Pest control is multifaceted, with dozens of factors responsible for effectiveness. Failure to consider and implement any one of them can result in poor results, and, in turn, negative feedback from coaches, players and fans. As you read through these treatment strategies, evaluate your current pest control procedures in light of the information in this article.
ID is the starting point
Is it spurge, chinch bugs or brown patch? Knowing the actual pest before you begin control measures is the only way to go. Why? How can you know how to kill something before you know its name? Doing so would be like the dude (Joe Loop) in “Be Cool,” who was paid to kill Chili Palmer but ends up whacking some other guy by mistake. The misidentification causes all sorts of problems as the movie rolls along, but we’ll let you save those adventures for a rainy day when field maintenance activities are limited.
When it comes to identifying pests of turf, several good resources are available. Online Web pages from Virginia Tech and Purdue are helpful, while “Controlling Turfgrass Pests,” by Shurtleff, Fermanian and Randell, is a good book for both identification and control strategies. Other sources include pesticide manufacturers; the next time a chemical company representative comes to ask for your business, ask them for an identification guide.
Timing is paramount
Knowing what to kill is important, but knowing when to do it can’t be overlooked either. In fact, some may argue that timing is a more influential factor than identification.
You never really know how well a sprayer is working until you check it out.
PHOTO BY FREDERICK FISHEL, UNIVERSITY OF FLORIDA.
One of the hallmarks of good timing is knowing and implementing control measures during the pest’s most vulnerable stage. Each pest has one; it just has to be found and utilized for effective control. With weeds, the issue of treating before or after the plant is growing is always a consideration. It begs the question, “Which life stage is more vulnerable?” For example, crabgrass is a year in and year out problem for many sports turf managers. Controlling it after it’s up and growing well can be done with postemergence herbicides, but a well-timed preemergence application is usually more effective. The same is true for insects, as the challenge is to determine whether the adult, larvae or nymph is most vulnerable.
Even though integrated pest management (IPM) has been around since the days of the cotton boll weevil, it remains an effective foundation for controlling pests in turf and ornamentals. Though IPM is a circular process that starts with a pest-resistant plant, employs various strategies and ends with evaluation of the entire process, scouting and monitoring is a natural consideration.
As technicians are out and about in the sports complex going about their routine duties, taking a few minutes to get down on their hands and knees to look closely at off-color turf is a wise endeavor. Scouting is a simple process. It’s usually best to start at the point of abnormal appearance and work outwards towards the healthy turf.
Surface insects and weed seedlings are easily spotted in this first stage; digging is required when inspecting for subsurface pests and rotting roots. A golf course cup cutter, pocketknife or sod spade can be used for subsurface investigation.
In terms of controlling weeds and other pests, it’s wise to establish thresholds for each. At the first symptoms of pathogen activity, weed growth or insect damage are spotted, the degree of infestation can be compared with the predetermined level of tolerance for consideration of possible control action. The degree or intensity of culture usually affects the threshold level. For example, on Little League fields, a higher number of clover or dandelion plants are allowable than on a college baseball field. In many cases, the implementation of sound cultural practices can offset the threat that mild pest invasions pose.
Curative versus preventative
The decision to treat curatively or preventatively fits well with the IPM model. In addition to the degree of culture or intensity of use, the history of the field has a lot to do with the treatment approach. If sod webworms have been a recurring pest in a particular field for the past three years, it’s more likely that a treatment would be justified than if they have been a sporadic occurrence. Pests best treated preventatively, such as crabgrass or gray leaf spot, should be managed in much the same way.
Read the label
Other than application rate, how many items do you really check out on the label? There are so many pieces of valuable information that can be gleaned from a quick 15-minute read. For example, in most cases, information on optimal temperature range and wind speed restrictions are provided. Pesticide manufacturers stress the importance of reading the label.
Bobby Walls, product development manager with Professional Solutions Group at FMC, indicates that “when applying post- emergence products, surfactant additions can be helpful in keeping the product in contact with the leaf blade. The key is getting good coverage.” As with other specific details, refer to the pesticide label for suggestions on inclusion of a surfactant.
Other pertinent bits of information to pay attention to include:
- Directions for the most appropriate timing of the application
- Recommendations for the correct amount of water to use as a carrier
- Size of mesh screen to use in the spray system
- Agitation requirements, if necessary
- Suggestions for use of spray pattern indicators
- Restrictions on other products that may be perceived to enhance herbicide performance
- Indications for enhancement with the addition of adjuvants, crop oil concentrates or spreader-stickers
- Specific guidelines for the amount of the product to mix with water
- Possible need for circulation of the herbicide mixture through the hoses and spray tank
Not all pests are created the same in terms of frequency, capacity for damage, ability to spread and cost to treat. In each pest control category, some are just simply tougher than others to control. In addition, in terms of weeds, the very nature of the existing population (especially on native soil fields) is problematic. Weed scientists tell us that there are 10,000 weed seeds in the average cubic foot of soil … ouch. That’s the agronomic equivalent of shooting fish in a barrel or a cornerback trying to cover all the eligible receivers by himself. As a result, it makes good sense to prioritize.
A brief rundown of the species to focus on in each category might look something like this:
Weeds – nutsedge, Poa, prostrate knotweed, crabgrass
Insects – grubs, sod webworms, aphids, billbugs
Diseases – gray leaf spot, summer patch, spring dead spot, Pythium, brown patch
Reasons for pesticide failure
In most situations, pesticide applications work well to control target pests. However, the following factors can reduce effectiveness at times.
Volatilization – Volatilization primarily involves the upward movement of the product away from the turf. This occurs by a large percent of the applied pesticide turning from a liquid state to a vapor or gaseous state. There are no pests to kill in the air, so this is a reduction in active ingredient on the turf surface. Volatilization effects can be limited by avoiding application on hot, windy days and choosing low-volatility ingredients.
Prostrate knotweed is a good indicator of a compacted field.
PHOTO BY JOHN C. FECH, UNL.
Temperature – Most products are designed to work in moderate temperature conditions. For example, when temperatures are cold, foliar sprays for broadleaf weeds aren’t effective. Likewise, when temps are 90 degrees Fahrenheit and above there is reduced effectiveness. The bigger concern with high temperatures is that the herbicide application will cause foliar burn on the turf and nearby ornamentals. Care must be taken when applying herbicides in the high end of the safe temperature range not to injure shrubs and flower beds in close proximity to the turf.
Equipment calibration – One of the most dramatic factors is that of equipment calibration. It is ridiculous to assume that any piece of equipment applied exactly the desired amount of product every time it is used. Orifices get plugged and worn, nozzles get bent or crushed; even tires that become lopsided can cause inaccuracies.
The best way to deal with this is a spray check. For boom sprayers, attach glass jars underneath each nozzle, let the sprayer run for a minute, and then measure the amounts in each jar. In most cases, some will have put out the right amount, some less than desired, some more than desired, and some will be completely plugged, delivering no product at all. For dry spreaders, mark off a 1,000-square-foot section of turf. Weigh out the correct number of pounds of product to deliver 1 pound of nitrogen (usually 3 to 4 pounds of product) and apply it over the section. If there is not enough in the hopper to cover the area, or there is a considerable amount left in the hopper after the area is covered, then calibration is necessary.
Drift – Drift is the physical movement of the pesticide away from the target site. Applications can fail because drift is too great, causing the concentration to be reduced. However, the larger concern with drift is an undesirable effect on plants or people adjacent to the area that was sprayed. Drift can be greatly reduced if pesticide applications are made when wind speeds are 5 mph or less.