Presentation on theme: "What’s Wrong With Your Plants and Why?"— Presentation transcript:
1What’s Wrong With Your Plants and Why? Biotic vs. Abiotic ProblemsPlants can be injured and damaged by biotic (living) and abiotic (non-living) agents.Based solely on symptoms, however, determining whether the condition is caused by a biotic or an abiotic agent can be challenging. In many cases, a proper diagnosis of abiotic diseases requires thorough examination of the site, knowledge of relevant past and present environmental conditions, in-depth knowledge of plant species biology, site management history, and an orderly series of tests to determine possible causes.I’ll discuss some general characteristics that can help to differentiate between biotic and abiotic stresses.Tony GloverRegional Extension Agent
3Abiotic vs. Biotic Problems Abiotic – non-living agent (non-infectious).Extreme temperaturesExcess or deficient water, light or nutrientsSoil compaction, soil grade changesDamage from cultural practices: herbicides, fertilizers, pruning, mulchingAbiotic agents or factors include environmental conditions such as extreme temperatures; excess or deficient water, light or nutrients; soil compaction; and abnormal conditions such as drought, flooding and/or adverse cultural practices.Most abiotic diseases cause generalized symptoms such as wilting, yellowing, thinning and the development of smaller than normal leaves, limited root growth or slow growth.
4Abiotic vs. Biotic Problems Biotic – living agent (infectious).Pathogens - parasitic microorganisms that cause disease (fungi, bacteria, viruses, phytoplasma)Pests – insects, mites, nematodes or mammals feeding on or damaging plants.Abiotic agents or factors include environmental conditions such as extreme temperatures; excess or deficient water, light or nutrients; soil compaction; and abnormal conditions such as drought, flooding and/or adverse cultural practices.
5Abiotic vs. Biotic Problems Symptom ProgressionBiotic disease – symptoms progress and nearby plants become infected.Abiotic disease – generally a lack of symptom progression. Does not spread.Exception – nutritional deficiency symptoms progress slowly.The progression of symptoms is one of the most important characteristics associated with problems caused by biotic or living agents.Diseases often exhibit both primary and secondary symptom. For example, decayed tree roots primary symptom and yellowing leaves due to damaged roots are secondary symptom. Secondary invaders in later stage of disease can also complicate diagnosis.Look for lack of symptom progression with abiotic diseases. For example, in the case of herbicide damage, initial symptoms of 2,4-D injury include leaf deformation may initially be similar to infectious agent like a virus. However, herbicide injury the symptoms appear suddenly and new leaves may be free of symptoms indicating a lack of progressionAbiotic disease – Herbicide Injury
6What’s Wrong? Biotic or Abiotic Diseases are the exception, rather than the rule. Because diseases are difficult to diagnose it is often faster to rule out the involvement of other factors than to verify the presence of disease. It is important to rule out the possibility of abiotic disease problems and one of the best times to do this is during the site visit. Ruling out abiotic problems can be challenging.But where do you start?What’s Wrong?Biotic or Abiotic
7Steps in Problem Diagnosis Know the PlantInspect the Site and Look for PatternsLook for Symptoms or SignsExamine cultural practices and weather conditionsIdentify Potential CausesConsult Resources and Reach Diagnosis
8Steps in Problem Diagnosis Know the PlantIdentify the species and cultivar affectedKnow what problems commonly affect the species. For example:Red Maple – Phyllosticta Leaf Spot, gloomy scaleFlowering Dogwood – Powdery Mildew, spot anthracnose
9Steps in Problem Diagnosis Know the PlantWhat’s normal for specific plant?Fall Needle Drop on White Pine
10Steps in Problem Diagnosis Know the PlantLook at the Whole Plant (foliage, stems, branches, leaves, and roots)Note the color, size, and thickness of the foliageCheck the trunk and branchesExamine the Roots
11Check the Trunk and Branches Look for wounds, cankers, exit holes and other cluesPitch Tubes on Bark, Southern Pine Beetle
12Check the Trunk and Branches Sapsucker damage to sugar mapleDon’t mistake sapsucker damage for borer exit holes
19Deep Planting or Covered Later Check for flare at base of trunk
20Girdling RootsGirdling roots are a common problem with trees that are planted too deep
21Too Much Mulch Over The Root Ball Problems caused by too much mulchKeeps trunk tissue wetCan increase rodent damageMulch can intercept rain and irrigationCan keep poorly drained soils too wetCan encourage surface rootsCan encourage development of stem girdling rootsToo much mulch was placed over the root ball. This keeps trunk tissue wet, can increase rodent damage on the buried portion of the trunk, can intercept rain and irrigation meant for the roots, can keep poorly drained soils too wet, can encourage surface roots, and can encourage development of stem girdling roots.
