| Pearl Millet Diseases - Fungal |
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Bipolaris leaf spotBipolaris setariae (Saw.) Shoem
Cercospora leaf spotCercospora penniseti (Chupp)
Curvularia leaf spotCurvularia penniseti (Mitra) Boedijn
Dactuliophora leaf spotDactuliophora elongata Leakey
Downy mildewSclerospora graminicola (Sacc.) Schroet.
Plasmopara penniseti Kenneth & Kranz.
Drechslera leaf spotDrechslera dematioidea (Bubak & Wroblewski) Subram. & Jain
ErgotClaviceps fusiformis Loveless
Claviceps africana Frederickson, Mantle & de Milliano
Exserohilum leaf blightExserohilum rostratum (Drechs.) K.J. Leonard & E.G. Suggs
False mildewBeniowskia sphaeroidea (Kalchbr. Cke.) Mason
Head mold Various fungi
Myrothecium leaf spotMyrothecium roridum Tode ex. Fr
Phyllachora leaf spotPhyllachora penniseti Syd.
Phyllosticta leaf blightPhyllosticta penicillariae Speg.
Pyricularia leaf spotPyricularia grisea (Cke.) Sacc
Rhizoctonia blightRhizoctonia solani Kuhn
Rhizoctonia zeae Voorhees
RustPuccinia substriata Ell. & Barth. indica Ramachar & Cumm.
Seedling blight Various fungi
SmutMoesziomyces penicillariae (Bref.) Vanky
Southern blightSclerotium rolfsii Sacc.
Top rotFusarium moniliforme Sheldon
Zonate leaf spotGloeocercospora sorghi Bain & Edgerton
| Bipolaris Leaf Spot Bipolaris setariae (Saw.) Shoem |  |  |
Foliar symptoms vary, as brown flecks, fine linear streaks, small oval spots, large irregular oval, oblong, or almost rectangular spots measuring 1-10 x 0.5-3 mm. Large fusiform lesions are sometimes produced. Lesions may expand and coalesce. Lesions may be solid dark brown but usually become tan or greyish brown with a more or less distinct dark brown border (Luttrell 1954).
Pathogen and disease characteristics:
Pigmented conidia are fusoid to obclavate fusoid, straight to usually slightly curved, thin-walled but becoming moderately thick walled at maturity, pale or moderately dark olivaceous brown, 44-151 x 10.6-19.6 um, 4 to 13 septate (Luttrell 1954).
The pathogen causes seed decay, seedling blight, leaf spot, and head mold of pearl millet. Young plants and maturing plants most susceptible to foliar blight (Wells and Burton 1967). Seedling blight is more pronounced at temperatures of 25 oC and less (Wells 1967).
Host Range:
Pearl millet, napiergrass, browntop millet (Panicum fasciculatum Swartz) (sic), Arundinella nepalensis (Bhowmik 1972), sugarcane, teosinte, maize (Nishihara 1967), sorghum, Paspalum scrobiculatum, Panicum miliaceum, barley (Hordeum vulgare), wheat (Triticum aestivum), oat (Avena sativa), Cogongrass (Imperata arundinacea, old nomenclature, now I. cylindrica), bermudagrass (Cynodon dactylon) (Misra et al. 1974).
Geographic distribution:
Continental United States, Hawaii (Raabe et al. 1981), India, Japan (Nishihara 1967), Zimbabwe, Zambia (Singh et al. 1990).
Nomenclature discrepancies:
Synonyms or similar pathogens:
Several "Helminthosporium" species differ only slightly based upon thickness of conidial walls and conidial sizes (Luttrell 1954, Luttrell et al. 1974). Some confusion and possible controversy exists in regards to descriptions, taxonomy, and host range of this and other potentially very similar fungi, including:
Drechslera setariae Saw.
Helminthosporium setariae Saw.
Helminthosporium sacchari (van Breda de Haan) Butl. (Misra et al. 1974)
Helminthosporium stenospilum
Helminthosporium australiense Bugnicourt (Chand and Singh 1966)
Bipolaris urochloae (Putterill) Shoem has been implicated in causing ABrown leaf spot@ (Singh et al. 1990)
Host Range and Geographic Distribution of Bipolaris Species Pathogenic to Pennisetum Species (Table)
Seed transmission:
Can be isolated from seed (Wells and Winstead 1965, Wilson et al, 1993) and transmitted to seedlings from seeds (Shetty et al. 1982).
Primary citation(s):
As indicated above.
