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Home , Plant pathology

1/23/2017

Learning Objectives

• Define Basic Plant Pathology & • Economic importance of plant Troubleshooting Plant Problems • Pathogenic and Non-pathogenic diseases • triangle Department of Plant Pathology University of Georgia • Fungal diseases, fungi reproduction and fungal

Paul Pugliese, MPPPM infection & Natural Resources Extension Agent Bartow County Cooperative Extension Coordinator • and how viruses are spread • How diseases are caused by

History of Plant Pathology Plant Diseases

• American Phytopathological Society – 1908 • Fungi (80%) • Irish Potato Famine – 1844 • (10%) . intro. potato in 1760 & pop. grew from 2-9m • Viruses (5%) . 2m died; 2m emigrated to America • Nematodes (5%) • – 1904 – 1940 • (<1%) . Chestnuts once composed 50% of eastern hardwoods • Dutch Disease – 1930 – Present • Over 10,000 species of fungi can cause disease in • Sudden Oak Death – 2000 – Present !! • Over 100,000 fungi are beneficial – strictly saprophytic.

Disease Disorder Terminology

• DON’T BE FOOLED - DO NOT ASSUME THAT ALL SIGNS AND SYMPTOMS OBSERVED ARE CAUSED BY A DISEASE 1 2 ORGANISM! . Biotic (pathogenic) – living disease with random symptoms** . Abiotic (non-pathogenic) – environmental/chemical stress with uniform symptoms** • A positive diagnosis of a plant disease is often difficult or nearly impossible on the basis of symptoms alone…

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1 1/23/2017

Disease Symptom Terms

• Canker • Necrosis • (yellowing)** • rot • Concentric spot • Scab • Damping off •Scorch • Decline •Soft rot • Dieback • Wilt • Galls • Witches’ broom • Leaf Curl • Anthracnose

I. Foliage Diseases II. Stem & Branch Diseases • Can cause significant damage to / • Generally are not considered lethal • May result in total defoliation • Primarily an aesthetic issue • Cankers may weaken stems/trunks • Usually not practical to treat large trees • Dieback of entire branches or canopy • Prevention is the key to managing: • Often spread to adjacent plant hosts . Sanitation • Chemical treatments are limited . Proper • Early Detection is the key to management! Adequate sunlight and good air circulation . Proper watering and drainage • Vascular wilt diseases cannot be treated! . Maintain / vigor and health • If in doubt, cut it out!!!

III. Root Diseases Troubleshooting Tip:

• Often cause to decay or rot • DO NOT ASSUME THAT JUST BECAUSE • Results in reduced uptake of water and nutrients YOU FIND AN OR A DISEASE THAT THEY ARE THE SOLE REASON FOR • Trees can become susceptible to throw THE PLANT’S DECLINE! • Often very difficult to diagnose . Secondary Diseases – saprophytic, beneficial, or “weak” • Management options are limited . Primary Diseases – parasites • Prevention is the key to managing . Combination of primary and secondary diseases • Almost always the result of environmental . Other Stress Factors…. “complex” stress**

2 1/23/2017

Disease Triangle Black spot on Rose

Right Timing Host

Disease

Environment Prune  Mulch  Spray

Fungal Diseases

Disease-causing fungi

Hyphae Mycelium

3 1/23/2017

Pycnidia develop releasing conidia in tendrils. The can remain viable for at least 2 Fruiting Bodies years in dead .

Phomopsis tip blight

Fusarium

Powdery Mildew cleistothecium

Thielaviopsis spores

Pythium oospore

4 1/23/2017

Powdery Mildew – Discula on Dogwood Fungal disease of on most broad-leaved trees and shrubs causing little lasting damage except possible dwarfing or distortion on heavily infected leaves.

Control: Oak Leaf Blister Primary causal agent: Taphrina sp. Chemical control on trees is neither practical nor necessary. Consider raking and removing fallen leaves and composting.

