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.


Pesticides can be used on high tunnel and greenhouse crops if: 1) the crop and pest/disease is on the label, AND the products specifically says it can be used in the greenhouse; OR 2) the crop and pest/disease is on the label, AND the product is ‘silent’ about use in the greenhouse in the greenhouse. Products that specifically prohibit greenhouse use cannot be used in greenhouses or high tunnels regardless of the crops or pests/diseases listed on the label.

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 19: Fungicides and Bactericides Labeled for Vegetable Bedding Plants.

Anthracnose (Colletotrichum coccodes)

Primarily a pathogen of ripe fruit, anthracnose occurs on fruit that is left on the plant for a long period of time. The disease is most common on red peppers that have a long ripening period. Latent infections can occur on immature fruit. The pathogen can be seedborne and survives in the soil through the production of sclerotia. Rotate away from solanaceous plants for at least 2 years. Start with certified, disease-free seed and transplants. Plant in well-drained fields. Control solanaceous weeds. Some resistant cultivars are available. Apply fungicides preventively where anthracnose has been a problem. See fungicides below.

Anthracnose (Colletotrichum acutatum

Anthracnose caused by Colletotrichum acutatum is relatively new to the pepper industry in the U.S. It is fairly widespread in the southern U.S. and has occurred for consecutive years in several New England states. Unlike C. coccodes, this species attacks fruit of all ages and is very aggressive. During warm and wet weather conditions, significant losses to peppers can occur. Do not plant peppers in the same area following disease for at least 1 year. Remove all diseased plant material from the field. Most peppers are susceptible but North Star and Paladin were the least susceptible in one report. Cabrio has performed better than Quadris for this disease.

azoxystrobin (Quadris): 6.0 to 15.5 fl oz/A; PHI 0d, REI 4h, Group 11. Do not rotate with other Group 11 fungicides.

azoxystrobin plus difenoconazole (Quadris Top): 8.0 to 14.0 fl oz/A; PHI 0d, REI 12h, Groups 11 & 3. 

chlorothalonil (Bravo Weather Stik):  1.5 pt/A; PHI 3d, REI 12h, Group M5.

copper hydroxide (Kocide 3000): 0.75 to 1.25 lb/A; PHI 0d, REI 48h, Group M1. Do not apply in a spray solution having a pH of less than 6.5 or tank mix with Aliette.

cymoxanil plus chlorothalonil (Ariston): 2.0 to 2.44 pt/A; PHI 3d, REI 12h, Groups 27 & M3.

difenaconazole plus benzovindiflupyr (Aprovia Top): 10.5 to 13.5 fl oz/A; PHI 70d, REI 12h, Groups 3 & 7.

famoxadone plus cymoxanil (Tanos): 8.0 to 10.0 oz/A; PHI 3d, REI 12h, Group 11 & 27. Tank mix with an appropriate contact fungicide.

flutriafol (Rhyme): 7.0 fl oz/A; PHI 0d, REI 12h, Group M3.

fluxapyroxad plus propiconazole (Priaxor): 4.0 to 8.0 fl oz/A; PHI 0d, REI 12, Groups 7 & 11.

mancozeb (Dithane F45): 1.2 to 2.4 lb/A; PHI 7d, REI 24h, Group M3.

mancozeb plus copper hydroxide (ManKocide): 2.0 to 3.0 lb/A; PHI 7d, REI 48h, Groups M3 & M1.   

polyoxin D (OSO 5%SC): 3.75 to 13.0 fl oz/A; PHI 0d, REI 4h, Group 19.

pyraclostrobin (Cabrio EG): 8.0 to 12.0 oz/A; PHI 0d, REI 12h, Group 11. Rotate to a non-Group 11 fungicide after 1 application.

tetraconazole (Mettle 125ME): 6.0 to 8.0 fl oz/A; PHI 0d, REI 12h, Group 3. Rotate to a non-Group 3 fungicide after 2 applications.

trifloxystrobin (Flint Extra): 3.0 to 3.8 fl oz/A; PHI 3d, REI 12h, Group 11.

Damping-Off and Seed Decay

Do not allow transplant growing medium to remain wet. Maintain ventilation. Do not use unpasteurized growing media. Keep tools and hose nozzles clean and off of the greenhouse floor. Do not use treated seed for food, feed or oil purposes.

fludioxonil (Maxim 4FS): 0.08 to 0.16 oz/00 lb seed; REI 12h, Group 12. For protection against seedborne and soilborne fungi. Does not control Pythium and Phytophthora.

mefenoxam (Apron XL): 0.085 to 0.64 fl oz/100 lb seed; REI 48h, Group 4. Do not apply a preplant or at plant application of products containing mefenoxam.

propamocarb HCl (Previcur Flex): 1.2 pt/A; PHI 5d, REI 12h, Group 28. Pythium and Phytophthora damping-off. For greenhouse or high tunnel use, see label: apply in evening to avoid intense sunlight after application. Phytotoxicity may occur if applied directly to dry growing media, especially in intense sunlight.

