Turf's most (un)wanted pests
Determining the worst turf pests in the United States is not easy. We realize that if we crowned a "champion" pest, it might not relate much to your experiences as a turf manager (or maybe it will-read on). After all, what you deal with in Texas is not what you deal with in Minnesota, which is not what they deal with in Pennsylvania. And what golf-course superintendents deal with is often very different from what lawn-care operators must address.
Despite the limitations inherent in the process, we thought it would be interesting to try to identify the most serious offenders. In case you were tempted to think otherwise, there's nothing scientific about this, and it doesn't even come close to including all troublesome turf pests. Take it for what it is: an informal look at who is dealing with what, and where.
We gathered our information from eight university and extension turf specialists from around the country. We deliberately defined "worst pest" loosely. After all, "worst" could mean "most difficult to control" or "most prevalent" or "most likely to get you fired," three very different things. But we figured these experts would be in touch with the pests that worry turf managers most and that require their greatest efforts.
While no pest was a universal problem, a couple came close. Conversely, some regions must cope with pests that are causing substantial problems, even though they are limited to narrow geographical ranges and are practically unheard of in other regions.
Does any single pest stand out as the turf pest in terms of time, effort and money spent to control it? After speaking with the experts, we have little doubt about which pest ranked highest overall: crabgrass. Worst insect? grubs. Worst disease? Brown patch (or simply "patch" or "patch complex," as some referred to it).
More importantly, however, it's clear from this exercise that every region has a unique mix of pest problems. Here's what our experts had to say their respective regions.
Southeast most (un)wanted: In Florida Turf expert: Dr. Phil Busey, University of Florida (Ft. Lauderdale, Fla.).
* Insects. Busey did not hesitate to name mole crickets-tawny being the most common type-as the No. 1 insect pest of Florida turf, especially fine turf such as golf courses and athletic fields.
Busey also mentioned grubs, which he feels have become more prevalent in the past few years; and chinch bugs, which have been a problem for decades. But these do not, in Busey's opinion, equal mole crickets in severity.
* Weeds. In the "weeds" category, Busey lists goosegrass as perhaps "the" major economic pest of fine turf such as bermudagrass. In St. Augustinegrass, dollar weed ranks high. Virginia button weed is prevalent in most turf types in Florida. Sedges and alligator weed (especially on sod farms) are also problems, and tropical signalgrass is a weed that is increasingly problematic in all turf types.
* Diseases. A "disease" that Busey feels should rank high on the list is nematodes, particularly sting nematodes. These microscopic roundworms can cause turf to become chlorotic and unresponsive to fertility. Their effects are especially severe in Florida's typically sandy soils, but the most difficult aspect of nematodes is the lack of good controls. Nemacur is fairly effective, explains Busey, but it's use is highly restricted and therefore not always an option.
Other disease problems include take-all root rot in St. Augustinegrass, caused by the same pathogen implicated in bermudagrass decline, which also is a problem in Florida. However, Busey states that many of the traditional disease problems are not prevalent in Florida. Gray leaf spot and brown patch are essentially "textbook" diseases in this area, he says.
In South Carolina Turf expert: Dr. Bert McCarty, Clemson University (Clemson, S.C).
* Insects. McCarty agrees with Busey: Mole crickets are the worst offenders. South Carolina is well within mole crickets' range, which extends through North Carolina and into southern Virginia.
Turf managers in McCarty's area also deal with grubs, though they aren't the problem they are in more northern areas. Cutworms and armyworms must be watched, too, but typically are more of a "nuisance," says McCarty.
* Weeds. McCarty lists Poa annua as the overall worst weed in his area. Because of annual bluegrass's genetic diversity, control is often inconsistent, he explains. This is frustrating for turf managers and researchers such as McCarty, who are looking for better ways to deal with this ubiquitous pest.
Paspalum spp. (bullgrass, dallisgrass and bahiagrass) are difficult to deal with, mainly because of a lack of effective herbicides, but also because, like Poa annua, their genetic diversity and varying biotypes result in inconsistent control.
McCarty also notes that kylinga and purple and yellow nutsedge have increased in the past 5 to 10 years. He attributes this to better crabgrass pre-emergents. They have reduced the need for post-emergence treatments, which historically have helped keep the sedges in check.
