Disease Control : New England Vegetable Management Guide : UMass Amherst

NOTES: For the disease control products listed below, one product trade name and formulation are 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 detail.

Bottom Rot (Rhizoctonia solani)

Rotate crops with unrelated non-host plants. Do not plant in fields with undecomposed crop residues. Plant in well-drained sites and avoid overhead irrigation. Cultivars with upright growth habits are less susceptible.

azoxystrobin (Quadris F): 0.40 to 0.80 fl oz/1000 row feet; PHI 0d, REI 4h, Group 11. See label for tank mixing restrictions.
Bacillus amyloliquefaciens strain D747 (DoubleNickel 55) OG: 0.125 to 1.0 lb/A as a soil drench; PHI 0d, REI 4 h, Group BM02.
boscalid (Endura): 8.0 to 11.0 oz/A; PHI 14d, REI 12h, Group 7. Suppression only.
iprodione (Rovral 4 F): 1.5 to 2.0 pt/A; PHI 14d, REI 24h, Group 2. Lettuce only. Direct application to soil and plant base. Do not cultivate after application.
polyoxin D zinc salt (VEGGIETURBO 5% SC): 6.5 to 13.0 fl oz/A; PHI 0d, REI 4h, Group 19.
Trichoderma asperellum (ICC 012), T. gamsii (ICC 080) (Bio-Tam 2.0) OG: See label for in-furrow, drench, and broadcast rates; REI 4h, Group BM02. See label for application instructions.

Gray Mold (Botrytis cinerea)

Avoid close planting and orient rows in the direction of prevailing winds. Do not plant in poorly drained areas. Utilize raised beds when available. Minimize damage to lettuce incurred through cultural practices (e.g., scouting, weeding, etc.) or by other pathogens and pests. Avoid overhead irrigation. Do not plant where excessive plant residues are present. Transplanting mature plants results in more breakage. Romaine types are especially susceptible.

boscalid (Endura): 8.0 to 11.0 oz/A; PHI 14d, REI 12h, Group 7. Apply at seeding or transplant. A protective fungicide barrier is needed to maximize control.
cyprodinil plus fludioxonil (Switch 62.5 WG): 11.0 to 14.0 oz/A; PHI 0d, REI 12h, Groups 9 & 12.
Laminarin (Vacciplant): 14.0 to 22.0 fl oz/A; PHI 0d, REI 4h, Group P04. For preventive use. See label for restrictions.
penthiopyrad (Fontelis): 14.0 to 24.0 fl oz/A; PHI 3d, REI 12h, Group 7.
polyoxin D zinc salt (VEGGIETURBO 5% SC): 3.75 to 13.0 fl oz/A; PHI 0d, REI 4h, Group 19.
Ulocladium oudemansii U3 strain (BotryStop WP) OG: 2-4 lbs/A; REI 4h, Group NC. Begin application when conditions are conducive to disease development.

Powdery Mildew (Golovinomyces cichoracearum)

Lettuce powdery mildew is favored by warm weather and dry to mildly humid conditions. Unlike many other pathogens, growth of powdery mildew is inhibited by water on leaf surfaces. The fungus presents as powdery white growth on both upper and lower surfaces of leaves. Older leaves are affected first. Affected leaves eventually turn yellow (chlorotic), then die. Plants affected before maturity are often not marketable. Plant resistant varieties when available. Rotate between fungicides to minimize risk of resistance.