Early Blight of Tomato

Entomosporium

5 1/23/2017

Brown rot of Peach Cedar-Apple Rust

Fusiform Rust Causal Agent: Cronartium quercuum

Fusiform Rust Aecia Telia

Black Knot Common gall on cherries, plums, and peaches.

Symptoms include dieback of branches, thin crowns, and gnarly black galls on trunk or branches. Cankers and Galls on trunks/branches - Seiridium Canker

Control: Prune branch galls six to eight inches below infection. It is impractical to remove trunk galls. Distinct, sunken lesions which lead to dieback and death

6 1/23/2017

Dutch Elm Disease DED Yellowing, flagging and branch dieback Wilt Sample Hosts: Maple Ash Magnolia Redbud Yellowwood Tuliptree, Yellow Poplar

Staining under bark Symptoms include curling, drying, interveinal chlorosis or reddening, defoliation, wilting, dieback and death.

Infection occurs on stressed trees and is initiated through the roots and wounds.

Ganoderma – secondary fungi causing root and butt rot.

Hosts: Dealing with Trunk and/or Root Decay Problems Maple Beech Hickory • In most cases, refer clients to certified Ash for a proper, Walnut on-site evaluation. Sweetgum • Certified arborists can Sycamore be located by using the ISA web site: Oak www.isa-arbor.com Baldcypress

Visual examinations of soft spots, wounds or actual decay fungi are only indicators. Devices that take actual cores or use other methods to evaluate the extent of fungal damage are preferred.

NEW DISEASES ON THE HORIZON Sudden Oak Death, SOD, Phythophthora ramorum

• Phythophthora ramorum is a - borne fungal pathogen that was accidentally shipped to the Eastern USA in nursery stock from the west (CA, OR, WA). • This pathogen has been shown to affect over 100 different ornamental plants. • At this point, we are primarily examining and testing camellias, rhododendrons, azaleas, viburnums and mountain laurels all of which seem to be very susceptible to attack. • This virulent pathogen has damaged and/or killed many western tree species but we do not know what it will do to eastern varieties, especially our oaks.

7 1/23/2017

High magnification 400X

Bacterial Diseases

Bacterial diseases are spread by wind-blown rain, , and mechanical transmission by people.** Very High magnification Electron microscopy

Bacterial spots/blights Bacterial Wilt

Bacterial Crown Gall Bacterial Wilt on Melon

8 1/23/2017

Branch and/or Trunk: Fire Blight

Fire blight

Symptomology: Sudden blighting, death of blooms Bacterial ooze may be visible Blighted leaves stay attached Forms Sheppard's crook Oak Leaf Scorch

Causal agent : Pierce’s Disease Infection through feeding Fastidious vascular bacteria insects such as sharpshooters and treehoppers. Adults can infect Throughout their lives.

9 1/23/2017

Other Hosts for Leaf Scorch

Viruses (Courtesy J. R. Hartman).

Virus Vectors

Virus particle magnified 100,000 times!

Variegations Nematodes

10 1/23/2017

Endo- & Ecto-Parasitic Nematodes

Plant parasitic nematodes Lesion have stylets

Lance Nematode

Root penetration by the stylet can prevent root elongation, disrupt cell division, and provide an entrance for other pathogenic organisms.**

Phytoplasmas/-like Foliar Nematodes

Planthoppers

Aster Yellows on Coneflower

Sooty Mold Cultural & Environmental Problems that Mimic Diseases

• Soil Compaction • Nutrient deficiencies • Improper Planting • Cold or Heat damage • Air • Excess soil moisture • Mechanical damage • Soil acidity/alkalinity • injury • Woodpeckers • Parasitic plants • Too much mulch • stress • Competition/close planting • Insects • Improper pruning • Lichens, , and Spanish • Over/Under watering moss • Too much sun/shade

11 1/23/2017

Herbicide Injury Molybdenum deficiency

Heat injury to Rhododendron

Mechanical damage – weed eaters and lawnmowers

Eastern – parasitic plants that reduce tree vigor. They are primarily spread from tree to Herbicide Injury - Oak tree by bird droppings.

