Saturday, April 30, 2011

Macrophomina phaseolina

Macrophomina phaseolina is a very destructive gungi belongs to family Botryosphariaceae. It has been recorded up till now that this fungi can infect more than 500 plants causing rottning of plant especially charcoal rot in many plants.

Macrophomina phaseolina is a non host specific fungi. This is a soil born fungi which can resist unfavorable environmental condition with the help of its resting bodies known as sclerotia. (Short et al., 1980) In PDA, pycnidia are not produced except under some specific incubation conditions (Gaetán et al., 2006) and only sometimes in host crops (Mihail and Taylor, 1995), and their importance in the epidemiology of the fungus likely depends on the host involved as well as the fungal isolate (Ahmed and Ahmed, 1969).

Sclerotia are minute, black, round to oblong or irregular in shape with mycelial attachment. Kamalakannan A, et al 2005). Microsclerotia in soil, infected seeds or host tissues serve as primary inoculum (Abawi and Pastor-Corrales, 1990). Root exudates induce germination of microsclerotia and root infection of hosts. Increase in sclerotial population of M. phaseolina in soil resulted in great root infection by M. phaseolina (Dawar & Ghaffar,1998).

The sclerotia float freely on soil surface when field is flooded for irrigation and become primary inoculum for emerging seedlings. (Abawi and Pastor-Corrales, 1990) Additional sclerotia become dislodged and rise to the water surface in the flooded seed bed or any other factor, such as water wave action due to wind that disturbs the surface layer during growing season (Keim and Webster, 1974; Webster et al., 1976). However, mycelium of M. phaseolina in the soil is not considered as a major source of inoculum (Norton, 1953; Smith, 1969; Meyer et al., 1974).


(image) J. B. Sinclair and P. A Backman, eds. APS Press. St. Paul, MN

Short GE, Wyllie TD, Bristow PR (1980) survival of Macrophomina phaseolina in soil and residue of soybea. Phytopathol 70-13

Gaetan SA, Fernandez L, Madia M (2006) Occurence of charcoal rot caused by Macrophomina phaseolina on canola in Argentina. Plant Dis 90-524

Mihail JD, Taylor SJ ()1995) Interpreting vairibility among isolates of Macrophomina phaseolina in pathogenicity, pycnidium production and chlorate utilization. Cab J Bot 73. 1596-1603

Ahmed N, Ahmed QA (1969) Physiologic specialization in Macrophomina phaseolina. Ashby causing stem rot of jute, Chorcorus species. Mycopath39. 129-138

Kamalakannan A, Mohan L, Valluvaparidasan V, Mareeswari L, Karuppiah R (2005) First report of Macrophomina root rot (Macrophomina phaseolina) on medicinal coleus (Coleus forskohlii) in India. New Disease Reports 11, 48

Abawi GS, Pastor-Corrales MA (1990) Seed transmission and effect of fungicide seed treatments against Macrophomina phaseolina in dry edible beans. Turrialba 40: 304–339

Dawar S, Ghaffar A (1998) Effect of sclerotium inoculum density of Macrophomina phaseolina on charcoal rot of sunflower. Pak J Bot 30: 287-290

Webster RK, Bolstad J, Wick CM, Hall DH (1976) Vertical distribution and survival of Sclerotium oryzae under various tillage conditions. Phytopathol 66: 97-101

Smith WH (1969) Germination of Macrophomina phaseolina sclerotia as affected by Pinus lamberitina root exudes. Canadian J Microbiol 15:1387-1391

Meyer WA, Sinclair JB, Khare MM (1974) Factors affecting charcoal rot of soybean seedlings. Phytopathol 64: 845-849

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