Improved procedure for mass inoculum production of Fusarium species in a short period of time

An improved method of conidia production is described and compared to a conventional method growing Fusarium species on LSPDA medium under near-ultraviolet (NUV) light for 21 days. In the improved procedure, Fusarium spp. were grown in PDB for three days and subsequently spread as aliquots onto LSPDA, SNPMA and WA media. To remove excess water, the cultures were dried in a laminar flow cabinet for 20 to 30 min. Air-dried plates were incubated under NUV light at 25 ºC for 3 days. To compare aggressiveness of conidia produced by either method, wheat ears were inoculated at the mid-flowering. Disease incidence (% infected kernels) and Fusarium head blight severity as well as fungal biomass produced in the infected kernels were determined. The improved method effectively triggered sporulation of Fusarium spp. and gave high yields of conidia per unit of area within two days of incubation on solid media which is significantly higher compared to spore quantities produced with the conventional method. The average number of conidia produced by Fusarium spp. using the improved and conventional methods ranged from 56 to 156 and 0.8 to 38.6×106 (per plate), respectively. Spore production quantity was highly variable with the conventional method using different Fusarium species. However, morphology of conidia was similar in both assays. The aggressiveness of Fusarium inocula produced by both methods was not significantly different with respect to the ability to cause FHB and to colonize wheat kernels (P≤0.05). Microscopy examination showed the high conidiation rate from phialides on hypha.