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FOREST SERVICE HANDBOOK
JUNEAU, ALASKA
FSH 3409.11 - FOREST PEST MANAGEMENT HANDBOOK
Region 10 Supplement No. 3409.11-96-1
Effective March 15, 1996
POSTING NOTICE. Supplements are numbered consecutively by title and
calendar year. Post by document name. Remove entire document and replace with
this supplement. Retain this transmittal as the first page of this document. The
last supplement to this Handbook is R-10 Supplement No. 1 to chapter 60.
This supplement supersedes R-10 Supplement 1 to chapter 60.
Document Name
Superseded
New
(Number of Pages)
61-63
8
0
3409.11,60
0
10
Digest:
62: Updates Region 10 direction regarding hemlock dwarf mistletoe.
/s/Kimberly Evart Bown for
PHIL JANIK
Regional Forester
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FSH 3409.11 - FOREST PEST MANAGEMENT HANDBOOK
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62 - DISEASES.
1. Hemlock Dwarf Mistletoe. Hemlock dwarf mistletoe is a seed bearing plant
that parasitizes western hemlock trees and has rarely been found on Sitka spruce
and mountain hemlock. Hemlock dwarf mistletoe weakens trees and reduces their
growth rate, seed crops, life expectancy, and lumber quality.
Resource impacts caused by hemlock dwarf mistletoe are not all known. However,
they are considered significant enough to require consideration be given them when
developing management prescriptions for infested stands. Managers should
recognize the beneficial ecological aspects of hemlock dwarf mistletoe as well as the
reduction to the timber resource. Wildlife habitat and elements of structural
diversity can be enhanced by the disease. With the timber resource only impaired
at high levels of dwarf mistletoe, careful management of the disease may achieve
these benefits without experiencing timber resource loss.
The spread of hemlock dwarf mistletoe is mainly by seed dispersal within
predictable distances. Therefore, effective levels of management can be achieved by
the orderly application of existing control procedures and techniques with standard
silvicultural practices.
Hemlock dwarf mistletoe management includes detection, evaluation, prevention,
and suppression. Detection and evaluation are necessary before prevention or
suppression action is taken. Prevention is the primary means of reducing losses.
Suppression is used only when needed to supplement prevention actions.
a. Objective. The objective of hemlock dwarf mistletoe management in
Alaska is to achieve disease levels that are consistent with resource
objectives. This may range from attempted elimination of the disease in
some settings to manipulating it to moderate levels in others. Site
specific management objectives for this disease should be clearly
documented in the silvicultural prescription.
b. Policy. It is Region 10 policy to:
(1) Take full advantage of timber sales, timber stand improvement,
alternative harvesting systems, and reforestation programs to manage
for acceptable levels of hemlock dwarf mistletoe.
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(2) Consider hemlock dwarf mistletoe effects in all resource
management plans within the spruce-hemlock type, except on the
Chugach National Forest and the Yakutat Ranger District of the
Tongass National Forest; both are locations where the disease is absent.
(3) Make maximum use of Knutson-Vandenberg (K-V) or Protection and
Management (P&M) funds and Forest Health Protection (FHP) funds
when K-V funds are not available to accomplish (1) and (2).
c. Responsibility.
(1) The Forest Supervisor is responsible for hemlock dwarf mistletoe
management on the Forest/Areas.
(2) Each District Ranger is responsible for all phases of hemlock dwarf
mistletoe management as delegated by the Forest Supervisor. These
responsibilities usually include (1) recognizing both the ecosystem value
and the negative effect on timber caused by the disease; (2) planning,
organizing, and directing hemlock dwarf mistletoe management
projects; and (3) cooperating with Regional Office Forest Health
Management (FHM) personnel in biological evaluations.
(3) The FHM Staff Group is responsible for providing technical
assistance to Forest/Areas on all phases of hemlock dwarf mistletoe
management and approving suppression projects involving FHP funds.
These responsibilities are met by periodic activity or management
review, by providing technical assistance when requested by Forest
Supervisors and District Rangers, by conducting biological evaluations,
and by providing detection, evaluation, prevention, and suppression
training.
d. Definitions. Several terms are used to describe hemlock dwarf
mistletoe management activities. These include:
(1) Biological Evaluation. The collection and analysis of stand level
information to determine potential hemlock dwarf mistletoe impacts
and the need for and feasibility of prevention or suppression measures.
(2) Detection Survey. An extensive survey made to determine the
presence or absence of hemlock dwarf mistletoe, usually made during
other surveys or visits to the area. Detection Report 5200-1 should be
used to report incidence of hemlock dwarf mistletoe on all lands.