Cercospora penniseti (Chupp)
| Symptoms: Foliar lesions are typically oval, 1-8 x 0.8-2.5 mm, with dark brown margins and pale tan to grey or white centers, dotted with rows of black conidiophore tufts. Lesions can form on stems. Pathogen and disease characteristics: Conidiophores arise in clusters from small, brown, substomatal stromata. Conidia are almost filiform (approximately 91-136 x 4 um), widest in the basal cell or in the first |  |  |
Host range:
Pearl millet
Geographic distribution:
India (Narayanaswami and Veerraju 1970), United States, possibly Malawi (Wiehe 1953), and possibly Tanzania (Mbwaga et al. 1993).
Nomenclature discrepancies:
Synonyms or similar pathogens:
Cercospora fusimaculans Atk (Wiehe 1953, Alagianagalingam et al. 1971).
Cercospora sorghi Ellis & Everhart (Mbwaga et al. 1993)
Cercospora typhoides (Sharma and Jain 1967)
Phaeoramularia fusimaculans
Seed transmission:
Not demonstrated to be seed transmitted.
Primary citation(s):
(Luttrell 1954, Rachie and Majmudar 1980)
Curvularia penniseti (Mitra) Boedijn
| Symptoms: Small yellow-brown spots on leaves expand to oblong lesions. Center of lesions change to brown and margins remain yellow. Lesions are more common on leaf margins. Pathogen and disease characteristics: Conidia are 3-septate, clavate, almost always slightly curved at the third cell from the base which is larger than the others. Cell at each end are subhyaline or pale, intermediate cells are brown, third cell from the base is usually more pigmented and darker, 29-42 x 13-20 um at broadest part. |  |
Host range:
Oryza, Pennisetum, Sorghum, Triticum, isolated from Allium, Dolichos, and Richardia.
Geographic distribution:
Australia, India, Indonesia, Malawi, Nepal, Nigeria, Pakistan, continental United States, Hawaii (C. lunata, Raabe et al. 1981), Zimbabwe.
Nomenclature discrepancies:
Synonyms or similar pathogens:
Acrothecium penniseti Mitra
Other species of Curvularia can be isolated from pearl millet, including:
Curvularia lunata (Wakker) Boed. A toxin produced by the pathogen is related to host and cultivar specificity (Gour et al. 1992).
Curvularia geniculata (Tracy & Earle) Boed.
No information is available to indicate if symptoms caused by other species of Curvularia differ from symptoms caused by C. penniseti.
Seed transmission:
Curvularia species are frequently isolated from seed.
Primary citation(s):
(Luttrell 1954, Sivanesan 1990a)
| Dactuliophora elongata Leakey Symptoms: Symptoms begin on upper leaf surface as pin-point isolated brown lesions. As lesions increase in size, they become brownish at edge and dirty white or straw colored toward the center. In wet weather, irregular water-soaked areas develop around the spots and turn necrotic. Well-developed lesions have no definite shape or are roughly oval or semi-circular, zonate with kidney-shaped patches of necrotic tissue and brown or yellow tissue in between. Black sclerotia develop in upper surface of necrotic tissue. Pathogen and disease characteristics: |  |
Tan aerial mycelium without sclerotia develops on PDA. On the host, white mycelium appressed to the cuticle on the lower leaf surfaces. Obclavate-ellipsoid to pyriform, brown sclerotia develop on erumpent, cup-shaped sclerotiophores. Sclerotia germinate by producing germ tubes over the entire surface after 4 to 8 hours.
Host range:
Pearl millet.
Geographic distribution:
Nigeria (Tyagi,1985). Mali (J.P. Wilson, personal observation)
Nomenclature discrepancies:
Disease symptoms illustrated in Williams et al. (1978) and attributed to zonate leaf spot (Gloeocercospora sorghi) are probably those of Dactuliophora leaf spot.
Seed transmission:
Not known to be seed transmitted.
Primary citation(s):
(Tyagi,1985)
Sclerospora graminicola (Sacc.) Schroet.
| Symptoms: Symptoms often vary as a result of systemic infection. Leaf symptoms begin as chlorosis at the base and successively higher leaves show progressively greater chlorosis. Infected chlorotic leaf areas can support abundant white asexual sporulation on the lower leaf surface. Severely infected plants are generally stunted and do not produce panicles. Green ear symptoms result from transformation of floral parts into leafy structures. Pathogen and disease characteristics: Asexual sporangia are produced during the night with moderate temperatures and high humidity. Optimum sporangium production occurs at 20 oC. No sporulation below 70% relative humidity. Sporangia germinate to liberate 1 to 12 zoospores, which encyst and germinate by germtube. Sporangia generally do not remain viable very long after daybreak. Sexual oospores are thick-walled, spherical, and brownish yellow, 22 to 35 um in diameter. Oospores form in colonized plant tissue and can survive from 8 months to 13 years under laboratory conditions. |  |
Host range:
Pearl millet. Host specificity is important in determing host range for this pathogen. S. graminicola has been reported from maize, sorghum, Echinochloa crusgalli, Panicum miliaceium, Pennisetum leonis, P. spicatum, Setaria italica, S. lutescens, S. verticillata, S. viridis, S. magna, Euchlaena maxicana, and Agrotis alba. Cross inoculation studies to different hosts have usually been unsuccessful when attempted.
