Fig. 3.

Sensitivity of Aphelenchoides fragariae species-specific PCR primers. Three 6-mm diam. Asplenium nidus (Bird's Nest Fern) leaf disks were spiked with increasing increments of individual A. fragariae ranging from 1 to 1,000 nematodes. Lane numbers 1 to 20 correspond to the number of nematodes in each DNA extraction (1 to 19 nematodes are shown). No amplification product was obtained with the 20 nematode extraction due to a processing error (Lane 20). Lane M contains DNA molecular size marker, lane N contains the PCR reaction without DNA template and lane 22 contains the PCR reaction with known A. fragariae DNA.