BEAN ROOT HEALTH BEAN ROOT HEALTH H. F. Schwartz H. F. Schwartz Colorado State University Colorado State University
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
0
500
1000
1500
2000
2500
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