Geographic distribution:
On page 2 of the primary citation, a reference to Farlow (1884) indicates that S. graminicola has been identified in the United States on "other millets". On page 3, the continental U.S. is included in the geographic distribution of the pathogen. Despite this information, THIS PATHOGEN HAS NOT BEEN REPORTED ON PEARL MILLET IN THE UNITED STATES, AND ALL EFFORTS TO RESTRICT ITS ENTRY SHOULD BE CONTINUED. S. graminicola has been reported on pearl millet in the countries listed below.
Africa: Chad, Egypt, Gambia, Malawi, Mozambique, Niger, Nigeria, Zimbabwe, Senegal, South Africa. Also Mali, Burkina Faso, Ivory Coast, Sudan, Kenya, Uganda, Tanzania, Ghana, Togo, Zambia (S.B. King, personal communication)
Asia: India, Pakistan. Also Israel (S.B. King, personal communication)
Nomenclature discrepancies:
Synonym:
Scleropthora macrospora (for example: Manivasakam et al. 1986, Mangath 1986).
Alternative disease name:
Green ear disease
Seed transmission:
Evidence for seed transmission is inconsistent and controversial. It has been suggested that this disease can be transmitted by oospores on the seed surface. To prevent introduction of S. graminicola, seed treatment is recommended.
Primary citation(s):
(Singh et al. 1993).
Downy Mildew
Plasmopara penniseti Kenneth & Kranz.
Symptoms:
Small, diffuse watersoaked stripes or spots expand to irregular brown stripes between the veins. Stripes may coalesce and turn necrotic. Streaks may enlarge beyond veins and turn greyish brown. "Down" of asexual sporulation is profuse and whitish to dingy. Only local lesions form. Usually only the lower leaves are affected.
Pathogen and disease characteristics:
Sporangiophores emerge from stomata, dichotomously branched once or twice, then branched irregularly monopodially to subdichotomously two or three times at right angles. Oospores have not been observed.
Host range:
Pearl millet.
Geographic distribution:
Ethiopia.
Nomenclature discrepancies:
Use of "downy mildew" as the common name for this disease may cause confusion with the more serious systemic disease caused by Sclerospora graminicola.
Seed transmission:
Not known to be seed transmitted.
Primary citation(s):
(Kenneth and Kranz 1973).
Drechslera dematioidea (Bubak & Wroblewski) Subram. & Jain
Symptoms:
Infection of seedlings results in 1- to 3-mm long coalescing lesions with extensive necrosis (Wilson and Hanna 1992).
Pathogen and disease characteristics:
Conidia straight, cylindrical to clavate, rounded at the ends, golden brown to dark brown, thick-walled, 2 to 7 (commonly 3 to 4) distoseptate, 20-70 x 10-16 um.
Host range:
Pearl millet, Agrostis, Anthoxanthum, Avena, Cynodon, Dactylis, Eragrostis, Festuca, Hordeum, Lolium, Paspalum, Phleum, and Triticum. Also isolated from Iris, Leucospermum, Pinus, and Pseudotsuga.
Geographic distribution:
Australia, Europe, New Zealand, North America, South Africa, India.
Nomenclature discrepancies:
Synonyms or similar pathogens:
Helminthosporium dematioideum Bubak & Wroblewski
Helminthosporium tetramera McKinney (Yadav et al. 1975)
Seed transmission:
Seed borne.
Primary citation(s):
(Sivanesan 1990b)
Claviceps fusiformis Loveless
| Symptoms: Cream to pink mucilaginous droplets of "honeydew" ooze out of infected florets on pearl millet panicles. Within 10 to 15 days, the droplets dry and harden, and dark brown to black sclerotia develop in place of seeds on the panicle. Sclerotia are larger than seed and irregularly shaped, and generally get mixed with the grain during threshing.
Pathogen and disease characteristics: Sclerotia germinate to form 1 to 16 fleshy stipes, 6 to 26 mm long. Each stipe bears an apical, globular capitulum, light to dark brown, with numerous perithecial projections. Asci are interspersed with paraphyses and emerge through ostioles. Thread-like ascospores are hyaline, aseptate, and measure 100-170 x 0.5-0.7 um. |  |
Sclerotia germinate following rain. Ascospores infect emerged stigmas before pollination. Conditions favoring the disease are relative humidity greater than 80%, and 20 to 30 oC temperatures. Honeydew production promotes secondary infection caused by asexual conidia. Honeydew consists of two types of asexual conidia.
Host range:
Pearl millet, Cenchrus ciliaris, Panicum antidotale, Pennisetum hohenackeri Hochst.
