FOREST PEST CONTROL

(Lecture outline)

(Chapter 1 - Introduction)

I. Forests of Virginia

- 63% of state is covered with forests

- 3 physiographic regions

- Mountains - mostly deciduous, white pine most common pine, Virginia pine

- Historically, selection influenced forest condition - generally

Quality has decreased.  Fire not common for mgmt.

- Piedmont - Loblolly and Virginia pine dominant

- Coastal Plain - loblolly, yellowpoplar, sweetgum, hickory

- Site prep, burn, mechanical, plant, chemical

II. Forest Health

- Abiotic

- Biotic

- Usually combination that ultimately kills tree

- Cultural avoidance

- Plant in right site

- Reduce competition. Use TSI. Sanitation cuts

- Use pesticides when economical

 

(Chapter 2 - Insects)

I. Pesticide application is appropriate only when:

- Unacceptable health effects occur

- Causal agent is still present and active

- Alternative control measures are less acceptable

- Pesticide registered for this use is available

- Landowner is aware of costs & benefits

 

II. Diagnosis

- Insects are classed by type of injury

 

III. Management considerations

- Avoid monocultures

- Avoid extended ranges of tree species

- Avoid overuse of pesticide (environmental impacts & host plant develops resistance)

- Avoid poor nursery practices

- Be aware of age and competition stresses on tree health

- Avoid careless logging practices

 

IV. Major insect types

- Bark beetles - feed on cambium, girdle, and disrupt conductive tissues

- Southern pine beetle - look for pitch tubes

- Ips

- Defoliators - gypsy moth, tent caterpillars, webworm, locust leafminer, cankerworm

- Watch for frass, skeletonizing,

- Sap feeders - aphids, scales, sapsucking insects

- Cause much damage in pine seed orchards. Kill young regeneration

- Bud & stem feeders:

- White pine weevils, Nantucket tip moth can kill entire young plantations

- Root feeders - most serious in tree nurseries & young plantations

- Chemical control may be necessary

- Cone & seed - can greatly impact seed potential in Loblolly in coastal plain & Piedmont

 

(Chapter 3 Disease)

I. Beneficial and destructive pathogens

II Classical and Urban forests

III. Biotic, abiotic, Complex

IV. Major diseases:

- Fomes annosus root rot

- Important in southern pine, loblolly, sandy soils if cut in winter - susceptible

- Moves through air and root grafts

- Borax

- Oak decline

- Wood decay

- Fusiform rust - (Cronartium fusiformae)

- Economically important in southern pine & nursery seedlings

- Gall forming - serious in southern pine

- Alternate host on oaks

- White pine blister rust - has alternative host - Ribes (gooseberry, currants)

- Needle cast - spring fungicidal application

- Damping off

- Air pollution - SO₂ - can be mistaken for diseases

- Fungicides

 

(Chapter 4 Weeds)

I. Definition of “weeds” depends on the management objective

- Proper identification of trees & shrubs is essential

- It is important to understand the impact of plant competition on crop trees

- Trees/shrubs & vines/herbaceous plants

- Spacing & distribution critical for chemical control

II. Herbicides

- Reduce need for repeated weed control

- Do not require exposure of mineral soil

III. Vegetation Treatments

- Site preparation (seedling establishment)

- Before crop is planted:

- Slash treatment, control weeds (competition), soil treatments

- Burning, chemical, mechanical

- Wide variety of chemicals (herbicides)

- Usually in spring, summer or fall just prior to planting

- Usually broadcast applications

            - Herbaceous Weed Control

- Used just after planting to control new “weeds”

- Must use “selective” herbicide to protect crop trees

- In Virginia, common only for 1st year of stand establishment

- Crop Tree Release (pine release)

- Depends on economic feasibility

- Selective herbicide must be used

- Between 2nd & 5th year

- Timber Stand Improvement

- Well after stand establishment (5th year to 15 or 20)

- Sometimes mechanically

- Chemically - common to use injection applications underneath bark 

 

(Chapter 5 - Herbicide applications)

I. Type of application depends on:

- Herbicide label

- Size, species of target plant

- Terrain, adjoining property land uses

- Weather conditions

II. Aerial applications (applicators - pilots require Certification in Category 11)

- Broadcast aerial applications (foliar)

- Fast, efficient, economical

- Reconnaissance is critical

- Avoid wind drift

- Observe wind speed & direction, set limits

- Constantly observe for changing conditions

- Tobacco, grapes, vegetable gardens very sensitive

- Avoid lakes, streams, ponds, and wet sites

- Pilot is key

- Off-target movement is to be avoided (drift)

- Map target areas. Show boundaries

- Application plan must be prepared & understood by all

- Helicopters are popular in Virginia

- Microfoil (Amchem) eliminates fine droplets

- Drop size is larger thereby reducing drift, also using lower pressure

- Thicken liquids also reduce drift

- Granular herbicides sometimes broadcast aerially

- “Carriers” may be used to extend effectiveness of herbicide

- Directed aerial

III. Ground applications

- Operations generally simpler, less costly, more adaptable to ground

- Drift not normally a problem

- Best suited for gentle terrain, low density brush

- Broadcast

- Machine-mounted: liquid and dry granules or pellets

- Hand-held (manual) sprayers & spreaders