University of Minnesota researchers uncover new species of devastating water molds
In the lush forests and waterways of Minnesota, an invisible army is advancing. University of Minnesota researchers recently identified 14 new species of devastating water molds from the genus Phytophthora—Greek for "plant destroyer"—during a comprehensive 2020-2023 survey 2 . These pathogens join 8 previously known species in the state, creating a total threat portfolio of 22 destructive organisms 2 .
With a global host range exceeding 5,000 plants—including oaks, crops, and ornamentals—these molds cause diseases like sudden oak death and root rot that can decimate entire ecosystems 2 .
As climate change fuels wetter conditions ideal for mold spread, this discovery sounds an urgent alarm for North America's forests.
Despite their fungal-like appearance, Phytophthora species are water molds (oomycetes) genetically closer to algae. They produce mobile spores that swim through wet soils and waterways, infecting plant roots and stems. Once established, they:
Preventing water/nutrient flow
Cell-dissolving enzymes that rot tissues
That survive winters
The UMN team deployed a four-step detection strategy across forests, nurseries, and wetlands 2 :
Placed bait in 120 water bodies, collected soil/root samples
Transferred baits to growth media, cultured microbes
Sequenced marker genes and compared to databases
Inoculated saplings, monitored lesion development
| Species | Habitat | Primary Hosts | Threat Level |
|---|---|---|---|
| P. abietivora | Forest soils | Fir, spruce | High |
| P. plurivora | Nurseries, urban areas | Oaks, maples | Critical |
| P. riparia | Riverbanks | Willows, cottonwoods | Moderate |
| P. pini | Pine plantations | Pine species | High |
| (10 others) | Varied | Woody ornamentals | Moderate-High |
The study identified 14 species never before documented in Minnesota, with P. plurivora (aggressive oak killer) among the most concerning 2 3 . Key findings include:
| Environment | Positive Sites | Avg. Species |
|---|---|---|
| Forest waterways | 76% | 1.8 |
| Plant Nurseries | 93% | 3.2 |
| Urban Parks | 82% | 2.1 |
| Wetlands | 63% | 1.2 |
Essential research reagents and materials used in Phytophthora studies:
Selective growth (suppresses fungi/bacteria)
Example: Isolating Phytophthora from soilAmplify DNA barcode regions
Example: Species identification via sequencingNutrient base for culture growth
Example: Maintaining pure pathogen strainsDisease susceptibility testing
Example: Pathogenicity assays"Early detection is key to mitigating large economic losses"
The discovery underscores a critical need for proactive defense. The team is now:
Through waterways and human activity
Like antagonistic fungi (Trichoderma)
For disease reporting
In the silent war between plants and pathogens, knowledge is our strongest root system. Vigilance today prevents forests vanishing tomorrow.