Also P. squamulatum and P. massaicum (Dwarakanath Reddy et al. 1969)
Geographic distribution:
THIS PATHOGEN HAS NOT BEEN REPORTED ON PEARL MILLET IN THE UNITED STATES AND ALL EFFORTS TO RESTRICT ITS ENTRY SHOULD BE CONTINUED. Countries where pearl millet ergot has been observed or reported include:
Africa: Botswana, Burkina Faso, Gambia, Ghana, Malawi, Niger, Senegal, Somalia, Tanzania, Uganda, Zambia, and Zimbabwe. Also Nigeria, Chad, Benin, Cameroon, Togo, Ivory Coast, Mali, Sudan, Kenya, Uganda, Zambia (S.B. King, personal communication)
Asia: India, Pakistan.
Nomenclature discrepancies:
Synonyms or similar pathogens:
Claviceps microcephala (Wallr.) Tul.
Sphacelia spp., and Cerebella sorghi-vulgaris Subram. (Wallace and Wallace 1949).
Alternative disease name:
Asali disease
Seed transmission:
Sclerotia can contaminate seed lots. A 10% NaCl solution is effective for separating sclerotia and fragments from seed by flotation. This technique can be used only for relatively small quantities of seed. Sclerotia can be removed from small individual seed lots by hand.
Primary citation(s):
(Thakur and King 1988).
Ergot
Claviceps africana Frederickson, Mantle & de Milliano
Symptoms:
Sphacelial (condial) "honeydew" sporulation has been reported on pearl millet (Frederickson and Mantle 1996). Sclerotial formation has not been reported.
Pathogen and disease characteristics:
Occurrence of the disease has usually been the result of artificial inoculation, except for the observation by Sundaram (1974), which, because of the geographic location, may have been Claviceps sorghi.
From sorghum: Sclerotia (4-6 x 2-3 mm) bear a small distal sphacelial cap. White medulla is bound by thin red-brown cortex. Flower parts are persistent on sclerotia. Stromata are initially pale, translucent, and proliferate from sclerotium at 1 or 2 places. Stipes are pigmented purple in distal part of stipe. Stipes measure 8-15 x 0.3-0.6 mm, capitula are sub-globose, 0.5-1.3 mm, perithecia measure 86-135 x 123-226 um. Ascospores dimensions usually up to 45 x 0.8-1.2 um. Macroconidia are hyaline, mononucleate, oblong to oval, slightly constricted at center with a vacuole at each end, 9-17 x 5-8 um. Microconidia are hyaline, mononucleate, spherical, 2-3 um diameter (Frederickson et al. 1991)
Host range:
Sorghum, pearl millet, guinea grass (Panicum maximum). The literature is not clear.
Geographic distribution:
Infection on pearl millet has been observed in Zimbabwe, possibly Nigeria and possibly India. Geographic distribution of the pathogen on sorghum is wider than that reported for pearl millet.
Nomenclature discrepancies:
The literature suggests cross infection of pearl millet with Sphacelia sorghi McRae. Futrell and Webster (1966) reported 1% of inoculated florets became infected in Nigeria. Sundaram (1974) reports infections in India, with subsequent cross inoculations onto sorghum and pearl millet. Few experimental details are described. Dwarakanath Reddy et al. (1969) produced 20% infection on pearl millet. Frederickson and Mantle (1996) achieved successful inoculations with C. africana. Frederickson et al. (1991) indicate that there are at least two Claviceps species, C. africana and C. sorghi, that have been lumped under Sphacelia sorghi in the literature.
Seed transmission:
No information available. Literature does not indicate if sclerotia form in pearl millet.
Primary citation(s):
(Frederickson and Mantle 1996).
| Exserohilum Leaf Blight Exserohilum rostratum (Drechs.) K.J. Leonard & E.G. Suggs Symptoms: Foliar lesions (1-2 x 2-5 mm) are straw colored with brown margins. Lesions are often dark brown at first and then become light brown. Blighting often occurs on leaf tips and margins. Pathogen and disease characteristics: Pigmented conidia are quite variable but approximately 200 x 8 um, straight or slightly curved, rostrate shaped with 6 to 16 septa. Terminal septa are particularly dark and thickened. Distinct hilum forms on the basal cell. |  |
Host range:
Pearl millet, corn, sorghum, Setaria italica Beauv., Eleusine coracana Garten.
Geographic distribution:
India, United States
Nomenclature discrepancies:
Synonyms:
Helminthosporium rostratum Drechs.
Exserohilum rostrata (Drechs.) Shoem.
Drechslera rostrata
Seed transmission:
Can be isolated from seed (Wells and Winstead 1965, Wilson et al. 1993). Seedling infection from contaminated seed has not been demonstrated.
