Coniferous Tree Diseases and Insect Pests by 37p5jxgU

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									         Forest Pathology
(Additional to information in Chapter 8)


                    Spotting an unhealthy
                            Forest
Healthy Forest Trees

       Because they live so much longer
        than people, we often perceive
        trees as being practically
        immortal. However, trees also
        follow the same cycle of birth,
        growth, reproduction and death
        that governs all living things.
Healthy Forest Trees


         Like other living
           organisms forest trees
           are susceptible to
           attacks from insect
           pests and diseases.
Healthy Forest Trees

        Common basics to Manage Forest
         diseases
        Before looking at some common
         specific Forest Diseases and Insect
         Pests you will need some additional
         information and basic knowledge
     The following information is from:
        www.forestpathology.org/mgmecol.html
Epidemiology




         the study of disease in populations
          and factors that affect rate of
          disease increase.
Control vs. management of disease.


       "Control" implies to some reduction of
        disease to zero and absolute control
        over nature.
       “Management” is the word that is in
        vogue now, because it has an
        implication of tolerating a certain level
        of disease. It acknowledges that we
        may influence nature, but do not have
        total control over it.
Symptoms

      these, of course, are observable
       changes in the plant that indicate the
       presence of disease.
Damage, effects

       decrease in quantity or quality of trees
        or their products (can include non-
        timber values here). Growth reduction
        may be a symptom if you are thinking
        of it as a way to detect disease, or an
        impact if you look at it from that point
        of view.
Loss, impact


             decrease in economic
              returns and cost of
              measures taken to reduce
              it.
Quantifying diseases


        It is necessary for justifying control
         measures.
        It is one way that institutions and
         scientists decide what is important to
         study. It can be used to justify funding for
         research or management.
        Ecologically, it can be a way of
         determining what factors are important in
         determining forest structure and
         dynamics.
Loss to disease is difficult to quantify

        We often don't have enough research to
         know how much growth loss, mortality
         and cull are attributable to the disease.
        Is it a loss if the tree was not going to
         be harvested?
        What about compensatory growth?
         When one tree dies, trees beside or
         under it may be released and increase
         growth as a result.
Compensatory growth


       If mortality is scattered randomly,
        compensatory growth from neighbors
        may cover the loss. If it is clumped
        into a disease center, release is less
        of a factor and the net loss may be
        more. How can we account for that?
Approaches to Management




           Silviculture
           Resistance
           Other
Silviculture



           activities that are incorporated
            into stand management, using the
            usual techniques of silviculture.
Silviculture includes:

       thinnings that remove diseased
        individuals or those with infection courts,
        removing inoculum and releasing healthy
        individuals.
       practices that select resistant species
        when likelihood of a disease is high, by
        planting or favoring.
       choosing even-aged vs. uneven-aged
        management based in part on disease
        considerations.
Resistance
(Breeding or Genetic Engineering)

        Breeding programs are underway for white
         pine blister rust, fusiform rust, dutch elm
         disease, and chestnut blight, and have
         already had significant success in all but the
         latter.
        Resistant cultivars or hybrids are known for
         some other diseases such as sycamore
         anthracnose.
        Selecting the best, probably resistant trees to
         serve as seed trees is a low-tech approach to
         "breeding" (artificial selection).
Other
(not commonly used methods)

       Most direct methods of control, such as
        fungicides, are used only in nurseries and on
        especially valuable landscape trees.
       An exception is stump removal to reduce
        inoculum of root-rot pathogens. It seems to be
        approaching the level of being operational in
        high value stands in the Pacific Northwest.
       Fire, may be considered a silvicultural
        technique. It is sometimes used for mistletoe to
        kill residual small trees after a clearcut, or for
        brown spot needle blight on longleaf pine to
        reduce inoculum when seedlings are in the
        grass stage.
What do you think a disease is?



