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 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.

Alternaria Damping Off

Buy seed certified as disease-free or treat with hot water at 122°F for 25 minutes (see Hot Water Treatment of Seed, page 78). Brassica crop seed is susceptible to seed vigor loss from hot water treatment. Seed should be treated as close to planting as possible.

Alternaria Leaf Spot and Head Rot

Alternaria leaf spot and head rot are caused by at least three species of the fungus Alternaria, and may be seed-borne. Start with certified disease-free seed, or treat seed with hot water. Practice a 3-year crop rotation with all brassica crops. Take measures to decrease the amount of time that leaves are wet: increase row and plant spacing to improve air circulation and irrigate with overhead irrigation early in the mornings on sunny days or use drip irrigation instead of overhead irrigation. Control brassica weeds. Avoid working in fields when foliage is wet. Promptly incorporate plant debris after harvest, or mow if tillage is not possible in late fall crops. Differences in variety susceptibility exist but no resistant varieties are available. Avoid overhead irrigation to prevent broccoli head rot.

azoxystrobin (Quadris): 6.0 to 15.5 fl oz/A; PHI 0d, REI 4h, Group 11. Do not repeat the application or rotate with other strobilurins. See label for list of allowed brassica crops.

azoxystrobin plus difenoconazole (Quadris Top): 12.0 to 14.0 fl oz/A; PHI 1d, REI 12h, Groups 11 & 3.

Bacillus amyloliquefaciens strain D747 (DoubleNickelOG): 0.25 to 3.0 lb/A; PHI 0d, REI 4 h, Group BM 02. Disease suppression only. For improved control; mix or rotate with a chemical fungicide.

boscalid (Endura): 6.0 to 9.0 oz/A; PHI 0d, REI 12h, Group 7. Maximum 2 applications per year.

botanical extract (EcoswingOG): 1.5 to 2.0 pt/A; PHI 0d, REI 4h, Group BM 01.

chlorothalonil (Bravo Weather Stik): 1.5 pt/A; PHI 7d, REI 12h, Group M 05.

copper hydroxide (Kocide 3000): 0.5 to 0.75 lb/A; PHI 0d, REI 48h, Group M 01.  Do not apply in a spray solution having a pH less than 6.5 or tank mix with Aliette.

cyprodinil plus fludioxonil (Switch 6.25 WG): 11.0 to 14.0 oz/A; PHI 7d, REI 12h, Groups 9 and 12.

difenoconazole plus cyprodinil (Inspire Super): 16.0 to 20.0 fl oz/A; PHI 7d, REI 12h, Group 3 and 9. Apply in sufficient volume to achieve thorough coverage. 

fenamidone (Reason SC): 8.2 fl oz/A; PHI 2d, REI 12h, Group 11. Do not alternate with other Group 11 fungicides.

flutriafol (Rhyme 2.08 SC): 5 to 7 fl oz/A; PHI 7d, REI 12h, Group 3.

fluxapyroxad plus pyraclostrobin (Priaxor Xemium): 6.0 to 8.2 fl. oz/A; PHI 3d, REI 12 h, Groups 7 and 11.

mancozeb (Manzate Pro Stick): 1.6 to 2.1 lb/A; PHI 7d, REI 24h, Group M 03. Cabbage and broccoli only.

penthiopyrad (Fontelis): 14.0 to 30.0 fl oz/A; PHI 0d, REI 12h), Group 7.

polyoxin D (OSO 5%SC): 6.5 to 13.0 fl oz/A; PHI 0d, REI 4h, Group 19.

potassium bicarbonate (PB 133, AKA MilStopOG): 2.5 lb to 5.0 lb/100 gal; PHI 0d, REI 1h, Group NC. See label for small volume application rates.

pseudomonas chloraphis (HowlerOM): 2.5 to 7.5 lbs/A. PHI 0d, REI 4h, Group BM 02. Use preventatively. 

pydiflumetofen plus fludioxonil (Miravis Prime): 11.4 fl oz/A; PHI 7d, REI 12h, Groups 7 and 12.

pyraclostrobin (Cabrio EG): 12.0 to 16.0 oz/A; PHI 0d, REI 12h, Group 11.

triflumizole (Procure): 6 to 8 fl oz/A; PHI 1d, REI 12h, Group 3.

