BEAN ROOT HEALTH. H. F. Schwartz Colorado State University

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1 H. F. Schwartz Colorado State University

2 Seed Rots seed-borne organisms that rot the seed prior to germination; Penicillium, Pythium, Aspergillus Aspergillus species Pre-emergence emergence Damping Off damping-off organisms that attack the stem tissue near the soil line; Pythium,, Rhizoctonia, Fusarium species Post-emergence Damping Off results from tissue collapse starting in the leaves as a wilt, yellowing, death; Pythium,, Rhizoctonia, Fusarium species Root Rots & Wilts soil-borne organisms that reduce root vigor and health; Pythium,, Rhizoctonia, Fusarium species

3 Diagnostics Pythium Diseases

4 Diagnostics Rhizoctonia Root Rot

5 Diagnostics Rhizoctonia Root Rot

6 Diagnostics Fusarium Root Rot

7 Diagnostics Fusarium Root Rot

8 Diagnostics Fusarium Wilt (Yellows)

9 Diagnostics Fusarium Wilt (Yellows)

10 Disease Development - Role of Fungi survive as spores, mycelium &/or sclerotia in soil and multiply on: Weeds Host Crops Non-host Crops

11 Factors Favoring Disease Soil Moisture High Moderate to High Low to High Soil Temperature Low to High Low to Moderate Moderate to High Soil Compaction Poor Drainage Herbicide Toxicity Yes Crop Rotation < 2 years Potato, Sugar Beet strains < 2 years

12 Disease Management Under Varying Water Conditions Disease Potential Deficient Average Excess

13 Disease Management Under Varying Temperatures Disease Potential < 80 F Average > 90 F

14 Disease Management

15 Soil-borne Disease Management Seed Treatment application of bioactive chemicals, antagonists or symbiotic microorganisms to seed prior to sowing Seed Enhancement post-harvest treatments that improve germination, seedling growth, or sowing; includes priming, coating, seed conditioning

16 Non-systemic Seed Treatment thiram, captan,, PCNB (terrachlor( terrachlor) Locally Systemic Seed Treatment fludioxonil (Maxim), thiabendazole Systemic Seed Treatment carboxin (Vitavax), metalaxyl (Apron), mefenoxam, azoxystrobin Plant Growth Regulator & Enhancers enhance seed vigor, emergence, growth; PGR, polymers, uniform seed shape/size Biological Control Agents Bacillus subtilis, Gliocladium catenulatum, Streptomyces griseoviridis, Trichoderma harzanium, Coniothyrium spp.

17 Disease Management

18 Soil-borne Disease Management C:N C:N Amendment amendments with high C:N ratios suppressed Fusarium root rot of bean; chlamydospores require Nitrogen to germinate in the soil suppression is often eliminated by addition of fertilizer or crop debris with high levels of Nitrogen do not supplement organic matter with ammonium nitrate which may enhance root rot disease

19 Compost Plant 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

20 Composting Process - Phases Initial mixing period with mesophilic ( F) growth Thermophilic ( 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

21 Composting Process - Phases Standards minimum temperature of 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 microorganisms or other amendments

22 Composting 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

23 Compost Plant 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

24 Compost 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

25 Disease Management

26 Diagnostics Abiotic Stress

27 Diagnostics Abiotic Stress

28 Disease Management

29 Soil Compaction Effects on Dry Beans Ave Yield C-NPTR C-PTR NC-NPTR NC-PTR

30 Soil Compaction Effects on Dry Beans C-NPTR C-PTR NC-NPTR NC-PTR $ Return/A

31 I P M Strategy - Root Rots Volunteers / Sanitation Crop Rotation Variety Selection Seed Quality Planting Date Tillage Irrigation Fertility Pesticides / Compost Effectiveness Low High Moderate Low High High Moderate Moderate Moderate Graphic by H. F. Schwartz, C S U

32 Questions?? H. F. Schwartz Colorado State University