       “Any deviation in the normal
        functioning of a plant caused by some
        type of persistent agent or condition.”
Determining Disease


                This is a useful model of
                 disease because it
                 emphasizes the
                 interaction of the
                 environment, a pathogen,
                 and a host (suspect) to
                 produce disease.
Types of diseases



           biotic diseases
           abiotic diseases
           decline diseases (term commonly
            used when the cause of a disease
            is not known).
Abiotic diseases


           Air Pollutants
           Frost and Winter Injury
           Water - Not enough or Too much
           Nutrient Deficiency
           Salt (Deicing salt)
           Chronic Wind Stress
           Lightning
Decline disease characteristics


           a usually slow, progressive
            deterioration in health and vigor
           primarily affects a mature cohort of
            trees
           decreased growth and increased twig
            and branch dieback (applies more to
            hardwoods than to conifers)
           the etiology is complex and may
            involve important contributions from
            abiotic and biotic factors.
Diseases by affected tree part



          modified by considering certain
           types of agents separately:
Foliage diseases

   Rhabdocline            Elytroderma
    pseudotsugae on         deformans causes a
    Douglas fir, one-       severe disease of
    year life cycle.        ponderosa and
                            Jeffrey pines, even
                            in natural stands
   Lophodermium spp.
                                          Elytroderma
Canker

     A lesion on the bark   •Pitch Canker, Fusarium
                             circinatum (Fusarium
      of a stem or shoot,    subglutinans f.sp. pini)
      usually with a         •frap.cdf.ca.gov/pitch_cank
      sharply delimited      er/
      necrosis of the
      cortical tissue.       •Sudden Oak Death,
                             Phytophthora ramorum,
     Annual and             • www.suddenoakdeath.org
      Persistent Cankers
Decays, stem decay

      Decay in stems of living trees, focused on the
       inner wood.

          •Red rot, Dichomitus squalens (Ponderosa Pines)
             •www.fs.fed.us/.../field-guide/sds/red.shtml



          •Annosum root rot, Heterobasidion annosum (conifers,
          ALL)
             •Associated with southern pine beetle infections.
Decays, stem decay

•   Butt rot, Phellinus
    sulphurascens            www.cals.ncsu.edu/.../Armillaria/
                             Armillaria.htm
    (Douglas-fir and other
    non-cedars)


•   Oak fungus,
    Daedalea quercina
    (Oaks, ALL)
Root diseases

          Root-Infecting Vascular Wilt - Black-
           Stain Root Disease, Leptographium
           wageneri
          Cortical Root Rots - Port-Orford Cedar
           Root Rot, Phytophthora lateralis
          Annosum Root Rot, Heterobasidion
           annosum
          Armillaria Root Rot, Armillaria spp.
Vascular wilts & Stain Fungi


        Oak wilt,
         Ceratocystis
         fagacearum
Shoot blights


        A disease with       • Usually caused
         sudden, severe       by Shoot and Bud
         leaf damage and      insects which feed
         often with general   on the growing
         killing of flowers   maristem of the
         and shoots.          plant.
Rust

      A fungus in the order
       Uredinales or the       •Western gall rust,
                               P. harknessii
       disease it causes.
       Rust fungi are highly   •White Pine Blister
                               Rust, Cronartium
       specialized, obligate   spp.
       parasites of higher
       plants and often have
       complex life cycles
       involving two
       unrelated hosts.
Bark Beetle
Sucking Insect


             Aphids



                        Western
                        Blackheaded
                        Budworm and
                        Hemlock Sawfly


              White Pine Weevil
Shoot & Bud Insects
 Defoliators


   www.entomology.wisc.edu/raffa/labs/vol2/
The End – For Now. . . .


       Fall 2008
Assignment #8:
(Using your Text and/or the Internet) 48 points

           Other pathogens and insects also cause
            diseases and damage in the forest. For
            each of the following please provide the
            following information.
            –   Common name of Disease or Insect
            –   Scientific Name
            –   List tree species affected by this disease or
                insect
            –   Common symptoms (how can you recognize
                this infection)
Assignment:
(continued)

           Provide information for the following:
            –   Virus
            –   Bacteria
            –   Nematode
            –   Defoliators (Insect)
            –   Bark Beetle
            –   Sucking Insect
            –   Shoot & Bud Insect
            –   Root Insect

								
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