You’ve just been hired on the job, or maybe given a new assignment.

This set of fields are brand new to you. So, there is real uncertainty as to the current state of drainage patterns, irrigation efficiency, fertilization techniques used, team usage routines and, of course, weed problems.

Creating a tool – a weed map – that makes you aware of and keep an open mind about what may be problematic – the areas that have a deep history of weed infestations and which ones are under control for the most part – will be helpful.

But a weed map is not just for new hires.

The power of specific documentation can benefit veteran field managers by shifting from an “it’s all in my head” (he said tapping his temple) system to a widely accessible, multi-feature approach that has great capacity to transfer important information to any authorized person in the organization.

Greater knowledge can help prevention

In all categories of pest control – weeds, insects, diseases – and even some nonliving maladies such as compaction and irrigation repair, preventing damage is much easier than fixing it after the fact.

One of the most helpful prevention techniques is a weed map. A weed map identifies where weeds are, where they have been and provides insight into where they are likely to be in the near future.

As opposed to prevention, relying on curative agents for pest control has been described by a colleague of mine to be like “pushing a lopsided boulder up a steep hill.” In the case of turf pests and abiotic problems, the weeds are fully grown, the disease infestation is raging, the insects are feeding heavily and the soil particles are already smashed together when curative approaches are utilized. Sure, they can work, but pressing the easy button of prevention is always preferred.

A map directs resources toward areas of need, saving time and money and reducing herbicide applications.

Image Courtesy Of John C. Fech

Specifically, for the benefit of the sports turf manager, a weed map identifies and documents trouble spots and historic areas of infestation.

This knowledge helps to control weeds in their most vulnerable stage – generally nonemerged seedlings for annual grasses and small, newly sprouted plants for broadleaves and sedges – rather than falling into the trap of blasting the entire field with curative, postemergence products.

Acting on information from the map helps direct resources toward the areas of greatest need, saving time and money and usually reducing overall herbicide applications.

In short, weed mapping gives sports turf managers the opportunity to avoid spraying areas of a field where no weeds are present and restrict spraying to areas already or historically infested.

Creating a map

Maps have been used for many years and for good reason. We all know the “X” marked where the buried treasure was in the days of the pirates.

This theme was reprised in the movie “Romancing the Stone,” where the cast scrambled across Colombia to find the coveted emerald green gem.

In the case of a weed map, it’s not the actual undesirable plants or weed seeds that we are interested in for resale, it’s the critical information about their location and possible re-infestation of important parts of a field that is wanted.

Many mapping techniques can be used, from the sophisticated to the simple. Regardless of which technique is chosen, the central idea is to create a master record book – or a centralized location where all workers can access information that is saved securely.

Some situations call for a physical map, such as a master record white board in a conference room, using a grease pencil to mark specific recent outbreaks.

When many fields are involved or several weed species are found from year to year, it makes sense to go electronic. Many different software programs are available for this purpose, even open source packages such as Google Docs or Box, places where all crew members can gain access and documents are safely stored in the cloud for now and the future.

Regardless of the format, it’s best to start with traditional hot spots such as between the hash marks, at the goal mouths and where players stand. Weeds such as prostrate knotweed and goosegrass tend to tolerate these areas quite well.

Once these areas are documented, historic areas of infestation can be noted. Maps that contain several colors – red, blue, green, orange, brown – are easy to read and understand quickly. When creating a weed map, consider if the tools chosen allow for color use.

Populating the map

Once the map is created, it’s time to make good use of it. The usage will begin with initial entry of the observations. In order to be efficient when entering the observed weeds, it’s best to have a plan, rather than random entries that don’t make sense at the end of the day when everyone is tired and sometimes forgetful.

It’s best to start with traditional hot spots such as between the hash marks, at the goal mouths and where players stand.

Generally, two approaches for scouting (one-time observation of events) and monitoring (a regular predetermined set of observation of events) exist. The first is a protocol where all employees scout all the time, before and after striping, while driving to the supply shed, moving goals, etc. The second is when dedicated scouts are assigned the task of taking a certain amount of time each day and setting it aside for inspections, no matter what else is going on that particular day or week. Each approach has pros and cons; factors such as the number of fields, availability of employees and overall field usage will influence the decision to choose one over the other.

Identification of troublesome weeds is key to the process. It can be hard to identify a weed in a ditch or vegetable garden where a stem, leaves, roots and inflorescence are usually present, but in a sports field or golf course where the turf is mowed daily at a low height, it can be tough to figure out which species has invaded.

Once these areas are documented, historic areas of infestation can be noted.

Fortunately, many good resource books and websites are helpful in noting the key characteristics of weedy species. One of the best for northern turfs is the “Weed of the Month” page for the Turfgrass Science Department at Purdue University. In the south, the “Turfgrass Weeds” page provides great visuals and identification features of various species.

Taking notes

Notations on a map can take on many forms, as directed by the need for various weed infestations, years in which noticed, or preferences of the field manager. As mentioned above, colors can be helpful, conveying a certain weed, usage level or association with a particular equipment installation or herbicide application. Current infestation levels of a particular weed might be noted in colors as well.

For example, an infestation (previous or current) of goosegrass might be designated on the map as “GG 171615” in red, to convey that a particular area was heavily infested over the past three years. Red usually gets one’s attention, so it would make sense that red means severe, green is moderate and blue is light, for example. But any color scheme can work as long as everyone on the team understands it.

In addition to the current and previous infestation levels of a particular weed species, it may be beneficial to note preventive and curative control measures that were taken as well. Historical records can be very helpful as the actions fade from memory. You can also note new weeds to the surrounding area, or at least to the field. If unmown areas of a nearby neighborhood park become infested with an uncommon weed, it can be helpful to make a notation off to the side so that planning for intervention can occur.


Mapping is only good to the extent that the information is shared and understood by all. Communication with other crew members, managers, owners, stakeholders and coaches is important to preventing and controlling weed populations throughout the year. In most cases, weed map reports need not be complicated or sophisticated; however, sharing pertinent information can be helpful in other areas of sports turf management.

If a renovation is needed but the owners are resistant to it because of temporary loss of use, documentation of severe weed problems can be a visual and monetary reminder that spending money on renovation upfront will improve playing conditions and reduce maintenance costs down the road.