GF Corner: Herbicide Use

May 20, 2013
By Jeff Harris, General Foreman, Wright Tree Service

When I started to apply herbicide years ago, the process was much different than it is today. Luckily, things change. I have experienced firsthand the progress our industry has made in personal protective equipment (PPE), licensing, record keeping, and training. Here is a short overview of things to keep in mind when supervising herbicide applicators.

In the past, PPE meant gloves, but only if you wanted to use them. Today, personal safety is the most important factor to consider when applying herbicide. At a minimum, PPE should include: a long sleeve shirt, long pants, rubber boots, eye protection, and chemical resistant gloves. Keep in mind that leather gloves and boots should not be worn, because they will absorb chemicals and transfer them to your skin.

The crews used to work under what was considered an “umbrella” herbicide license that the Division Manager held. Today, each applicator is state certified and go to re-certification workshops every two years.

In the past, record keeping was poor at best. Today, detailed spray records are kept to comply with state and federal laws on herbicide applications. On the spray record, applicators should include the following information:

  • Date and time of application
  • Wind direction and speed
  • Cloud coverage
  • Location, including street address and pole tag number
  • Area treated (acres, feet by feet)
  • Trees, stumps, plants, brush; species treated
  • Target pest
  • Type of treatment (basal, cut stump, ground foliar), number of sprays, herbicide used, trade name, EPA regulation number
  • Amount of herbicide used

Applicators should be as accurate as possible when recording the use of herbicides, with updates taken every hour on a spray record. Applicators may also find it helpful to keep records for their own personal use, including what worked well and what did not work as well as anticipated.

In the past, little to no training was done. A General Foreman or supervisor would bring the chemicals out to the jobsite and tell the crew to spray the stumps. We were told to use enough to get good control, but not too much. We were cautioned that if we were to over-apply, the treatment area may look like the moon.

This leads me to the most important change I’ve seen in herbicide application throughout my career: integrated vegetation management (IVM). IVM is the practice of using different types of treatment depending on the time of year and the intended outcome. This has grown to be a best practice across the industry, and training around this concept has improved greatly. Below is a short overview of three common treatments.

Applicators may use a basal bark herbicide in order to control woody plants. This method is faster and more cost effective than removing the trees and then treating the stumps. This is recommended for trees with a stem diameter of six inches or less. Equipment cost is low, as it requires only a backpack. Basal bark applications can be completed at any time of the year. They are extremely effective for sensitive areas or inaccessible areas, and are ideally used in low density areas. By using a basal bark treatment, applicators will increase selectivity by individually targeting undesirable species. However, this is very labor intensive. Every tree that you want to control has to be treated. In addition, the application will not be effective on older trees with thick bark, and it should only be used in areas where it is acceptable to leave dying and dead vegetation standing. If you have a high tree count, you may want to consider another type of treatment.

Stump treatment is recommended as soon as possible after a stump cut is made. Stump treatments will eliminate or greatly reduce stump regrowth. We use a dye in our stump treatments to identify which stumps have been treated and to show stump coverage.
Stumps up to three inches in diameter should be completely covered. Stumps greater than three inches in diameter should be treated around the cambial layer. Applicators should use caution and watch as to not over apply, as run off will cause grass or other surrounding vegetation to die. Equipment cost is also low with this method, as only a backpack sprayer or small spray bottles are necessary. Small spray bottles may work better in residential areas because they are less noticeable to the public and they take up less room in the truck.

Foliar treatments require an applicator to apply a herbicide/water mixture directly to the leaves of the tree. Low volume foliar treatment can be completed with a backpack sprayer or an ATV with a tank and small pump. High volume foliage treatments may require tracked vehicles with large 300-500 gallon tanks and two hose reels. With high volume treatments, applicators will want to add anti-drift agent to the herbicide mix. The cost of equipment with these methods can be high.

No one treatment will work for all locations. The best treatment will need to be determined for each individual location.

In addition to management and safety education and training resources at Wright Tree Service, I have found the herbicide companies that we purchase supplies from to be very helpful in terms of overall training and advice on what products to use on what tree species. If applicators have any problems with off-target herbicide kills, I have also found that the herbicide companies are very helpful in figuring out what happened and why.

I encourage all supervisors to keep in mind how far our industry has come in the area of herbicide application and how many resources are out there – one important one being each other.