White Pine Blister Rust

Presented by Dwight ScarbroughEntomologist USDA Forest ServiceForest Health Protection

March 19, 2013 EditionOxford Suites, Boise, Idaho, USA

Presentation Developed by James Hoffman Plant pathologist (Retired)Principles of Plant Pathology and Important Forest and Range Diseases in Idaho

1Presentation OutlineSection 1: Introduction to the Basic Principles of Plant Pathology.Section 2: Important Plant Pathogens in Forest and Range Ecosystems in Idaho.Section 3: Decline Diseases: A Complex of Biotic and Abiotic Origins.Section 4: Hazard Trees and Your Safety.2Section 1:Introduction to the Basic Principles of Plant Pathology3What is a Plant Disease?A disturbance that interferes with a plants normal structure, function, or physiological processes.

As opposed to a tree injury which is caused by a single event (e.g. hatchet blow to a tree)4This is a broad definition to cover all diseasesDisease DefinitionsParasite an organism that lives on or in another organism.

Host an organism that provides nutrition for an invading parasite.

Pathogen an agent that causes disease.5An common understanding of these basic terms is of primary importance. Disease Triangle Disease is the product of three interacting factors

Host PlantEnvironmentPathogen

Disease6Disease is a process resulting from the interactions of three variables

Signs of Diseases

The physical presence of the pathogen on the surface or inside the plantFruiting bodies, fungal tissues, dwarf mistletoe shoots, etc.Geeks look for spores (under a microscope)7Tree diseases can be identified by signs and symptoms. Signs are actual pathogen tissue. For example, The orange sporulating blisters are a sign of white pine blister rust, the fungal fruiting bodies are the reproductive structures of a decay fungus, and the mats of white mycelium are the body of a root disease organism. Symptoms

The expression of the host to the pathogen infection.

Tissue death, abnormal growth forms, branch or top-dieback, lesions, yellowing, decay, defoliation, etc.

8Symptoms, on the other hand, are expressions by the tree as a response to the pathogen. Dead branches are a symptom of white pine blister rust

Examples:Pine needle cast, Juniper witches broom, Aspen Shepard's crook

Is this a diseased cottonwood tree?No, its early fall!9Its really important to know about the growth habit and appearance of the host. Types of DiseasesTree Disease Concepts, Paul D. Manion

Biotic diseases (Infectious)

Abiotic diseases (Non-infectious)

Decline diseases- (Complicated as many pathogens are involved over a long time period.)10To make a correct management recommendation it is first necessary to identify whether the tree disease is infectious or non-infectious.FungiParasitic PlantsBacteriaMycoplasmas = PhytoplasmasVirusNematodesOthers?Types of Biotic Diseases (Infectious plant disease agents)11All these agents may be present, which agent do you think is responsible for more tree diseases? Next slide for the answerMoisture imbalances (Drought)WindTemperatureNutrient and mineral imbalancesAir pollutionSoil acidity or alkalinityOthers?Types of Abiotic Diseases (Non-infectious plant disease agents)12In the western US, drought is a chronic challenge to plant growth and developmentCommon Categories of Fungal DiseasesFoliage diseases

Cankers (usually stem rusts)

Decays and Rots

Root diseases

Vascular wilts

13Fungal diseases are generally grouped by the part of tree affected.Management Techniques for Plant DiseasesRegulatory MethodsQuarantines and InspectionsCultural MethodsHost EradicationRotation to Non-host SpeciesSanitationAltering the Environmental ConditionsBiological ControlChemical ControlNo Control

14Management of forest pathogens requires a complete understanding of host-parasite relationships, an assessment of the damage potential of the pathogen, and a realistic benefit/cost evaluation of the various proposed control or management actions. Strategies include all of the above techniques, and are best presented within the context of management of the representatives of the various disease categories that followSection 2:Important Plant Pathogens in Forest and Range Ecosystems in Idaho15Foliage DiseasesNeedlecasts Needle BlightsShoot Blights

Mostly caused by fungi

Cause spotting and discoloration

Cause premature defoliation

May reduce growth

Only a problem when infection occurs over consecutive years16More serious in conifers because:1) They can not refoliate;2) They depend on only a few years of needles for their growth.

