Got Creeping Bentgrass Problems?

Imagine this. Rain followed by heat stress = creeping bentgrass problems. Just last week we diagnosed our first cases of summer patch and Pythium root rot on creeping bentgrass putting greens for 2014 in North Carolina. So without further delay, here’s the info you need.

The symptoms of summer patch on creeping bentgrass appear as circular patches or rings, ranging from a few inches to a foot in diameter. They often have the classic “frog-eye” symptom. Turf within these patches initially turns off-colored, is prone to wilt, grows poorly, and may appear sunken in the turf stand. Over a period of a few weeks, the turf continues to decline, turns yellow or straw brown and eventually collapses to the soil surface. The outer edges of the patch are usually orange or bronze when the disease is actively developing. The patches recur in the same spot annually, and can expand at a rate of 2 to 4 inches per year.

Summer patch symptoms on a creeping bentgrass putting green

Summer patch symptoms on a creeping bentgrass putting green

The summer patch fungus attacks the roots, stolons, and rhizomes in the spring when soil temperatures reach 65°F. Summer patch symptoms are rarely seen during the early stages of disease development, instead, the symptoms appear in mid-summer after considerable damage has been done to the root system. Heat, drought stress, and nutrient deficiencies are the main factors that encourage the expression of summer patch symptoms. In North Carolina, the symptoms typically appear in early to mid-July. For more information about summer patch, including control recommendations, click here.

Just like last year, we have found Pythium root rot to be active in the upper thatch layer around roots closest to the plant. With that being said, if you are treating for Pythium root rot, don’t water those fungicides in TOO much. I encourage you to probe several healthy and weak areas to come up with an average thatch and root depth to determine where YOUR target area is, which may or may not be the same as your buddy across the street. Also, even though PRR tends to show up more often in low lying/wet areas, it can develop in higher/drier areas as well under the right conditions.

Pythium root rot symptoms on creeping bentgrass putting green. Note how it follows drainage pattern!

Pythium root rot symptoms on creeping bentgrass putting green. Note how it follows drainage pattern!

We typically recommend about an 1/8 – 1/4″ post-application irrigation for both summer patch and PRR, which in most cases equals about 3-5 minutes with part-circle heads. Either way, you may want to take the time to see how long it takes to put that amount out. This is a critical step towards maximizing your fungicide application.

For more information about Pythium root rot, including control recommendations, click here.

Dollar Spot Alert!

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.

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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.