23Steps in Problem Diagnosis Inspect the Site and Look For PatternsDetermine prevalence of problem.Large area, all plants – generally abiotic.Scattered, localized – generally biotic.Check for distribution of symptoms.Uniform – generally abiotic.Random – generally biotic.Are the symptoms/patterns related to geography? (soil, low spot, etc)Is the damage limited to one type of plant?Multiple plant species - often abioticOne species – often biotic
24Observation of Field Patterns Abiotic Problem Symptoms distributed in a large area. Damage pattern is uniform.Gas leak from building
25Observation of Patterns Random vs. Uniform Leaf Spot (Fungal)Marginal Leaf Scorch
26Observation of Field Patterns Random vs. Uniform Boxwood Phytophthora Root RotOak Nutrient Deficiency
27Observation of Field Patterns Random vs. Uniform Random PatchesUniform StripesBermuda spring dead spotFertilizer application problems
28Steps in Problem Diagnosis Know the PlantInspect the Site and Look for PatternsLook for Symptoms and/or SignsExamine Cultural Practices and Weather ConditionsIdentify Potential CausesConsult Resources and Reach DiagnosisExamine injured parts and list the symptoms. Is injured part chlorotic, necrotic, discolored or distorted? Are the symptoms in patches, yellowing, leaf spots?
29Look for Symptoms and/or Signs Symptoms - plant reactions or alterations of a plant’s appearance due to a disease or disorder.Signs - actual presence of the pathogen, it’s parts or by-products seen on a diseased host plant.
31SignsVisible or physical presence of a pathogen or pest. Signs - visible presence of the pathogen, it’s parts or by-products seen on a diseased host plant
32Steps in Problem Diagnosis Know the PlantInspect the Site and Look for PatternsLook for Symptoms and/or SignsExamine Cultural Practices and Weather ConditionsIdentify Potential CausesConsult Resources and Reach DiagnosisExamine injured parts and list the symptoms. Is injured part chlorotic, necrotic, discolored or distorted? Are the symptoms in patches, yellowing, leaf spots?
33Steps in Problem Diagnosis Examine Cultural Practices and Weather ConditionsAsk questions - Collect as much background information as possibleWhen was the problem noticed?Was the damage sudden or gradual?Has the problem spread?How old are affected plants?What cultural practices have been performed recently? Herbicide Sprays?
35Steps in Problem Diagnosis Identify Potential CausesConsult Resources and Reach DiagnosisGet Laboratory AssistanceTake samples (plant, soil)Don’t forget picturesSynthesize Information and Identify potential causesWhen you have finished collecting information about the turfgrass and site, identify potential causes.Test likely causes and consult resources. Submit samples to agricultural or plant disease lab, soils labs; use literature and resources to reach diagnosis.
