Disease Control

Management practices that will reduce disease in greenhouses and high tunnels are the use of resistant varieties, sanitation, fungicides, and cultural practices that keep the humidity below 90%.

See also: Table 20: Fungicides and Bactericides Labeled for Vegetable Transplants

Bacterial Canker (Clavibacter michiganensis pv. michiganensis)

Symptoms of bacterial canker include brown leaf margins and/or lesions, sometimes with a yellow border. Lower leaves wilt, sometimes only on one side. The vascular system in the stem is often brown. Stems may split, forming cankers. Adventitious roots may be observed. Small, raised white spots with brown centers may be seen on fruit. Clavibacter may be seedborne or may overwinter in crop debris and on wooden stakes, greenhouse benches, or other structures. It is easily spread on workers’ hands and tools. Disease is favored by high humidity and temperatures 70°F–95°F. When symptoms occur, remove affected plants, including roots, from the greenhouse. Wash hands thoroughly before handling healthy plants. Do not work with plants when they are wet. There are few effective bactericides to control this disease. If extensive bacterial canker occurs in the greenhouse, steaming of the soil is advised. Rotate out of tomatoes for at least 2 years. Use copper or streptomycin on plants before transplanting. Disinfect stakes before reusing. Resistant cultivars are not available. Hot water treatment may be used to destroy the pathogen in seed: see Hot Water Treatment of Seed in the Disease Management section.

FRAC Group BM02:

• Bacillus subtilis strain QST 713 (Serenade ASO^OG): 2 to 4 qt/A; PHI 0d, REI 4h. See label for tank mix rates and restrictions for greenhouse use.

Gray Leaf Spot (Stemphylium lycopersici, S. solani, and S. botryosum)

See the Tomato, Outdoor disease control section for more information about gray leaf spot.

FRAC Group 3:

• azoxystrobin + difenoconazole (Quadris Top): 8 fl oz/A; PHI 0d, REI 12h, Groups 11 & 3. See label for instructions for adjuvant use. For resistance management, do not use for transplant production.
• difenoconazole + fluopyram (Luna Flex): 8 to 13.6 fl oz/A; PHI 0d, REI 12h, Groups 3 & 7. 
• mandipropamid + difenoconazole (Revus Top): 5.5 to 7 fl oz/A; PHI 1d, REI 12h, Groups 3 & 40. Begin applications prior to disease development. Do not make more than 2 sequential applications before alternating to a fungicide from a different FRAC Group.
• tetraconazole (Mettle 125ME): 6 to 8 fl oz/A; PHI 0d, REI 12h. 

FRAC Group 7:

• difenoconazole + fluopyram (Luna Flex): 8 to 13.6 fl oz/A; PHI 0d, REI 12h, Groups 3 & 7. 
• fluopyram + pyrimethanil (Luna Tranquility): 11.2 fl oz/A; PHI 1d, REI 12h, Groups 7 & 9. 

FRAC Group 9:

• fluopyram + pyrimethanil (Luna Tranquility): 11.2 fl oz/A; PHI 1d, REI 12h, Groups 7 & 9. 

FRAC Group 11:

• azoxystrobin + difenoconazole (Quadris Top): 8 fl oz/A; PHI 0d, REI 12h, Groups 11 & 3. See label for instructions for adjuvant use. For resistance management, do not use for transplant production.

FRAC Group 22:

• mancozeb + zoxamide (Gavel 75DF): 1.5 to 2 lb/A; PHI 5d, REI 48h, Groups M03 & 22.

FRAC Group 40:

• mandipropamid + difenoconazole (Revus Top): 5.5 to 7 fl oz/A; PHI 1d, REI 12h, Groups 3 & 40. Begin applications prior to disease development. Do not make more than 2 sequential applications before alternating to a fungicide from a different FRAC Group. 

FRAC Group M01:

• copper hydroxide (Nu-Cop 50WP^OG): 1 lb/A (processing),3.2 lb/A (fresh market); PHI 0d, REI 48h. 
• mancozeb + copper (ManKocide): 1.7 to 3 lb/A; PHI 5d, REI 24 or 48h, Groups M03 & M01. 

