Grey leaf spot turf disease is an issue in the Richmond, Virginia area for most homeowners. Gray leaf spot needs specific conditions to develop enough to impact a lawn, and there are other grass fungus types that are more commonly encountered, such as brown patch fungus. However, when we consider the impact on fescue fungus can have, grey leaf spot turf disease can be devastating due to its correlation with the planting of tall fescue seed.
As explained in an article from the North Carolina State University Extension about this fescue fungus, “Gray leaf spot initially appears as spots on the leaves that are round or oval, tan in color, and have a dark brown border. When the leaves are wet or humidity is high, the leaf spots turn gray and fuzzy with profuse seed production. In time, the leaf spots expand and girdle the leaf, causing it to die back from the tip. Significant damage to the turf stand may occur as the disease continues to progress.”
Gray leaf spot differs from the more familiar brown patch fungus in a couple of key ways. First, brown patch is most common in fescue lawns in Virginia from about May through August, following the summer’s warmth and humidity as its primary triggers. Meanwhile, grey leaf spot is more common at the end of the summer and the beginning of the fall before temperatures begin to cool below 70F. Second, between the two grass fungus types, brown patch isn’t discriminating with lawn maturity, but gray leaf spot is. The younger a stand of fescue turf is, the more susceptible it is to developing grey leaf spot turf disease. Both of these differences are why this fescue fungus is connected with the application of tall fescue seed.
For a turf type tall fescue lawn in a transition zone state like Virginia, seeding is something that is usually best to have done on a yearly schedule to maintain a healthy and thick population of turf. Fescue should be seeded in the fall, typically between early September and early November, to give the baby grass as much time as possible to mature and develop deep roots before the challenges posed by the heat of the following summer. This window of opportunity varies slightly between lawns based on how wooded they are, the irrigation set up on the property, and the changes in the weather year to year.
September is the month in which there is overlap between summer heat and humidity and seeding season, and this is where grey leaf spot turf disease becomes a potential issue. Keep in mind, fescue has moderate resistance to this fungus, so it is not a common problem in most lawns. However, when it does show up, it can escalate quickly and pose serious risks for a newly seeded lawn.
Unfortunately, some of the practices necessary for the aftercare of tall fescue seed to ensure successful germination and development also support the development of fescue fungus. New seed must be kept damp with a frequent watering schedule, but this moisture increases the risk of gray leaf spot. About a month has to be spent staying off the lawn, especially where mowing is concerned, but this excess growth can block airflow, also increasing the risk of gray leaf spot. Additionally, a strong blend of fertilizing nutrients should be applied before and during seeding to encourage quick growth before the lawn shuts down for the winter, but increases in a yard’s nitrogen content can be linked with the development of fungus as well.
At the end of the day, none of these practices should be hedged out of fear for fungal development. Weather conditions are typically a greater contributor to the risk of grey leaf spot turf disease than anything else, and we cannot control the climate and its impact on year to year weather patterns. Most years, September brings cooler and drier weather, with conditions for fungus being nonexistent by October.
With that in mind, it is rarely worth compromising on quality seeding aftercare practices to prevent a disease that is low risk. Instead, it is valuable for homeowners investing in the seeding of their lawn to understand gray leaf spot and the conditions that put a lawn at possible risk. It is of paramount importance to monitor your lawn closely as your baby grass germinates and develops to alert your turf management company at the first signs of anything unusual. The sooner a lawn can be treated with fungicide, the less damage the fungus can do.