(3) Evaluation Survey. A survey of individual stands to collect
information on infection severity, the location of infestations within
stands, and cost estimate of appropriate suppression measures, as well
as possible courses of action and their expected outcome.
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(4) Prevention. Treatment of sites in such a manner that developing
stands will not become infected.
(5) Suppression. Reduction of hemlock dwarf mistletoe infections to a
level commensurate with the management objectives. It may vary from
removal of infected tree parts to complete stand replacement.
Suppression consists of three broad treatment categories:
(a) Sanitation. Removal of hemlock dwarf mistletoe infected trees in
lightly infected stands in conjunction with silvicultural thinning.
(b) Stand Replacement. Destruction of severely infected stands followed
by replacement with disease-free trees.
(c) Pruning. Removal of infected tree parts.
(6) Management to Moderate or Desirable Levels. Manipulation of
dwarf mistletoe to stated levels that maximize resource values.
e. Detection. The general distribution of hemlock dwarf mistletoe in
Alaska is known; however, actual incidence within local areas, is
generally unknown. Precise distribution information will be obtained by
two primary means: (1) Field observation where all forest workers are
expected to be on the alert for dwarf mistletoe infections while
performing normal field work. Recon surveys, timber cruising, trail
maintenance, and other activities afford excellent opportunities for
forest workers to note the presence of hemlock dwarf mistletoe; and
(2) Detection Surveys in circumstances where no other surveys are
scheduled for a local area and it is essential that presence or absence of
the disease be known. Detection surveys designed solely for this
purpose may be conducted. Also see FSM 3411 and FSM 3412.
Hemlock dwarf mistletoe data gathered during field surveillance or
detection surveys should be stored on compartment data bases (SIS).
2. Hemlock Dwarf Mistletoe Suppression. The objective is to reduce
infestation severity where the disease is above management objectives.
a. Presuppression Survey. Biological evaluation surveys (see FSM
3421) should serve as presuppression surveys.
b. Prevention. The objective is to prevent establishment of hemlock
dwarf mistletoe in stands where it is not present. It is far more efficient
to prevent dwarf mistletoe from becoming established in uninfected
stands than to bear the cost and inconvenience of removing trees from
infected stands or replacing severely infected stands. Preventing the
development of hemlock dwarf mistletoe in currently uninfected stands
should be given high priority.
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(1) Clearcut Layout. Clearcutting without residuals is the most effective
method of reducing hemlock dwarf mistletoe. Clearcut layout with as
large an area/perimeter ratio as possible will reduce the area colonized
from infection sources on the edges. Locating clearcut boundaries in
uninfected stands and along natural openings, or keeping boundaries
with infected stands as short as possible, will further prevent hemlock
dwarf mistletoe from spreading to the new stand. In timber managment
areas with high incidence of hemlock dwarf mistletoe and western
hemlock is a significant future stand component, clearcutting with
minimal residual hemlock may be the most desireable silvicultural
method. This action can drastically reduce or eliminate the disease for
several centuries on sites with moderate or good potential timber
productivity. Managers should be aware that these actions can alter the
beneficial ecosystem functions or negative timber impacts from this
disease for a long time.
(2) Reforested Areas. Reforested areas should be examined for living
infected residuals and how those residuals may effect the future stand
conditions. This is particularly important in areas where hemlock will
be a major component of the future stand.
Removal of infected residuals during harvest presents the best
opportunity for reducing hemlock dwarf mistletoe in an area. This
treatment should be given high priority in areas with high existing
incidence of the disease, low desired future incidence, and where
western hemlock is a major species to be managed. Stand development
processes (particularly western hemlock's faster height growth
compared to slower vertical spread of the parasite) may make residual
control unnecessary on sites with moderate and good potential tree
growth and where infected residuals are not tall. Treat boundaries as in
the clearcut layout above.
(3) Unevenaged Management. To reduce residual tree incidence and
infection in new trees as they become established, infected overstory and
residuals should be removed during harvest. Large infected trees and
those on the periphery of leave groups will contribute the most to spread
of the disease. Consider favoring spruce or species other than western
hemlock when hemlock dwarf mistletoe is left in the overstory.
(4) Thinning and Selective Harvesting. When sources of inoculum are
present, these actions have the potential to increase dwarf mistletoe
levels by increased light stimulating fruit/seed developement and by
favoring spread through seed escapement from dense canopy structure.
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(5) Species Manipulation. In heavily infected areas, favoring Sitka
spruce or other species over western hemlock during the next rotation
will reduce the incidence of hemlock dwarf mistletoe. A mixture of
species is desirable on most sites.