FRAC Group M03:

• mancozeb (Dithane F-45 Rainshield): 1.2 to 2.4 qt/A; PHI 5d, REI 24h. Start applications when seedlings emerge or transplants are set. 
• mancozeb + copper (ManKocide): 1.7 to 3 lb/A; PHI 5d, REI 24 or 48h, Groups M03 & M01. 
• mancozeb + zoxamide (Gavel 75DF): 1.5 to 2 lb/A; PHI 5d, REI 48h, Groups M03 & 22.

Gray Mold/Botrytis Blight (Botrytis cinerea)

White ring spots or “ghost spots” may appear on green fruit due to early infection that was halted by the fruit. Brown lesions and gray, fuzzy fungal growth may be visible on affected stems and leaves. Management of the environment is particularly important in controlling this disease. Keep humidity below 80% by heating and ventilating, especially at night. Avoid wetting the foliage during times when drying is slow. Practice strict sanitation, removing senescent tissues and infected crop debris. Pruning of lower leaves to clean-cut stubs aids in disease prevention by improving air circulation through the crop. Fungicide rotations and combinations are important because resistant strains have become common.

FRAC Group 7:

• fluopyram + pyrimethanil (Luna Tranquility): 11.2 fl oz/A; PHI 1d, REI 12h, Groups 7 & 9. See label for specific instructions for greenhouse use.
• penthiopyrad (Fontelis): 0.5 to 0.75 fl oz/per gallon of spray per 1360 sq ft.; PHI 0d, REI 12. Make no more than 2 sequential applications before switching to a fungicide with a different mode of action.

FRAC Group 9:

• cyprodinil + fludioxonil (Switch 62.5 WG): 11 to 14 oz/A; PHI 0d, REI 12h, Groups 9 & 12. After two applications, alternate with another fungicide with a different mode of action for two applications.
• fluopyram + pyrimethanil (Luna Tranquility): 11.2 fl oz/A; PHI 1d, REI 12h, Groups 7 & 9. See label for specific instructions for greenhouse use.
• pyrimethanil (Scala SC): 7 fl oz/A; PHI 1d, REI 12h. Use only in a tank mix with another effective fungicide recommended for Early Blight. Apply only in well-ventilated plastic tunnel houses or glass houses. Ventilate for at least 2 hours after application.

FRAC Group 12:

• cyprodinil + fludioxonil (Switch 62.5 WG): 11 to 14 oz/A; PHI 0d, REI 12h, Groups 9 & 12. After two applications, alternate with another fungicide with a different mode of action for two applications.
• fludioxonil (Emblem, aka Spirato GHN): 5.5 to 7 oz/A; PHI 0d, REI 12h. Alternate with a different mode of action (FRAC group) after 2 applications.

FRAC Group 17:

• fenhexamid (Decree 50 WDG, aka Elevate 50 WDG): 1 to 1.5 lb/A; PHI 0d, REI 12h. Treated greenhouse tomatoes cannot be used for processing. Do not make more than two consecutive applications per crop cycle. 

FRAC Group 19:

• polyoxin D (Affirm WDG): 6.2 oz/A; PHI 0d, REI 4h. For production of seedlings and transplants only. Not for field use. Not for production of edible commodities.

FRAC Group BM02:

• Bacillus subtilis strain QST 713 (Cease^OG): 3 to 6 qt/100 gal/A; PHI 0d, 4h.

FRAC Group M01:

• copper sulfate basic (Cuprofix Ultra 40 Disperss^OG): 0.75 to 3 lb/A (fresh market), 0.75 to 1.33 lb/A (processing); PHI 0d, REI 24h (greenhouse), 48h (all other applications).

FRAC Group NC:

• potassium bicarbonate (MilStop^OG): 1.25 to 5 lb/100 gal water; PHI 0d, REI 1h. Do not mix with other soluble pesticides or fertilizers not compatible with mild alkaline solutions. Do not store unused spray solution. See label for small volume application rates.

Late Blight (Phytophthora infestans)

Younger foliage tends to be more susceptible to late blight than older foliage. Large, irregular, brown lesions appear on leaves and petioles. Lesions may be surrounded by a light-colored halo. Under humid conditions, white sporulation may be observed on the undersides of leaves. Entire leaves may wilt and turn brown. Firm brown lesions may also appear on fruit. Protectant fungicides are a key tool for management; however, many strains of P. infestans have become resistant to mefenoxam, so fungicide rotation is critical. Avoid the use of overhead irrigation. Promptly remove or incorporate old tomato crops after harvest in high tunnels; remove all debris and clean greenhouse thoroughly after harvest. Eliminate cull piles and volunteer plants of both tomato and potato. Some resistant cultivars are available.