azoxystrobin (Quadris F): 12.0 to 15.5 fl oz/A; PHI 0d, REI 4h, Group 11. See label for instructions and precautions.
azoxystrobin plus flutriafol (TopGuard EQ): 6.0 to 8.0 oz/A; PHI 7d, REI 12h, Groups 3 & 11. See label for tank mixing restrictions.
Bacillus mycoides Isolate J (LifeGard WG) OG: 4.5 oz/100 gal water/A; PHI 0d, REI 4h, Group P06. See label for additional volumes and rates.
Bacillus subtilis strain QST 713 (Serenade ASO) OG: 2.0 to 4.0 qt/A; PHI 0d, REI 4h, Group BM02. See label for precautions. Leafy vegetables on the label (no crops specified).
copper oxychloride plus copper hydroxide (Badge X2) OG: 0.75 to 1.5 lbs/A; PHI 0d, REI 48h, Group M1. May cause slight crop injury. See label for application restrictions. Labeled for greenhouse use.
cyprodinil plus fludioxonil (Switch 62.5 WG): 11.0 to 14.0 oz/A; PHI 1d, REI 12h, Groups 9 & 12. For suppression only.
fluopyram (Velum Prime): 5.0 to 6.84 fl oz/A; PHI 0d, REI 12h, Group 7. For suppression only. Do not make more than 2 sequential applications before rotating to different Group.
flutriafol (Rhyme): 5.0 to 7.0 fl oz/A; PHI 7d, REI 12h, Group 3. Apply as a preventive.
fluxapyroxad plus pyraclostrobin (Merivon Xemium): 4.0 to 11.0 fl oz/A; PHI 1d, REI 12h, Groups 7 & 11. Make no more than two sequential applications before alternating with fungicides that have a different mode of action.
hydrogen peroxide plus peroxyacetic acid (ZeroTol 2.0) OG: see label for application rates; PHI 0d, REI 1h, Group NC. Use as a preventive or curative. See label for application instructions and specific dilution rates.
myclobutanil (Rally 40WSP): 5.0 oz/A; PHI 3d, REI 24h, Group 3. For lettuce only.
paraffinic oil (JMS Stylet-Oil): 3.0 to 6.0 qt/100 gal water; PHI 0d, REI 4h, Group NC. For lettuce only. Spray for thorough coverage of upper leaf surface. An organic formulation is available. Not labeled for use in New Hampshire.
Penthiopyrad (Fontelis): 14.0 to 24 fl oz/A; PHI 3d, REI 12h, Group 7. May be applied to lettuce in greenhouses (see label for rates).
polyoxin D zinc salt (VEGGIETURBO 5%SC): 6.5 to 13.0 fl oz/A; PHI 0d, REI 4h, Group 19. Apply as foliar spray in sufficient water to achieve thorough coverage. See label for restrictions.
potassium bicarbonate (MilStop SP): 2.0 to 5.0 lb/100 gal water/A; PHI 0d, REI 1h, Group NC. Thorough crop coverage is required. May be used in greenhouses. See label for application restrictions.
potassium salts of fatty acids (M-Pede) OG: See label for application rates; PHI 0d, REI 12h, Group NC. See label for precautions and application methods.
Pseudomonas chlororaphis strain AFS009 (Howler EVO) OG: 2.5 to 7.5 lbs/A; PHI 0d, REI 4h, Group BM02. May be used in greenhouse applications. See label for restrictions.
pydiflumetofen plus fludioxonil (Miravis Prime): 9.2 to 13.4 fl oz/A, PHI 0d, REI 12h, Groups 12 & 7.
pyraclostrobin (Cabrio EG): 12.0 to 16.0 oz/A; PHI 0d, REI 12h, Group 11. Do not rotate with other Group 11 fungicides. See label for crop injury warnings.
Quinoxyfen (Quintec): 4.0 to 6.0 fl oz/A; PHI 1d, REI 12h, Group13. For lettuce only. See label for application precautions.
Reynoutria sachalinensis extract (Regalia): 0.5 to 4.0 qt/A; PHI 0d, REI 4h, Group P05. Ensure thorough coverage. See label for specific rates and application methods.
Streptomyces lydicus strain WYEC 108 (Actinovate AG) OG: 3.0 to 12 oz/A; PHI 0d, REI 4h, Group BM02. Apply to foliage with spreader-sticker for best results.
Sulfur (Microthiol Disperss) OG: 4.0 to 10.0 lb/A; PHI 0d, REI 24h, Group M02. See label varying rates and application timing. Thorough coverage is required.
Swinglea glutinosa extract (EcoSwing) OG: 1.5 to 2.0 pts/A; PHI 0d, REI 4h, Group BM01. May be used in enclosed spaces. See label for application restrictions.
Triflumizole (Procure 480 SC): 6.0 to 8.0 fl oz/A; PHI 0d, REI 12h, Group 3. Do not make more than 2 applications per crop year. Not labeled for use in Maine.