(6) Recreation Sites and Similar Areas. New development and existing
sites should consider the incidence of hemlock dwarf mistletoe in the
hazard tree analysis. Brooms and upper tree structual weaknesses
resulting from the disease can pose falling object hazards. Opening
infected stands will intensify infestations. Therefore, even moderately
infected stands can pose future hazard tree concerns.
c. Funding. Full advantage should be taken of timber sales,
reforestation, and timber stand improvement projects to accomplish
hemlock dwarf mistletoe management. Preventing and suppressing
hemlock dwarf mistletoe infestations are accomplished by silvicultural
treatments and are basic to good forest management as is planting and
thinning. K-V, P&M, or Brush Disposal (BD) funds will be used for
most hemlock dwarf mistletoe control in Region 10 and include:
(1) Surveys. Extensive surveys designed to identify areas in need of
stand improvement treatments are financed with P&M funds. P&M
funds are available for these surveys upon request (FSH 2409.26d).
Initial intensive surveys for Sale Area betterment and K-V Collection
Plan preparation of should be financed with Timber Sale Preparation
funds.
Surveys used for final planning of K-V treatments (listed on an
approved SAI plan) to be conducted after the sale closes, may be
financed with K-V funds (FSH 2409.26d). Activities cannot be added to
SAI plans once a timber sale closes (FSH 2409.26d). P&M funds can
also be used for stand surveys after a timber sale.
FHP funds may be used for surveys in conjunction with suppression
projects if K-V or P&M funds are not available or are insufficient to do
the total job required.
(2) Residual Tree Removal. If commercial size stands infected by
hemlock dwarf mistletoe are to be harvested, sufficient K-V funds
should be collected to finance any removal of infected undesirable trees
that may be left after the timber sale.
K-V, P&M, and BD funds should be used to finance infected residual
tree removal. FHP funds may be used for residual tree removal if the
project meets the criteria for suppression projects (FSM 3430).
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(3) Sanitation. Sanitation should be financed by K-V and P&M funds.
FHP funds may be used for the exclusive purpose of removing infected
trees in acceptably stocked precommercial stands if the project meets
the criteria for a suppression project (FSM 3430). Hemlock dwarf
mistletoe sanitation, which is accomplished during harvest, site
preparation, or precommercial thinning is a normal part of the timber
stand improvement function and should not be financed with FHP
funds.
However, additional costs associated with those treatments, which
accrue as a result of consideration for the hemlock dwarf mistletoe, may
be financed with FHP funds.
(4) Stand Replacement. FHP funds may be used for destruction of
severely infected stands which do not or will not meet management
objectives and cannot be economically harvested.
(5) Recreation Areas. P&M funds are normally used to remove infected
trees or tree parts for the purpose of controlling the spread of hemlock
dwarf mistletoe in recreation areas. FHP funds may be used for this
activity if the project meets the criteria for a suppression project. Tree
or tree part removal for the purpose of reducing public safety hazard or
for esthetics should not be financed with FHP funds.
Accomplishments made on hemlock dwarf mistletoe suppression
projects financed with FHP funds will be reported on Form 3400-5,
Forest Insect and Disease Accomplishment Report (see FSH 3090.11,
section 26.3). Reports are due in the Regional Office at the end of each
fiscal year.
Hemlock dwarf mistletoe suppression accomplishment with K-V and
P&M funds will be reported in TRACS-SILVA.
3. Management Practices.
a. Surveys and Evaluation.
(1) Biological Evaluation. Properly conducted evaluations of hemlock
dwarf mistletoe infestations give land managers necessary biological,
economical, and environmental impact data to decide for or against
suppression. Evaluation surveys will be made in all stands being
considered for hemlock dwarf mistletoe suppression regardless of
whether K-V, P&M, FHP, or BD funds will be used for the treatments.
Biological evaluations of hemlock dwarf mistletoe infestation can be
made by FHM pathologists or foresters who have received training.
Information to be collected during the evaluation survey includes:
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-Location and description of infestation by severity classes in the
stand.
-Other data normally required for developing silvicultural
prescriptions.
-The survey intensity needed to adequately assess the significance of
hemlock dwarf mistletoe will vary from stand to stand.
(a) Precommercial Size Stands. Unless hemlock dwarf mistletoe was
severe in the previous stand, surveys in precommercial size stands
aimed at separate entry to control the disease are generally not
warranted. However, in areas where previous stands were severely
infested or current severe infestation is suspected, the most effective
data collection method is an intensive systematic survey. A stand
examination (FSH 2409.26d R-10) or systematic walk-thru will provide
the information required. Other survey methods are available from
FHM Staff. Data needed include:
-Location of the hemlock dwarf mistletoe infected areas within the
stand.
