Root and Cutting Rots
Phytophthora spp. and Pythium spp.
26 host plants
Last updated
This profile contains verified disease data from extension databases. Regional field notes and expert review are in progress.
Root and cutting rots cause decay of roots and propagation material, particularly in wet conditions. Improve drainage in growing areas. Avoid overwatering. Use well-drained growing media. Remove infected plants immediately. Select pathogen-tested propagation stock. Proper drainage and good site selection are critical to prevent root disease problems. Monitor plants for early signs of decline or wilting Early detection and prompt management of symptoms help limit disease spread.
Root rots thrive in waterlogged soil, so drainage is your most important intervention. Avoid overwatering and ensure the planting site drains well. Remove severely affected plants to prevent spread to neighbors through root contact or contaminated soil. When replanting, choose resistant species or improve soil structure before putting anything back in the ground.
Quick Reference
Management
Most active during active propagation periods (spring and fall in nurseries) when warm, moist conditions in cutting beds or containers remain constant. Risk peaks when cutting material is fresh (first 2-3 weeks after placement in propagation media). Pythium more problematic in warm conditions (65-75°F); Phytophthora in cooler propagation areas (50-60°F). Year-round risk in heated propagation systems. # Source: PNW Plant Disease Management Handbook
Overwatering; poor drainage; contaminated propagation media or cutting surfaces; recycled or contaminated irrigation water; warm temperatures (65-75°F optimal for Pythium), cool temps (50-60°F) for some Phytophthora spp.; waterlogged or mist-heavy cutting beds. # Source: PNW Plant Disease Management Handbook - Root and Cutting Rots
Cultural Controls
- Use tissue cultured plants (if possible) to avoid the problem altogether. Take cuttings from field plants above the splash zone; rain and irrigation can splash soil particles and microorganisms onto plants. Do not take cuttings from obviously or subtly diseased plants. Take cuttings in the morning when stems are more turgid and less susceptible to wilting. # Source: PNW Plant Disease Management Handbook