Hosts: Ash Dogwood Elm Maple Oak Pecan Walnut River Birch

12 1/23/2017

Lichens Improper Pruning

Lichens obtain water and nutrients from air and the microbes on bark.

Soil Compaction… Drought Stress – on Maple, Pine, Poplar

Angel Oak, Charleston, SC – 1500 years old!

Woodpecker Injury

Insect Leaf Galls

13 1/23/2017

Applied Controls:

1. Host resistance** 2. Cultural control 3. Mechanical control 4. Sanitation 5. Biological control 6. Chemical control

Resistant Plants Cultural Disease Controls

ASK QUESTIONS!!!! • Avoiding the pathogen Which disease? . Buy and plants from a reputable source Are diseases in your area? . Inspect plants prior to purchase Has it been tested? . Control alternate hosts . Cultivation & deep plowing PLANTS MAY LOSE . rotation RESISTANCE . Mulching . Sanitation Example: Do not plant Bartlett Pears in Georgia!

Cultural Disease Controls Cultural Disease Control

• Avoiding conducive environmental conditions • Sanitation . Moderate soil moisture; improve drainage** • Disinfest tools . Reduce humidity and increase air circulation • Remove diseases plants . Avoid over-head irrigation promptly . Water early in the morning • Remove scenescent plant . Fertilize plants properly parts promptly . Be aware of activities surrounding your plants: Minimize Root disturbance Avoid Soil compaction

14 1/23/2017

Pest Prevention is Key! Chemical Disease Control • “REAP” what you sow… • , bactericides, nematicides • Resistance: use locally recommended varieties • Exclusion: use disease-free (or certified) plants & • Protectants • Avoidance: fall sanitation program to avoid potential inoculum for •Systemics next year. • Fumigants remove/destroy diseased plants and plant parts to reduce inoculum. • Protection: optimal cultural conditions for plants to stay stress- free. scouting/monitoring to catch problems early preventative fungicides at regular intervals manage for resistance; rotate or tank mix chemicals

Troubleshooting Techniques Georgia • The Process of Elimination: Management . Have client submit plant samples Handbook . Have client submit soil samples . Have client email pictures . Ask questions to investigate problem • Site Visitations: . Rarely “diagnose” diseases in the field www.ent.uga.edu/pmh . Take hand lens or magnifying glass . Take sampling equipment i.e. bags, jars, etc. . Soil sample probe, bucket, shovel . Take digital camera . Pruners or pocket knife . Take both landscape pictures and close-ups

Sampling Tips Tips on Making Recommendations

• Advise client how to take a proper sample: • Don’t Forget the “Big Picture” . 6-8” section of symptomatic plant preferred . Avoid giving the quick/easy answers . Include both healthy and unhealthy tissues . Take the opportunity to teach… . Keep sample cool and dry!! . Integrated Pest Management (IPM) . Bag in a zip-lock bag to contain insects, etc… . Sustainable Practices . Collect sample the same day you travel to office . Reducing use . If samples are stored, keep in a refrigerator . Some clients may need assistance with taking . Conserving soil and water samples… only if really needed! . Conserving beneficial insects . Tree preservation

15 1/23/2017

Know Your Limitations Know Where to Find the Answer…

• Master Gardener Volunteers are trained to assist with home • It’s okay to tell the client “I don’t know” issues/questions: • You are NOT expected to know the answer to every . Be sure you know what your client’s question is concerning… question… practically impossible . Example: Bermudagrass lawn or pasture? . All commercial clients/questions should be deferred to the local • Never make up an answer!! Extension Agent • Let the client know that you will research their question . Don’t try to give too much information over the phone… clients can only absorb so much through conversations. and get back with them… . It’s okay to say “We have a great publication on that subject that I • Recommendations should be based on University or can send to you by email or regular mail, which ever you prefer.” Government research . Any questions clients may have regarding commercially contracted services and/or disputes should be referred directly to the County • Always look up pesticide recommendations!! Extension Agent.