Black Leg (Phoma lingam, Leptosphaeria maculans)

Black leg is a fungal disease of brassica crops. Use 3- to 4-year crop rotation. Start with certified, disease-free seed, or treat seed with hot water. Inspect seedlings for infection before planting out into the field. Take measures to decrease the amount of time that leaves are wet: increase row and plant spacing to improve air circulation and irrigate with overhead irrigation early in the mornings on sunny days or use drip irrigation instead of overhead irrigation. Control brassica weeds. Avoid working in fields when foliage is wet. Promptly incorporate plant debris after harvest, or mow if tillage is not possible in late fall crops.

fluxapyroxad plus pyraclostrobin (Priaxor Xemium): 6.0 to 8.2 fl. oz/A; PHI 3d, REI 12 h, Groups 7 and 11.

iprodione (Rovral 4F): 2.0 pt/A; PHI 0d, REI 24h, Group 2. Broccoli ONLY.

potassium bicarbonate (MilStopOG): 2.5 to 5.0 lb/100 gal; PHI 0d, REI 4h, Group NC. See label for small volume application rates.

pyraclostrobin (Cabrio EG): 12.0 to 16.0 oz/A; PHI 0d, REI 12h, Group 11.

thiram (Thiram 42-S):  8 lb/A. Seed treatment; REI 24h, Group M3.

Black Rot (Xanthomonas campestris pv. campestris)

Black rot is a bacterial disease of brassica crops. Practice a 3-year crop rotation with all brassica crops. Start with certified disease-free seed or treat seed with hot water. Take measures to decrease the amount of time that leaves are wet: increase row and plant spacing to improve air circulation and irrigate with overhead irrigation early in the mornings on sunny days or use drip irrigation instead of overhead irrigation. Control brassica weeds. Avoid working in fields when foliage is wet. Promptly incorporate plant debris after harvest, or mow if tillage is not possible in late fall crops.

acibenzolar-S-methyl (Actigard): 0.5 to 1.0 oz/A; PHI 7d, REI 12h, Group P 01. Suppression only.

copper hydroxide (Kocide 3000): 0.5 to 0.75 lb/A; PHI 0d, REI 48h, Group M 01.  Do not apply in a spray solution having a pH less than 6.5 or tank mix with Aliette.

mancozeb plus copper hydroxide (ManKocide): 1.0 to 1.75 lb/A; PHI 7d, REI 48h, Groups M 03 & M 01. Not labeled for cauliflower.

pseudomonas chloraphis (HowlerOM): 2.5 to 7.5 lbs/A. PHI 0d, REI 4h, Group BM 02. Use preventatively. Not labeled for cauliflower.

Club Root (Plasmodiophora brassicae)

There is currently no way to eliminate club root from infested soil, but the pathogen can be slowed down by practicing a long crop rotation and increasing soil pH. Maintain soil at a pH of 7.0 to 7.2 by applying lime a maximum of 1000 lbs/A per application. Practice a routine 3-year rotation for all brassica crops; if club root is detected in a field, rotate out of brassicas in that field for 7 years. After a 7-year crop rotation, pH adjustment and fungicide applications may reduce the viable club root spores to below economic threshold levels of infection for many growing seasons to come. Cold, wet soils favor club root development and spore survival. Resistant varieties of some brassica crops are available. Prevent the movement of infested soil and irrigation water into uninfested fields.

cyazofamid (Ranman): 12.9 to 25.75 fl oz/100 gal (transplant drench); PHI 0d, REI 12h, Group 21. Tank mix with an organosilicone surfactant. Transplant soil drench or soil incorporation. See label for details.

fluazinam (Omega 500 F):  6.45 fl oz/100gal (transplant drench); PHI 7-50d, REI 12h, Group 29. Transplant soil drench or incorporation. PHI varies by crop. See label for details.