Downy Mildew (Bremia lactucae)

Lettuce downy mildew is favored by cool, rainy weather. Night temperatures of 43°F to 50°F and day temperatures of 55°F to 70°F with 100% humidity are ideal for disease development. As temperatures increase, the disease disappears. Plant resistant cultivars. Use irrigation practices that reduce leaf wetness and humidity. Protect greenhouse grown transplants with fungicides to prevent the disease from being introduced to the field.

acibenzolar-S-methyl (Actigard 50 WG): 0.75 to 1.0 oz/A; PHI 7d, REI 12h, Group P01. Apply preventively on a 7-10 day schedule. See label for crop injury warnings and restrictions.
ametoctradin plus dimethomorph (Zampro): 14.0 fl oz/A; PHI 0d, REI 12h, Groups 45 & 40.
azoxystrobin (Quadris F): 12.0 to 15.5 fl oz/A; PHI 0d, REI 4h, Group 11. Proceed with caution with regard to tank mixes and adjuvants. Do not rotate with other Group 11 fungicides.
copper oxychloride plus copper hydroxide (Badge X2) OG: 0.75 to 1.5 lb/A; PHI 0d, REI 48h, Group M01. Rate and REI vary with product.
copper hydroxide (Kocide 3000): 0.75 to 1.5 lb/A; PHI 0d, REI 48h, Group M01. Do not apply in a spray solution having a pH less than 6.5 or tank mix with Aliette. Injury may occur to sensitive lettuce cultivars.
cyazofamid (Ranman 400SC): 2.75 fl oz/A; PHI 0d, REI 12h, Group 21. Should be tank mixed with a surfactant. See for label restrictions.
cymoxanil (Curzate 60 DF): 3.2 to 5.0 oz/A; PHI 3d (head) and PHI 1d (leafy), REI 12h, Group 27. For lettuce only. Must be applied as tank mix with a protectant fungicide.
dimethomorph (Forum): 6 fl oz/A; PHI 0d, REI 12h, Group 40. Must be applied as tank mix with another fungicide with a different mode of action. Not labeled for use in Maine.
famoxadone plus cymoxanil (Tanos): 8 to 10 oz/A; PHI 1d, REI 12h, Groups 11 & 27. Tank mix with appropriate contact fungicide with a different mode of action. Do not make more than one application before alternating to a fungicide with a different mode of action.
fenamidone (Reason 500 SC): 5.5 to 8.2 fl oz/A; PHI 2d, REI 12h, Group 11. Do not make more than one application before alternating to a fungicide with a different mode of action. Do not alternate with Quadris.
fluopicolide (Presidio): 3.0 to 4.0 fl oz/A; PHI 2d, REI 12h, Group 43. Must be tank mixed with a fungicide with a different mode of action.
fluxapyroxad plus pyraclostrobin (Merivon Xemium): 8.0 to 11.0 fl oz/A. PHI 1d, REI 12h, Groups 7 & 11.
mancozeb (Dithane F45): 1.2 to 1.6 qt/A; PHI 10d (head) or PHI 14d (leaf), REI 24h, Group M03. For lettuce only. See label for application restrictions.
mancozeb plus copper hydroxide (ManKocide): 1.0 to 2.0 lb/A; PHI 10d, REI 48 h, Groups M03 & M01. May cause injury to some varieties of lettuce. See label for restrictions.
mandipropamid (Revus): 8 fl oz/A; PHI 1d, REI 4h, Group 40. Addition of a spreading/penetrating adjuvant is recommended.
oxathiapiprolin (Orondis Gold 200): 4.8 to 9.6 fl.oz/A; PHI 0d, REI 4h, Group 49. Begin foliar application prior to disease development.
propamocarb hydrochloride (Previcur Flex): 2.0 pt/A; PHI 2d, REI 12h, Group 28.
pyraclostrobin (Cabrio EG): 16.0 oz/A; PHI 0d, REI 12h, Group 11.
Streptomyces lydicus strain WYEC 108 (Actinovate AG) OG: 3.0 to 12.0 oz/A (soil); PHI 0d, REI 4h, Group BM02. Apply to soil. See label for instructions.

