IPM Programs: Don't forget about the Trees

We're always talking about Integrated Pest Management (IPM) for the turf we maintain, but what about the problems associated with our trees? Are there ways that both IPM programs can overlap so that woody plants are not managed in isolation from the other vegetative components on the golf course?
When making any management decision on the golf course, the entire landscape should always be considered.

On most golf courses, trees are an important component of golf course design, playability and aesthetics. When certain pests target specimen trees, there needs to be a plan of attack to effectively manage them.

But what is the definition of pest found in trees:
A landscape pest is any organism that competes with desirable plants for resources, threatens the health, structure and appearance and diminishes personal enjoyment, comfort and the safety of the landscape. (International Society of Arboriculture)

Landscape pests include:
• Insects and anthropods
• Microorganisms
• Mollusks
• Weeds, vines and parasitic plants
• Vertebrates

IPM on trees is similar to turf in that the goal is to manage pests and their damage at levels tolerable to the client. The focus is on pest prevention and suppression rather than eradication.

An effective IPM program for your trees should complement other IPM programs that you have for your turf and should be achieved in a cost effective manner.

Thresholds
IPM practitioners for trees use three types of action thresholds in managing pests in trees:
• Population action threshold
• Physiological action threshold
• Aesthetic action threshold

To effectively determine the appropriate action thresholds for landscape pests on trees requires knowledge, experience, and foresight. Factors to consider when establishing an action threshold are:
• Client tolerances and expectations
• Plant value, condition and susceptibility
• Pest damage potential
• Time of year
• Site conditions
• Prevailing weather conditions
• Inspection frequency
• Potential for natural pest control

As in turf, monitoring is a critical component in any IPM program. Information needs to be collected on the site, the plant and any sort of information on the pest. The more detail for each section will make the control options more evident.
Below is a list of information that will come in handy:
• Date
• Location
• Host
• Pest or Symptom
• GDD and/or plant phenology indicators
• Action Taken

It's also important to bring some tools to help make the job a little easier. Trapping devices, binoculars, a hand lens and a field guide to assist in the identification of trees and there pests in the field.

In addition, phenology calendars and degree day models assist in monitoring pests and proper timing of pesticide applications. Below is a list of how you could both monitor insects for turf and trees that relate to the first and/or full bloom of trees that may be on your golf course:

Pest Preventative Tactics

For any IPM program to be successful, particularly trees, there are two basic pest preventative tactics that should be kept in mind at all times:
1. Minimize plant stress by encouraging favourable plant development conditions
2. Minimize pest activity by discouraging favourable pest development conditions

Plant stress is a reversible impairment of plant function that results from a deficiency or excess of one or more survival factors. Both abiotic and biotic agents can cause plant stress and need to be examined before the appropriate action can be taken. It is also a good idea to consider both abiotic and biotic agents that may have been a problem in the past.

So, what are some of the Best Management Practices Superintendents can use to improve the growing conditions for trees in addition to keeping the turf healthy as well?
• Balanced Fertility ‐ Look at your soil tests a little closer and determine if there are any deficiencies in the soil that may correlate with plant stress and decline
• Irrigation requirements and watering practices ‐ Are you trees being over‐watered due to nearby irrigation and is the water quality of the water having negative impacts on the health of certain trees?
• Traffic Control ‐ Has there recently been construction around/or near the trees that would cause compaction and/or potential damage to the roots?
• Specific site conditions and appropriate plant selection ‐ consider hardiness zones, soil pH, light requirements
• Pruning ‐ Have you considered removing and destroying local pest infestation before an outbreak? Has the crown been cleaned of dead branches which act as breeding and feeding sites?

Written By: Darryl James