banan e
Mycosphaerella musae and Cercospora "Non-Virulentum" from Sigatoka Leaf Spots Are Identical
R .H . STOVE R ee e s•e•• seeese•eeeeesee e Tela Railroad C ° Mycosphaerella musae Comparaison des Mycosphaerella musa e La Lima, Cortè s and Cercospora souches de Mycosphae- y Cercospora "no Hondura s "Non-Virulentum " relia musae et de Cerco- virulenta" de Sigatoka from Sigatoka Leaf Spots spora "non virulent" son identical Are Identical. isolées sur des nécroses de Sigatoka.
ABSTRACT RÉSUM É RESUME N Cercospora "non virulentum" , Des souches de Cercospora Cercospora "no virulenta" , commonly isolated from th e "non virulentes", isolée s comunmente aislada de early streak stage of Sigatok a habituellement lorsque les estadios tempranos de Sigatoka leaf spots caused b y premières nécroses de Sigatoka , causada por Mycosphaerella Mycosphaerella musicola and dues à Mycosphaerella musicola musicola y M. fijiensis, e s M. fijiensis, is identical to et M . fijiensis, apparaissent su r identica a M. musae. Ambas M. musae . Both produce th e les feuilles, sont identiques à producen el mismo conidi o same verruculose Cercospora- celles de M. musae. Les deux entre 4 a 5 dias en agar. like conidia within 4 to 5 day s souches produisent les mêmes No se produjeron conidios on plain agar. No conidia ar e conidies verruqueuses aprè s en las hojas . Descarga s produced on banana leaves . 4 à 5 jours de culture sur de de ascosporas de M. musae Discharge of M. musa e l agar pur . Aucune conidic son mas abundantes en hoja s ascospores from massed lea f n est produite sur les feuilles infectadas con M . musicola spots is more abundant fro m de bananiers . La décharg e que con M . fijiensis. Cultivos leaves infected wit h d ascospores de M . musae à de Cercospora "no virulenta " M . musicola than with partir de nécroses fusionnées y M. musae pueden causar M . fijiensis . Cultures of entre elles est plus abondante esporulación en hojas jovene s Cercospora "non-virulentum" quand les feuilles sont infectée s de variedades Cavendish and M. musae can cause avec M . musicola qu avec después de ser inoculadas, spotting on young leave s M . fijiensis. Des cultures d e pero el período de incubación of Cavendish varieties afte r souches non virulentes d e excede los 70 dias . M . Musae inoculation but the incubation Cercospora et de M. musa e es un endofito en hojas de period exceeds peuvent provoquer des lésions banano infectadas, con Sigatoka 70 days . M . musae is a n sur des jeunes feuilles de l a en América Central, Mexico, endophyte in banana leave s variété Cavendish, mais la Ecuador, Surinam y el Caribe . infected by Sigatoka pathogen s période d incubation es t in Central America, Mexico , supérieure à 70 jours . M. musa e Ecuador, Surinam and th e est un champignon endophyte Carribbean . des feuilles de bananier s infectées par les pathogène s responsable des deu x cercosporioses en Amériqu e centrale, au Mexique, e n Equateur, au Surinam et dans la Caraïbe .
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KEYWORD S MOTS CLÉ S PALABRAS CLAVE S Musa, Mycosphaerella, Musa, Mycosphaerella , Musa, Mycosphaerella , Cercospora, blotches, Cercospora, cercosporiose, Cercospora, cercosporiose , conidia, lesions . conidie, lésions . conidio, lesiones .
