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Mycosphaerella Primer |
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| General Information Summary | ||
| Pathogens & Hosts | Taxonomy | Characteristics | Disease Types | Management | Graphics | References | |
Authors
Andrew K. Gonsalves, Educational Specialist
Stephen A. Ferreira, Extension Plant Pathologist
Department of Plant Pathology, College of Tropical and Agriculture and Human Resources
University of Hawaii at Manoa
Twenty Mycosphaerella species have been reported to occur in Hawaii (Raabe, et al., 1981). The following is a list of the reported pathogens from this genus (Mycosphaerella) and the hosts they infect. The list is organized by the scientific name of the pathogen species (CAPITAL LETTERS), followed by the various susceptible plant hosts. Words in blue indicate what symptom or disease a given pathogen causes on the listed hosts.
MYCOSPHAERELLA ARTOCARPI
breadfruit (Artocarpus cummunis (syn.: A. altilis, A. incisa))
MYCOSPHAERELLA BERKELEYI
Brown Leaf Spot:
peanut (Arachis hypogaea)
MYCOSPHAERELLA BRASSICICOLA
Ringspot:
cabbage (Brassica oleracea var. capitata)
MYCOSPHAERELLA CITRULLINA
Gummy Stem Blight:
watermelon (Citrullus vulgaris = C. lanatus)
cantaloupe (Cucumis melo var. cantalupensis)
cucumber (Cucumis sativus)
pumpkin (Cucurbita pepo)
MYCOSPHAERELLA CYANEAE
On Leaves of:
Cyanea angustifolia
MYCOSPHAERELLA DIANELLA
Hawaiian dianella or ukiuki (Dianella sandwichensis)
MYCOSPHAERELLA EUGENIAE
ohi'a ha or ha (Eugenia sandwichensis)
Eugenia sp.
MYCOSPHAERELLA FIJIENSIS
banana (Musa acuminata, AAA)
MYCOSPHAERELLA FRAGARIAE
Leafspot:
Fragaria sp.
strawberry (Fragaria chiloensis var. ananasa)
MYCOSPHAERELLA FREYCINETIAE
ie'ie (Freycinetia arborea)
MYCOSPHAERELLA HAWAIIENSIS
On Living Leaves of:
'ape ape (Gunnera petaloides)
MYCOSPHAERELLA HEDYCHII
On Living Leaves of:
white ginger (Hedychium coronarium)
MYCOSPHAERELLA KADUAE
On Leaves of:
Gouldia sp.
Other:
Kadua grandis
Kadua sp.
MYCOSPHAERELLA METROSIDERI
Leafspot:
'ohi'a lehua (Metrosideros collina)
MYCOSPHAERELLA MUSICOLA
Leafspot:
banana (Musa acuminata, AAA)
MYCOSPHAERELLA PINODES
Ascochyta Blight:
pea (Pisum sativum)
edible-podded pea (Pisum sativum)
MYCOSPHAERELLA ROSIGENA
Leafspot:
Rosa sp.
MYCOSPHAERELLA SCAEVOLAE
Scaevola chamissoniana
Scaevola glabra
Scaevola mollis
MYCOSPHAERELLA SP.
Stem-End Rot:
papaya (Carica papaya)
Other:
corn, maize (Zea mays)
MYCOSPHAERELLA STRIATIFORMANS
Leaf Splitting Disease:
sugarcane (Saccharum officinarum)
KINGDOM: Mycetae (fungi)
DIVISION: Eumycota
SUBDIVISION: Ascomycotina (The sac fungi)
CLASS: Loculoascomycetes
ORDER: Dothideales
GENERAL CHARACTERISTICS
The number of different species in the genus Mycosphaerella have been reported to range from 500 (Streets, 1982) to 1,000 (Alexopoulos and Mims, 1979). It is the largest genus in the Dothideaceae with the majority of species being saprobic. There are, however, many species that are economically important plant pathogens. Mycosphaerella occurs on the leaves and stems of several hundred different host plants (Tomilin, 1979; Corlett, 1991). Most species are saprobic (Agrios, 1988). However, many have been described as pathogenic to cultivated and ornamental plants and forest trees (Corlett, 1991). The genus is complex; primarily because of the large number of species. This is especially a problem since many of the species were originally described in the genus Sphaerella (now considered a synonym of Mycosphaerella).
The three spore(-like) structures are spermatia (produced in spermogonia), ascospores (produced in perithecia), and conida of the Cercospora-type (produced in sporodochia) (Agrios, 1988).
Perithecia are subepidermal (Streets, 1979). They are formed when sexual hyphae are fertilized by compatible spermatia (Agrios, 1988). The ascospores are hylaline, ellipsoidal, and 2-celled (Streets, 1979). They are packaged in groups of eight in structutres known as asci.
Since other biological characteristics vary from species to species, for more detailed information, consult the specific Mycosphaerella sp. summary of interest. However, many of the species listed have not been studied in great detail. A good summary for detailed biological information can be found in the [Mycosphaerella musicola] summary; the pathogen that causes yellow Sigatoka of banana (Persley, 1993).
TYPES OF DISEASES
Mycosphaerella spp. have been described to cause the following types of diseases: brown leafspot, ringspot, gummy stem blight, leafspot, ascochyta blight, stem-end rot, leaf splitting disease, yellow and black Sigatoka, and black leaf streak.
The disease can spread to healthy hosts either as conidia or as ascospores. Once in contact with compatible host tissue, the spores can germinate and penetrate the plant through the leaf stomata. Fungal fruiting bodies (spermagonia, sporodochia) then form. Conida produced from sporodochia is released and disseminated; this enables the condia to infect another host plant. Also, the spermatia can fertilize compatible sexual hyphae to form the perithecia where ascpores are produced. Like the conidia, these ascospores can then be released and disseminated to begin the infection process again (Agrios, 1988).
In general, Mycosphaerella diseases are managed with a combination of measures. These include: quarantine, sanitation by removing infected tissue, and by year-round fungicidal spray applications (Agrios, 1988).
For more specific control programs and approaches, please see the species summaries.
Below is a list of graphics that are available for this Genus:
Leafspot of strawberry
This may be caused by Mycosphaerella fragariae.
Agrios, G.N. 1988. Plant Pathology, 3rd edition. Academic Press, Inc: San Diego. 803 pp.
Corlett, M. 1991. An Annotated List of the Published Names in Mycosphaerella and Sphaerella (Mycologia Memoir No. 18). J. Cramer: Berlin. 328 pp.
Farr, , D.F., G.F. Bills, G.P. Chamuris, and A.Y. Rossman. 1989. Fungi on Plants and Plant Products in the United States. APS PRESS: St. Paul, Minnesota. 1252 pp.
Raabe, Robert D., Ibra L. Conners, and Albert P. Martinez. 1981. Checklist of Plant Diseases in Hawaii. Hawaii Institute of Agriculture and Human Resources, College of Tropical Agriculture and Human Resources, University of Hawaii (Information Text Series 022).
Streets, R.B. 1982. The Diagnosis of Plant Diseases: a field and laboratory manual emphasizing the most practical methods for rapid identification. The University of Arizona Press: Tucson, Arizona.
Tomilin, B.A. 1979. Opredelitel'gribov roda Mycosphaerella Johans. 319 pp.
JUNE 1994
1-MYCOSP