Troubleshooting Tips Troubleshooting Tips

#1: Ask most of your questions so that they cannot #4: Never be absolutely positive in your diagnosis- be answered by a yes or no. tell the client what you think is the problem. #2: Form your initial opinion, if you must, but keep #5: If in doubt about any information, tell the client it to yourself and try to eliminate everything else you will check on the control recommendation and first. Don't jump at the obvious! call them back. #3: Don't be afraid to say you don't know, and don't feel that you have to apologize for not knowing.

Troubleshooting Tips Troubleshooting Tips

#6: When a third party might be involved or there is a chance #7: Use the plant diagnostic clinic whenever you for legal repercussions - Remember we are Government. have some doubt of what could be the problem. Do the taxpayers or your county really want you to get in the middle of something that might turn into a lawsuit? If #8: Don't worry about telling a person what they you think "yes" in this particular situation, give it to your don't want to hear. Tell them what you think, and agent. A visit will need to be made. Such cases cannot be don't let them put words in your mouth! handled over the phone.

Example: Tree health questions involving a “target”. Example: Misapplication of by a landscaper.

16 1/23/2017

Troubleshooting Tips Troubleshooting Tips

#9: If someone says they read or heard that you do something #10: If you pick up on the fact a person seems happy a certain way and they are asking if you agree, answer with your honest thoughts. However, never disparage the person with the way they are doing something, no matter or article being quoted. This will immediately destroy your how foolish or wrong it might seem to you, don't credibility. Instead say, "Perhaps that's the experience of come out directly and tell them they are doing that person, but I feel (or the University feels) this something wrong! Only an open mind will accept ______." Never belittle an authority! NOTE: Quoting the University or a specialist and crediting them with the suggestions to change. information gives you immediate credibility.

Troubleshooting Tips Five Steps to #11: Don't work with Commercial Clients (i.e., Pesticide Companies, Nurseries, Lawn Care Maintenance People, , Bee keepers, etc.). Let the agent handle their Trouble-shooting special needs. #12: Never make appointments for the Agent by saying: "I'll Ornamental ask the agent to stop by and see you." or "The agent will return your call this afternoon" unless you know what you are saying is likely to happen. Let the office secretary Plant and Site make those statements. Problems

Step # 2 Step #1 Learn About the Site Identify the Plant • Weather records • Observe other plants in the neighborhood • Structure/texture of the soil • Drainage • Soil pH and nutrients

17 1/23/2017

Step # 3 Step #4 Ask Questions Be Prepared to Ask for Samples • Helpful Diagnostic tools: • Never insult the client  Hand lens • Never make rash statements until you have all the facts  White paper • Take the lead during the  Pocket knife conversation  Zip-lock plastic bag  Container for insects  Soil Bags

Step #5 Step #5 Focus on the Plant Focus on the Plant Above ground symptoms Above ground symptoms Leaves: Stems:  Leaf spots – possibly caused by  Cankers diseases, spray damage or chemical injury  Mechanical injury  Marginal burn – drought or excess  Insect wounds fertilizer  Borers Shot Hole – insect feeding, disease   Internal decay fungi  Yellowing – deficiency, spider mites,  Animal browsing lace bugs or root problems**

Step #5 Left: Unhealthy Right: Healthy Focus on the Plant Below ground symptoms Roots:  Are they healthy white or dark brown?  Rotted, decayed appearance?  Planted too deep?  Internal bark browning?

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80% of Plant Problems More plants are killed Result from the Inability in Georgia from too of the Plant to Tolerate or Adapt to the much water than from Environment** the lack of water

Questions Avoiding Plant Stress It’s a Killer!!!

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