Don’t dilly-dally

Summer turf diseases tend to spread quickly and can be incredibly destructive if not carefully managed. Heat and moisture drive many of the common warm weather turf diseases and with a lot of regions having had a wet winter and spring, the risk of diseases like pythium blight and brown patch is increased. The key is to get on top of these diseases before they become truly problematic.

In Columbia, Mo., Tom Boland, operations manager for Columbia Landcare, is expecting a dryer season, which should mean less turf disease for his region. They’ve been battling drought, which has brought its own challenges, but may just keep common turf diseases at bay. Still, it wasn’t long ago that turf disease ran rampant in the area.

“A couple years ago we had a very rainy and hot season and we definitely saw a lot of problems,” Boland says. “It can be frustrating, but the bottom line is that we can’t control the weather. We just have to do the best we can to deal with what we get.”

Brown patch is one of the more problematic diseases in Boland’s area and becomes active in regions where there is hot, wet weather.

Bruce Martin, professor of plant pathology and physiology at Clemson University says that brown patch typically crops up when day temperatures exceed about 90 Fahrenheit and night temperatures exceed 68 degrees Fahrenheit.

“If there is moisture, one will see leaf lesions that appear tan, with drawn brown borders to the lesions,” Martin says.

“These lesions can consume the whole leaf and eventually blight the turf canopy. When this happens, usually around mid-summer, the patches are most visible and can be several feet in diameter, varying in the amount of leaf damage that occurs.”

A proactive approach. Turf diseases are one of those problems that can damage client relationships even though the manifestation of the disease is typically not preventable. Jeffrey Johns, owner of Coastal Greenery in Brunswick, Ga., says that while it’s easy to prevent insects, it’s very challenging to be proactive with turf disease because it is so heavily tied to weather.

“It’s like the common cold,” Johns says. “You can get your flu shot and prevent the flu – as you might spray to prevent insects – but there’s nothing you can do to prevent the common cold. Because we can’t do much to prevent summer turf disease, our goal is to be instantly reactive. We treat it at the very first sign.”

Johns says that crews are well-educated to be careful with the amount of water and fertilizer they put down as those are two things that can increase the likelihood of disease.

“Nitrogen makes the grass green but too much can also cause diseases to stick their ugly heads out,” Johns says.

“The one preventative thing we can do is manage proper irrigation and fertilization. That’s not going to prevent everything but our goal is to do what we can.”

Since some of the watering may be done outside of the LCO visits, Martin says that clients also need to be educated on the proper way to irrigate and encouraged to keep things on the “dry side” whenever possible. “Irrigate when the turf really needs it, just at incipient drought stress,” Martin says.

“At that time, water deeply to wet the root zone and turn the irrigation off until the next incipient drought stress appears.”

In addition to education on watering, Johns says that educating the customer about the likelihood of turf diseases appearing is also critical. “This is an area where you can get customer backlash, which can be either prevented or resolved with education,” Johns says.

“We send out quarterly newsletters and mass mail our community if we know a type of disease is going to be prevalent that season. It’s important to prepare your customers so they know what to expect. If you’ve had heavy rains, tell your customers some of the signs of a problem they could see on their grass.”

Also take that opportunity to make sure your customers know you’re looking for the first sign of disease and on top of the situation. “If you don’t prepare them, and disease does appear, they might think it’s something you did,” Johns says.

“When it comes to turf disease, customer education is key.”

Made in the blade
Which summer diseases are most common is also dependent on grass type. Brown patch, for instance, is more common in tall fescue and other cool season grasses, says Bruce Martin, professor of plant pathology and physiology at Clemson University. He shares some of the other common summer turf diseases based on grass type.
 

Tall fescue/cool season grasses In addition to brown patch, grey leaf spot may also occur in fescues or ryegrasses, generally appearing in mid to late summer when weather is hot and humid. Overall symptoms are frequently mistaken for brown patch, but careful observation shows small brown lesions that develop on leaves and will girdle the leaf blades, eventually consuming the leaf. The lesions have a dark brown border but the center stays a dark or brown color whereas with brown patch, the lesion centers are tan.
Zoysia and centipedegrass The most damaging disease would generally be large patch (caused by a strain of Rhizoctonia solani). Infections occur in late summer, fall and continue into the spring, appearing as a water-soaked rotting of the lower leaf sheaths. Symptoms of leaf sheath rot may not be visible in fall as the turf goes into dormancy but large patches may then result in the spring near greenup and persist after. The margins of the patches may show active infections which appear as yellow to bronze-colored shoots along patch margins.
Bermudagrass The most common summer turf disease is leaf spot (Bipolaris spp.) but the most damaging in transition zone environments is spring dead spot. Leaf spot can cause thinning of the bermudagrass canopy. Small, purple lesions develop on senescing leaves, ultimately killing the leaves, and infections move into crowns and roots, killing tillers and causing a general thinning and decline. Spring dead spot is characterized by areas of dead or very weak turf, present right from spring greenup, with infection taking place on roots in late summer into fall.