Golfdom, February 2018

varied temperature ranges This likely explains variability of product efficacy among golf courses and emphasizes the need for a programmatic approach to managing Pythium root rot The disease initially develops as small spots of water soaked turfgrass As the disease progresses the symptoms coalesce rapidly and may severely affect large areas of turfgrass Figure 2A Stand symptoms may appear as distinct patches or may develop in large irregular areas Roots normally are stunted and necrotic and may even smell rotten The disease is difficult to diagnose based on symptoms alone and we suggest getting a laboratory diagnosis before pursuing a management strategy for Pythium root rot On that note there is still confusion even among turfgrass pathologists on the difference between Pythium root rot and Pythium root dysfunction DISTINGUISHING BETWEEN ROOT ROT AND ROOT DYSFUNCTION Pythium root rot develops on cool season putting greens during the summer months when soils are warm and wet The symptoms develop in areas where water collects but the disease can affect higher areas after rainfall The disease is most severe on putting greens in enclosed environments and or shaded for long periods throughout the day Symptoms appear in late May or early June but can continue to develop new spots or continue to expand as long as soils are warm and wet On warm season grass putting greens the disease is most severe under low light conditions especially during the fall winter and spring Symptoms develop as small tan or whitish patches that may appear to run with water Figure 2B The symptoms are hard to distinguish from other bermudagrass diseases such as take all root rot As with cool season grass the disease is prevalent when soils are wet Continued on page 32 FIGURE 1A FIGURE 1B February 2018 Golfdom 31 Golfdom com PHOTOS BY LEE BUTLER BLIGHT VERSUS ROOT ROT Pythium blight of creeping bentgrass A and bermudagrass B putting greens