PCNB (Blocker 4F): Rate varies depending upon application method - see label; REI 12h, Group 14. For transplant applications, mix 3 pts into 100 gal water and use 0.5 to 0.75 pts solution per plant, based on severity of field infestation. Maintain agitation to hold product in suspension. For banded applications, apply as a 12-inch band, in 25 gal water per acre or 5.5 fl oz water per 100 ft of row based on 40-inch row spacing. For broadcast applications, apply in 30 gal water prior to planting. For all application methods, thoroughly incorporate into soil after application.

Downy Mildew (Hyaloperonospora parasitica)

Resistant varieties of some brassica crops are available. Take measures to decrease the amount of time that leaves are wet: increase row and plant spacing to improve air circulation and irrigate with overhead irrigation early in the mornings on sunny days or use drip irrigation instead of overhead irrigation.  

acibenzolar-S-methyl (Actigard): 0.5 to 1.0 oz/A; PHI 7d, REI 12 h, Group P 01.

ametoctradin plus dimethomorph (Zampro): 14.0 fl oz/A; PHI 0d, REI 12h, Groups 45 and 40.

azoxystrobin (Quadris): 6.0 to 15.5 fl oz/A; PHI 0d, REI 4h, Group 11.

Bacillus amyloliquefaciens strain D747 (DoubleNickelOG): 0.12 to 1.0 lb/A as a soil drench; PHI 0d, REI 4 h, Group 44. Suppression only. For improved control, mix or rotate with an approved chemical fungicide.

chlorothalonil (Bravo Weather Stik): 1.5 pt/A; PHI 7d, REI 12h, Group M 05. See label for replant restrictions.

copper hydroxide (Kocide 3000): 0.5 to 0.75 lb/A; PHI 0d, REI 48h, Group M 01. Do not apply in a spray solution having a pH less than 6.5 or tank mix with Aliette.

cyazofamid (Ranman):  2.75 fl oz/A (foliar application); PHI 0d, REI 12h, Group 21. Tank mix with an organosilicone surfactant. 

dimethomrph (Forum): 6.0 fl oz/A; PHI 7d, REI 12h, Group 40. Apply in combination with a labeled rate of another non-group 40 fungicide.

fenamidone (Reason SC): 5.5 to 8.2 fl oz/A; PHI 2d, REI 12h, Group 11. Do not alternate with other Group 11 fungicides.

fluazinam (Omega 500F): 15.35 fl oz/A (foliar application); PHI 7d, REI 12-48h, Group 29. Cabbage and Chinese cabbage ONLY. REI = 48h for handset irrigation, 12h for all other activites.

fluopicolide (Presidio): 3.0 to 4.0 fl oz/A; PHI 2d, REI 12h, Group 43. Tank mix with a fungicide from a different group.

fosetyl aluminum (Aliette WDG): 3.0 to 5.0 lb/A; PHI 3d, REI 12h, Group 33. Do not mix with copper fungicides. Lower rates of Aliette (2 to 3 lb) can be used when tank mixed with another fungicide labeled for downy mildew control.

mancozeb plus copper hydroxide (ManKocide): 1.0 to 1.75 lb/A; PHI 7d, REI 48h, Groups M 03 & M 01. Broccoli and cabbage only.

mandipropamid (Revus): 8.0 fl oz/A; PHI 1d, REI 4h, Group 40. A spreading/penetrating type adjuvant must be added.

mefenoxam (Subdue MAXX): 25 to 50 pt/A; PHI 7d, REI 48h, Group 4. Do not apply foliar sprays without a labeled tank mix partner.

