3.2. Diagnosis via molecular methods
Rapid and accurate identification of the particular formae spe-
cialis that causes Fusarium wilt of strawberry would also be of great
Table 1
Comparison of symptoms caused by four major soilborne pathogens of strawberry.
use. Such precision could be used to distinguish between Fof and non-pathogenic Fusarium oxysporum recovered from plant material and could also be employed to test field soil so as to gauge the risk of planting strawberry in that particular field. Toward this objec- tive, Suga et al. (2013) developed PCR primers that amplified a diagnostic DNA sequence from Fof but not from other formae speciales of F. oxysporum or non-pathogenic strains of this species. Whereas there were no false negatives, six strains identified as Fof based on the PCR detection method were found to be non- pathogenic to strawberry (Suga et al., 2013). In addition, using the same primers, no amplicon was obtained from a subset of Fof isolates originating in the U.S. (Gordon, unpublished results). In China, Li et al. (2014) used both real-time PCR and a semi-selective medium to detect and quantify F. oxysporum following fumigant treatments. There was a strong correlation between results ob- tained with these two methods, both of which were predictive of disease incidence in a greenhouse trial. However, it appears that results of both procedures were based on total F. oxysporum and not solely the strain causing Fusarium wilt of strawberry. Thus, further work will be required to produce a robust method for detection of Fof based on PCR.