Survival of southern pine seedlings after inoculations with Pythium and cold storage in the presence of peat moss

Cold storing bareroot pine (Pinus spp.) seedlings grown in the southern U.S. for as little as 1 week in a cooler (just above freezing) in the fall (November to mid‐December) has been shown to reduce seedling survival after outplanting. In contrast, survival of container‐grown seedling is typically not affected when stored for 4 weeks in coolers in November and December. Wounds sustained by seedlings as they are lifted from nursery beds may allow Pythium spp. to infect bareroot seedling roots. Once in the cool, moist storage environment, Pythium multiplies and may result in seedling mortality after outplanting. Bareroot loblolly pine (Pinus taeda) and container‐grown loblolly, longleaf (Pinus palustris), slash (Pinus elliottii) and shortleaf pine (Pinus echinata) seedlings were inoculated with either Pythium dimorphum or Pythium irregulare, cold stored with or without peat moss and monitored for survival after outplanting. Peat moss did not increase bareroot loblolly pine survival or reduce Pythium populations when seedlings were inoculated with Pythium prior to storage. Pythium irregulare reduced survival of longleaf and shortleaf pine grown in peat moss and perlite, respectively. Pythium did not affect loblolly or slash pine, but wounding their roots did reduce seedling survival when grown in containers.