36Most Common Diseases of 2009 Ornamentals Phytophthora Root and Crown RotBoxwood, Juniper, Hydangea, Leyland Cypress, Pansy, Petunia,Fungal Leaf Spots (Oak Leaf Blister, Anthracnose, and other leaf spots)Armillaria Root RotOakleaf Hydrangea, CotoneasterPythium Root RotPansy and other flowersPowdery MildewDogwood, Crape Myrtle, RoseBotryosphaeria Canker /DiebackLeyland Cypress, Japanese Maple, CleyeraBacterial Leaf SpotsBasil, Begonia, Oakleaf Hydrangea, English IvyAzalea Leaf GallSooty MoldVarious Trees and Shrubs (Hackberry Woolly Aphid)
38Diseases Caused by Phytophthora Some of the most economically important and damaging diseases on woody plants in the Southeast, USA, and worldwideThe name Phytophthora derives from Greek and literally means “plant destroyer.”Cause problems annuallyNotorious Phytophthora diseases include rhododendron root rot, sudden oak death, and potato late blight.Particularly serious in or following “wet” yearsDiseases often are associated with wet or saturated soils
40Phytophthora 101 Phytophthora species resemble fungi but are not. They are most closely related to aquatic organisms, such as brown algae and diatoms.Phytophthora organisms are often referred to as ‘water molds’ because they do need water to complete their life cycle.This group of organisms produces swimming spores .
44Phytophthora as Pathogens of Woody Plants They can attack all parts of the plantBlight & dieback on shoots & foliage —uncommonCankers on stems & trunk —e.g., “bleeding” cankers – occasionallyRoot & crown rots — most common
45Symptoms—Above Ground Appear after roots are diseasedChlorosis & yellowing of the foliagevery slight at first, then becoming obviousStunted growthOverall wilting & declineCankers - orange/red/brown discolorationon stems and trunkdistinct margin between healthy & diseased tissuesPlant death
47Trunk and Stem Cankers “bleeding” cankers - maple
48Trunk and Stem Cankers “bleeding” cankers - Oak Slide 28.The next few slides show what P. ramorum cankers look like compared to cankers caused by other fungi or insects. On the left is a photo of the outer bark, showing the bleeding canker caused by P. ramorum. On the right is the same tree with the outer bark removed to reveal the inner bark under the bleeding.outer barkinner barkPhoto: Bruce Moltzen, Missouri Department of Conservation
49Symptoms—Below Ground Must expose roots for examinationthis usually requires digging!need to know what healthy roots look like!Reduced root volume/lack of feeder rootsRoots discolored - red, brown, dark brownhealthy roots are white or off-whiteCortex sloughing/root rotCankers on root crownmay move up stem above ground
53Field DiagnosisAbove-ground symptoms alone usually are not diagnostic—merely indicate vascular dysfunctionTherefore, look below ground at roots & crownTogether, these may be diagnosticOther pathogens also can cause root rotArmillaria, Fusarium, Sclerotium, Thielaviopsis, etc.and sometimes Pythium spp., especially on boxwood
54Fungal Leaf Spot Diseases Typically have tan to gray centers surrounded by a darker borderFungal fruiting structures (pycnidia, spores, etc.) can be seen within the leaf spotDefoliation is commonFungi survive on fallen leavesProlonged leaf wetness, high humidity and poor air circulation increase disease developmentSpores are spread by wind and water-splashing, but can also be spread by insects, on clothes, tools, and hands
56Defoliation due to Entomosporium leaf spot disease - Indian Hawthorn Less water stays on this protected area
57Oak Leaf BlisterCommon fungal disease on oaks, especially red oaks (s. red and water oak)Disease favored by cool, wet springsSymptoms appear in late spring as yellow, blisterlike, circular, raised areas
58Oak Leaf Blister Spots become dull brown with age As leaves mature, become resistant to infectionAffects appearance not tree healthFungicides not needed, but one application of chlorothalonil or mancozeb before budbreak will control disease
63Boston Ivy Leaf SpotThe fungus Guignardia bidwellii f. sp. parthenocissi causes distinct, angular, tan, spots to form on Boston ivy leaves in the spring and summer. A dark brown halo or margin along the edge of the spot is usually present. Within the tan areas, small black dots (fungal fruiting structures where new spores develop) can be observed soon after the spot reaches full size. Branch dieback occurs if the disease is very severe.