Signs of Foliage Diseases

Signs

Fungal fruiting bodies are often visible on the surface of infected needles

Snow BlightLophodermium needle castElytroderma needle cast17Snow blight kills needles under snow. Lophodermium is an annual foliage disease.Elytroderma is both annual and perennialSymptoms of Foliage Diseases

Leaf spots or discolorationDead/dying foliageThin crownsDegrees of Defoliation

Dothistroma needle castPine needle cast18Generally, only one-years foliage is killed; most damage occurs in the lower crown where there is more moistureOn small trees or in extreme infection periods, only current years foliage is retained

Lodgepole pineNeedlecast19Note upper right: new emerging candles are disease free.Last years foliage is all red.2-year old foliage fell off.3-year old foliage was uninfected.Other Foliage Diseases

Snow MoldElytroderma NeedlecastMarssonina Leaf Spot of Aspen20Elytroderma needle cast occurs on Ponderosa and Pinyon pine--causes premature death of needles and small tufted brooms on twigs and branches. Marssonina Needle Blight of aspen causes dark spots scattered over the leaf surface. Damage is mostly aesthetic.Snow moldcaused by fungi that attack plants under a cover of snow. Foliage matted together in a thick gray felt.

ElytrodermaSmall, dense witches brooms21On ponderosa pine this foliage disease becomes perennial within the twigs, resulting in compact witches broomsCedar-apple RustGymnosporangium sp.

Orange Jello on Junipers in springGalls on junipers in fall22On junipers the telial stage of the fungus forms in the spring and, when hydrated, forms masses of orange gelatinous material.In the fall of the year hardened galls are found on junipers.On rosaceous hosts, hairy looking fungal structures are formed on the underside of the leaves in late summer. Control of Foliage DiseasesControl usually not needed nor is it practicalMaintain mixed species composition in standMaintain healthy, vigorous trees Role of fire?High value trees both protective and controlling fungicides23In a forest, there are no practical controls.In a small landscape, rake up and dispose of the fallen foliage in the fall.In high value landscapes fungicide treatments can be applied prior to leaf emergence.Cankers a symptom of diseaseLocalized area of dead bark or cambiumOften sunken because the tree continues to expand around the infection site

Very commonMore common on thin-barked species (aspen)

Usually caused by fungal infections that enter through wounds

24Read textIdentifying Cankers

Hail damage25Hail can be severe enough to girdle a twig, or allow infectious organisms an entry point.Fungal Canker SymptomsExpanding edgesCallus ridges and sunken woodDead wood inside margin

Black knot of cherryCytospora cankerTarget canker1226Read notesSigns of CankersSometimes fruiting bodies are invisible

27Fungal fruiting structures associated with cankers are usually ephemeral.

Often perennial & expand until the tree is girdled

Most important & common group of diseases in aspen

Cause direct mortality

Provide entry point for decay fungiCankers of Aspen28Aspen has the largest range of any tree species in the Northern Hemisphereunfortunately it sacrifices longevity for this distinction.Its bark is too thin to defend itself!If a stand has too many cankers it may be time to renew it by cutting or fire.

Rust Galls and CankersCause diseases of leaves branches and stems

Rust colored spores

All require a living host (obligate parasites)

Complex lifecycle often involving 2 different plant hosts and up to 5 spore stages!

29Read notesWestern Gall Rust

Most common canker in pines in this area

A pine-to-pine rust

Causes hip cankers that rarely girdle the tree

Wind-snapping at canker is common

Fungus enters through needles30Read

Western Gall RustAttacks all 2-3 needle pines:ponderosa, lodgepole, scots, and Austrian pines.31This is probably one of the more common forest disease in southern Idaho.

Western Gall Rust -Hip cankers on stems create weak areas32Read

White Pine Blister RustIntroduced from Europe in the early 1900s

Lethal, invasive disease

Infects all species of white, 5-needle pines

In Central Rockies this would be limber, whitebark, and bristlecone pines

Alternate host = currants and gooseberries33American hosts have not evolved with the fungus and therefore do not have genetically evolved capacity to defend themselves against itSymptoms of White Pine Blister Rust

Cankers are often gnawed on by rodents

Swollen cankers with orange marginsRoughened bark as a result of past fruiting

Branch death (flagging)

34Read notesSigns of White Pine Blister Rust

Resinous, diamond shaped cankers on branches/stems

Orange blisters and spores that infect the alternate host

35Read

White pine blister rust in the Central Rockies200536Distribution in 2005.Note large areas of white pine habitat still uninfected in Mexico, Arizona, and UtahOther Rusts

Spruce and Fir Broom RustCommon but do not cause serious damage

Comandra Blister RustCommon and important in lodgepole and ponderosa pines Infects all hard pinesCauses top-kill37Symptoms are similar to other disease agentsDecays (Rots)Top rot, usually resulting from top breakage or damageStem or trunk rotsButt rotRoot rot38The majority of tree decays are butt rots.How does Mr. Jim know this? Hes looked high and lowNext image!