FRAC Group 3:

• mandipropamid + difenoconazole (Revus Top): 5.5 to 7 fl oz/A; PHI 1d, REI 12h, Groups 3 & 40.

FRAC Group 21:

• cyazofamid (Ranman 400SC): 2.1 to 2.75 fl oz/A; PHI 0d, REI 12. See label for surfactant recommendations. For use in transplant production only. Alternate applications with fungicides from a different FRAC Group.

FRAC Group 40:

• mandipropamid (Micora): 5.5 to 8 fl oz/A; PHI 1d, REI 4h. For use in greenhouses with permanent flooring only, on tomato transplants for resale to customers only. Do not make more than 2 consecutive applications. See label for surfactant recommendation.
• mandipropamid + difenoconazole (Revus Top): 5.5 to 7 fl oz/A; PHI 1d, REI 12h, Groups 3 & 40. 
• oxathiapiprolin + mandipropamid (Orondis Ultra): 5.5 to 8 fl oz/A; PHI 1d, REI 4h, Groups 49 & 40. 

FRAC Group 49:

• oxathiapiprolin + mandipropamid (Orondis Ultra): 5.5 to 8 fl oz/A; PHI 1d, REI 4h, Groups 49 & 40. 

FRAC Group BM02:

• Bacillus subtilis Strain QST 713 (Cease^OG): 3 to 6 qt/100 gal/A; PHI 0d, REI 4h.

FRAC Group M01:

• copper hydroxide (Kocide 3000): 0.5 to 1.5 Tbsp/1000 sq ft (1 Tbsp is equal to 1 lb/A); PHI 0d, REI 48h or 24h if extra safety precautions are met. Do not apply in a spray solution having a pH less than 6.5 or tank mix with Aliette. An OMRI-listed formulation is available (Kocide 3000-O^OG).
• copper soap (Camelot O^OG): 2 gal/30 to 100 gal water; PHI 0d, REI 4h. Do not reapply within 3 days, do not apply more than 0.53 lb Cu/acre to tomato.

FRAC Group M03:

• mancozeb (Dithane M45): 1.5 to 2 lb/A; PHI 5d, REI 24h.
• mancozeb + zoxamide (Gavel 75DF): 1.5 to 3 lb/A; PHI 5d, REI 48.

FRAC Group NC:

• hydrogen peroxide + peroxyacetic acid (Oxidate 2.0^OG): 1:40 dilution; PHI 0d, 1h fogging/spraying or 0h other methods . Do not tank mix with copper. 

FRAC Group P07:

• phosphorous acid (K-Phite 7LP): 3 to 5 qt/20 gal water/A; PHI 0d, REI 4h.

Leaf Mold (Passalora fulva, previously called Fulvia fulva)

Symptoms begin as yellow spots on the upper sides of older leaves. Fuzzy, olive-green sporulation appears on the undersides of leaves. Leaves may turn brown and wither but typically stay attached to the plant. This disease is most common in indoor production and is most severe in poorly ventilated structures. The pathogen produces large numbers of conidia on infected tissue, and the disease can spread rapidly throughout a greenhouse by air currents, water, insects, and workers. Start with certified disease-free seed. Use resistant cultivars. Improve air circulation by adequate row/plant spacings and removal of lower leaves. Avoid the formation of water droplets on leaves by watering in the morning. Reduce relative humidity by a combination of heating and venting, especially at night. Avoid excessive nitrogen fertilization. When possible, remove diseased leaves and destroy them. At the end of crop cycle, remove and destroy all plant residue.

FRAC Group 3:

• mandipropamid + difenoconazole (Revus Top): 5.5 to 7 fl oz/A; PHI 1d, REI 12h, Groups 3 & 40.

FRAC Group 11:

• famoxadone + cymoxanil (Tanos): 8 oz/A; PHI 3d, REI 12h, Groups 11 & 27.

FRAC Group 19:

• polyoxin D (Oso 5%SC^OG): 6.5 to 13 fl oz/A; PHI 0d, REI 4h.

FRAC Group 22:

• mancozeb + zoxamide (Gavel 75DF): 1.5 to 2 lb/A; PHI 5d, REI 48h, Groups M03 & 22.