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Young cv Valery plants about six month s et introductio n old derived from meristem cultures wer e inoculated by smearing a suspension o f Previous studies showed that a variety o f hyphae and conidia from agar cultures on fungal flora is present in leaf spot caused the underside of the youngest leaves . The by Mycosphaerella musicola (= Pseudo- plants were then placed inside a close d cercospora musae) (STOVER, 1963, 1969) . clear plastic container where a saturate d M. musae was found to be one of th e atmosphere was maintained for at least most ubiquitous species (STOVER, 1969) . A 12 h per day . similar flora was found in leaf spots caused by M. fijiensis (= Paracercospora fijiensis) (ANON ., 1983) . In addition, i n young lesions caused by M. fijiensis, a ~►~z results fungus called Cercospora "non-viru- Most young streak lesions caused by lentum" was prevalent, especially in area s Mycosphaerella fijiensis yielded Cerco- sprayed with benomyl (STOVER, 1977a , "non-virulentum" colonies, although 1977b). Additional studies with M. musae spora usually fewer than the Sigatoka pathogen and Cercospora "non-virulentum" are (Tables 1 and 2) . The widespread use o f reported here and the results reveale d benlate ended in 1977 and, in 1978, the that the latter is the samed as M. musae. proportion of C "non-virulentum" colo - nies tended to be higher than in the 1980s. These colonies were previously shown to have resistance to up 7000 ppm e0•• method s of benomyl (STOVER, 1977h). Fungi were isolated by laying leaf piece s from the early streak stage of the Sigatok a Table 1 disease on Martin s medium (MARTIN , Proportion of Mycosphaerella fijiensis 1950). Five pieces, about 5-11 x 1-2 mm , and Cercospora "non-vinilentum " were taken from each young lesion , isolated from young streak lesions. dipped in 5% chlorox (sodium hypochlor- ite 5.25%) for 5 min and then washed in M. fijiensis C."non-virulentum distilled water . Hyphae growing from the Honduras n colonies n colonies Farm isolated % isolated leaf pieces were transferred to Mycophyl Agar (BBL Microbiology Systems) . Fungi 1978 identified as one of the two Sigatoka Mopala 90 100 0 0 pathogens or the faster growing Cerco- Sta . Rosa 71 87 11 1 3 Ceibita 86 100 0 0 spora "non-virulentum" (STOVER, 1977b) Indiana 49 58 36 24 were retained, all other fungi were dis - Limones 44 54 37 46 carded. Hyphae from the study fung i Omonita 61 71 25 29 were streaked on 3% agar and the devel- Echeverry 45 52 42 48 opment of Cercospora conidia was Coyoles 16 76 5 2 4 observed over a period of about one Isletas 40 80 10 2 0 week at room temperature (23°C-26°C) . 1980-83 Mycosphaerella spp . ascospores were dis - Mopala 35 100 0 0 charged from leaf spot areas with mass Sta .Rosa 68 100 0 0 infection according to the guidelines fo r Ceibita 42 71 17 2 9 Indiana 62 86 10 1 4 monitoring ascospores for fungicide resis- Limones 65 93 5 7 tance (ANON ., 1983) . Ascospores charac- Omonita 75 89 9 1 1 teristic of Sigatoka pathogens and Copen 56 62 13 1 4 M. musae were transferred to tubes con- Corozal 115 77 0 0 taining Mycophyl Agar . Colony and spor- Cobb 67 75 0 0 ulation characteristics of hyphae isolates Cobb 79 94 5 6 from young lesions and Mycosphaerella Las Flores 84 95 4 5 ascospores were compared . Naranjo Chino 67 91 7 9
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SIGATOKA LEAF SPOT S
C. "non-virulentum" was also present i n most early streak lesions caused b y Mycosphaerella musicola prior to the arri- val of M. fijiensis in Central America , Mexico and Surinam (Table 2) . In some instances, C. "non-virulentum" was more abundant than the Sigatoka pathogen . Photo 1 Cercospora colonies o n When colonies from single ascospore iso- Mycophil Agar from single lates of M. musae were compared to colo- ascospores of Mycosphaerell a nies of C. "non-virulentum", the y musae from banana leaves appeared to be identical (Photo 1) . infected with M . musicola in . From top to Conidia production on plain agar were Guadeloupe bottom, colonies are 7 days also identical (Photo 2) . Conidia were (7-9 mm), 10 days (12-14 mm ) 55-200 pm long (average 127) x 2 .6-3.2 and 14 days (21-22 mm). pm (average 2 .9). Conidiophores were Cercospora "non-virulentum ° 24-46 pm long (average 35) with on e colonies were identical to th e septum . Conidia were verruculose an d colonies shown . usually had a scar. Colonies that pro- duced smooth-walled conidia with a fain t scar or no scar were occasionally isolated . Conidia were produced in 4-5 days . In addition to conidia, ahout one culture i n twenty produced a few spermagonia wit h spermatic . Perithecia or ascospores were not found on Mycophyl Agar. Inoculation of young cv Valery plants with a mixture of mycelium and conidi a of C. "non-virulentum" resulted in the appearance of spots after 70 days incuba- tion (Photo 3) . Similar results were obtained with ascospore-derived cultures of M. musae. Symptoms of natura l M. musae infection were not observed on Photo 2 Cavendish varities in the field . Verruculose conidia o f Cercospora "non-virulentum " (upper) and Cercospora musa e Table 2 (lower) on water agar after Proportion of Mycospharella musicola 5 days at room temperature i n and Cercospora window light (1,000X) . Severa l "non-virulentum" conidia were produced on each isolated from young streak lesions. conidiophore and usually ha d a scar where attached. Percentage M. C "non- Location musicola virulentum " e e • e discussio n