-The approximate number and location of infected overstory trees.
- The number, location, and species composition of potential crop trees.
This information is needed to develop an appropriate site specific
silvicultural treatment strategy.
(b) Commercial Size Stands. Hemlock dwarf mistletoe evaluation
surveys should be made in infected commercial size stands only where
timber sales or other intensive treatments are proposed. The survey
should collect accurate information to determine (1) the silvicultural
prescription, and (2) selections of trees for leave and cut.
The survey should closely look at proposed treatment boundaries to
insure that adjacent pockets of infection are included in the treatment.
The location of and severity of infections should be mapped in addition
to the regularly measured stand characteristics. This information
should be collected during the sale planning phase to insure appropriate
inclusion in the prescription and K-V plan development.
(c) Other Areas. For areas where suppression will be confined to
harvesting or destroying scattered residuals, hemlock dwarf mistletoe
surveys may be conducted in any manner that will establish the number
of infected trees per acre, their spatial distribution, and their location
within the stand.
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(2) Economic Projects. Economic evaluations are required of proposed
hemlock dwarf mistletoe suppression projects. This will assist in
assigning funds to those that are the most cost efficient. The analysis
requires a with and without treatment comparison of costs and returns
over time. Where maximum returns are desired from the wood products
and short rotations are contemplated, it appears a separate treatment
for hemlock dwarf mistletoe is not a worthy investment. Therefore, an
economic analysis for hemlock dwarf mistletoe control should
incorporate broader management objectives of the area.
(3) Environmental Impact Evaluation. The beneficial and adverse
environmental impacts of hemlock dwarf mistletoe suppression must be
determined before a decision for or against suppression can be made.
Beneficial impacts must outweigh adverse impacts. Beneficial impacts
of hemlock dwarf mistletoe control include reduction of tree mortality in
overmature stands, maintenance of site productivity, and cessation or
retardation of disease spread into disease free portions of the stands.
Adverse impacts include creation of slash, removal or change in wildlife
habitat, reduced structural diversity, temporary unsightly conditions,
and possible creation of understocked openings in stands.
For projects using FHP funds, an environmental analysis report must be
prepared, and will be the responsibility of the proposing unit.
(4) Post-Control Evaluation. Forests shall conduct post-suppression
evaluations of all suppression projects. Items to be measured are
thoroughness of infected tree removal, economics, and adherence to
FSM guidelines. The FHM Staff Group, along with their research
counterparts, will periodically evaluate all phases of hemlock dwarf
mistletoe management.
b. Sanitation. Sanitation of infected stands during thinning should be
conducted (at the next entry) as part of the normal silvicultural
prescription. In stands to be kept longer than 120 years, this should be
a high priority as greater infestation occurs in older stands if forms of
inoculum are present.
Hemlock dwarf mistletoe infestations spread from a point source such as
an infected residual or edge tree. Thinning crews should favor spruce in
areas within 30' of an infected residual. This is the maximum distance
that most seeds are dispersed from a given source.
(1) Criteria for Crop Tree Selection. In stands with a planned rotation
of more than 100 years, and reducing the disease is an objective, crop
tree selection priority is:
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-Uninfected dominants and codominants, spruce and hemlock.
-Dominants and codominants with hemlock dwarf mistletoe confined to
branches in the lower one-third of live crown, interspersed with spruce
where possible.
-Intermediates with no visible infections.
-Dominants and codominants with hemlock dwarf mistletoe confined to
less than 50 percent of the branches in the lower one-half of live crown.
An attempt should be made to obtain acceptable stocking with trees in
the highest priority before selections are made from the next lower
priority class
If there is not acceptable stocking of potential crop trees meeting these
priorities and reducing the disease is an objective, the stands should not
be thinned.
c. Pruning and Removal. Pruning infected branches for disease
reduction alone is not an economical suppression method in commercial
forest stands. Other recognized benefits, such as wood quality
improvement, may make this operation economically feasible. In
recreation and similar high-value sites, hemlock dwarf mistletoe
infected trees can be treated by removing witches-brooms. This
treatment will help to maintain tree vigor but will not stop the spread of
hemlock dwarf mistletoe within the stand unless branches with visible
hemlock dwarf mistletoe plants are removed annually for several years.
However, it may still be a good practice in areas where hazard removal
is warranted.
d. Stand Destruction. Sometimes stands are so severely infected that
stocking levels of potential trees, volume production, or other
management objectives cannot be met.
In these cases, the stands should be removed and the site reforested.