Primary citation(s):
(Young et al. 1947, Mohan et al. 1988)
Beniowskia sphaeroidea (Kalchbr. & Cke.) Mason
Symptoms:
Small, white cushion shaped sporodochia, circular to elongate (1.5 mm long), are formed singly and in clusters on leaves. Infected leaves become chlorotic and necrotic from the point of infection to the apex of the leaf.
Pathogen and disease characteristics:
A network of aerial hyphae culminate in spirally twisted, corkscrew apices at the periphery of the sporodochium. Hyphae are hyaline to very light tan. Conidia are hyaline, spherical, averaging 10 um in diameter. Spores may have imperceptible roughenings and may be borne in short chains.
Host range:
Andropogon marginatus Steud., Chaetochloa poiretiana Hitchc. (=Setaria poiretiana (Schult.)Kunth.), Panicum palmifolium Willd. (=Setaria palmifolia (Willd.) Stapf.), Pennisetum japonicum Trin., Pennisetum nepalense Spreng., Pennisetum purpureum Schumach, Setaria aurea Hochst., Setaria geniculata, Setaria verticillata (L.) Beauv. and Sorghum vulgare Pers.
Geographic distribution:
On pearl millet: Malawi (Wiehe 1953), Zimbabwe (Mtisi and de Milliano 1991), Tanzania (Mbwaga et al. 1993). On other hosts: United States, Japan, Trinidad, Java, Uganda, Malawi, Zimbabwe, South Rhodesia, South Africa, Sudan.
Nomenclature discrepancies:
Synonyms or similar pathogens:
Ceratium sphaeroideum Kalchbr. & Cke.
Beniowskia sphaeroideum Kalchbr. & Cke.
Beniowskia penniseti Wakefield
Albugo sp.
Seed transmission:
Not known to be seed transmitted.
Primary citation(s):
(Taber et al. 1978, Brown and Hanlin 1982)
| Head Mold Various fungi Symptoms: Pink, white, brown or grey fungal growth on grain. Apparently asymptomatic seed may be contaminated. Pathogen and disease characteristics: Many pathogens cause grain molds. Grain molds on pearl millet tend to be more severe with humid conditions during grain fill (Wilson et al. 1993, Ingle and Raut 1994) and if grain harvest is delayed (Wilson et al. 1995). Several fungi cause grain molds, and these differ by the region of cultivation, crop management, environmental conditions prior to harvest, and storage conditions. |  |
 | Host range: See information for specific pathogens. Geographic distribution: See accompanying table and information for specific pathogens. |
Nomenclature discrepancies:
See information for specific pathogens.
Seed transmission:
These fungi are seed-borne by definition. Not all are pathogenic to seedlings.
Primary citation(s):
See accompanying table:
Fungi Isolated From Pearl Millet Seed (Table)
Myrothecium roridum Tode ex Fr
Symptoms:
Water soaked oval spots on leaves rapidly increase in size and turn dirty brown. Necrotic tissue can crack and develop holes.
Pathogen and disease characteristics:
In culture, sporodochia are sessile, up to 1.5 mm diameter, often confluent. Spore masses are viscous and green at first, later becoming hard and black. No setae in sporodochia. Conidia are cylindrical with rounded ends, colorless to pale olive green to black in mass, mostly 6-8 x 1.5-2.5 um. (Ellis 1971, Barron 1968)
Host range:
Pearl millet, Guar [Cyamopsis tetragonoloba (L.) Taub], Moth (Phaseolus acontifolius Jacq., black gram (Phaseolus mungo L.), green gram [Vigna radiata (L.) Wilkzee], pigeonpea [Cajanus cajan (L.) Millsp.], cowpea (Vigna sinensis Endl.), pea (Pisum sativum L.) soybean (Glycine max Merr.), peanut (Arachis hypogaea L.), okra [Abelmoschus esculantum (L.) Moench.], cotton (Gossypium hirsutum L. and Gossypium arboreum L.), potato (Solanum tuberosum L.) tomato (Lycopersicum esculentum Mill), eggplant (Solanum melongena L.), wheat (Triticum aestivum L.), maize (Zea mays L.) (Gaikwad 1988).
Geographic distribution:
India. A Myrothecium species has been isolated from pearl millet stalks in the United States, but species appears to be M. verracaria (J.P. Wilson, personal observation).
Nomenclature discrepancies:
None.
Seed transmission:
Can be isolated from seed (Girisham et al. 1985)
Primary citation(s):
(Ellis 1971, Barron 1968)
Phyllachora penniseti Syd.
Symptoms:
Leaves can be covered with numerous small elongate dark or black pustules, which are 2-3 mm long when isolated, but become confluent in mass. Both surfaces of the leaves can be affected. Symptoms usually develop after most vegetative growth has occurred or during grain fill.
