The state of Minnesota has been surveyed extensively for Heterobasidion. Over 130 different stands were surveyed in Minnesota with the focus being in southeast Minnesota. Close to 1,000 samples were collected to process and test for the presence of H. irregulare. The majority of the samples were processed with our molecular techniques, first with traditional PCR and then qPCR, which is a more sensitive method of detection.
Spore samplers were used for the surveys to collect spores of Heterobasidion. The type of spore samplers used were rotation impaction samplers. Each sampler consists of two small plastic rods that are coated with silicone. The samplers are programmed to spin four minutes every hour. This amount of exposure time limits the amount of dust and pollen that could accumulate on the rods and impact analysis. The samplers were deployed at each site for approximately one week and then collected. The rods were processed in the lab and DNA was extracted. A qPCR assay was then used to determine the amount of spores per rod.