Description
The dilution plate count of Fusarium is obtained by a surface plating technique. After homogenizing of a specified quantity (preferably 40 g), a serial dilution is carried out. Of each dilution 0.1 ml is spread plated onto the medium in duplicate. After incubation at 25.0 ± 1.0 oC for 5-7 days under alternating light-dark conditions (12 h light/12 h dark), the colonies with a characteristic appearance are counted. Each colony type is counted separately. Representative colonies of each type may be purified on SNA [Spezieller Nährstoffarmer agar] (3.3) and identified to species level (3.4). The number of cfu of each Fusarium species per gram of sample is calculated. The direct plating count of Fusarium is performed by placing 100 particles (often kernels or seeds) onto the medium, 5-10 on each 9 cm Petri dish. If only the amount of Fusarium inside the sample is of interest the sample should be surface disinfected before plating. The number of particles, from which at least one Fusarium colony grows out, is recorded. Each colony type is counted separately. Representa¬tive colonies of each type may be purified on SNA and identified to species level (3.4). The percentage infection of each Fusarium species is calculated.