 Stripe rust (yellow rust) 9 Agropyron species Yellow leaf rust 9 Agropyron mosaic 32 Stripe smut 11 Orchardgrass Snow molds 27 Anthracnose 23 Ascochyta leafspot (A. sorghi) 24 Anthracnose 23 Take-all26 Ascochyta leafspot (A. sorghi) 24 Uromyces leaf rust 10 Bacterial brown stripe 3 Bipolaris foot rot 20 Bacterial wilt 5 Bipolaris foot rot 20 Bluegrass Brown spot/halo blight 5 Agropyron mosaic 32 Crownrust8 Blind seed 14 Anthracnose 23 Ergot 14 Brown blight 19 Ascochyta leafspot (A. sorghi) 24 Halo blight/brown spot 5 Cocksfoot mild mosaic 32 Bacterial stripe 3 Head smuts (loose smuts) 12 Cocksfoot mottle 31 Bacterial wilt 5 Loose smuts (head smuts) 12 Cocksfoot streak 31 ·Ergot 14 Bipolaris foot rot 20 Powdery mildew 13 Flagsmutll Blind seed 14 Rhizoctonia blight 26 Leaf blotch (Rhynchosporium) 16 Blister smuts (leafspot smuts) U Snow molds 27 Bromegrass mosaic 32 Stem rust (black stem rust) 8 Leaf scald 16 Leafspot (Drechslera catenaria) 19 Cocksfoot mottle 31 Stripe rust (yellow rust) 9 Leafspotlblotch (Drechslera dactylidis) 19 Crownrust8 Stripe smut 11 Leaf streak (Rhynchosporium) 16 Ergot 14 Take-all26 Leaf streak (Scolecotrichum) 15 Flag smut 11 Translucent leaf stripe 6 Leaf rust 10 Mastigosporium leaf fleck 16 Leafspot (Drechslera poae) 20 Fescues Powdery mildew 13 Leafspot smuts (blister smuts) 12 Agropyron mosaic (red fescue) 32 Phleum mottle 33 Melting out 20 Anthracnose 23 Purple leafspot 22 Powdery mildew 13 Ascochyta leafspot (A. sorghi) 24 Rhizoctonia blight 26 Red thread 27 Bacterial brown stripe 3 Ryegrass mosaic 30 Rhizoctonia blight 26 Bacterial wilt 5 Snow molds 27 Ryegrass mosaic 30 Barley yellow dwarf 33 Stem rust (black stem rust) 8 Snow molds 27 Bipolaris foot rot 20 Stripe rust (yellow rust) 9 Stem rust (black stem rust) 8 Blister smuts (leafspot smuts) 12 Stripe smut 11 Stripe rust (yellow rust) 9 Brown blight (meadow fescue) 19 Translucent leaf stripe 6 Stripe smut 11 Brown spot/halo blight 5 Uromyces leaf rust 10 Take-all26 Crownrust8 Yellow slime 2 Uromyces leaf rust 10 Ergot 14 43 Reed canary grass Bacterial brown stripe 3 Anthracnose 23 Anthracnose 23 Barley yellow dwarf 33 Ascochyta leafspot (A. sorghi) 24 Crownrust8 Bipolaris foot rot 20 Bacterial brown stripe 3 Ergotl4 Blackish-brown stripe 5 Bacterial wilt 5 Drechslera leafspot (D. catenaria) 19 Bromegrass mosaic 32 Bipolaris foot rot 20 Leafspotlblotch (Septoria bromi) 24 Brown leafspot 18 Ergot 14 Phleum mottle 33 Brown spot/halo blight 5 Head smuts (loose smuts) 12 Powdery mildew 13 Ergot 14 Leaf streak (Scolecotrichum) 15 Rhizoctonia blight 26 Flag smut 11 Loose smuts (head smuts) 12 Stripe smut 11 Halo blight/brown spot 5 Powdery mildew 13 Tawny blotch 22 Leaf blotch (Rhynchosporiurn) 16 Rhizoctonia blight 26 Leaf scald 16 Yellow leaf rust 9 Phalari.s spp. Leaf streak (Rhynchosporium) 16 Anthracnose 23 Timothy Rhizoctonia