Puerto Cortes, Honduras 46 3 5 Cercospora "non-virulentum" was first Coto, Costa Rica 23 77 detected as a prevalent co-inhabitant with Palmar, Costa Rica 39 6 1 the black Sigatoka pathogen of youn g Changuinola. Panama 56 2 1 lesions in plantations sprayed with hen - Armuelles, Panama 39 6 1 late. It developed tolerance to benomyl Ecuador 91 9 before Mycosphaerella fijiensis, and this Surinam 31 30 increased its prevalence in black Sigatoka Tapacliula, Mexico 95 5 lesions in henomyl-sprayed areas (STOVER , Martinique 49 1 2 1977a, 1977b). A similar Cercospora was Guadeloupe 78 20 also found to he common in youn g
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and ZAPATER, 1990), it should be possibl e to enhance ascospore production by M. musae in cultures producing sperma- gonia and spermatia . Although M. musae readily produces conidia in vitro, conidia Photo 3 have never been found in vivo. 47 Lesions caused by inoculatio n of Mycosphaerella musae on the underside of the two youngest leaves of cv Valery • . • • references plants produced in vitro. The lesions appeared on the ANON ., 1983. oldest leaves after 70 days . Black and yellow Sigatoka. Improved identifi- cation and management techniques. Cora l lesions of Mycosphaerella musicola in Gables (Florida) : Du Pont de Nemours, 17 p . Martinique (CHEVALIER-CEDENO, 1983) . CHEVALIER-CEDE O R ., 1983 . Moreover, in Martinique, ascospores Observaciones sobre una ceps cambiante d e believed to be M. musae yielded verrucu- Cercospora sp . no virulenta aislada de un a lose Cercospora conidia and spermagoni a lesion joven en hoja de banano provocad o por Mycosphaerella musicola Leach . Boletin on V8 juice agar (VAN DER BERG-LORIDAT , semestral de la comisi n de protecci n fito- 1989) . Cultures with a few smooth sanitaria par el Caribe (FAO), 12, 45-50 . conidia were occasionally obtained and , in a few cultures, perithecia were forme d MARTIN J .P., 1950. Use of acid, rose bengal and streptomycin i n with ascospores measuring 13-14 pm. the plate method for estimating soil fungi . The source of Cercospora "non-viru- Soil Sci ., 215-232 . lentum" was believed to be related to th e MOURICHON X., ZAPATER M.F., 1990. two Sigatoka pathogens . The result s Obtention in vitro du stade Mycosphaerell a reported here showed that C. "non-viru- fjiensis forme parfaite de Cercospora fijien- lentum" and M. musae were identical , sis . Fruits, 45 (6), 553-557 . producing the same colonies and conidi a PONT W., 1960. in culture . Both were pathogenic but wit h Three leaf speckle diseases of the banana i n an incubation period of 70 days or more . Queensland . Queensland J . of Agric . Sci., 17 , In Australia, PONT (1960) demonstrated a n 273-309 . incubation period of six weeks to the STOVER R .H ., 1963. "brown blotch" stage when young leaves Leaf spots of bananas caused by were inoculated with M. musae. Furthe r Mycosphaerella musicola: associated asco- development ceased until the inoculate d mycetous fungi . Canadian J . Botany, 41 , leaf was well down the plant . 1481-1485 . STOVER R .H ., 1969. The unusual features of M. musae in th e The Mycosphaerella species associated with American tropics is its close association banana leaf spots . Tropical Agric., 46, 325- with M. musicola and M. fijiensis. It doe s 332 . not alone cause symptoms in the field , STOVER R .H ., 1977a. but appears to behave as an endophyte in Extranuclear inherited tolerance to benomy l lesions caused by the two Sigatoka patho- in Mycosphaerella fijiensis var . difformis . gens. M. musae appears to be much more Trans. Br. Mycol . Soc., 68, 122-124 . common and ascospore discharges occu r STOVER R .H ., 1977b . more frequently from leaf spotting caused A non-virulentum benomyl tolerant Cercos- by M. musicola (STOVER, 1969) . pora from leaf spots caused by Mycos- There are two reports of isolates from phaerella fijiensis var. difformis and M . musi- cola . Trans . Br. Mycol. Soc ., 69, 500-502 . M. musicola lesions producing perithecia and ascospores similar to M. musae in VAN DER BERG-LORIDAT A ., 1989. culture (CHEVALIER-CEDE O, 1983 ; VAN DER Note sur les différentes espèces de , BERG-LORIDAT, 1989) . In view of recently Mycosphaerella . Martinique : CIRAD-IRFA (internal document), 7 p . reported in vitro techniques for ascospore production by M. fijiensis (MOURICHO N
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