IDENTIFYING THECONSEQUENCES OF PESTSAND DISEASES FOR TREES

FORESTS = TREESForests are complex ecosystems that provide:

a variety of valuable products, such astimber, fuel wood, and non-wood forestproducts, and contribute to the livelihoods ofrural communities.

vital ecosystem services, such ascombating desertification, protectingwatersheds, maintaining biodiversity, andenhancing carbon sequestration, and play animportant role in preserving social and culturalvalues.

It is critically important to protect thesevaluable resources from disturbances such asfire, pollution, invasive species, insects anddiseases.

While they are integral components of forestecosystems, insects and diseases haveconsiderable influence on the health of forests,trees outside forests and other wooded lands.

They can adversely effect tree growth, vigourand survival, the yield and quality of wood andnon-wood products, wildlife habitat,recreation, aesthetics and cultural values.

Forest insect pests and diseases may alsoresult in the limitation of plantationprogrammes, the abandonment of a given treespecies and the necessity to clearcut largeareas dominated by infested trees.

WHAT ARE PESTS AND DISEASES?

Pests are usually insects or small animalsthat cause damage to plants or trees.

Diseases are caused by harmful pathogens ormicrobes which include some types ofbacteria and fungi. They are so small that youcan usually only see the results of theiractivities and not the cause.

LEARNING OBJECTIVES

Describe the major categories ofinsect pests of forest trees.

Describe the major categories ofdisease problems of forest trees.

Describe management techniquesfor controlling insect and diseasepests in forest trees.

TERMS

Bark borers Biological

controls Chemical

controls Defoliators Management

controls

ParasitePathogenRoot feedersSap suckersTip feedersWood borers

DO YOU KNOW WHAT CAUSESTHESE PROBLEMS IN TREES?

WHAT ARE THE MAJOR CATEGORIES OFINSECT PESTS OF FOREST TREES?

One of, if not the most deadly, pests of forest treesare insects.

Some insects are pests to all kinds of trees, whileother only affect certain species.

Insects can cause damage to trees in a variety ofways.

BARK BORERS

As the name suggests, barkborers are insects that attacktrees by tunneling underneaththe bark.The soft cambium and newly

produced wood and bark cellsare destroyed.This effectively girdles the tree

cutting off the supply ofnutrients, killing the tree.

BARK BORERS

In addition, the damage caused bybark borers often provides an entrypoint for diseases and other pests toattack the tree.One of the most common insects of

this type is the Southern Pine BarkBeetle.Many Ponderosa pine in New Mexico

have been killed by bark beetleinfestations.

PINE / SPRUCE / SILVER FIR BARK BEETLE

Bark beetles

DEFOLIATORS

This type of insect causes damage to thetree by feeding on the leaves or needles ofthe plant.

In most cases, insect larvae, instead of theadults, do this type of damage.

GYPSY MOTH

Euproctischrysorrhoea

Hyphantria cunea

Tortrix viridana

WOOD BORERS

Insects in this category eat their waythrough the sapwood and heartwood ofthe tree.

This damage causes the wood to weaken.

The most well known insect in thiscategory is the termite.

TERMITES AND TERMITE DAMAGE.

ASH BORER

TIP FEEDERS

Insects that attack young twigs,stems, or buds are known as tipfeeders.These insects attack the most

tender parts of the tree.

SAP SUCKERSThese insects are equipped with penetrating

mouthparts that allow them to feed on treesap.

These insects rarely cause the tree to die,however, trees are weakened and growth isslowed.

Common examples of sap suckers are aphidsand scale insects.

APHIDS AND SCALE INSECTS ONCONIFERS.

ROOT FEEDERS

Root feeders are insects in the soil aroundthe tree that feed on the tree’s roots.

These insects cause the most damage totree seedlings.

Examples of this category are white grubsand wireworms.

GRUBS AND WIREWORMS.

WHAT ARE THE MAJOR CATEGORIES OFDISEASE PROBLEMS OF FOREST TREES?Diseases are most often caused by parasites.

A parasite is an organism that relies on otherorganism for their food.

These parasite organisms can be classified intofive major categories: fungi, bacteria, nematodes,viruses, and mistletoes.

FUNGUS

Of the five major categories of parasiteorganisms listed above, fungi are the cause ofthe most important diseases that affect foresttrees.

Whereas, fungi reproduce and spread by tinyspores, they can multiply very quickly.

FUNGUS

Fungus diseases can attack any part of thetree.

Stem diseases are generally considered themost dangerous as far as causing death tothe tree.

FUNGUS

Leaf and root diseases generally do not kill thetree, just weaken the plant and slow down itsgrowth.

Examples of a stem diseases are Dutch elmdisease, chestnut blight, fusiform rust, andvarious types of heart rot.

FUNGUS DAMAGE

WHAT ARE SOME MANAGEMENTTECHNIQUES THAT CAN BE EMPLOYEDTO CONTROL INSECT AND DISEASEPESTS IN FOREST TREES?

The key to a healthy forest is good forestmanagement.

In the controlling of insect and disease pests,there are several alternatives a forest managerhas to choose from.

CONTROLLING INSECTS

In controlling the negative effects of insects onforest trees, there are three basic types of controls.

They are: Biological Controls, ManagementControls, and Chemical Controls

BIOLOGICAL CONTROL

Natural controls for most insect pest exist innature. (lady bug)

However, these natural controls are slow.

Whenever foresters alter these natural controls tomanage insect pests, they become biologicalcontrols.

Bacillus thuringiensis

Serratia marcescens

BIOLOGICAL CONTROLS

Every insect has a natural enemy. An example of a biological control would

be the introduction of a new predator ofan insect pest into the infected area. Another example is the introduction of a

pathogen. A pathogen is any disease-causing

organism. The pathogen that attacks the specific

insect pest may be available and can beintroduced into the insect population.

Apanteles sp.

Exorista fasciata

Formica rufa

Forficula auricularia Mantis religiosa

Libellula quadrimaculata Chrysopa perla

MANAGEMENT CONTROLSThese controls consist of various management

practices that the forester can employ.

These would include the removal of infestedtrees and tree parts, the use of insect resistanttree varieties, maintaining proper treepopulations, and prescribed burns.

CHEMICAL CONTROLS

The use of pesticides on foresttrees is regulated by theEnvironmental ProtectionAgency (EPA).

Pesticides offer a quick andeffective short-term solutionto insect pests; however, oftenother control measures needto be used for long-term forestmanagement.

This is a very expensiveoption.

DISEASE CONTROL

The most effective control of forest diseaseis good management by the forester.

Many kinds of diseases can be preventedfrom entering a forest by dusting thestumps of cut trees with borax or creosote.

DISEASE CONTROLBy removing damaged trees from the forest,

the likelihood of disease infestation is reduced.

In most cases, once a tree becomes diseased,little can be done.

Therefore, prevention is the answer to ahealthy forest.

REVIEW / SUMMARYWhat are the major categories of insect

pests of forest trees?What are the major categories of disease

problems of forest trees?What are some management techniques

that can be employed to control insect anddisease pests in forest trees?