BEAN ROOT HEALTHBEAN ROOT HEALTH

H. F. SchwartzH. F. SchwartzColorado State UniversityColorado State University

BEAN ROOT HEALTHBEAN ROOT HEALTHSeed RotsSeed Rots

seedseed--borne organisms that rot the seed prior to borne organisms that rot the seed prior to germination;germination; PenicilliumPenicillium, , PythiumPythium, , AspergillusAspergillus speciesspecies

PrePre--emergence Damping Offemergence Damping Offdampingdamping--off organisms that attack the stem tissue off organisms that attack the stem tissue

near the soil line;near the soil line; PythiumPythium, Rhizoctonia, Fusarium , Rhizoctonia, Fusarium speciesspecies

PostPost--emergence Damping Offemergence Damping Offresults from tissue collapse starting in the leaves results from tissue collapse starting in the leaves

as a wilt, yellowing, death;as a wilt, yellowing, death; PythiumPythium, Rhizoctonia, , Rhizoctonia, Fusarium speciesFusarium species

Root Rots & WiltsRoot Rots & Wiltssoilsoil--borne organisms that reduce root vigor and borne organisms that reduce root vigor and

health;health; PythiumPythium, Rhizoctonia, Fusarium species, Rhizoctonia, Fusarium species

BEAN ROOT HEALTHBEAN ROOT HEALTHDiagnostics Diagnostics –– PythiumPythium Diseases Diseases

BEAN ROOT HEALTHBEAN ROOT HEALTHDiagnostics Diagnostics –– Rhizoctonia Root Rot Rhizoctonia Root Rot

BEAN ROOT HEALTHBEAN ROOT HEALTHDiagnostics Diagnostics –– Rhizoctonia Root Rot Rhizoctonia Root Rot

BEAN ROOT HEALTHBEAN ROOT HEALTHDiagnostics Diagnostics –– Fusarium Root Rot Fusarium Root Rot

BEAN ROOT HEALTHBEAN ROOT HEALTHDiagnostics Diagnostics –– Fusarium Root Rot Fusarium Root Rot

BEAN ROOT HEALTHBEAN ROOT HEALTHDiagnostics Diagnostics –– Fusarium Wilt (Yellows) Fusarium Wilt (Yellows)

BEAN ROOT HEALTHBEAN ROOT HEALTHDiagnostics Diagnostics –– Fusarium Wilt (Yellows) Fusarium Wilt (Yellows)

BEAN ROOT HEALTHBEAN ROOT HEALTHDisease Development Disease Development -- Role of Role of

Fungi survive as spores, mycelium &/or sclerotia in soil and multiply on:

Weeds

Host Crops

Non-host Crops

BEAN ROOT HEALTHBEAN ROOT HEALTHFactors Favoring DiseaseFactors Favoring Disease

Soil Soil MoistureMoisture HighHigh

Moderate Moderate to Highto High Low to HighLow to High

Soil Soil TemperatureTemperature Low to HighLow to High

Low Low to Moderateto Moderate

ModerateModerateto Highto High

SoilSoilCompactionCompaction

Poor DrainagePoor Drainage

Herbicide Herbicide ToxicityToxicity

YesYes

CropCropRotationRotation < 2 years< 2 years

Potato, Potato, Sugar Beet Sugar Beet ––strainsstrains

< 2 years< 2 years

Disease Management Under Varying Water Conditions

Disease Disease PotentialPotential

DeficientDeficient AverageAverage ExcessExcess

Disease Management Under Varying Temperatures

Disease Disease PotentialPotential

< 80 F< 80 F AverageAverage > 90 F> 90 F

BEAN ROOT HEALTHBEAN ROOT HEALTHDisease ManagementDisease Management

SoilSoil--borne Disease Managementborne Disease Management

Seed TreatmentSeed Treatmentapplication of bioactive chemicals, antagonists application of bioactive chemicals, antagonists or symbiotic microorganisms to seed prior to or symbiotic microorganisms to seed prior to sowingsowing

Seed EnhancementSeed Enhancementpostpost--harvest treatments that improve harvest treatments that improve germination, seedling growth, or sowing; germination, seedling growth, or sowing; includes priming, coating, seed conditioningincludes priming, coating, seed conditioning

BEAN ROOT HEALTHBEAN ROOT HEALTHNonNon--systemic Seed Treatmentsystemic Seed Treatment

thiramthiram, , captancaptan, PCNB (, PCNB (terrachlorterrachlor))Locally Systemic Seed TreatmentLocally Systemic Seed Treatment

fludioxonilfludioxonil (Maxim), (Maxim), thiabendazolethiabendazoleSystemic Seed TreatmentSystemic Seed Treatment

carboxincarboxin ((VitavaxVitavax), ), metalaxylmetalaxyl (Apron),(Apron),mefenoxammefenoxam, , azoxystrobinazoxystrobin

Plant Growth Regulator & EnhancersPlant Growth Regulator & Enhancersenhance seed vigor, emergence, growth; PGR, enhance seed vigor, emergence, growth; PGR,

polymers, uniform seed shape/sizepolymers, uniform seed shape/sizeBiological Control AgentsBiological Control Agents

Bacillus Bacillus subtilissubtilis, , GliocladiumGliocladium catenulatumcatenulatum, , StreptomycesStreptomycesgriseoviridisgriseoviridis, , TrichodermaTrichoderma harzaniumharzanium, , ConiothyriumConiothyrium sppspp..

