Phytophthora, Greek for "plant destruction," is a soil-inhabiting pathogen that forms eukaryotic microorganisms known as, oomycetes. The oomycetes of Phytophthora sp. produce spores that lie in wait for years until wet conditions in the soil provide a suitable host. Once the plant host arrives, in this case, raspberries, the resting Phytophthora, potentially Phytophthora rubi, spores germinate, producing motile (able to swim) spores that travel via water in the soil system, allowing the spores to reach and penetrate the host plant roots. Once a plant has become infected, it will appear drought-stressed, presenting with discolored leaves and wilt, typically declining after the first warm weather of the season. The best management practice currently in place is based on proper water management (avoiding prolonged saturation, soil compaction, and providing good drainage) and cutting away infected tissue.
Located in agricultural zone 5b, Katya Lewis, noticed after a very wet season that her raspberry plants had been affected by the Phytophthora pathogen. She had reached out to the berry specialist at Cornell University, who stated when root rot sets in it will only become progressively worse, triggering unhealthy plants and reduced fruit yields. Early in the spring of 2022, the raspberry canes (branches that bear fruit) were severely damaged by wilt. Typically, raspberry canes will produce leaves the first summer (primocane), fruit the second summer, and then die back, only producing fruit once per cane. Hopefully, Wine Cap mycelium can create a beneficial environment for the raspberries and reduce the effects of Phytophthora.
Katya had planted five strains of raspberries (Joan J, Prelude, Caroline, Eden, and Himbo Top) in several rows measured 150' in length x 1' in width. After we sent the Wine Cap sawdust spawn, she inoculated half of each of the rows that were most infected, particularly Joan J, which had experienced issues with drainage, on August 18th, 2022. The spawn was covered with wood chips.
In Progress - Results expected in May 2023
Wine Cap mycelium colonized the rows and spread to the Phytophthora-infected raspberry roots by October 4th, 2022