White RotFibrous, usually whitishBreak down lignin leaving some cellulose intactVariable appearanceBrown RotBrown in color, cubical, crumblyBreaks down cellulose leaving lignin 39Decays are often classified by the type of rot they cause1--White rots are produced by fungi that attack both carbohydrate and lignin components of wood2--Brown rots develop as the result of selective utilization of carbs (mostly cellulose) by the fungus, leaving behind the brownish lignin component of the wood. Indicators of DecayInfection courtsFire scars, logging scars, broken/dead tops, fallen trees, old-growth characteristics

SymptomsExposed decay, cracks, decayed branch stubs, sparse foliage, cavity nesting birds

SignsConks, fruiting bodies fungal tissues, carpenter ant activity40ReadStem DecaysDecay in trees

Generally in inner wood

aka heart rot

Caused by fungi, that often form conks (sign)

41Stem decays are never predictable in length or diameter. Use caution when sawing as the stem may twist unexpectedly!

White Trunk Rot (Phellinus tremulae)

On aspen onlyWhite rotMost infected trees have conksConks 42One visible conk indicates total cull of the aspen stem.SaprotsPouch fungus insect correlation

In the sapwood

On dying or newly killed trees

Cryptoporous volvatuspouch fungus43This is one of the most commonly observed conks on conifer trees in southern Idaho.Root DiseasesMost involve decay of the roots and lower stem root and butt rots

Hard to DiagnoseSymptoms are nonspecific, not diagnostic, and may not appear

Greatest concernStructural failure (snapping, uprooting) of green trees!

44Growth loss - impairment of root functionDirect mortality - killing of cambium and girdling root collarIndirect - decay weakens structure of roots and butt

Root Disease Spread

Subway: root-to-rootAirborne: by spores45So how does root disease spread Rather, why isnt it everywhere?

Signs of Root Disease -Fruiting Bodies

Phaeolus schweinitzii The cow-pie conk46Sometimes signs of fungi are obscured by leaf litter.Symptoms of Root Disease

Basal resinosisThin crown, stress crop, branch dieback47Symptoms of root disease can be confused with insect damageExpanding mortality centersDecay in roots

Symptoms of Root Disease48Often there is no sign of the fungal organism, only the decayed wood and a stand of dead trees.Vascular WiltsMostly caused by fungiInvade conducting tissues, disrupt water movement, and cause wiltingInfect wounds on stems or rootsDiagnoses based on symptoms49Mostly on hardwoods in urban areas.

Black Stain Root Disease

Pinyon pine in CO, ID, UT, NVVectored by insectsTrees develop thin, chlorotic crownsExpanding infection centersBlack streaks in roots50Infects Ponderosa pine and Douglas-fir in other areas.Parasitic PlantsTrue Mistletoes (Phoradendron spp.)

Dwarf Mistletoes (Arceuthobium spp.)

Dodder (Cuscuta spp.)51Read

True Mistletoes--JuniperOnly true mistletoe in Great Basin

Shrubby, photosynthetic plant

Acquires water from the host plant

SW-CO and NM, AZ, UT, & NV

Bird dispersed

52Dispersed by birds feeding on the seeds and then defecating Dwarf Mistletoes(Genus Arceuthobium)

Parasitic plants that occur on all western conifers

Host specific

Most common and damaging tree disease in the Western US

Largest impact is growth reduction

Brooms may create fuel ladders for fire53Read notesDwarf Mistletoes Arceuthobium spp.

Very common on conifers

Small, leafless, parasitic flowering plant

Obtains water and nutrients from host plant

Sticky seeds are explosively discharged adhering where they land

Limber pine dwarf mistletoePinyon pine dwarf mistletoe54ReadSymptoms of Mistletoe

Branch swelling and cankersWitches brooms - reduced vigor, dieback

55Read

Stunted growth

62-year old Bonsai Douglas-fir

(Pathologist now the same vintage.)

56Douglas-fir dwarf mistletoe can infect the apical meristem of a tree and grow systemically with it all its life. The witches brooms can become enormous! Weighing over 1000 pounds.

