Disease Control : New England Vegetable Management Guide : UMass Amherst

NOTES: 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 26 and Fungicides and Bactericides Alphabetical Listing by Trade Name for more information on products with the same active ingredients.

The symbol ^OGindicates 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, in the Disease Management section). 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 seedborne. Start with certified disease-free seed or treat seed with hot water. Practice a 3-year crop rotation with all brassica crops. Use proper plant and row spacing to ensure good air circulation. Irrigate in the morning. Avoid overhead irrigation if possible. Control weeds, especially those in the family Brassicaceae. 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. Varieties differ in susceptibility but no resistant varieties are available.

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. Use sufficient water volume to provide thorough coverage.
Bacillus amyloliquefaciens strain D747 (DoubleNickel 55^OG): 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 (Ecoswing^OG): 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 500 SC): 8.2 fl oz/A; PHI 2d, REI 12h, Group 11. Do not alternate with other Group 11 fungicides.
flutriafol (Rhyme): 5.0 to 7.0 fl oz/A; PHI 7d, REI 12h, Group 3.
fluopyram (Velum Prime): 5.0 to 6.84 fl oz/A; PHI 0d, REI 12h, Group 7.
fluxapyroxad plus pyraclostrobin (Priaxor Xemium): 6.0 to 8.2 fl. oz/A; PHI 3d, REI 12 h, Groups 7 and 11.
laminarim (Vacciplant): 14.0 to 22.0 fl oz/A; PHI od, REI 4h, Group P04. See label for application methods and restrictions.
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 zinc salt (OSO 5%SC): 6.5 to 13.0 fl oz/A; PHI 0d, REI 4h, Group 19.
potassium bicarbonate (PB 133, AKA MilStop SP^OG): 2.0 to 5.0 lb/100 gal; PHI 0d, REI 1h, Group NC. See label for small volume application rates.
Pseudomonas chlororaphis (Howler^OG): 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.
thyme oil (Guarda): See label for rate; PHI 0h, REI 0h, Group NC. See label for application methods and rates.
triflumizole (Procure 480SC): 6.0 to 8.0 fl oz/A; PHI 1d, REI 12h, Group 3.

Black Leg (Phoma lingam, Leptosphaeria maculans)

Symptoms of this fungal disease include grayish lesions with dark borders on leaves and stems. All brassica crops are susceptible. Rotate away from brassicas for at least 3 years. Start with certified, disease-free seed, or treat seed with hot water. Inspect seedlings for infection before planting out into the field. Use proper plant and row spacing to ensure good air circulation. Avoid overhead irrigation if possible. Control weeds, especially those in the family Brassicaceae. 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 (MilStop SP^OG): 2.0 to 5.0 lb/100 gal; PHI 0d, REI 1h, 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. Use as seed transplant.

Black Rot (Xanthomonas campestris pv. campestris)

Symptoms of this bacterial disease include yellow to brown lesions, most often on the leaf margins. Some lesions will have a characteristic V shape and blackened veins. Practice a 3-year crop rotation with all brassica crops. Start with certified disease-free seed or treat seed with hot water. Use proper plant and row spacing to ensure good air circulation. Avoid overhead irrigation if possible. Control weeds, especially those in the family Brassicaceae. 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 50WG): 0.5 to 1.0 oz/A; PHI 7d, REI 12h, Group P 01. Suppression only.
Bacillus thuringiensis subsp. kurstaki strain ABTS-351 + methyl salicylate (Leap ES): See label for rate application; PHI 0d, REI 4h, Group 11A. See label for application methods and 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.
laminarim (Vacciplant): 14.0 to 22.0 fl oz/A; PHI od, REI 4h, Group P04. See label for application methods and restrictions.
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.
Pseudomonas chlororaphis strain AFS009 (Howler^OG): 2.5 to 7.5 lbs/A. PHI 0d, REI 4h, Group BM 02. Use preventatively. Not labeled for cauliflower.

Club Root (Plasmodiophora brassicae)

Initial symptoms include stunting, yellowing, and wilting. This disease is characterized by marked swelling and deformity of roots. There is currently no way to eliminate club root from infested soil, but the pathogen can be suppressed 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 400SC): 12.9 to 25.5 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/A (transplant drench); PHI 7-50d, REI 12h, Group 29. Transplant soil drench or incorporation. PHI varies by crop. See label for details.
Bacillus Subtilis strain QST 713 (Serenate ASO): 2.0 to 4.0 gt/A; PHI 0d, REI 4h, Group BM02.
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 brassicae)

Symptoms include angular yellow to orange lesions on the upper sides of leaves with dark sporulation on the underside. Resistant varieties of some brassica crops are available. Use proper plant and row spacing to ensure good air circulation. Avoid overhead irrigation if possible. Control weeds, especially those in the family Brassicaceae.

acibenzolar-S-methyl (Actigard 50WG): 0.5 to 1.0 oz/A; PHI 7d, REI 12 h, Group P 01. Use another registered downy mildew fungicide at the same timing as the Actigard 50WG (can tank mix as foliar spray). See label for details
ametoctradin plus dimethomorph (Zampro): 14.0 fl oz/A; PHI 0d, REI 12h, Groups 45 and 40.
azoxystrobin (Quadris F): 6.0 to 15.5 fl oz/A; PHI 0d, REI 4h, Group 11.
Bacillus amyloliquefaciens strain D747 (DoubleNickel LC^OG): 1.0 to 6.0 lb/A (folair application); PHI 0d, REI 4 h, Group BM02. 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 400 SC): 2.75 fl oz/A (foliar application); PHI 0d, REI 12h, Group 21. Ranman 400SC Tank mix with an organosilicone surfactant. See label for details and re-plant restrictions
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.
ethaboxam (Elumin): 8 fl oz/A; PHI 2d, REI 12h, Group 22. See label for use restrictions. Do not make more than 2 applications per year. Use an adjuvant for tank mix.
fenamidone (Reason 500 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 (tight-heading varieties) ONLY. See label for restrictions
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): 2.0 to 5.0 lb/A; PHI 3d, REI 12h, Group P07. 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): 0.25 to 0.5 pt/A; PHI 7d, REI 48h, Group 4. Labeled for vegetable transplants grown for retail sales to consumers. Do not apply foliar sprays without a labeled tank mix partner.
mefenoxam plus chlorothalonil (Ridomil Gold Bravo SC): 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 (Premix)): 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.
potassium salts of phosphorous acid (Fosphite): 1.0 to 3.0 qt/100 gal/A; PHI 0d, REI 4h, Group P07. Do not apply to plants that are 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 MilStop SP^OG): 2.0 to 5.0 lb/100 gal; PHI 0d, REI 1h, Group NC. See label for small volume application rates.
Pseudomonas chlororaphis Strain AFS009 (Howler^OG): 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 (Regalia^OG): 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 seedborne. 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 (DoubleNickel^OG): 0.125 to 1.0 lb/A at planting; PHI 0d, REI 4h, Group 02. See label for application methods and rates.
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 (MycoStop^OG): See label for rate information; REI 4h, Group 4. See label for rate per lb of seed and application methods
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), crater rot (root crops), and bottom or head rot (cabbage). Lesions caused by Rhizoctonia are brown to black and may be sunken. 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 – 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. Note: pathogen referred to as Corticium solani on label.
polyoxin D zinc salt (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. Symptoms vary with host and include yellow and/or necrotic spots, mosiac, leaf deformity, and interveinal chlorosis. Environmental conditions also affect symptom expression. Partially resistant cultivars include 'Nabyeng', 'Kongng', 'Tip Top', and 'Ta Feng'. These cultivars may be intolerant of heat.

Disease Control