Phytophthora capsici Crown Rot and Blight

Avoid planting into soils that are known to be contaminated with Phytophthora capsiciP. capsici can survive in the soil for many years; a 3-year or longer rotation with plants other than pepper, tomato, eggplant, cucurbits, or legumes may help reduce losses. If planting into infested soils, subsoil to improve drainage, use resistant varieties, and plant on dome-shaped raised beds that will shed water. Break beds to allow water to leave field through lowest paths; do not let water pool or stand around plants. Avoid bringing Phytophthora-contaminated soil into clean or fumigated fields on farm equipment by working in clean fields first and cleaning equipment after working in contaminated fields. Avoid planting low, wet areas with susceptible crops. Do not throw rotting host crops purchased off-farm on fields, or into compost piles for use on fields. Alternating between two or more soil-applied fungicides, beginning at planting, and continuing throughout the season, has been shown to be more effective than foliar applications. Several products are labeled for drench or trickle applications. See label rates and directions.  

For crown and stem rot:

ametoctradin plus dimethomorph (Zampro): 14.0 fl oz/A; PHI 4d, REI 12h, Groups 45 & 40. Labeled for foliar, soil and drip applications. Do not use in greenhouse or high tunnel crops.

Bacillus subtilis Strain Strain QST 713 (Serenade SoilOG): 2.0 to 6.0 qt/A; PHI 0d, REI 4, Group 44. Apply Serenade Soil as an in-furrow spray in 5-15 gallons of water at planting.

cyazofamid (Ranman): 2.75 oz/A; PHI 0d, REI 12h, Group 21.  Labeled for foliar, soil drench or overhead irrigation application.

dimethomorph (Forum): 6.0 oz/A; PHI 0d, REI 12h, Group 40.  Suppression only. Must be applied as a tank mix with another fungicide with a different mode of action. Do not make more than 2 consecutive applications of Forum before alternating to a non-Group 40 fungicide. Do not use in greenhouse or high tunnel crops.

fluopicolide (Presidio): 3.0 to 4.0 fl oz/A; PHI 2d, REI 12h, Group 43. Must be applied in a tank mix with another labeled fungicide with a different mode of action. Labeled for foliar, soil and drip applications. Do not use in greenhouse or high tunnel crops.

mefenoxam (Ridomil Gold SL): 1.0 pt/A; PHI 7d, REI 48h, Group 4.  Apply as banded spray after transplant, see label. Ridomil may cause yellowing of pepper leaves especially if soil applications are made when the soil is dry. See label for plant back restrictions and precautions. Does not control foliar/fruit phase. Resistance is a common problem.

oxathiapiprolin (Orondis Gold 200): 2.4 to 19.2 fl oz/A; PHI 0d, REI 4h, Group 49.  Apply at planting in furrow, in transplant water, or by drip irrigation.

phosphorous acid (ProPhyt): 4.0 pt/100 gal to transplants prior to transplanting, or 5 fl oz/1000 row ft as in-furrow drench at planting; PHI 0d, REI 4, Group 33. 

Streptomyces lydicus strain WYEC (Actinovate AGOG):  3.0 to 12.0 oz/A; Group NC. See label.

For foliar and fruit rot:

famoxaone plus cymoxanil (Tanos): 8.0 to 10.0 oz/A; PHI 3d, REI 12h, Groups 11 & 27. Disease suppression of foliar and fruit phase ONLY.  Rotate with an appropriate fungicide with a different mode of action. Must be tank-mixed with a contact fungicide.

mefenoxam plus copper (Ridomil Gold/Copper): PHI 7d, REI 48h, Groups 4 & M1. Recommended to be used in conjuction with Ridomil Gold SL. See label for rates and restrictions. Do not use in greenhouse or high tunnel crops.

oxathiapiprolin plus mandipropamid (Orondis Gold 200): 5.5 to 8.0 fl oz/A; PHI 0d, REI 4h, Groups 49 & 40.  Begin prio to disease development.

phosphorous acid (ProPhyt): 6.0 pt/A; PHI 0d, REI 4, Group 33.

Streptomyces lydicus strain WYEC (Actinovate AGOG):  3.0 to 12.0 oz/A; Group NC. See label.

Bacterial Canker (Clavibacter michiganense pv. michiganense)

Traditionally a tomato disease, bacterial canker can now also infect peppers and arrives on infected seed.  Damage appears as irregular-shaped brown leaf spots, defoliation, and an occasional tiny, round, brown fruit spot with a white center. Foliar damage resembles bacterial spot or paraquat injury symptoms. Management is similar to methods listed below for bacterial spot.   