* Diseases. Overall, brown patch is the most troublesome disease, according to McCarty. Bentgrass frequently suffers from dollar spot and Pythium blight in addition to brown patch, while St. Augustinegrass is susceptible to gray leaf spot.
McCarty, like Busey, noted that nematodes could be severe, especially on sandy soils. The lack of good control measures makes them particularly troublesome.
Northeast most (un)wanted: In Pennsylvania Turf expert: Dr. Peter Landschoot, The Pennsylvania State University (University Park, Pa.).
* Insects. Grubs are the primary insect pest in Landschoot's region, but are spotty and often do not require routine treatment. Japanese beetles are responsible for most of the grub damage. Chinch bugs also cause some damage but do not constitute a major pest problem according to Landschoot.
* Weeds. Landschoot explains that, in terms of dollars spent and pesticides applied, crabgrass is the mostsignificant weed in his region. Collectively, broadleaf weeds roughly equal crabgrass in significance, much of that accounted for by dandelions and clover.
On golf courses, Landschoot notes that Poa annua is probably the biggest weed problem. However, many superintendents now try to manage their Poa annua rather than eliminate it, so defining it as a weed depends on your approach. Crabgrass and goosegrass are also prevalent on golf courses.
* Diseases. Dollar spot probably costs golf courses more than even crabgrass, according to Landschoot. Brown patch and Pythium blight are factors as well, followed by gray leaf spot on perennial ryegrass courses.
Midwest most (un)wanted: In Minnesota Turf expert: Bob Mugaas, extension horticulturist, University of Minnesota (Minneapolis, Minn.).
* Insects. Mugaas happily reports that turf insects are not generally a serious problem in his area. When present, grubs largely consist of June beetles, which have a 3-year lifecycle. Therefore, they tend to be cyclical, varying in severity from year to year.
* Weeds. Weeds haven't been quite so kind to Northern turf managers. Crabgrasses are, according to Mugaas, the No. 1 problem, but dandelions are nearly equal in severity.
A weed problem that seems to be increasing in severity is ground ivy, at least in urban and suburban areas. Mugaas attributes this to maturing urban forests, which increasingly shade turf and favor the ground ivy.
Poa annua is a serious problem on courses that fight it, though many superintendents have instead chosen to manage it, something that Landschoot mentioned also.
* Diseases. The most serious disease on lawns, and some sports turf and sod farms are primarily "patch-disease complex." No other diseases are consistent problems on general turf.
On golf courses, snow mold is the most serious disease. Mugaas says that snow mold is fairly manageable, but can be devastating if you don't address it. Similarly, dollar spot is a disease that demands attention. Pythium blight and brown patch also can be problems when hot, humid weather occurs.
In Nebraska Turf expert: Farther south, Dr. Roch Gaussoin, University of Nebraska (Lincoln, Neb.).
Gaussoin's first reaction to our question was to name traffic and compaction (i.e. people) as the No. 1 pest of turf. And he makes a good point. After steering him back to traditional pests, here's what he had to say.
* Insects. For insects, Gaussoin left little doubt: grubs. He didn't even mention another one.
* Weeds. Gaussoin's difficult weeds were led by crabgrass-easy to control, but a large overall economic pest; followed by yellow nutsedge-not only expensive to treat, but resurgent, requiring multiple applications. Other weeds that made this list include ground ivy and wild violet-just plain hard to kill; sand bur-an aggravating weed common in sandy sites where pre-emergents are not as effective; and one you've probably not heard of: windmill grass. This is a weed of the High Plains that, according to Gaussoin, is "impossible to kill unless you use a non-selective heribicide."
* Diseases. Necrotic ring spot and summer patch are two diseases that Gaussoin sees many turf managers struggle with in Kentucky bluegrass. The best approach to avoiding these diseases is resistant varieties. However, Gaussoin says that many turf managers do not use them and end up struggling with the diseases each year.
Tall fescue's nemesis is brown patch and perennial rye's is gray leaf spot. The latter is particularly troublesome because of a lack of resistant varieties. However, the disease seems to cycle and Gaussoin notes that last year was not a bad one for gray leaf spot.
Southwest most (un)wanted: In Arizona Turf expert: Dr. David Kopec, University of Arizona (Tucson).
* Insects. According to Kopec, grubs can be problematic in the Southwest. Desert generally is not a favorable habitat for grubs, but irrigated turf is like an oasis in the middle of a desert, acting like a magnet to draw and concentrate grubs.
