Common Conifer Diseases of Forests. Nancy R. Pataky Director, Plant Clinic University of Illinois

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1 Common Conifer Diseases of Forests Nancy R. Pataky Director, Plant Clinic University of Illinois

2 Tri-State University Plant Clinic Contacts Illinois (University of Illinois) Plant Clinic 1401 W. St.Mary s Rd Urbana, IL Iowa (Iowa State University) Plant and Insect Diagnostic Clinic 327 Bessey Hall Ames, IA Wisconsin (University of Wisconsin) Plant Disease Diagnostics Clinic 1630 Linden Drive Madison, WI

3 May thru mid-september Plant Clinic 1401 W. St. Mary s Rd. Urbana, IL 61802

4 Today Our Focus is on the Forest Forest Landscape Nursery

5 Conditions necessary for plant disease to occur Host Plant Disease Pyramid Time Pathogen Favorable Environment

6 Pathogen-Agent causing the infectious disease A.Fungi Most conifer diseases are caused by a fungal pathogen. B.Bacteria C.Virus D.Nematodes One disease discussed today is caused by a nematode.

7 Conifer Diseases Prevalent in Forests 1.Foliar Disease 2.Foliar & Stem Disease 3.Stem Disease 4.Wilts 5.Root / Butt Rots

8 Needle cast New needles green, one year old needles brown, two year old needles cast (dropped) Swiss needle cast Lophodermium Cyclaneusma needle cast Rhizosphaera needle cast

9 Needle blight affects needles of any age with affected needles usually remaining attached Brown Spot Needle Blight Dothistroma Needle Blight

10 Management of Needle Diseases Forest Trees: Most have no impact But be certain of your diagnosis Ornamental: Improve air flow Resistant varieties, where possible Ex. Norway Spruce resistant to Rhizosphaera Protective fungicides Rhabdocline, Rhizosphaera, Swiss Needle Cast in Spring Cyclaneusa & Lophodermium in Summer

12 Diplodia Blight of Pine Symptoms appear on both foliage and stems Cankers may be present

13 Diplodia Blight of Pine Fruiting bodies and spores Spores Fruiting bodies on needles Fruiting bodies on cones

14 Diplodia Canker Phase

15 Diplodia/Sphaeropsis tip blight and canker Hosts Austrian, Scotch, & Ponderosa pine (& other stressed conifers) Symptoms & signs Shoot tip die-back Branch cankers on stressed trees Fruiting bodies at base of needle clusters and on cone scales

16 Diplodia Management Forest Trees: Impact mostly to seedlings Ornamentals: Serious Remove infected wood or cones when dormant Do not plant susceptible pines near mature, infected trees Fungicides? three sprays: bud break, half candle, full candle

17 Efficacy of Sprays for Diplodia? Latent infection of healthy Austrian & Scotch pines is common. (Kentucky study, 2001) If fungicides are used, pick systemic product Stressed trees more susceptible (multiple studies) especially drought

19 Stem Diseases Cankers are the primary symptom. Dieback follows. Often stress related. Cytospora on spruce

20 Cytospora of Spruce Typically affects lower part of tree first and moves upward each year

21 Cytospora Canker of Spruce

22 Cytospora (Leucostoma) Canker of Spruce Gummy exudate and canker below. Probably won t see fruiting bodies.

23 Management: Cytospora Canker of Spruce Forest Trees: Not an issue. Urban stress absent Ornamentals: Find source of stress Correct stress Remove dead wood Improve vitality

24 Scleroderris Canker (Gremmeniella abietina) Causes shoot and possibly tree death Scotch, Jack, Red pines Northern Wisc Stress is definitely a factor Infection 1 o May-July via buds or needles, but symptoms next spring

25 Scleroderris Canker of Conifers 1. Lake Strain Young trees 6 or less Bud dieback, orange base to needles Cankers on young trees lowest branches under snow Yellow-green stain in cambium 2. European Strain All pines Much more serious may kill trees Not in Midwest

26 Orange base to needles in Spring Threat to young trees 6 or less

27 Scleroderris Canker Management Ornamentals: Not an issue Forest Trees: Do not replant in an affected area Use only disease-free stock in the Spring Chemicals available in nurseries Quarantines on Christmas trees grown in areas with European strain Some resistant varieties

28 White pine blister rust Hosts Needs both White Pine Ribes (currant and gooseberry) Currant Favored by cool, moist conditions and in low lying areas White pine

29 White pine blister rust Spores released by Ribes specis in midsummer to early fall cause yellow or reddish spots on pine needles. Infected pine needles may turn yellow and drop. Fungus moves into branch and swollen and blistered pine twigs & branches develop 2-3 years later. Girdled branches are blister rust flags..probably what we see first

30 White Pine Blister Rust Cankers Later Exude Resin

31 White pine blister rust Management Prune infected branches well before they reach the trunk May work on ornamental trees Not practical for forest Remove alternate hosts within 1,000 ft Seek rust-resistant planting stock **Interesting Note: The first quarantine laws were enacted in 1912, because of the need to control movement of this fungus. The fungus is from Asia but white pine is native. Imported on European white pine breeding stock

32 Pine gall rusts Immature gall Pine Hosts Austrian and Scotch pine Symptoms & signs Swellings and galls on main stems or branches 2 yr-old galls release yellow spores in spring W. gall rust pathogen reinfects pine only E. gall rust pathogen infects oak (red/black) then back to pine (all within 3-4 wks) Mature & active gall

33 Pine gall rusts Galls often not noticed during first year after infection Before spring, remove infected pine branches or whole trees Check nearby wild areas Apply Bayleton or mancozeb every 7-14 days during pine shoot elongation.

