Damping-Off, Seed Decay, Root Rot, and Stem Canker (Pythium, Rhizoctonia, Fusarium, etc.)
Seedlings and young plants are highly susceptible to infection and disease severity is increased by low soil temperatures and soil compaction. Seed decay and damping-off can be controlled by using high-quality seed with high germination and vigor, and by practices that encourage rapid germination and emergence. Seed treatments are not effective against infections later in the season. Plant early in well-drained and well-fertilized soil. Use a 3- to 4-year rotation.
FRAC Group 4:
- mefenoxam (Apron XL): 0.64 to 1.28 fl oz/100 lb seed; REI 48h. For protection against Pythium damping-off, early-season Phytophthora (0.64 fl oz/100 lb seed), and systemic downy mildew (1.28 fl oz/100 lb seed).
FRAC Group 7:
- pydiflumetofen (Trebuset): 0.15 to 1.53 fl oz/100 lb seed; REI 12h. For Fusarium root rot. See label for plant-back intervals.
- sedaxane (Vibrance): 0.08 to 0.16 fl oz/100 lb seed; REI 12h. Labeled for seed decay, seedling blights, and Rhizoctonia damping-off. See label for plant-back intervals.
FRAC Group 12:
- fludioxonil (Maxim 4FS): 0.08 to 0.16 oz/100 lb seed; REI 12h. For protection against seedborne and soilborne fungi.
FRAC Group BM02:
- Bacillus amyloliquefaciens strain D747 (Double Nickel LCOG): 0.125 to 1 lb/A (soil), 0.25 to 3 lb/A (foliar); PHI 0d, REI 4h.
- Streptomyces lydicus strain WYEC 108 (Actinovate AGOG): 1 to 12 oz/A; REI 4h. Can be applied to seed.
- Trichoderma harzianum Rifai strain T-22: (Root Shield GranulesOG): 5 to 12 lb/A; REI 4h. In-furrow at time of planting.
Rhizoctonia Root Rot and Stem Canker
Rhizoctonia root rots and stem canker are caused by strains of the soilborne fungus Rhizoctonia solani that are common throughout all soils. The pathogen survives between crop seasons as sclerotia (survival structures), mycelium in the soil, or in infected plant debris. It is spread in infested soil or plant debris by wind, rain, irrigation water, and machinery. When soil becomes infested, the problem will persist indefinitely. Seedlings and young plants are highly susceptible to infection and disease severity is increased by low soil temperatures and soil compaction. Seed treatments are not effective against infections later in the season.
The disease may be reduced by sowing seed as shallowly as possible in warm, moist soil. Land preparation that minimizes soil compaction and structural damage will lessen disease severity. Rotate crops with a cereal or pasture crop (avoid beets, beans, brassicas, and potatoes, which can increase inoculum). Cover crops and other practices that increase organic matter and improve soil structure are recommended. Some brassica crops (mustard, rape) used as green manure have been reported to suppress Rhizoctonia. Avoid incorporating green manure immediately before planting and damaging roots by shallow cultivation. Fungicides can manage Rhizoctonia root rot on young seedlings if applied as a seed treatment or soil drench.