Diagnosing Tree Diseasesseasesseases: The Good, The Bad, and the Ugly!
Fred BakerFred Baker Department Wildland Resources Utah State University DiseaseDisease
Any deviation from the normal function of a plant . . . DiseaseDisease
Any deviation from the NORMALNORMAL function of a ppplant . . .
FoliageFoliage
ColorColor Densityyy Leaf size and shape Wilting?Wilting? RetentionRetention TwigsTwigs
Annual Twig Growth (3(3--5 yrs)yrs)5 Abnormal buds –– color,,, number RetentionRetention Sapwood discoloration Evidence of pests Large Branches
Amount of dead wood Excessive ppgruning Wound closure rate CankersCankers Bacterial wetwood TrunkTrunk
CavitiesCavities CankersCankers Frost Cracks LightningLightning Mechanical injury RootsRoots
ColorColor Evidence of pppests Abundance Mechanical Injury RootsRoots
Rooting Area PavementPavement Disturbance Soil Typypype SoilSoil
DrainageDrainage Wateringgg pHpH TypeType PesticidesPesticides Ground cover Root Diseases
Kill trees by: Killinggg cambial tissue Weakening support and trees windthrow Stressinggg trees and bark beetles attack Root disease symptoms
Reduced leader growth OffOff--colorcolor foliaggge Less foliage Swollen butts Pitch flow at butt and on roots Bark beetle attack “Stress Cone Croppp” Root diseases:
Spread along roots slowly Cause syypmptoms in a patch or center Persist on the site in root biomass
Root Disease complexes
Root pathogens often occur together!
Ash yyyellows: a slowslow--declinedecline disease caused by ‘Candidatus Phytoplasma fraxinifraxini’’ Ash yellows in white ash
Incurable, perennial, often debilitating Tree
Symptoms: combinations of here slow growth subnormal greenness or chlorosis diminished or lost apical dominance reduced fruit & seed set & viability witches'-brooms rootlet necrosis decline ending in death Symptoms of ash yellows conditioned by
• tolerance or resistance of hosts • aggressiveness of pathogen •environmental influences. Phytoplasmal diseases most common & severe in areas of warm to tropical climate; cold winters can cure some plants, kill vectors Drought stress can trigger dieback and decline in trees that are otherwise able to tolerate phytoplasmal infection Drought-triggered dieback in white ash affected by ash yellows Interspecific differences in apparent tol erance (nat ura l s tand s st udi ed)
Si&lSpecies & place AdilthAverage radial growth (diseased / healthy) Fraxinus velutina, Utah 1.0 several sites in Zion Canyon
F. pennsylvanica , 2 sites, NYS, 0700.70 5 yr after growth of healthy and diseased groups diverged
F. americana, 2 sites, NYS 0.61 5 yyrr aafterfter ggrowthrowth ooff healthyhealthy aandnd diseased groups diverged Phytoplasma detection
• microscopic — transmission EM (little used now)
— DAPI fluorescence (obsolete)
• immunological (little used)
• recombinant DNA-based techniques PCR + product analysis DAPI: a DNA-binding fluoro- chrome (4',6-diamidino-2- phenylindole.2HCl) Ash yellows
deliquescent branching
Rootlet necrosis in higgyhly susce pt. spp. Importance of rootstockrootstockrootstock tolerancetolerance
Velvet ash on its own or on white ash roots
V / V - healthy V / W - AshY V / V - AshY Special Thanks to Wayne Sinclair for his info on Ash Yellows Hazard Trees
A tree at risk of failure A targgget of value
SwollenSwollen branchbranch stubsstubs Fruiting bodies
CankersCankers CavitiesCavities Aspen Decline 180 160 Arizona 140 Colorado 120 Utah f plots
100oo 80 60
umber umber 40 NN 20 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11 22 33 44 55 55 11 22 33 44 55 66 77 88 99 00 >1 41- 61- 71- 81- '1 - '1 '11- '21- 51- 31 - 91-1
Age Class 101-1 111-1 121-1 131-1 141-1 Too Old for the site. .
Utah Aspen
100
e age 80 ss 60
80) 40 dex (ba
nn 20 0 Site I 0 50 100 150 200 Age 14000 Latitude-elevation relationship of aspen Latitude-elevation relationship of affected aspen (>25% mortality of aspen component) 12000
10000 et) ee 8000 ation (f
vv 6000 Ele 4000
2000
0 30 32 34 36 38 40 42 44 46 48 50 Latitude (degrees) Aspen Decline
Too OldToo Old On Marggginal sites At lower elevations DroughtDrought Aspen Decline
Too OldToo Old On Marggginal sites At lower elevations DroughtDrought
The FIX: DISTURB ASPEN!!! Global Trade
So what?what?So
Pitch Canker What you can do: Know what is normal! KlKnow your plants Know your insects and diseases Know your plant sources Know your I&D man: County Extension Agent State Department of Agriculture USDA Forest Service Forest Health Mgmt