5.2.32
BIOLOGICAL CONTROL OF DAMPING-OFF CAUSED BY FUSARIUM ACUMINATUM USING TRICHODERMA PSEUDOKONINGII APPLIED AS FILM COATING ON PINE SEEDS

M GURER

Forestry Research Institute, PO Box 24, 06501, Bahgeiievier, Ankara, Turkey

Background and objectives
Biodegradable polymers can be considered as those macromolecules that show breakdown in biologically active environments. Microbial pesticides are living microorganisms, such as fungi bacteria, viruses, protozoa and nematodes. The application of antagonists by seed treatments is thought to be an economical alternative, since only relatively small amounts of inoculum are needed.

Materials and methods
Conidia of Trichoderma pseudokoningii were produced by growing the organism on PDA for 1 week at 23C. Chitosan solution was prepared from chitosan (3% w/v) in dilute acetic acid (1% v/v) [1]. For chitosan-lignosulphonate coatings, conidial suspensions were added to chitosan asetate solutions and mixed with pine seeds. The seeds were dripped into a solution of 5% (w/v) sodium lignosulphonate. Seeds treated as described were removed and allowed to air dry on waxed paper. To determine the germination and conidial production, chitosan lignosulphonate coated seeds were placed in PDA at 23C and Jacobsen apparatus.The effectiveness of seed coating with chitosan-lignosulphonate of Trichoderma and combination with 50% tolclofos-methyl to control damping-off disease were determined in pots and in forest nursery.

Results and conclusions
Pine seeds film-coated with Trichoderma chitosan-lignosulphonate produced abundant conidia and germinated at levels of 90.4 and 83.0% in PDA and in Jacobsen apparatus, respectively. Seed coating with chitosan-lignosulphonate of T. pseudokoningii and in combination with 50% tolclofos-methyl to control damping-off disease caused by Fusarium acuminatum was trialled in plastic pots which were artificially infested, and in the forest nursery. The results of this research show that chitosan-lignosulphonate matrices can be used to formulate conidia of T. pseudokoningii and represent a feasible approach to applying microorganisms to pine seeds. The best results were achieved with the Trichoderma chitosan-lignosulphonate coated on pine seeds with 71.0 and 53.3% in nursery and in pots, respectively.

References
1. Gdrer M, Wilkins RM, 1993. 9th International Symposium on Microencapsulation, pp. 187-190.