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Haverford College
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Inside the Arboretum: Pesticide Usage

The college engages in three fundamental areas of grounds maintenance: Trees, beds/shrubs, and grass ("turf"). Each setting requires unique approaches to reduce the use of herbicides, insecticides and fungicides in order to ensure the health and safety of humans and pets and to minimize negative impact on the environment.

Here are the highlights of our program; their rationale; and the issues about which we remain mindful as we safely preserve, protect and beautify the College grounds. (The term "pesticide" is used to describe, generally, the means by which undesirable plants, animals and fungi are chemically managed.)

Guidelines for Applying Pesticides at Haverford College

Every employee who sprays pesticides at Haverford College is certified in chemical handling and application. Every applicator is required by PA State Law to attend classes to maintain their license.

As required by state law, individuals on the Pesticide Sensitivity List are contacted at least 12 hours in advance. Notification is required when making applications within 500 feet of listings in the PA Pesticide Hypersensitivity Registry.

In addition, twenty-four hours notice is given to all Haverford College Community members providing the following information.

  • Date of application
  • Location
  • Start and end times
  • Brand names of chemical
  • EPA Registration number
  • Active ingredient
  • Contact information
  • Contact information and Business License Number (BU-7718)

Pesticide application records and notifications are kept for 3 years. Most pesticides are applied with a hand held pump sprayer or 16 gallon pressurized tank sprayer. The campus is primarily spot sprayed. Every attempt is made to apply chemicals directly to the weed or pest only, not the surrounding area.

Pesticides are selected according to their warning label/signal word

  • Ranked by increasing toxicity, they are: Caution, Warning, Danger, Danger Poison.
  • Haverford College generally selects chemicals with the least amount of toxicity ('Caution')
  • On occasion, it is necessary to select a chemical with a Warning label.
  • Haverford College never applies pesticides classified above a Warning label.

When diluting pesticides for application, chemical companies recommend a range of active ingredient. Haverford uses the low end of the recommended range.

The EPA heavily regulates pesticide use and has applied strict safety standard for use and exposure to pesticides.

  • There is a 10X factor applied to all pesticides approved by the EPA.
  • With this standard in place, once a safe tolerance level of exposure to a pesticide is determined, the permissible level is cut by 90% to account for the sensitivity in children.
  • This is taken into consideration when label rates are approved for use.
  • If it doesn't fit this tight criteria, it is not approved for use.

Those with extreme sensitivity to a specific pesticide may get some skin irritation. It is recommended that the irritated skin be washed with soap and water.

Grassy Areas ("Turf")

Haverford College has an aggressive turf management program by which pesticides are incorporated as a last resort.

Each year, maintained turf areas are aerated and over seeded.

  • Aerification reduces compaction and allows air and water to get to grass roots.
    • Weeds thrive in compacted soils
  • Maintained turf areas are over seeded with a Kentucky Blue Grass/Perennial Rye mix.
  • 8,650 lbs in 2011.
  • Filling in bare spots and sparse turf areas helps grass compete against weeds.
  • Soil tests are performed every two years.
  • Measures pH, organic matter and nutrients/soil fertility.
  • Haverford's turf program is developed from soil test results.

Proper Fertilization

  • Based on soil test results, the turf is fertilized between 2 and 4 times per year.
    • Earthworks, a local company, produces fertilizer made primarily of composted chicken manure.
  • One application of synthetic fertilizer is the carrier for pre-emergent broadleaf weed control in spring.

Correct mowing heights

  • Excluding Athletics, the campus is maintained at 3"
    • Helps prevent weed seed from germinating by shading the weed.
  • Clippings are not collected as they return nitrogen to the soil.


  • In-ground irrigation systems have sensors and only activate as needed.
  • Supplemental watering (water cannons) in Athletics is done manually.


  • Pesticides are used as a last resort to contain large infestations of weeds or keep weeds to a minimum in high profile areas.
  • Every attempt is made to apply pesticides in the early morning hours before faculty, staff and students start moving around campus.
  • In the event the boom sprayer is needed, the guidelines are as follows:
    • Timing: Two crew members arrive at 5 am, one pesticide applicator and one assistant to flag and monitor the area.
    • Flags are removed once the area has dried which the label deems safe.
      The label is the law. Most labels stipulate waiting until the spry has dried. The EPA determines a very conservative safety level for these products and then dictates a 10X buffer to ensure the public safety.
  • Fungicides are only applied in areas that receive supplemental irrigation or if we are experiencing an extremely wet summer.
  • Spraying schedule is dictated by weather. Hotter and more humid weather dictates additional fungicide applications in irrigated areas.
  • Periodically, every two to three years, an area is boom sprayed with weed killer to keep large infestations under control.
    • When this is needed, the same guidelines for fungicides are followed (timing, monitoring and removing the flags when the area has dried).
  • Spring fertilizer with pre-emergent is applied by tractor and spreader.
  • Because of campus irrigation practices, fungicides are sometimes needed. They are applied by tractor and boom sprayer.

Trees and Beds

The goal of this program is to effectively care for the diverse collection of mature, young and historic trees while protecting the environment we work and live in. Because we have such a mature and historic collection of trees, care and monitoring helps reduce the risks (due to falling limbs) and cost of maintaining these treasured assets.

Tree care and maintenance is monitored through integrated pest management (IPM). This program is the integration of management strategies (including biological, cultural, use of indigenous plants, chemicals with lower toxicity to humans) into a comprehensive program for pest control. Therefore, our goal is to reduce the amount of and/or dependency on chemicals regulated the EPA. Over the last 12 years all of the chemicals applied to trees have been evaluated and changed to chemicals that carry a 'Caution' signal word on the label (as opposed to the more powerful 'Warning' or even higher level restriction). Learn more.

We've also changed the way in which any chemicals are applied such that our approaches are much more highly targeted (as opposed to generic or wholesale treatment of the tree collection). Two specific examples of this has been the release of beneficial insects, particularly in the Pinetum, to control outbreaks of pests that can be controlled by such biological measures, and secondly by using improved injection methods that reduce the risk of airborne chemicals. Both of these methods have reduced the potential impact on humans.

Plant bed maintenance (including tree rings) is driven by our zero tolerance towards weeds. Pre and post-emergent weed control is used as little as possible. Weeds that do appear get sprayed on a selective basis to eradicate only the weeds. Blanket weed spraying is not done. Spray notices may convey the impression that spraying is extensive when in fact spraying is done on a spot basis. In other words, chemical is only applied to visible weeds. We are obligated to notify the campus community the areas that are being treated but please bear in mind that the area is not being blanketed with chemicals.

Haverford College has conducted and passed a self-audit for the EPA. All of the chemicals that are applied on campus are recorded on documents that we are required (by the state) to maintain. We endeavor to exceed what is required by the government agencies, and we do.