Bacterial Leaf Spot (Xanthomonas campestris pv. vesicatoria)

Bacterial leaf spot is one of the most destructive diseases of peppers in New England. There are 11 identified races (0-10). Chemical controls are often ineffective. Effective management requires rotating to fields where solanaceous crops and weeds have not existed for at least 2 years, and growing resistant varieties. Success using resistant varieties requires growing a variety with resistance to the race present in your crop, which requires identifying the race(s) present with lab testing. X10R™ varieties provide intermediate resistance to all strains.  Maintain proper nutrient levels and avoid using dolomitic (high magnesium) lime before planting peppers. Hot-water treat pepper seeds at 122°F for 25 minutes to eliminate seedborne inoculum. Grow your own transplants or contract to have them grown locally. Disinfect used flats, cell-packs, bench tops, machinery, etc. with a 1:9 mix of bleach and water; rinse well with fresh water. Scout fields weekly for plants with small brown leaf spots. Work infected fields last. Do not use high pressure, air-blast sprayers, which cause increased leaf infection in rows adjacent to spray alleys and spread bacterial diseases across rows. Destroy crop residue after harvest to encourage rapid decomposition.

acibenzolar-S-methyl (Actigard 50 WG): 0.33 to 0.75 oz/A; PHI 14d, REI 12 h, Group 21. Do not use on bell peppers. Actigard is a plant activator and should be applied preventatively before disease symptoms are observed.

Bacillus amyloliquefaciens strain D747 (DoubleNickel LCOG ): 0.25 to 3.0 lb/A; PHI 0d, REI 4 h, Group 44. Disease suppression only. For improved control; mix or rotate with a chemical fungicide.

Bacillus mycoides Isolate J (LifeGard LCOG ): 4.5 oz/100 gal water; PHI 0d, REI 4, Group 44.

copper hydroxide (Kocide 3000): 0.75 to 1.25 lb/A; PHI 0d, REI 48h, Group M1. Do not apply in a spray solution having a pH of less than 6.5 or tank mix with Aliette.

mancozeb plus copper hydroxide (ManKocide): 2.0 to 3.0 lb/A; PHI 7d, REI 48h, Groups M3 & M1.

streptomycin (Agri-Mycin 17): 200 ppm (1 lb/100 gal); REI 12h, Group 25. Only for greenouse use on transplants, Streptomycin cannot be used in the field. Apply when the first true leaves appear and continue every 4 to 5 days until field transplanting.

Cucumber Mosaic Virus (CMV)

Many different strains of CMV occur and the host range includes plants in more than 31 different families. In pepper, the symptoms can be confused with Tomato spotted wilt virus (TSWV) as well as other virus diseases. The disease is spread by several species of aphids in a nonpersistent manner, meaning that the virus does not remain in the aphids for a long period of time and insecticides are therefore not useful for CMV control. Reduce weeds, especially chickweed, pokeweed, and milkweeds as much as practical. Isolate pepper fields from cucurbits and Prunus spp. (e.g. cherry trees) which are the overwintering host of the green peach aphid, especially where there has been a history of CMV.

Potato Virus Y (PVY)

Potato Virus Y (PVY) has a worldwide distribution. Three main strains have been described that differ in distribution and symptomatology. Symptoms vary widely with cultivars and virus strain combinations, ranging from mild mosaic to severe foliar necrosis. One strain can cause a symptomless current season infection that leads to next-generation infection. Primary symptoms of PVY include mottling, yellowing, leaf drop, and premature plant death. Early infections can cause stunting and a decrease in fruit set. PVY is a member of the plant virus family Potyviridae, the largest and most significant virus group, and has caused significant losses in agricultural, forage, and horticultural crops. Hosts include solanaceous plants, legumes, and plants in the Chenopodiaceae family (e.g. spinach, chard, beets). PVY is transmitted in a non-persistent manner by more than 25 species of aphids and may also be transmitted mechanically by foliar contact. Long-distance transport is by winged aphids. Insecticides may slow the spread of disease within a crop, but may actually increase insect probing and be counterproductive because only a few seconds of insect feeding is required for virus transmission. Minimize contact disease spread by minimizing mechanical damage during cultivation, spraying, and harvest. Remove virus-infected plants. Resistant cultivars are available.

Tobacco and Tomato Mosaic Virus (TMV, TomMV)

Several strains of TMV exist, including the closely related tomato (TomMV) strain. Symptoms on pepper and tomato can vary considerably as will the severity of disease and the effect on yield. Both strains can be seedborne or transferred from previously infected plant debris, weeds, transplants, other crops, or workers using tobacco products. Unlike other viruses, TMV and TomMV are easily spread from plant to plant by contact with hands and tools. Insects are not considered to be important vectors. Grow resistant varieties. Control weeds as much as practical. Do not plant susceptible peppers or tomatoes for at least two years on land that previously had TMV infected crops. Handle plants as little as possible. Do not allow workers to use tobacco products while working with plants.

Tomato Spotted Wilt Virus (TSWV)

The host range for TSWV is one of the largest of any virus. Hundreds of plant species are susceptible including many commercial floriculture crops. Do not raise tomato, pepper, eggplant, or cauliflower transplants in the same greenhouse as ornamentals. Monitor thrips in the greenhouse and control as necessary. Control greenhouse weeds, as many are hosts to TSWV.