Abstract
Among eight techniques employed for detection of fungi from sugarcane setts, galvanized tray with newsprint was found to be most suitable technique. In case of fuzz, out of ten techniques, Khulna newsprint with untreated seeds (fuzz and caryopses) was found to be superior to others.
Eighteen different fungi were found to be associated with setts of four sugarcane varieties collected from three sugar mill zones representing foundation, certified and commercial crops. The sett-borne fungal infections varied with respect to variety, seed tier and place of collection. Among eighteen fungi- Aspergillus flavus, A. niger, Botrytis cinerea, globosum, Cladosporium herbarum,
Chaetomium
Cochliobolus
Myrothecium
spicifer, Drechslera sacchari, Fusarium oxysporum, verrucaria, Phoma sorghina, Rhizopus nigricans and Trichoderma harzianum appeared to be new record as sett-borne fungi of sugarcane in Bangladesh. In case of fuzz, 25 different fungi were recorded from 40 sugarcane fuzz samples where all of them are new records for sugarcane in Bangladesh. The most predominant fungi, in order of prevalence were C. lunata, A. flavus, A. alternata, D. sacchari, F. moniliforme and C. spicifer. The fungi varied greatly with respect to fertile fuzz, caryopses and unfertile fuzz.
Among eighteen fungi, eleven- A.terricola, A. alternata, C. paradoxa, C. spicifer, C. falcatum, C. lunata, D. sacchari, F. moniliforme, F. oxysporum, P. sorghina and M. verrucaria- were found pathogenic to germinating setts and settlings. Of the 25 fungi, eighteen- A. terricola, A. alternata, A. flavus, A. niger, B. cinerea, C. paradoxa, C. herbarum, C. spicifer, C. falcatum, tetramera, F. C. gloeosporioides, C. lunata, D. sacchari, D.moniliforme, F. oxysporum, M. verrucaria, P.
sorghina and T. harzianum were found pathogenic to fuzz.
The rate of transmission of test pathogens from sett to germinating sett was higher than transmission of the pathogens from sett to seedling resulting seedling mortality. Among the pathogens the highest transmission from sett to germinating sett and seedling were recorded for C. falcatum followed by C. paradoxa. In case of fuzz, the highest transmission from fuzz to germinating fuzz and seedlings were recorded for C. lunata followed by F. moniliforme.
The rate of transmission of C. falcatum, C. paradoxa and F. moniliforme from preplanted sett to harvested sett was higher than transmission of the pathogens from sett to plant. Higher level of sett-borne infection of the three test pathogens prior to planting resulted higher percent of germination failure, disease development in the field and higher infection in the harvested setts. Setts having 5% infection of C. falcatum and 10% infection of C. paradoxa and F. moniliforme showed significant difference in germination, yield and disease development in the field compared to healthy setts. Among the three test pathogens, C. falcatum has more sett-transmission ability than other two pathogens.
Interim seed standard for foundation and certified seeds against C. falcatum, Fusarium moniliforme and C. paradoxa have been suggested.