Pathogen and disease characteristics:
Pseudo-pycnidia develop in the stroma under the epidermis. Elliptical, cylindrical unicellular, hyaline conidia measure 10-15 x 2.5-3 um in diameter.
Host range:
Pearl millet, napiergrass (Moreau 1949), also described on Pennisetum benthami Stend. (Saccas 1954).
Geographic distribution:
Chad, Niger, Tanzania (Wallace and Wallace 1949), Republic of Guinea (and possibly Uganda, see below) on napiergrass (Moreau 1949)
Nomenclature discrepancies:
Synonyms or similar pathogens:
Described as anamorphic Placosphaeria sp. in Saccas (1954) and Jouan and Delasus (1971). Leptosphaeria penniseti isolated from napiergrass in Uganda was associated with Phyllachora and Stagonospora (Moreau 1949). Saccas (1954) indicates asci and ascospore dimensions of L. penniseti were consistent with Phyllachorapenniseti, although dimensions of L. penniseti differ from P. penniseti in Moreau (1949).
Alternative disease name:
Tar spot
Seed transmission:
Not demonstrated to be seed transmitted.
Primary citation(s):
(Saccas 1954, Jouan and Delassus 1971)
| Phyllosticta Leaf Blight Phyllosticta penicillariae Speg. Symptoms: Seedlings can be stunted and chlorotic. Leaf lesions measure approximately 5 x 2.5 mm. Lesions generally parallel-sided with dark brown margins and light brown necrotic centers. Coalesced lesions usually result in tattered leaf tissue. Leaf margins are frequently necrotic. Pycnidia form in necrotic tissue. |  |
Pathogen and disease characteristics:
Pycnidia average 75.8 um in diameter. Conidia are hyaline, single-celled, biguttulate, elliptical, and approximately 6.2 x 2.8 um.
Host range:
Pearl millet, possibly napiergrass.
Geographic distribution:
Chad, Niger, Senegal (Spegazzini 1914), continental United States. A Phyllosticta sp. was reported on napiergrass in Hawaii (Raabe et al. 1981). A Phoma sp. was isolated from seed in India (Mathur et al. 1973), possibly Tanzania (Mbwaga et al. 1993).
Nomenclature discrepancies:
Synonyms or similar pathogens:
Reference to Phoma spp. on seed (Mathur et al. 1973) and Phoma sorghina (Sacc.) Boerema on foliage (Mbwaga et al. 1993) may be P. penicillariae.
Seed transmission:
Can be isolated from seed (Wilson et al. 1993). Seedling infection from contaminated seed has not been demonstrated.
Primary citation(s):
(Saccas 1954, Jouan and Delassus 1971, Wilson and Burton 1990)
Pyricularia grisea (Cke.) Sacc
| Symptoms: Lesions on foliage are elliptical or diamond-shaped, approximately 2.5-3.5 x 1.5-2.5 mm. Lesion centers are grey and water-soaked when fresh but turn brown upon drying. Lesions are often surrounded by a chlorotic halo which will turn necrotic, giving the appearance of concentric rings. Pathogen and disease characteristics: Asexual conidia are pyriform, hyaline, mostly 3-celled with a small appendage on the base cell. Conidia measure approximately 17.5-30.8 x 5.9-8.8 um. (Mehta et al. 1953). Germination, appresoria formation, and invasion of host cells greatest at 25 OC (Yadava and Agnihotri 1980). |  |
 | Host range: Pearl millet, Napiergrass (Pennisetum purpureum, Buckley and Allen 1951) Geographic distribution: India, Singapore (on napiergrass, Buckley and Allen 1951), United States. |
Nomenclature discrepancies:
Synonyms:
Pyricularia penniseti (Prasda and Goyal 1970, Singh and Pavgi 1974a)
Piricularia grisea (Wells et al. 1969)
Pyricularia setariae (Rachie and Majmudar 1980)
Piricularia spp. (Mehta et al. 1953)
Alternative names for the disease:
Blast (Buckley and Allen 1951)
Leaf blast (Rachie and Majmudar 1980)
Brown leaf spot (Singh and Pavgi 1974a)
Leaf spot disease (Mehta et al. 1953, Prasda and Goyal 1970)
Pyricularia leaf spot (Singh and Pavgi 1974b, Hanna and Wells 1989)
Piricularia leaf spot (Wells et al. 1969)
Seed transmission:
Primary citation(s): As indicated above. Rhizoctonia solani Kuehn Rhizoctonia zeae Voorhees Symptoms: Disease can be expressed as seed decay, pre-and post-emergence damping off, stem lesions on seedlings, or stem canker on more mature plants. Invasion of sheath and blade tissue can cause banding pattern. Mid-rib is usually the last part of the leaf killed. Mature plants have considerable accumulation of dead brown leaves around the base of the plant. Individual culms may be killed. Root system is reduced with extensive killing and discoloration. Pathogen and disease characteristics: Rhizoctonia species often survive in soil as melanized hyphae and sclerotia, often associated with plant debris. R. solani forms yellow-brown mat-like stroma and distinct sclerotia in culture. R. zeae forms white to pink mycelium and spherical, reddish brown