68Armillaria Root Rot - Rose White fungal growth under barkDrainage?Irrigation? Death by watering hose?No fungicides for controlResistant plants best replacement option
69Bacterial Leaf SpotsPlant wetness, high humidity and warmer temperatures favor disease developmentBacterial cells spread by water splashing, tools, hands, or insectsNo Fruiting structures in spotsMany controlled with copper fungicides (Kocide)Oak Leaf HydrangeaAngular leaf spots running along veins
71Sooty MoldCommon name for group of black-colored fungi that grow on honeydew on plants and other surfacesFungal growth gives appearance of being covered with a layer of sootHoneydew produced by aphids, mealybugs, soft scales, whitefliesControl sooty molds by controlling the honeydew producing insect. Drenches with Merit or Safari for hackberry aphids (early spring)Sooty mold on crape myrtle
72Asian Woolly Hackberry Aphid Multicolored Asian lady beetle pupa
73Azalea Leaf Gall Occurs in cool, moist springs Spores for next year’s infection are released when leaf galls turn whitePrune infected leavesLeaves, and occasionally flower buds, become deformed, developing pink or white, soft fleshy growths called galls.
74Camellia Leaf GallLeaves, and occasionally flower buds, become deformed, developing pink or white, soft fleshy growths called galls.Spores for next year’s infection are released when backside of leaves turnwhiteCamellia leaf gall early symptoms and lastyear’s infected leaves
75Leaf Gall ControlRemove galls and destroy before they turn white with sporesDisease most severe when foliage becomes wet during leaf expansion in spring.Avoid planting in heavy shadeAvoid wetting foliage in springIf the disease was severe in previous years and galls were too numerous to pick, apply a fungicide before new leaves and flowers emerge.Applications can stop when leaves become full sizeBayleton. Apply first spray as new leaves and flowers appear. Repeat 2-3 times at 10-day intervals.Problem: Some leaves have red or yellow spots. Other leaves, and occasionally flower buds, become deformed, developing pink or white, soft fleshy growths called galls.Remove galls by hand. Apply first spray as new leaves appear. Repeat 2-3 times at 10-day intervals. Plant Azaleas resistant to leaf gall
76Powdery Mildew Common disease on dogwood and other plants Looks like baby powderUse Resistant Cultivars:Cherokee Brave, Karen’s Appl. Blush, Kay’s Appl. Mist, Jean’s Appl. SnowStart sprays at first sign of disease (early May)Fungicides:HeritageSpectricide ImmunoxFertilome Systemic FungicideFertilome Halt Systemic FungicidePowdery mildew will reduce growthOnce leaves are white fungicides are of little value
78Spot AnthracnoseSmall reddish spots on bracts and leaves, trees in sunRake leaves in fallHeritage, Daconil, Mancozeb, Halt, ImmunoxSpray before budbreak, after bract fall, and one month later, and September after new flower buds formHeritage, Daconil, Dithane/Protect, 3336, EagleHeritage, Daconil, Dithane/Protect, 3336, Eagle
79Dogwood Anthracnose Different disease than spot anthracnose Spots with reddish or purple bordersSpots enlarge over timeLeaf, twig blights, cankers, can kill treeBlighted leaves remain attached through winterResistant Cultivar ‘Appalachian Spring’
80Hydrangea – Leaf SpotSeveral fungi cause leaf spots on hydrangea – Cercospora, Corynespora, ColletotrichumOften in combination with powdery mildewAdequate plant spacing for good air circulationAvoid watering late in the dayRemove fallen leavesApply fungicide at first sign of disease:Heritage, Daconil*, Immunox Mancozeb*, Fertilome Systemic Fungicide* Poor control of powdery mildew, but good leaf spot controlUltra-fine Spray Oil
83Botryosphaeria Canker UGAJ. L. Williams-Woodward - UGA
84Control of Canker Diseases Difficult to control once infection has occurredPrevent canker diseases by proper establishment and care:Plant in well drained soilsadequate plant spacingIrrigate plants to prevent drought stress, mulch plantsRemove branches with cankers. Trace the dead wood back to the base of the canker and prune at bud or branch fork. Prune 4-6 inches below canker.Sterilize pruning tools frequentlyAvoid canker susceptible plantsFungicides are of little value