FRAC Group 27:

• famoxadone + cymoxanil (Tanos): 8 oz/A; PHI 3d, REI 12h, Groups 11 & 27.

FRAC Group 40:

• mandipropamid + difenoconazole (Revus Top): 5.5 to 7 fl oz/A; PHI 1d, REI 12h, Groups 3 & 40.

FRAC Group M01:

• copper hydroxide (Kocide 3000): 0.5 to 1.5 Tbsp/1000 sq ft (1 Tbsp is equal to 1 lb/A); PHI 0d, REI 48h or 24h if extra safety precautions are met. Do not apply in a spray solution having a pH less than 6.5 or tank mix with Aliette. An OMRI-listed formulation is available (Kocide 3000-O^OG).

FRAC Group M03:

• mancozeb (Dithane M45): 1.5 to 3 lb/A; PHI 5d, REI 24h. Adding a surfactant to spray solutions improves performance. 
• mancozeb + zoxamide (Gavel 75DF): 1.5 to 2 lb/A; PHI 5d, REI 48h, Groups M03 & 22.

Pith Necrosis (Pseudomonas corrugata)

This disease typically occurs in early planted tomatoes growing when night temperatures are cool, humidity levels are high, and when plants are growing vigorously because of excessive levels of nitrogen. The disease is associated with prolonged periods of cloudy, cool weather. Symptoms consist of yellowing and wilting of young leaves. Serious infections result in yellowing or wilting upper portions of plants with brown to black lesions on infected stems and petioles. When stems are cut longitudinally, the center of the stem (pith) may be extensively discolored, hollow, and/or degraded. Stems may be swollen, numerous adventitious roots can form, and infected stems may shrink, crack, and collapse. Preventive measures to minimize the occurrence of this disease in high tunnels include adequate ventilation to avoid high humidity levels, avoiding excessive nitrogen levels to prevent vigorous plant growth, thorough removal of infected crop debris, and crop rotation.

Powdery Mildew (several genera)

See the Disease Control section in Tomato, Outdoor for more information about this disease. 

FRAC Group 3:

• mandipropamid + difenoconazole (Revus Top): 5.5 to 7 fl oz/A; PHI 1d, REI 12, Groups 3 & 40.
• triflumizole (Trionic 4SC): 2 to 4 fl oz/100 gal.; PHI 1d, REI 12h. Apply only as foliar spray. For use in commercial greenhouse production only. See label for surfactant recommendation.

FRAC Group 7:

• fluopyram + pyrimethanil (Luna Tranquility): 11.2 fl oz/A; PHI 1d, REI 12h, Groups 7 & 9. For disease suppression only. See label for specific instructions for greenhouse use.
• penthiopyrad (Fontelis): 0.5 to 0.75 fl oz/ per gallon of spray per 1360 sq ft; PHI 0d, REI 12. Make no more than 2 sequential applications before switching to a fungicide with a different mode of action.

FRAC Group 9:

• cyprodinil + fludioxonil (Switch 62.5 WG): 11 to 14 oz/A; PHI 0d, REI 12h, Groups 9 & 12. 
• fluopyram + pyrimethanil (Luna Tranquility): 11.2 fl oz/A; PHI 1d, REI 12h, Groups 7 & 9. For disease suppression only. See label for specific instructions for greenhouse use.

FRAC Group 12:

• cyprodinil + fludioxonil (Switch 62.5 WG): 11 to 14 oz/A; PHI 0d, REI 12h, Groups 9 & 12. 
• fludioxonil (Emblem aka Spirato GHN): 5.5 to 7 oz/A. PHI 0d, REI 12h. Do not make more than 2 applications before rotating to a fungicide from a different FRAC group.

FRAC Group 19:

• polyoxin D (Affirm WDG): 6.2 fl oz/A; PHI 0d, REI 4h. 

FRAC Group 40:

• mandipropamid + difenoconazole (Revus Top): 5.5 to 7 fl oz/A; PHI 1d, REI 12, Groups 3 & 40.

FRAC Group BM02:

• Bacillus pumilus strain QST2808 (Sonata ASO^OG): 2 to 4 qt/100 gal of spray; PHI 0d, REI 4h. In greenhouse, for suppression only. 
• Bacillus subtilis strain QST 713 (Cease^OG): 3 to 6 qt100 gal/A; PHI 0d, REI 4h. In greenhouse, for suppression only. 