mefenoxam plus chlorothalonil (Ridomil Gold Bravo): 1.5 pt/A; PHI 7d, REI 48h, Groups 4 and M 05. See label for plant-back restrictions and restrictions on certain crucifers.

oxathiapiprolin and mandipropamid (Orondis Ultra): 5.5 to 8.0 fl.oz/A; PHI 1d, REI 4h, Groups 49 and 40. Begin foliar application prior to disease development. Use higher rate when disease is present. A spreading/penetrating adjuvant must be added.

phosphorous acid  (Fosphite): 1.0 to 3.0 qt/100 gal; PHI 0d, REI 4h, Group 33. Do not apply to plants that heat or moisture stressed. Do not apply directly to copper treated plants within 20-day interval to avoid plant injury.

potassium bicarbonate (PB 133, AKA MilStopOG): 2.5 to 5.0 lb/100 gal; PHI 0d, REI 1h, Group NC. See label for small volume application rates.

pseudomonas chloraphis (HowlerOG): 2.5 to 7.5 lbs/A. PHI 0d, REI 4h, Group BM 02. Use preventatively.

pyraclostrobin (Cabrio EG): 12.0 to 16.0 oz/A; PHI 0d, REI 12h, Group 11.

Reynoutria sachalinensis extract (RegaliaOG): 1.0 to 4.0 qt/A ground application; PHI 0d, REI 4 h, Group P5. Apply to ensure thorough coverage. See label for specific application instructions.

Fusarium Yellows

This fungal pathogen is soil-borne and may also be seed-borne. Plant resistant varieties. Prevent the movement of infested soil to clean fields. Provide adequate fertility; potassium deficiency increases disease severity.

Seed Decay and Damping-off

Buy treated seed. Do not use treated seed for food, feed or oil purposes.

Bacillus amyloliquefaciens strain D747 (DoubleNickelOG): 0.125 to 1.0 lb/A at planting; PHI 0d, REI 4h, Group 02. Suppression only.

mefenoxam (Apron XL): 0.32 to 0.64 fl oz/lb seed; REI 48h, Group 4. For Pythium damping-off protection.

Streptomyces griseoviridis strain K61 (MycoStopOG): See label for rate information; REI 4h.

thiram (Thiram 42-S): 8.0 fl oz/100 lb.; REI 24h, Group M 03.

Wire Stem, Crater rot, and Head rot (Rhizoctonia solani)

Diseases of brassica crops in this section caused by R. solani include wirestem and damping-off (seedlings) and bottom or head rot (cabbage). Rhizoctonia can be carried on the seeds of most brassica species and is ubiquitous in most soils, where it survives indefinitely. Start with certified, disease-free seed. Practice good sanitation in transplant production – sanitize transplant trays between uses and keep production tools and hoses off of the greenhouse floor when not in use. Successful sanitation in transplant production prevents further need for fungicide drenches. Use treated seed for direct seeding into field. Practices that encourage rapid germination and establishment limit disease development. Avoid planting transplants too deeply. Rotate crops. Do not plant susceptible crucifers in fields with undecomposed crop residues. No highly resistant varieties are available. Fungicide treatments in the field have limited effectiveness.

PCNB (Blocker 4F): Rate varies depending upon application method - see label; REI 12h, Group 14. Pathogen referred to as Corticium solani on label.

polyoxin D (OSO 5%SC): 6.5 to 13.0 fl oz/A; PHI 0d, REI 4h, Group 19.

Turnip Mosaic Virus

Turnip mosaic virus can infect most brassica crops but it is most commonly seen in Chinese cabbage and bok choy. It is spread by many species of aphids in a nonpersistent manner; therefore, insecticides are of little or no value in controlling its spread. This virus survives the winter in perennial weeds. It is spread by many species of aphids. Resistant cultivars include: Nabyeng, Kongng, Tip Top and Ta Feng. These cultivars may not be completely resistant and may have some intolerance to heat.