sclerotia immersed throughout agar medium. Classification of Rhizoctonia species is currently based on hyphal characteristics and colony morphology in culture (Sneh et al. 1991) Host range: Nearly all plants are susceptible to one or more anastomosis groups of R. solani or binucleate Rhizoctonia species. Some host specificity exists among the different anastomosis groups of R. solani. Pathogens of pearl millet have not been examined for anastomosis compatibility. R. zeae is primarily a pathogen of grasses. Geographic distribution: On pearl millet: United States and Tanzania (Mbwaga et al. 1993). Nomenclature discrepancies: Synonyms: Pellicularia filamentosa (Pat.) Rogers f. solani (Keuhn) Exner Alternative names for the disease: Soil rot Banded sheath and leaf blight Seed transmission: Not known to be transmitted by seed. Konde et al. (1980) has reported isolation of R. bataticola from seed. Primary citation(s): (Luttrell. 1954, Weber 1963) Puccinia substriata Ell. & Barth. var. indica Ramachar & Cumm. Symptoms: On pearl millet: small reddish-brown to reddish orange, round to elliptical uredinia develop mainly on foliage. As severity of infection increases, leaf tissue will wilt and become necrotic from the leaf apex to base. In infection sites developing late in the season, uredinia are replaced by telia which are black, elliptical, and subepidermal. Pathogen and disease characteristics: P. substriata var. indica is a macrocyclic rust with the uredinial, telial, and basidial stages formed on pearl millet. Urediniospores are generally elliptical, measuring 35 x 25 um, with four equatorial germpores. Spores have yellowish brown walls and are sparely echinulate, but more predominantly near the apex. Teliospores are generally 2-celled, although this can vary. Dark brown, club-shaped spores measure 49 x 21 um, and are born on a pedicel.The spermagonial and aecial stages develop on the alternate Solanum hosts. Uredinial sori may occassionally be parasitized by Darluca filum (Biv.), which forms pycnidia with 2-celled conidia (Ramakrishnan and Narasimhalu 1941) Host range: Uredinial hosts: Pearl millet, Pennisetum orientale, Panicum antidotale, Panicum maximum, Pennisetum violaceum. Also Pennisetum polystachyon (Ramakrishnan and Sundaram 1956). Geographic distribution: United States, Asia: India, Sri Lanka, Pakistan Africa: Chad, Congo, Ethiopia, Ghana, Guinea, Ivory Coast, Kenya, Malawi, Mozambique, Niger, Nigeria, Senegal, Sierra Leone, South Africa, Sudan, Tanzania, Uganda, Zambia and Zimbabwe. Also Burkina Faso (S.B. King, personal communication) Infection of the aecial host has been reported in Brazil (Figueiredo et al. 1971), India (Dalela and Mathur 1970), and the United States (Wilson and Williamson 1997) Nomenclature discrepancies: Synonyms: Puccinia penniseti Zimm. Puccinia substriata Ell. & Barth. var. penicillariae (Speg.) Stat. Other rust pathogens reported on pearl millet: Puccinia stenotaphri Cummins (Sathe 1969). Probably a synonym, the description of the fungus is similar to that in Wells et al. (1973). Puccinia substriata Ell. & Barth. var. decrospora (Eboh 1986) Seed transmission: Not known to occur. Primary citation(s): (Singh and King 1991). Various fungi Symptoms: The disease is expressed as pre- and post-emergence damping off, or stunted seedling growth Pathogen and disease characteristics: Many pathogens cause seedling blight. Those that cause seedling blights are often associated with grain molds foliar blights, or stalk rots. Seedling blights tend to be more severe with cool temperatures (Hart and Wells 1965, Wells and Winstead 1965). Host range: See accompanying table and information for specific pathogens. Geographic distribution: See accompanying table and information for specific pathogens. Nomenclature discrepancies: See accompanying table and information for specific pathogens. Seed transmission: Pathogens associated with grain molds are seed transmitted. See accompanying table and information for specific pathogens. Primary citation(s): See accompanying table: Moesziomyces penicillariae (Bref.) Vanky Immature, green sori larger than the seed develop on panicles during grain fill. A single sorus develops per floret. As grain matures, sori change in color from green to dark brown. Sori are filled with dark teliospores. Pathogen and disease characteristics: Chestnut-brown to black-brown sporeballs are composed of 200 to 1400 aggregated yellowish-brown globose to sub-globose teliospores. Teliospores germinate to produce promycelia with basidiospores and sporidia (Subba Rao and Thakur 1983). Infection occurs when sporidia