See where you spray

Has this scenario ever happened to you? You spray a herbicide to control weeds on a turf area then continue to see them growing vigorously a few days afterward. How about seeing streaks of dark-green and light-green grass after a liquid-fertilizer application? Mixing errors or product selection could be the cause-but sometimes the problem is not what you spray but how you spray it. Thorough, uniform coverage is essential to the success of any pesticide or fertilizer application.

Obviously, you want to avoid situations like these. Pest-control failure and uneven turf appearance causes customers to devalue your services. Luckily, you can prevent many of these unwanted results by using a spray-pattern indicator.

In general, you add spray-pattern indicators to the spray tank in relation to the volume of water in a ratio that the product label specifies. The indicator product changes the color of the contents of the spray tank, usually to a dark blue or green. After application, this color change is temporary, usually effective for several hours. However, some products may last up to 48 hours after application.

Recent refinements in many of today's spray-pattern-indicator products have made them easy to use. One popular feature that some products offer is that you don't need to measure them. The products use a water-soluble bag with a pre-measured amount of colorant in it. All you need to do is put the correct volume of water and active ingredient into the spray tank and drop in the bag of colorant.

Pre-measured bags of spray indicator offer you several benefits. First, a pre-measured dose provides a consistent and accurate application rate. Using the bags also saves time by eliminating the tedious need to measure product. In addition, because the container dissolves, you have no waste of which to dispose. Finally, using the bags means you reduce the possibility of being exposed to the colorant, which means no stains or spills onto your clothing or the mixing area.

Why use a colorant? Many reasons exist why you would want to temporarily change the color of a spray mix. Perhaps the most compelling benefit is the potential for increasing effectiveness by identifying clogged nozzles on your spray boom. If a nozzle is partially or completely clogged, it affects the proper amount and distribution of spray product. In most cases, it results in reduced product output-therefore controlling fewer pests or applying less-than-desired amounts of fertilizer. In some cases, where the nozzles are partially clogged, the spray pattern is distorted. It may apply the proper volume but in a larger or smaller area than you intended. Using a spray-pattern indicator, you'll see areas that are unmarked or are marked with a lighter color, thus raising a red flag for you that your sprayer is having problems.

Once you've identified that your boom nozzles are defective or worn, replace them. You then can perform a simple spray check on the unit using collection devices to measure the output of each nozzle. The resulting increase in performance will result in a significant cost savings. If you are a golf-course superintendent applying fungicides to a golf green, you can save several hundred dollars per green by applying the correct amount of chemicals. Additionally, you minimize the costly practice of re-treatment by spraying accurately the first time. You also can realize smaller cost savings by reducing boom overlap between passes over a green because each pass is more visible.

Training advantages Spray-pattern indicators can be helpful in training new employees to use spray equipment. Simply add the colorant to a tankful of water and let the untested employee test-spray some utility turf areas. During this time, the new applicator can observe the effect that boom/nozzle height, ground speed and tank pressure have on output. If you don't do so, you can end up with an untrained person who basically will be "experimenting" on the job site, which is potentially damaging to both the environment and your company's reputation. An employee who knows how to use the equipment, however, is a valuable asset.

A spray-pattern indicator is useful in other situations as well, such as on unfamiliar sites where the potential for spray drift is unpredictable. You typically can't determine wind patterns around trees and between houses until you've had several years of experience. Using a spray-pattern indicator can help you identify which areas are subject to influence by wind effects. You can note overspray onto tree trunks, car tires and play equipment and make adjustments accordingly. Use a colored, non-pesticide/-fertilizer formulation until you are familiar with an area.

Additional colorant advantages If you are a landscaper, you can make particularly good use of spray-pattern indicators. While consulting with a client on a prospective installation, for example, you can use colorants to indicate where you'll install planting beds, where you'll locate plants of various heights and colors and to help the customer visualize the eventual spread of a shrub in the landscape. Most landscapers have an ability to look at a design on paper and visualize its eventual appearance in reality; most customers, however, do not have this ability. Colorants can be helpful in allowing a customer to see that a red twig dogwood will be 2 feet by 2 feet at planting time but will grow to be 5 feet tall and 10 feet wide at maturity.

If you are a job foreman, you too can find spray-pattern indicators useful to locate specific areas of repair for the workers under your supervision. While explaining which irrigation heads to retrofit or where the new location of a perennial flower bed should be, use a colorant to locate the exact spot of activity. This is especially true in situations where other markers-such as permanent paints, small flags or lengths of ribbon-are objectionable. Within hours, the marking simply fades away, eliminating the possibility that a client, golfer or homeowner could trip over a string or flag that may accidentally remain on the job site.

Lawn-care companies have used spray-pattern indicators to communicate with their customers for many years. For example, when taking over a new account, the lawn may have many weeds. Using a colorant helps the customer see the extent of the weed population and the necessity of the lawn-care service. This visualization helps to validate the ability of the applicator to identify and control undesirable vegetation. Colorants can be useful later in the season, too, to make comparisons of effectiveness and how many weeds were killed.

You also can impress homeowners that have been your clients for several years when they see you are not spraying the entire lawn for broadleaf weeds when only a few problem areas exist. This practice communicates cost savings and environmental concern. Again, the use of a spray-pattern indicator makes this visible for the customer.

While no manufacturers claim it as a direct pest-control benefit, the use of colorants when applying pesticides in areas with pest damage can cosmetically mask the damage. In these situations, you may want to consider the use of longer-residual colorants.

A minor disadvantage In most cases, the effects of spray-pattern indicators are temporary and helpful. However, as with any product you apply, the possibility of undesirable results exists. With colorants, you occasionally hear reports of undesirable staining. For example, grave markers, irrigation heads, sidewalks, tree trunks, mail boxes and posts are all possible non-target items in the landscape that colorants could adversely affect. As a precaution, test the spray-pattern indicator on a nearby object where it won't be noticed, such as an alleyway or side-entrance driveway. If the product leaves no visible residue, proceed to use it on the eventual site.

All in all, spray-pattern indicators can be quite useful. They can help to improve product effectiveness, indicate potential for pesticide drift and save time and money.

John C. Fech is extension educator, horticulture, for the University of Nebraska-Lincoln Cooperative Extension office in Omaha, Neb. Dr. Roch E. Gaussoin is an associate professor and extension turfgrass specialist at the University of Nebraska-Lincoln.

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