Photo of the week: brown patch

White, fuzzy mycelium growing on a turfgrass sample suggests that brown patch, caused by Rhizoctonia might be involved. However, several other pathogens can cause similar mycelial growth. Under the microscope, however, the classic right angle branching of the mycelium seen in this photo — in combination with the location of the septa (cross walls), made brown patch a very good guess. The fact that the disease occurred on non overseeded bermudagrass, during a warm and wet period of California winter…