blight 26 Ascochyta leafspot 24 Anthracnose 23 Selenophoma leafspot (5. bromigena) 25 Crown rust8 Bacterial wilt 5 Septoria leafspot (S. bromi) 24 Ergot 14 Barley yellow dwarf 33 Stagonospora leafspot (S. bromi) 22 Rhizoctonia blight 26 Blind seed 14 Translucent leaf stripe 6 Tawny blotch 22 Blister smuts (leaf spot smuts) 12 Bro01us spp. Bipolaris foot rot 20 Annual ryegrass Ascochyta leafspot (A. sorghi) 24 Bromegrass mosaic 32 Bacterial wilt 5 Bacterial brown stripe 3 Brown spot/halo blight 5 Take-all26 Bipolaris foot rot 20 Crown rustS Perennial ryegrass Bromegrass mosaic 32 Drechslera leaf streak (D. phlei) 20 Red thread 27 Brown Jeafspot lS Ergot 14 Annual and perennial ryegrasses Brown spot/halo blight 5 Eyespot 21 Agropyron mosaic 32 Cocksfoot mottle 31 Flag smut 11 Anthracnose 23 Crown rustS Halo blight/brown spot 5 Bacterial brown stripe 3 Ergot 14 Leaf spot smuts (blister smuts) 12 Barley yellow dwarf 33 Halo blight/brown spot 5 Leaf streak (Scolecotrichum) 15 Bipolaris foot rot 20 Head smuts (loose smuts) 12 Mastigosporium leaf fleck 16 Blind seed 14 Leaf scald 16 Phleum mottle 33 Bromegrass mosaic 32 Leaf blotch (Rhynchosporium) 16 Powdery mildew 13 Brown blight 19 Leaf streak (Rhynchosporium) 16 Rhizoctonia blight 26 Brown spot/halo blight 5 Leaf streak (Scolecotrichurn) 15 Snow molds 27 Cocksfoot streak 31 Loose smuts (head smuts) 12 Stem rust (black stem rust) 8 Crown rustS Phleum mottle 33 Stripe rust (yellow rust) 9 Ergot 14 Powdery mildew 13 Stripe smut 11 Halo blight/brown spot 5 Ryegrass mosaic 30 Translucent leaf stripe 6 Leaf blotch (Rhynchosporiurn) 16 Selenophoma leafspot (S. bromigena) 25 Wild ryegrass Leaf scald 16 Septoria leafspot (5. bromi) 24 Agropyron mosaic 32 Leaf streak (Rhynchosporiurn) 16 Stagonospora leafspot (S. bromi) 22 Anthracnose 23 Leaf streak (Scolecotrichurn) 15 Stripe smut 11 Ascochyta leafspot (A. sorghi) 24 Mastigosporium leaf fleck 16 Translucent leaf stripe 6 Bipolaris foot rot 20 Net blotch 1S Sorghum Cocksfoot mottle 31 Phleum mottle 33 Bacterial stripe 3 Crown rustS Powdery mildew 13 Bacterial brown stripe 3 Ergotl4 Rhizoctonia blight 26 Bacterialleafblight 4 Flag smut 11 Ryegrass mosaic 30 Powdery mildew 13 Head smuts (loose smuts) 12 Snow molds 27 Loose smuts (head smuts) 12 Sudangrass Speckled leaf blotch 24 Powdery mildew 13 Anthracnose 23 Spermospora leafspot 17 Rhizoctonia blight 26 Ascochyta leafspot (A. sorghi) 24 Stem rust (black stem rust) S Stripe smut 11 Bacterial stripe 3 Stripe rust (yellow rust) 9 Bacterialleafblight 4 WARM-SEASON GRASSES Stripe smut 11 Ergot 14 Big bluestem S01oothbronnegrass Powdery mildew 13 Ascochyta leafspot (A. sorghi) 24 Ascochyta leafspot (A. sorghi) 24 Tall oatgrass Stem rust (black stem rust) S

44 Little bluestem Ascochyta Ieafspot (A. sorghi) 24 Switchgrass Spot blotch 21 Indiangrass Ascochyta Jeafspot (A. sorghi) 24