FRAC Group M02:

• sulfur (Microthiol Disperss^OG): 3 to 10 lb/A; PHI 0d, REI 24h. Do not use within 2 weeks of an oil spray treatment. Crops grown in greenhouses may be much more sensitive to sulfur injury. Do not apply if temperature will exceed 90ºF within 3 days following spraying.

FRAC Group NC:

• paraffinic oil (JMS Stylet-Oil): 3 to 6 qt/100 gal water; PHI 0d, REI 4h. Spray for thorough coverage of upper leaf surface.
• potassium bicarbonate (MilStop^OG): 1.25 to 5 lb/100 gal water; PHI 0d, REI 1h. Use solution within 12 hours of preparation. 
• potassium salts of fatty acids (M-Pede^OG): 1.5% to 2% v/v solution alone, or 1% to 2% v/v solution tank-mixed; PHI 0d, REI 12h.

FRAC Group P07:

• phosphorous acid (K-Phite 7LP): 1 to 4 qt/40 gal water/A; PHI 0d, REI 4h.

Soilborne Diseases

Several fungi including Rhizoctonia, Colletotrichum, Verticillium, Sclerotinia, and Fusarium, the oomycetes Pythium and Phytophthora, the bacterium that causes tomato canker, and root knot nematodes may become established in greenhouse soils or survive in tomato roots left from a previous crop. White rot (Sclerotinia sclerotiorum) on stems occurs erratically during moist, cool periods in the spring. Distribution of diseased plants in a greenhouse is random but is often associated with low spots. Plants of all ages are susceptible. The pathogen produces robust white mycelium and hardened black fungal survival structures called sclerotia that can survive several years in the soil. Cut infected plants off at the base and remove from the greenhouse. Depending on which soilborne pathogen is present, rotation or the use of resistant varieties in addition to the use of grafted plants with vigorous rootstocks may be viable alternatives. Otherwise, steam or chemical treatment of the soil is necessary. It should be considered, however, that treatment of soil may not entirely eliminate the pathogens and, in the case of Pythium, Rhizoctonia, and Fusarium, the pathogens may rapidly recolonize the soil. There is no effective chemical treatment for the wilt and decline diseases caused by Verticillium and Fusarium. The most effective management techniques are planting resistant cultivars, proper watering practices, and sanitation, including soil pasteurization. NOTE: the current Bayer label for Coniothyrium minitans (Contans) does not include tomato. The label does include most other vegetable crops, which are also hosts for the disease, and so the product can be applied prior to planting a labeled crop to act on sclerotia in the field and manage the disease in a subsequent tomato crop.

FRAC Group 21:

• cyazofamid (Ranman 400SC): 3 fl oz/100 gal water; PHI 0d, REI 12h. Pythium only. Soil drench. Tomato transplants only. . Do not use a surfactant in soil drench applications.

FRAC Group 28:

• propamocarb HCl (Previcur Flex): 3.4 to 6.8 fl oz/cube (rock wool), 32 fl oz /1000 sq ft (beds at seeding), 16 fl oz/1000 sq ft (beds after emergence) ; PHI 2d, REI 12h. Apply in the evening to avoid intense sunlight. May be applied to rock wool cubes, seed beds at seeding or after emergence, through drip, or as a soil drench. Pythium and Phytophthora only.

FRAC Group BM02:

• Bacillus subtilis strain QST 713 (Serenade ASO^OG): 0.1 to 3 fl oz/100 lb seed; PHI 0d, REI 4h. For suppression of seedling and root disease. See label for tank mix rates and restrictions for greenhouse use.
• Streptomyces sp. strain K61 (MycoStop^OG): See label for rate information; REI 4h. Rates vary by treatment method or unit of seed to be treated.
• Streptomyces lydicus WYEC 108 (Actinovate AG^OG): 3 to 12 oz/A soil drench; PHI 0d, REI 4h.

FRAC Group P07:

• phosphorous acid (K-Phite 7LP): See label for rates and application methods; PHI 0d, REI 4h. May be applied as a ground application, through chemigation, as a root dip or transplant drench, or to soil.

Viruses

See the Tomato (Outdoor) insect control section for information on controlling insect-vectored viruses in tomatoes.