Disease Control

NOTE: For the disease control products listed below, one product trade name and formulation is provided for each active ingredient (common name) as an example of rates, preharvest interval (PHI), restricted entry interval (REI), and special instructions. In many cases, there are other products available with the same active ingredient. Please see Table 28 and Fungicides and Bactericides Alphabetical Listing by Trade Name for more information on products with the same active ingredients.

The symbol OG   indicates a product is listed by the Organic Materials Review Institute (OMRI) as approved for use in organic production. See Organic Certification section for more detail.

Damping-Off, Seed Decay, Root Rot, and Stem Canker

Plant early in well-drained and well-fertilized soil. Use a 3 to 4-year rotation.

Bacillus amyloliquefaciens strain D747 (DoubleNickel LCOG): 0.5 to 4.5 pt/A; PHI 0d, REI 4 h, Group 44. Disease suppression only. For improved control; mix or rotate with a chemical fungicide.

fludioxonil (Maxim 4FS): 0.8 to 0.16 oz/100 lb seed; REI 12h, Group 12. For protection against seed-borne and soil-borne fungi.

mefenoxam (Apron XL): 0.16 to 0.64 fl oz/100 lb seed; REI 48h, Group 4 . For Pythium damping-off.  Early season Phytophthora protection (0.64 fl oz/100 lb seed), and systemic downy mildew protection (1.28 fl oz/100 lb seed).

Streptomyces lydicus strain WYEC (Actinovate AGOG):  3 to 12 oz/A; Group NC. Can be applied to seed.

Trichoderma harzianun Rifai strain T-22: (Root Shield GranulesOG): 5 to 12.0 lb/A; Group NC. In-furrow at time of planting.

Rhizoctonia root rot and stem canker

Rhizoctonia stem canker caused by strains of the soil-borne fungus Rhizoctonia solani is common throughout the world. The pathogen survives between crop seasons as sclerotia (survival structures), mycelium in the soil, or on or in infected plant debris.  It is spread in infested soil or plant debris by wind, rain, irrigation water, and machinery. When a soil becomes infested, it remains so indefinitely. 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. 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 increase inoculum). Cover crops and other practices that to increase organic matter and improve soil structure are recommended. Some brassica crops (mustard, rape) used as green manure have been reported to be disease suppressive. 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. (See above).