suspended in rain or dew infiltrate into boot (Wilson 1995). Aerial populations of sporidia are greatest when minimum and maximum temperatures range between approximately 21 and 31 oC, and maximum relative humidity is greater than 80% (Kousik et al. 1988). Host range: Pearl millet Geographic distribution: United States (Wells et al. 1963), India, Zimbabwe, Senegal, Chad, Niger, Nigeria, Malawi (Wiehe 1953, Saccas 1954, King 1970, Jouan and Delassus 1971, Rachie and Majmudar 1980), and Tanzania (Mbwaga et al. 1993). Also Zambia, Sudan, Cameroon, Burkina Faso, Ghana, Mali (S.B. King, personal communication). Nomenclature discrepancies: Synonyms: Tolyposporium penicillariae Bref. (Vanky, 1977) Tolyposporium senegalense Speng. Considerable confusion exists in the literature concerning smut of pearl millet. For further details, see A@ in Questionable or poorly described diseases of pearl millet reported in the literature, page . Seed transmission: Seed may be infested with teliospore balls, but infection does not take place through seedlings (Bhatt 1946). Teliospores may remain viable in the soil, where basidiospores and sporidia may be produced (Patel et al. 1959). Primary citation(s): As indicated above. Sclerotium rolfsii Sacc. Symptoms: Disease is expressed as seed decay, pre-and post-emergence damping off, stem lesions on seedlings, or stem cankers on more mature plants. Infection and rot restricted to lower stem. Mature plants have considerable accumulation of dead brown leaves around the base of the plant. Root system is much reduced with extensive killing and discoloration. Pathogen and disease characteristics: White mycelium and brown sclerotia often visible at base of plant. Very wide, nearly all annuals. Geographic distribution: United States (for pearl millet). Nomenclature discrepancies: Synonym: Pellicularia rolfsii (Sacc.) West Alternative disease name: White mold Seed transmission: Not known to be seed transmitted. Primary citation(s): (Weber 1963) Fusarium moniliforme Sheldon Symptoms: The panicle and immature leaves often remain in the whorl, where they become rotted and covered with a mass of white mycelium. Nodes will frequently be discolored. Pathogen and disease characteristics: Microconidia are abundant, primarily single-celled, formed in long chains and in false heads (Nelson et al. 1983). Host range: Numerous Gramineae. "Top rot" symptoms can occur on pearl millet, sugarcane, and sorghum. Geographic distribution: On pearl millet, only the United States and India. On sugarcane: United States, India, Australia, Hawaii (Ramakrishnan 1941) Nomenclature discrepancies: Alternative disease names: Twisted top Pokkah Boeng Pokkah Bong (name for disease on sugarcane). Seed transmission: F. moniliforme is frequently isolated from seed (See Table 4) Primary citation(s): (Wells 1956) Gloeocercospora sorghi Bain & Edgerton Symptoms: Foliar lesions appear as water-soaked spots which develop tan centers and dark brown borders and measure 3.5-5 x 2-3.5 mm. Spots enlarge forming roughly semi-circular blotches covering about half of the leaf width. Blotches are various shades of dark brown mottles with pale tan spots which may appear as concentric rings of alternating tan and brown. Note that disease symptoms of zonate leaf spot illustrated in Williams et al. (1978) were later attributed to Dactuliophora leaf spot (Tyagi 1985). Symptom expression of and differentiation between these two diseases need to be clarified. Pathogen and disease characteristics: Conidia borne on short erumpent stromata are attenuate-obclavate, hyaline, multiseptate and approximately 74.5-2.2 um. In moist weather, tiny salmon-colored globules of conidial masses are visible with a hand lens on the foliar lesions. Host range: Pearl millet, sorghum Geographic distribution: United States, Tanzania (Wallace and Wallace 1949), Malawi (Wiehe 1953). Nomenclature discrepancies: None Seed transmission: Very infrequently isolated from seed (Wilson et al. 1993). Seed transmission not demonstrated. Primary citation(s): (Luttrell 1954)Rust 
Aecial hosts: Eggplant (Solanum melongena L.), S. pubescens Willd., S. torvum Sw., S. xanthocarpum Schrad & Wendl., S. anguivi Lam., S. ferox L., S. incanum L., S. linnaeanum Hepper & P. Jaeger, S. gilo Raddi, S. nodiflorum Jacq., S. rostratum Dunal (Wilson et al. 1996), S. melongena var. insanum Prain, and S. pubescens Willd. (Ramakrishnan and Sundaram 1956). Euphorbia pulcherimma Willd (Rao et al. 1986) has also been reported as an aecial host, but the report is subject to some question. 
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