Scott Enebak Auburn University School of Forestry & Wildlife Sciences Important forest diseases in the southeastern United States

Tree Diseases Literally 1000’s of different tree diseases Only a problem when they interfere with human objectives –Pitch Canker –Annosus Root Rot –Fusiform Rust –Little Leaf Disease

–Brown Spot Needle Blight –Oak Wilt –Oak Decline –Dogwood Anthracnose –Hardwood Decay –Abiotic Disorders Tree Diseases

Signs & Symptoms Signs – The outward expression of the actual organism causing the disease –Conk, Mushroom, Spores, Bacterial slime, etc. Symptoms – An outward expression of the host that indicates that something is physiologically wrong with the tree –Decay, Canker, Resin flow, Swelling, Dead branch, Yellow foliage, etc.

Pitch Canker Fusarium subglutinans – native fungus Branch & stem dieback, deformity, growth reduction, tree mortality Slash, Loblolly, Shortleaf & Longleaf Pine Plantations, Natural Stands, Nurseries & Seed Orchards

Pitch Canker Wound pathogen Associated with overstocked stands, insect outbreaks & storm damaged trees

Pitch Canker Use appropriate species at appropriate densities – keep stand healthy & vigorous Do not add, or sparingly add Nitrogen to stand Plant disease-free seedlings from nurseries Use seed-tree (shelterwood) regeneration

Annosus Root Rot

Insert Fomes Movie Clip Here

Blue Pad – Example of Fomes Canker

Annosus Root Rot Heterobasidion annosum (Fomes annosus) Growth reduction, tree mortality All Southern Pines Associated with thinning and harvesting Soil factors influence stand risk Sandy, well-drained sites favor disease development Poorly-drained sites do not favor disease

Annosus Root Rot

Annosus Root Rot – High Risk Sites Reduce stocking levels (10' x 10') Avoid thinning as long as possible Prescribe burn stand prior to thinning Thin only during hot summer months Treat cut stumps with Borax Convert site to Longleaf pine

Annosus Root Rot - Medium Risk Reduce stocking levels (10' x 10') Reduce the number of thinnings Thin only during hot summer months Treat cut stumps with Borax

Cronartium quercuum f.sp. fusiforme Native disease – used to be obscure Forestry practices has increased incidence #1 Stem Disease in Southern US Stem deformation, growth reduction, tree mortality Slash, Loblolly, Shortleaf & Virginia pine Natural Stands & Plantations & Nurseries Fusiform Rust

Blue Pad – Example of Fusiform gall

Fusiform Rust

Use minimal amount of site preparation needed to get stand established Plant seedlings derived from genetically improved orchards - 2nd generation Plant disease-free seedlings Reduce alternate host using prescribed fires and/or herbicides Avoid addition of any fertilizer until at least age 8 Fusiform Rust

Phytophthora cinnamomii Growth reduction, stand stagnation & tree mortality Misidentified as a “beetle spot” Shortleaf, Loblolly & Slash pine Closely associated with soils that are: poorly-drained low in nutrients highly-eroded Little Leaf Disease

Blue Pad – Example of Increment Core of Tree

Avoid sites that favor the fungus high clay content poor internal drainage easily eroded Shorten stand rotation & objectives Add 400 lbs/ac every 4 yr to get stand to rotation Convert stand to less susceptible host Little Leaf Disease

Mycosphaerella dearnessii Defoliation, growth reduction, seedling mortality Lengthens rotation and stand failure Longleaf Pine Brown Spot Needle Blight

Serious infections result in defoliation of seedling

Plant resistant seedlings eastern U.S. sources better than western U.S. Use prescribed fires prior to planting or seed-fall if using natural regeneration Use winter prescribed fire every three years until seedlings are out of grass stage Once out of grass stage disease is inconsequential Brown Spot Needle Blight

Oak Wilt Ceratocystis fagacerum Native disease of Quercus spp. (oaks) Fungus is moved around by insects that visit wounds Mostly human problem in United States Once into vascular system – the fungus moves rapidly from tree to tree via root grafts

Oak Wilt Range of oak wilt in the United States

Oak Wilt Aerial view of Oak Wilt infection center moving through oak forest

Oak Wilt – Kills red oaks fast! Pictures of same oak tree taken two weeks apart

Oak Wilt The fungus will produce “pressure pads” on some oak species Insects are attracted to the fruity odor the fungus emits Perfectly happy to stay and eat

Oak Wilt

Oak Wilt – Leaf symptoms Live Oak – Intervienal Chlorosis Red Oak – Marginal Necrosis

Oak Wilt DO NOT WOUND OAKS IN THE SPRING Reduce inoculum –Eliminate infected trees and firewood Stop below-ground spread –Break root grafts: vibratory plow, backhoe, trencher, chemicals (VAPAM) Intervascular injection of select trees –Systemic fungicides

Oak Decline Range of oak forest type and symptoms of decline

Oak Decline Oak mortality is from a relationship between the environment, a root decay fungus and an insect Fruiting bodies (conks) at base of tree and mycelia fan under the bark of Armillaria mellea

Oak Decline Two-lined chestnut borer attacks and girdles stressed trees Branch die-back and tree mortality occurs as the food and water is disrupted

Oak Decline Environment – drought, heat and cold cannot be “managed” Maintain general health of stand Proper spacing – planting, thinning Careful and proper harvesting practices Proper moisture if landscape trees

Hardwood Decay 100’s of fungal species decay wood Normal natural part of the ecosystem

Hardwood Decay Minimize wounding Remove infected trees –Reduces risk –Reduces inoculum –Increases value of stand

Insert Dogwood Movie Clip Here

Dogwood Anthracnose Discula destructiva - introduced fungus Causes leaf blight, twig and branch blight, stem cankers and tree mortality Most severe: –Higher elevations –North facing slopes –Areas near water

Dogwood Anthracnose Symptoms of fungal infection on leaf (flower) bracts, leaf and stem

Dogwood Anthracnose Symptoms of fungal infection on stem and tree mortality

Dogwood Anthracnose High Risk Areas – Dogwood is becoming scarce with 100% mortality Low Risk Areas – Dogwood can survive without human intervention Landscape Settings – 10 Things for growing Healthy Dogwoods Outlook - Some resistant material has been located but will take years to get back into natural settings

Abiotic Disorders - I High Temperatures –Sunscald (summer and winter) –Leaf scorch Low Temperatures –Frost injury –Frost crack –Winter burning / Winter drying

Abiotic Disorders - II Moisture Extremes –Drought –Flooding Chemical Imbalances –Nutrient deficiencies –Herbicide injury –Air Pollution –Salt injury