Over the past couple of weeks, a very familiar turfgrass disease, dollar spot, has begun it’s assault across much of North Carolina. We have observed this disease on creeping bentgrass putting greens and fairways (mountains).
Dollar spot symptoms on creeping bentgrass putting green
The dollar spot fungus begins to grow and infect susceptible grasses in the spring when night temperatures exceed 50°F, even though symptoms of the disease may not appear until later in the spring or early summer. In addition, the pathogen requires extended periods of leaf wetness, 10 to 12 continuous hours. Heavy dews that often form during cool nights in the late spring or early summer are most conducive to the disease. Extended periods of wet, overcast weather can also lead to severe dollar spot epidemics on susceptible grasses. Dollar spot remains active throughout the summer in many areas, but disease activity typically slows when high temperatures consistently exceed 90°F.
Active dollar spot mycelium after one night of incubation!
Turfgrasses that are deficient in nutrients, especially nitrogen, are more prone to dollar spot and also recover from the damage more slowly than well-fertilized turf. The disease is also encouraged by drought stress, low mowing, excessive thatch accumulation, frequent irrigation, and low air movement. Certain cultivars of creeping bentgrass, perennial ryegrass, and Kentucky bluegrass are very susceptible to dollar spot, while others are fairly tolerant.
For more information about dollar spot, including control recommendations, click here.
June is in full swing and so is brown patch in tall fescue lawns and landscapes. Brown patch, caused by the fungus Rhizoctonia solani, is the most common disease in tall fescue during late spring and throughout the summer months in North Carolina. Brown patch infections can start as early as April in some years with full blown outbreaks occurring by late May and early June in most years. As the name implies, symptoms are brown to tan areas of turf that are roughly circular patches that range from a few inches to several feet in diameter.
Brown patch lesion on tall fescue leaf
The two most common mistakes managers of tall fescue make are fertilizing too late or too much in late spring and over watering. Tall fescue should not be fertilized after the first of May, unless you are using ultra low rates (< 0.25 lb N/M) with iron for a color effect. The recommended amount of nitrogen on tall fescue per year is 3-4 pounds per 1,000 square feet. Most people will apply a pound or two in the fall and a pound or two in the spring. When in doubt, submit a soil test to ensure you’re feeding your lawn the right nutrients at the correct amounts.
Watering should be done only as needed to prevent drought stress. When you do apply irrigation, do it deep and infrequent instead of watering every day. It is a common mistake for homeowners to set their irrigation system on a schedule and forget about it. Remember, fungi love water and if you over water, you’re giving the advantage to the fungi, not the turfgrass. The ideal time to water your lawn is in the early morning hours before sunrise. Irrigating during late afternoon or early evening is the worst thing you can do because this extends the leaf wetness period, however brown patch will love you for it!
Brown patch symptoms in tall fescue
Need help knowing when and how much to water your lawn? Try our online water management tool by clicking here.
For more information about brown patch, including control recommendations, click here.