Lettuce Drop, White Mold (Sclerotinia minor and S. sclerotiorum)

Do not plant seed contaminated with sclerotia (small black hardened fungal survival structures). Avoid planting into severely infested fields. Rotate with unrelated, non-host plants like grasses. Avoid excessive nitrogen fertilization and irrigate in the morning or with sub-surface drip irrigation to provide dry soil. Deep plow after harvest to bury sclerotia. Soil sterilization with chemicals, steam, or heat (solarization) treatments can significantly reduce inoculum levels. Biofumigation with mustard crop may provide a suppressive effect.

Bacillus subtilis strain QST 713 (Minuet) OG: 12.0 to 24.0 oz/A; PHI 0d, REI 4h, Group BM02.
boscalid (Endura): 8.0 to 11.0 oz/A; PHI 14d, REI 12h, Group 7. Apply at seeding or transplant. A protective fungicide barrier is needed to maximize control.
Coniothyrium minitans strain CON/M/91-08 (Contans WG) OG: Apply 1.0 to 4.0 lb/A; PHI 0d, REI 4h, Group NC. Spray on the soil surface and incorporate into the top 2" of soil. Fall application is best or 3 to 4 months before planting to allow for the biocontrol agent to infect the sclerotia of Sclerotinia. See label for application restrictions. May be used in greenhouse or covered structures.
cyprodinil plus fludioxonil (Switch 62.5 WG): 11.0 to 14.0 oz/A; PHI 0d, REI 12h, Groups 9 & 12. For Sclerotinia, make the first application at thinning and again 2 weeks later.
fludioxonil (Cannonball WG): 7.0 oz/A; PHI 0d, REI 12h, Group 12. Not labeled for use in Maine.
fluxapyroxad plus pyraclostrobin (Merivon Xemium): 8.0 to 11.0 fl oz/A. PHI 1d, REI 12h, Groups 7 & 11.
iprodione (Rovral 4F): 1.5 to 2 pts/A; PHI 14d, REI 24h, Group 2. Lettuce only. Direct application to lower stems and branches and adjacent soil surface. Do not cultivate after application.
penthiopyrad (Fontelis): 16.0 to 24.0 fl oz/A; PHI 3d, REI 12h, Group 7.
polyoxin D zinc salt (VEGGIETURBO/OSO 5% SC): 6.5 to 13.0 fl oz/A; PHI 0d, REI 4h, Group 19.
Streptomyces lydicus strain WYEC 108 (Actinovate AG) OG: 3.0 to 12.0 oz/A (soil); PHI 0d, REI 4h, Group BM02. Apply to soil. See label for instructions.
Trichoderma asperellum (ICC 012) plus T. gamsii (Bio-Tam 2.0) OG: See label for in-furrow, drench, and broadcast rates; REI 4h, Group NC.
Ulocladium oudemansii U3 strain (BotryStop WP) OG: 2.0-4.0 lbs/A; REI 4h, Group NC. Begin application when conditions are conducive to disease development.

Seed Decay

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

mefenoxam (Apron XL): 0.085 to 0.64 fl oz/100 lbs seed; REI 48h, Group 4. For Pythium damping-off protection. Not labeled for use in Maine.
fludioxonil (Maxim 4FS): 0.08 to 0.16 oz/100 lbs seed; REI 12h, Group 12. For protection against seedborne and soilborne fungi. Does not control Pythium or Phytophthora.
thiram (Thiram SC): 8.0 fl oz/100 lbs seed; REI 24h, Group M03.

Mosaic (Lettuce and Cucumber Mosaic Viruses)

Certified LMV- and CMV-free seed available. Plant certified disease-free seed away from old lettuce fields.

Yellows

Do not plant lettuce or other sensitive crops in fields or areas having a history of this disease. Control weeds in the Asteraceae family. Control leafhoppers, which carry the disease-causing organism (phytoplasma). See more information in the Carrot and Parsnip section.

Disease Control