Signs of MistletoeDwarf mistletoe plants Dwarf mistletoe basal cups57When shoots are shed small basal cups remain embedded in the bark

Douglas-fir dwarf mistletoeDwarf mistletoe shoots 58Douglas-fir dwarf mistletoe shoots are very smallSpread and IntensificationDwarf MistletoeSpread occurs from tree-to-tree and within crowns

Distribution is patchy with discrete infection centers

59Long distance spread---Plants of both sexes must be in fairly close proximity for pollination and seed production to occur.Spread and Intensification Plants tend to build up in bottom of crown and move up the crown

Mortality usually occurs from top down

Spread is quickest from an infected overstory to adjacent reproduction

60Management of Dwarf MistletoesPlant or favor non-host speciesPrune brooms/infectionsRemove infected trees/protect uninfected regenerationBuffer stripsSanitationEven-aged managementPartial cuttingFireDo nothingChemical controls

61Most management relies on cultural techniques. However, a plant growth regulator, Ethephon, is a chemical control. Ethephon (Chemical Name)Also marketed under the trade name of FlorelCauses abscission of dwarf mistletoe shoots preventing the development of fruit and seeds.Chemical Management of Dwarf Mistletoes62When Ethephon is sprayed on infected trees it causes dwarf mistletoe shoots to drop off before seeds are dispersed. Ethephon does not kill the entire mistletoe plant but it provides short-term protection (1-3 years). Reapplication is necessary until the infected overstory can be removed. Generally, pruning is more economical and effective than ethephon spraying.

Dwarf MistletoeBrooms and Fire Effectsincreases the fine fuels;are clustered in lower tree crowns;collect at base of trees;on steep slopes, brooms pinwheel downhill.

63As a precautionary note for fire-fighters, be aware that fighting fire in dwarf mistletoe infected stands can be dangerous as the witches brooms can burn off the tree, and roll down the hill igniting fires behind workers.

Is this a candidate stand for dwarf mistletoe control?64But fire can also be a great tool for managing dwarf mistletoe infected stands!Douglas-fir dwarf mistletoe control project with fire Before

Yes! But it took more than one match65After treatment! Site was replanted to lodgepole pine and Douglas-fir is now completely regenerated and disease-free.Dodder (Cuscuta sp.)

Mats of dodder plant-strandsVines attacking host66Perennial plant-parasitic vinesLeaves are reduced to scales Haustoria (root-like structures) enter hostsForms mats on hosts that prevent photosynthesisSection 3:Decline Diseases: A Complex of Biotic and Abiotic Origins67What Are Decline Diseases?Decline diseases are caused by the interaction of a number of interchangeable, specifically ordered biotic and abiotic factors which produce a gradual general deterioration, often ending in the death of trees.68Categories of Factors That Influence Decline Disease

Predisposing Factors: Long-term, slowly changing factors which alter a trees ability to withstand or respond to injury-inducing agents.

Inciting Factors: Short-term physiological or biological factors that generally produce dieback of small branches.

Contributing Factors: Include a collection of environmental factors and biotic agents.69

Categories of factors influencing DeclinesFrom: Tree Disease Concepts, Paul D. Manion70

Decline Disease CycleFrom:Tree Disease Concepts Paul D. Manion71Section 4:Hazard Trees and Your Safety 72

73 Size up snag hazards in work area. Never become complacent. Always look up. Get weather reports.

Scout out parking, sleeping, work areas, and safety zones. Advise co-workers of known hazards. Face your hazard and take appropriate action. Examine work area for other hazards. Take extra caution around heavy equipment. You are ultimately responsible for your own safety.

SNAG (Hazard Tree) SAFETY:74

Dont Let This Happen To You !!75Forest & Sade Tree Pathology Website:http://www.forestpathology.org/hazard.htmlFS-R1 Hazard Tree Safety Initiative Up the Ante Website:http://fsweb.r1.fs.fed.us/r1_www/projects/haztree_index.shtmlHazard Tree Information and Safety WebsitesFS-R6 Field Guide for Danger Tree Identification & Response:http://www.fs.usda.gov/detail/r6/forest-grasslandhealth/insects-diseases/?cid=fsbdev2_027046FS-R6 Hazard Tree, Long Range Planning for Developed Sites: http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsbdev2_026108.pdf76

For More Informationhttp://www.fs.fed.us/r1-r4/spf/fhp/field_guide/toc.htm77Additional Information sources in Utah or Nevada

John C. GuyonPlant PathologistUSDA Forest ServiceForest Health Protection4746 S. 1900 EastOgden, UT 84403Phone: (801) 476-4420jcguyon@fs.fed.us

in Southern Idaho

Dayle BennettBFO Group LeaderUSDA Forest ServiceForest Health Protection1249 S. Vinnell WayBoise, ID 83709Phone: (208) 373-4227ddbennett@fs.fed.us

78Heres how to reach us. Thank you for your attention and participation.