BEAN ROOT HEALTHBEAN ROOT HEALTHDisease ManagementDisease Management

SoilSoil--borne Disease Managementborne Disease Management

C:N AmendmentC:N Amendment

amendments with high C:N ratios suppressed amendments with high C:N ratios suppressed Fusarium root rot of bean; Fusarium root rot of bean; chlamydosporeschlamydospores require require Nitrogen to germinate in the soilNitrogen to germinate in the soil

suppression is often eliminated by addition of suppression is often eliminated by addition of fertilizer or crop debris with high levels of Nitrogenfertilizer or crop debris with high levels of Nitrogen

do not supplement organic matter with ammonium do not supplement organic matter with ammonium nitrate which may enhance root rot diseasenitrate which may enhance root rot disease

Compost Compost ––Plant Disease Control ExamplesPlant Disease Control Examples

• Greenhouse systems with ornamentals and vegetables

• Examples include fungi, bacteria, viruses, nematodes, insects

•Phytophthora Root & Wilt of pepper in NM

•Ashy Stem Blight of snap bean and Rhizoctonia root rot of black eye pea in FL

Composting Process Composting Process -- PhasesPhases

• Initial mixing period with mesophilic (77 –104 0 F) growth

• Thermophilic (113 – 167 0 F) phase (sanitization)

• Low temperature mesophilic phase (maturation or stabilizaton)

• Tailored Compost - enhancement of the natural ability of compost to suppress diseases by enriching it with specific disease-fighting micro-organisms or other amendments

Composting Process Composting Process -- PhasesPhases

• Standards – minimum temperature of 130 –150 0 F) for 3 – 14 days, depending on the composting system

•Tailored Compost - enhancement of the natural ability of compost to suppress diseases by enriching it with specific disease-fighting micro-organisms or other amendments

Composting Effects on PathogensComposting Effects on Pathogens• generation of heat during composting process

• production of toxic compounds, e.g., organic acids and ammonia

• lytic activity of enzymes produced in the compost

• microbial antagonism (antibiotics, parasitism)

• competition for nutrients

• natural loss in viability of the pathogen with time

• compounds that stimulate resting stages of pathogens into premature germination

Compost Compost ––Plant Disease Control MechanismsPlant Disease Control Mechanisms

• Successful competition for nutrients by beneficial micro-organisms

• Antibiotic production by beneficials

• Successful predation against pathogens by beneficials

• Activation of disease resistant genes in plants by composts

Compost ChallengesCompost Challenges• Quality, consistency & expense of the composted product

• Variable content of essential plant nutrients & impact on nitrogen fertility (C / N ratio)

• Salt (sodium, chloride) content in the compost

• Exposure of humans to pathogens in animal wastes

• Contamination of surface and ground waters and foods with pathogens and nutrients

BEAN ROOT HEALTHBEAN ROOT HEALTHDisease ManagementDisease Management

BEAN ROOT HEALTHBEAN ROOT HEALTHDiagnostics Diagnostics –– Abiotic StressAbiotic Stress

BEAN ROOT HEALTHBEAN ROOT HEALTHDiagnostics Diagnostics –– Abiotic StressAbiotic Stress

BEAN ROOT HEALTHBEAN ROOT HEALTHDisease ManagementDisease Management

BEAN ROOT HEALTHBEAN ROOT HEALTHSoil Compaction Effects on Dry BeansSoil Compaction Effects on Dry Beans

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500

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1500

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C-NPTR C-PTR NC-NPTR NC-PTR

Ave Yield

BEAN ROOT HEALTHBEAN ROOT HEALTHSoil Compaction Effects on Dry BeansSoil Compaction Effects on Dry Beans

0102030405060708090

100

C-NPTR C-PTR NC-NPTR NC-PTR

$ Return/A

I P M Strategy I P M Strategy -- Root RotsRoot Rots

Volunteers / SanitationVolunteers / Sanitation LowLowCrop RotationCrop Rotation HighHighVariety SelectionVariety Selection ModerateModerateSeed QualitySeed Quality LowLowPlanting DatePlanting Date HighHighTillageTillage HighHighIrrigationIrrigation ModerateModerateFertilityFertility ModerateModeratePesticides / CompostPesticides / Compost ModerateModerate

Graphic by H. F. Schwartz, C S UGraphic by H. F. Schwartz, C S UGraphic by H. F. Schwartz, C S U

EffectivenessEffectiveness

Questions ??Questions ??

H. F. SchwartzH. F. SchwartzColorado State UniversityColorado State University