Other pests include rove beetles, otherwise beneficial insect predators that bring sand mounds to the turf surface on golf greens, and earthworms, which do likewise. Two species of turfgrass aetenius are becoming more serious pests of tees and greens.
* Weeds. Topping Kopec's list of problem weeds are purple and yellow nutsedge, and chaff or khaki weed (Alternanthera sp.). Others Kopec mentions are wild parsley, Poa annua, several types of spurge and Southwestern cupgrass, which Kopec describes as "our equivalent of crabgrass."
* Diseases. Disease pressure isn't so severe in the dry air of the Southwest, but Kopec says that patch diseases in the fall can severely damage overseeded Poa trivialis and velvet bentgrass.
In Texas Turf expert: Dr. James McAfee, Texas A&M University (College Station, Texas).
* Insects. The problem insects McAfee mentions are grubs, chinch bugs (on St. Augustinegrass) and, as more occasional pests, sod webworms and fall armyworms. However, the top position belongs to fire ants. Though considered a "nuisance" pest in that they do not actually feed on turf, fire ants build their nests in turf (and anywhere else they want to), creating large mounds. The greatest problem with fire ants is, of course, the hazard they present to humans and animals with their severe stings.
* Weeds. Among the worst weeds, McAfee lists crabgrass, dallisgrass (especially in St. Augustinegrass) and bahiagrass as the most problematic grassy types; and dandelion, spotted spurge, henbit and chickweed as the most serious broadleaf weeds. Kylinga and yellow and purple nutsedge also rank on McAfee's list. On golf courses, Poa annua is a serious weed of greens, and goosegrass also is prevalent.
* Diseases. In McAfee's region, 90 to 95 percent of turf is St. Augustinegrass or bermudagrass. Disease problems, therefore, mostly are limited to pathogens active on these species. Brown patch, gray leaf spot and take-all root rot are the main problems on St. Augustinegrass, while bermudagrass usually suffers nothing more than a bit of leaf spotting.
On golf courses, Pythium and brown patch are the major pathogens of diseases of bentgrass greens, while bermudagrass decline is the primary problem for bermudagrass greens. Fairways in this region are nearly all bermudagrass and have few disease problems.
Northwest most (un)wanted: In Oregon Turf expert: Tom Cook, Oregon State University (Corvallis, Ore.).
* Insects. Cook describes his region as having the lightest insect pressure of any region in the country. However, the Northwest is host to one pest that most turf managers in other parts of the United States haven't even heard of: the European crane fly. The larvae of this pest hatch in fall and remain active through winter, which is relatively mild in this region.
By the time spring rolls around, turf that ought to be growing vigorously is instead thin and weak owing to the crane fly larvae, which have been feeding and growing all winter. Cook adds that another species of crane fly is becoming more prevalent. This one lays its eggs in spring, so feeding occurs during the warm season.
"Ninety percent of the time, you'd be fine if you did nothing," says Cook. "But occasionally, they can totally destroy an area. The challenge has been getting people to monitor through the winter. They're easy to find if you look." Aside from this, few turf insect problems exist in the Northwest. Cook does note, however, that in Eastern Oregon and Idaho, bluegrass billbugs can be serious at times.
* Weeds. False dandelion, or spotted catsear, is Cook's choice as the most common turf weed in his area. This weed is not serious in irrigated turf, but can gain a foothold in unirrigated turf. It is drought tolerant and outcompetes turf under drought stress. Once the weeds become established, they form rosettes that block out turf.
Veronica, oxalis, English daisy and heal-all are sometimes problems on golf courses, explains Cook. Spotted spurge, though present, is rarely a problem and crabgrass is a "distant memory." Poa annua, as in many other places, is a weed here if you choose to fight it, a turfgrass if you don't.
* Diseases. On lawns, red thread is a big issue because of the popularity of perennial ryegrass in the Northwest. The mild climate makes this a nearly year-round problem. Cook considers this disease primarily a cosmetic problem, but fields many calls regarding it. Necrotic ring spot is the primary problem on Kentucky bluegrass lawns.
Golf courses deal more with Fusarium patch (the same pathogen as pink snow mold) and anthracnose, which has been more serious in the past 5 to 10 years. According to Cook, this is due to lower mowing heights and drier conditions, which are becoming management standards. "[Superintendents] definitely need fungicides for this disease," notes Cook.
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