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 25 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 details.
Leaf Spots (Alternaria and Cercospora)
Leaf spot fungi do not infect the root but infection can reduce yield, and blighted foliage can reduce the value of fresh-packed plants. Hot water seed treatment can eliminate seedborne fungal pathogens but will not protect from airborne inoculum. To reduce infection by airborne inoculum, control weeds to improve airflow and encourage leaf drying, and plow under crop debris promptly in the fall. Practice a 3-year crop rotation out of brassicas.
azoxystrobin (Abound, AKA Quadris): 6.0 to 20.0 fl oz/A; PHI 0d, REI 4h, Group 11. Do not rotate with other Group 11 fungicides.
Bacillus amyloliquefaciens strain D747 (CX 9030OG, AKA Double Nickel 55OG): 0.25 to 3.0 lb/A; PHI 0d, REI 4h, Group BM2. Applied as foliar spray. See label for application methods and instructions.
copper hydroxide (Kocide 3000): 0.5 to 0.75 lb/A; PHI 0d, REI 48h, Group M1. For turnip greens only.
cyprodinil plus fludioxonil (Switch 6.25 WG): 11.0 to 14.0 oz/A; PHI 7d, REI 12h, Groups 9 & 12.
penthiopyrad (Fontelis): 16.0 to 30.0 fl oz/A; PHI 0d, REI 12h, Group 7.
pyraclostrobin (Cabrio EG): 8.0 to 12.0 oz/A; PHI 0d, REI 12h, Group 11. Do not rotate with other Group 11 fungicides.
Black Leg (Phoma Leaf Spot and Canker)
From foliar lesions, the fungal pathogen that causes black leg spreads into leaf veins to the petioles and eventually the main stem. On root crops, such as rutabaga and turnip, a dry rot of the bulb or hypocotyl develops. The neck and shoulder areas develop large, brown lesions, followed by an extensive dry rot deep into the fleshy tissue. Severely affected bulbs become shriveled and dry, and are often invaded by secondary fungal and bacterial decay organisms. Start with certified or treated seed, or treat seed with hot water or fungicides. Rotate out of brassicas for 4 years. Promptly incorporate infected crop debris after harvest. Eliminate cruciferous weeds, which can act as hosts. Apply foliar fungicides to protect susceptible cultivars (see above).
Seed Decay and Damping-Off
Damping-off diseases are favored by cool, cloudy weather, wet and/or compacted soils, high humidity, and overcrowding. Plant into well-drained and well-fertilized soil when conditions are conducive to fast germination and growth. Avoid excessive irrigation.
azoxystrobin (Abound, AKA Quadris): 0.4 to 0.8 fl oz/1000 row ft.; PHI 0d, REI 4h, Group 11. For Rhizoctonia root rot control applied as in-furrow application. See label for restrictions.
Bacillus amyloliquefaciens strain D747 (CX 9030OG, AKA Double Nickel 55OG): 0.125 to 1.0 lb/A; PHI 0d, REI 4h, Group BM2. See label for application methods and instructions.
fludioxonil (Maxim 4FS): 0.08 to 0.16 oz/100 lb seed; REI 12h, Group 12. For protection against seedborne and soilborne fungi. Does not control Pythium or Phytophthora. Use as seed treatment prior to seedling.
fluopicolide (V-10161 4 C, AKA Presidio): 3.0 to 4.0 fl oz/A; REI 12h, Group 43. Apply for Pythium root rot control as banded spray. See label for additional restrictions.
mefenoxam (Ridomil Gold SL): 1.0 to 2.0 pt/A; REI 48h, Group 4. Pre-plant incorporated or soil spray broadcast or band).
White Rust, White blister (Albugo candida)
Yield reductions are rare, but quality is reduced by the prominent signs of the pathogen. On radish, white rust can also infect flower shoots and cause root swellings. Use resistant cultivars where available and rotate to non-hosts where the disease is common. Proper fertility levels, especially of phosphorus and potassium, have been reported to reduce disease.
azoxystrobin (Abound, AKA Quadris): 6.0 to 20.0 fl oz/A; PHI 0d, REI 4h, Group 11. Do not alternate with another Group 11 fungicide.
copper hydroxide (Kocide 3000): 0.5 to 0.75 lb/A; PHI 0d, REI 48h, Group M1. Not labeled for rutabaga. An organic formulation is available.
copper oxychloride plus copper hydroxide (Badge X2OG): 1.0 to 2.25 lb/A; PHI 0d, REI 48h, Group M1. Labeled for rutabaga and turnip.
pyraclostrobin (Cabrio EG): 8.0 to 16.0 oz/A; PHI 0d, REI 12h, Group 11. Do not rotate with other Group 11 fungicides.