34 Gouty Oak Gall Caused by an insect (wasp)

35 Management of Rust Diseases White pine blister rust branches pruned and removed. Remove Ribes alternate hosts. No fungicides Pine gall rusts are pruned in early spring. Fungicides may help ornamental or nursery stock. Problem in nurseries Problem in Jack pine plantations

37 Vascular Diseases Pathogen invades the water conducting system of the tree Pine Wilt is the only vascular disease of conifers in the Midwest. Pine

38 Pine Wilt caused by pinewood nematode All pines are host except white pine (usually) Kills trees in a season

39 Vector Pine Sawyer Beetle

40 Wood extract for PWN assay

41 Pinewood nematodes viewed through a dissecting microscope

42 Pine Wilt Management Correctly Identify Remove tree before mid-march Chip, burn, or bury tree No chemicals effective

44 Root Rots Symptoms include off-color foliage, smaller than normal leaves, stem dieback, leaf scorch, branch death, wilt, decline, and possible plant death. White Pine

45 Armillaria root rot Hosts Hundreds of woody plants Symptoms & signs Young trees suddenly turn yellow, then reddishbrown, then die. (usually following moisture stress) White mycelium under the bark at the base of the tree Spongy or stringy white wood rot Honey mushrooms

46 Look for white mycelial fans of growth between bark wood

47 Aka Shoestring Root Rot because of rhizomorphs

48 Armillaria Root Rot Fruiting Bodies FBs Produced in late summer or fall

49 Armillaria root rot spread Airborne spores (occasional) Growth of fungus from tree to tree Rhizomorphs Root grafts

50 Armillaria Management Avoid using recently cleared land, especially deciduous forests. Remove infested stumps and roots may survive for decades in large stumps (for high value sites) Reduce stress. Use local seed source. No effective, practical control

51 Annosum Root Rot (Heterobasidion annosum) (Fomes annosus) Decay of roots and butt Often kills Over 200 hosts including red, white, Jack pine and white spruce Infects through freshly cut stumps and moves to healthy trees via roots Image by Joseph O Brien

52 Symptoms Reduced growth, but often none aboveground until the tree dies Windthrown trees Stained and resin soaked wood in butt of tree and roots leak resin Image by William Jacobi Wood soft and stringy Stringy yellow decay in roots

53 Annosum Root Rot White mycelium under bark Basidiocarps around base of stump mid-summer popcorn appearance fall bracket shaped Image by Paul A. Mistretta

54 Annosum Root Rot Management Treat cut stumps to prevent establishment Big problem in plantations where thinned Not so much of a forest problem Sporax* or other registered product Avoid planting in site formerly used for agriculture Avoid areas with a ph>6 Disease favored by well drained, sandy soils *Sporax by Wilbur-Ellis is a borate based fungicide registered for use to control this fungus

55 Schweinitzii Root and Butt Rot (Phaeolus schweinitzii) Common on conifers, esp Douglas fir Enters wounds Primarily root rot Forms very ornamental conks on stumps and roots (dye source) Start yellow-green then yellow-brown By Andrej Kunca then dark brown by Larry Grand

56 Schweinitzii causes a brown cubical rot of upper roots and lower bole Image by James Byler

57 White Pine Decline

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59 White Pine Decline Delayed bud break Reduced shoot elongation Wilting and browning Dead needles hold on Exact Cause Unknown

60 White Pine Roots White Pine Decline Healthy

61 Procerum root disease Hosts E. white, Austrian, & Scotch pine Vector implicated Weevils & bark beetles Symptoms & signs Delayed bud-break & reduced shoot length Wilting and uniform browning of needles Resin at base of tree & evidence of insect attack

62 Procerum root disease Leptographium procerum Conditions Various stress factors Common on wet or poorly drained sites Management Avoid using stress-prone planting sites Remove infected stumps.

63 Stained wood near the base of the tree and excessive sap exudate at the soil line are symptoms of this disease. Causal fungus

64 Management of Root Rot Diseases Promote tree health to ward off problems Plant in well drained sites Plant in site appropriate to species needs Remove stumps and roots of dead trees Fungicides may help in nursery setting Does it help to remove conks? NO!

65 Helpful References are Listed in Handout

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67 How to Submit a Sample to a Plant Clinic Address to local plant clinic Provide Information Sample live, symptomatic areas Provide enough to work with and share Do not use plastic Use sturdy box Provide Pictures

68 What do I send to a lab?

69 What do I send to a lab from these spruces?

70 Tri-State University Plant Clinic Contacts Illinois (University of Illinois) Plant Clinic 1401 W. St.Mary s Rd Urbana, IL Iowa (Iowa State University) Plant and Insect Diagnostic Clinic 327 Bessey Hall Ames, IA Wisconsin (University of Wisconsin) Plant Disease Diagnostics Clinic 1630 Linden Drive Madison, WI

71 Nancy Pataky Univ of Illinois Plant Clinic Director