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Nip Those Diseases In The Bud...

RICHARD LENTI | Landscape
You’ve done everything right. Watering schedules are providing optimum coverage with maximum efficiency. You fertilize the turf on a regular basis; its green, lush sheen is a testament to your tenacity. Yet still, it’s there: creeping, unwanted disease spoiling all your hard work.

There are a number of diseases to look out for, depending on where you live and the area’s climatic conditions. Yet in a survey commissioned by BASF, the diseases that were repeatedly named by lawn care operators as the most common recurring problem were brown patch and dollar spot.

Brown patch was named more than 43% of the time in the aforementioned survey. A destructive foliar disease of cool-season turfgrasses, such as creeping bentgrass, annual bluegrass, perennial ryegrass and tall fescue, brown patch also attacks warm season grasses, including St. Augustine grass, zoysia grass, and centipede grass.

It encompasses large circular or irregular shaped portions of the turf, up to several meters in diameter. Turf infected with these patches appears "sunken,” while the center may be less affected. The severity of the disease is greater under conditions of high relative humidity and rainfall or irrigation. Brown patch development can be very rapid; large blighted areas may develop within a 24- to 48-hour period.

Dollar spot, which was named nearly 20% of the time, appears as white or tan silver-dollar-sized spots of dead turf. Affected leaves initially show yellow-green blotches, which progress to a light straw color with a reddish-brown margin. Symptoms occur anytime from early spring to late summer, but the disease usually reaches peak activity when air temperatures and humidity are high, although symptoms also may appear in the fall.

The most severe cases of dollar spot occur on turf receiving closely spaced summer irrigation, but it also may occur on non-irrigated turf when humidity is high for long periods of time. Dollar spot is more severe under nitrogen deficiency or when grass grows slowly.

Photo Courtesty: Dow AgroScience

All turfgrasses are susceptible to dollar spot, with creeping bentgrass, ryegrass, annual bluegrass and rough bluegrass as the most susceptible cool-season grasses. Zoysia and Bermuda grass are the most susceptible warm-season grasses.

Combating any lawn disease begins with taking preventive measures to ensure the problem doesn’t take hold. Cultural controls used to fight brown patch include: the avoidance of high nitrogen applications; watering infrequently, but deeply in the morning while avoiding late-evening and night watering; and reducing thatch buildup through mechanical dethatching or core aerification.

To prevent dollar spot from taking hold, avoid extreme nitrogen deficiency. Late-spring applications of nitrogen fertilizer can help minimize dollar spot severity. Maintaining adequate levels of phosphorus, potassium, calcium, magnesium and other nutrients are also effective cultural controls, along with the promotion of good air circulation over the turf by pruning or removing trees, shrubs and other barriers.

Knowing the history of the turf can also help avoid an outbreak before it occurs. “If you know that the specific property is susceptible to a disease because it happened last year, chances are it will happen again,” says Jackie Costa, public relations for Dow AgroScience. “So then you’d want to prevent it with a program of fungicides for that particular problem.”

Since lawn care professionals may only see a customer’s lawn once every few weeks, when a client calls about a disease outbreak, it may be too late. That’s what makes having a preventive program in place so important.

One way to achieve that is by using broad-spectrum fungicides that control the disease, while supporting plant health and increased turf vigor. In the past, what were missing were fungicides that offered the residual protection that fit into a lawn care service schedule. Thanks to the new breed of fungicides available, that’s no longer a problem.

A product just hitting the market is Armada 50 WP fungicide from Bayer Environmental Science. Specifically designed for lawn care use and registered by the EPA, the fungicide provides control of brown patch and dollar spot, as well as 12 other turf diseases.

Packaged in water-soluble packets, it can be applied with a backpack or tank sprayers, providing both contact and systemic turf protection. Because it contains two different chemical families (trifloxystrobin and triadimefon, active ingredients from the strobilurin and sterol inhibitor chemistry classes, respectively), the product offers both preventive and curative disease control.

According to Bayer, its fast-acting formula provides control for 30 days, and it should be used on cool-season turfgrasses such as perennial ryegrass, tall fescue, fine fescue and Kentucky bluegrass.

Another product that’s effective in controlling dollar spot and brown patch is Eagle 20EW from Dow AgroScience. Its active ingredient is myclobutanil, and it is a specialty fungicide that’s labeled for use on major turf varieties, landscape ornamentals, and backyard fruit trees and vines.

Available in two sizes, its liquid formulation provides systemic protection. Best control of the labeled diseases is achieved when Eagle is applied on a 7-10 day application schedule.

The company also manufactures Fore Rainshield, a wettable powder in water-soluble packets that resists wash-off in wet weather. A turf and ornamental specialty fungicide, it provides control of brown patch and protects against other turfgrass diseases by attacking fungi at multiple sites in a non-selective manner, preventing organisms from adapting and mutating.

Designed for use during summertime conditions when heat, humidity and heavy irrigation combine to make turf most susceptible to disease, Fore Rainshield’s active ingredient is mancozeb. It works best when used on a preventive 7-14 day schedule.

Among the offerings from BASF, Insignia is a strobilurin-based fungicide, applied as a preventive or curative treatment for brown patch on a 14- to 28-day interval. It also controls 18 other diseases, and suppresses dollar spot.

Because the active ingredient acts as a respiration inhibitor, it is effective against the disease during all growth stages of the fungi and is safe for all warm- and cool-season turf when used according to label directions.

For dollar spot control, the company recommends its PropiconazolePRO, a systemic fungicide that is effective on cool- and warm-season turfgrasses. It stops the development of fungi by interfering with the biosynthesis of sterols in cell membranes. As a systemic compound, it has quick uptake resulting in good distribution.

Whether you’re fighting brown patch, dollar spot, or one of the dozens of fungi that attack turf, disease control is fast becoming an important service for lawn care companies. The products mentioned are just some of the tools at your disposal. The investment your clients have made in their lawns demands you be ever vigilant.

We’ve all heard the saying that an ounce of prevention is worth a pound of cure. Today’s fungicides make it possible to offer your customers a program that should prevent turf diseases from occurring. And in those cases when they pop up despite your best efforts, there is now an affordable cure.
 
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