Disease Control

Angular Leaf Spot (Pseudomonas syringae pv. lachrymans)

The symptoms of angular leaf spot appear as small, angular brown spots with a yellow halo on the foliage. Leaf spots eventually dry out and the centers fall out, leaving holes in the leaves. Spots are typically limited by veins of the leaves, producing the characteristic angular spots. On fruit, lesions are small, and appear water-soaked, sometimes with a tan to white center. Fruit is later affected by soft rot that can consume the entire fruit as the disease progresses. Avoid working in the fields when the foliage is wet. Plow crop residue under promptly after harvest to aid decomposition. Rotate out of cucurbits for 2 years. Plant resistant varieties when possible. Use pathogen-free seed or treat with hot water to kill the bacterium in the seed. Sprays may not be effective if applied too late or if environmental conditions are conducive to spread of the disease.

FRAC Group BM02:

• Bacillus subtilis strain QST 713 (Serenade ASO^OG): 2 to 4 qt/A; PHI 0d, REI 4h.

FRAC Group M01:

• copper hydroxide (Kocide 3000): 0.5 to 1.25 lb/A; PHI 0d, REI 48h. 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 octanoate (Cueva^OG): 33 gal/A; PHI 0d, REI 4h. Begin applications when environmental conditions favor disease development.
• mancozeb + copper hydroxide (ManKocide): 2 to 3 lb/A; PHI 5d, REI 48h, Groups M03 & M01.

FRAC Group M03: 

• mancozeb + copper hydroxide (ManKocide): 2 to 3 lb/A; PHI 5d, REI 48h, Groups M03 & M01.

FRAC Group NC:

• sodium carbonate peroxyhydrate (Percarb^OG): 1 to 3 lb/100gal; PHI 0d, REI 0/1h. Foliar application only.

FRAC Group P01:

• acibenzolar-S-methyl (Actigard 50WG): 0.5 to 1 oz/A; PHI 0d, REI 12h. Suppression only. See label for tank mix instructions. 

Anthracnose (Colletotrichum), Alternaria Leaf Spot, and Black Rot (Stagonosporopsis spp., formerly Didymella bryoniae)

Anthracnose symptoms appear on cucurbits as circular, water-soaked leaf spots. These eventually turn yellow/tan and can become brown and necrotic. The centers of the lesions may tear, creating a “shot-hole” appearance. Lesions on petioles and stems are typically elongated and do not girdle the stem. Masses of salmon-colored spores are produced in humid conditions. Anthracnose is seldom problematic in squash and pumpkin, but it is common in other cucurbits.

Alternaria leaf spot begins as small tan lesions with dark borders. As lesions expand, they develop concentric rings and yellow haloes. Lesions typically occur on older leaves first and do not appear on stems or petioles. Lesions may coalesce, blighting large areas of the leaves. The loss of photosynthetic area can lead to decreased yield. Spores may be seed-borne but it is unclear whether this is an important means of dispersal. Disease is favored by a leaf wetness period of at least 8 hours and an average temperature of 18°C.

Black rot (also known as gummy stem blight) is one of the most destructive diseases of cucurbits. Foliar symptoms start as marginal necrosis followed by larger, wedged shaped necrotic areas, often with a yellow halo. Stem cankers develop in the cortical tissue and a brown, gummy substance is produced. Tiny black fruiting bodies may appear in diseased tissue. Stems may be girdled, leading to wilt and decline. Small, water-soaked spots develop on fruit, enlarge, and exude a gummy substance. Black rot on butternut may appear as hardened tan to white areas which can develop concentric rings. Lesions may be dormant on mature fruit that is cured and stored under proper conditions, but chilling injury or high humidity may activate the disease and cause fruit collapse during storage. Check stored fruit weekly for signs of black rot.

Do not plant cucurbits for at least 2 years in fields where these fungal diseases have been a problem. Collect and burn or plow under plant debris after harvest. Manage weeds. Start with certified disease-free seed. Carefully scout transplants in greenhouse for diseased plants and remove them, improve ventilation in greenhouse, and reduce overhead irrigation. In the field, scout regularly and avoid injuring fruit before or during harvest. Immerse fruit in clean water containing a postharvest sanitizer. Chemical control can be obtained through a regular spray program of targeted and protective fungicides; apply these according to a disease forecasting system (Melcast). Full coverage of all plant parts is crucial to success. Rotate fungicide to deter resistance development. Cultivars with resistance to anthracnose are available. 

FRAC Group 1: 

• thiophanate methyl (Topsin M WP): 0.5 lb/A; PHI 1d, REI 24h. Anthracnose and black rot only.

FRAC Group 3:

• azoxystrobin + difenoconazole (Quadris Top): 12 to 14 fl oz/A; PHI 1d, REI 12h, Groups 11 & 3.
• difenoconazole + cyprodinil (Inspire Super): 16 to 20 fl oz/A; PHI 7d, REI 12h, Groups 3 & 9. Apply in sufficient volume to achieve thorough coverage. Greenhouse use for cucumber only.
• fluopyram + tebuconazole (Luna Experience): 6 to 17 fl oz/A; PHI 7d, REI 12h, Groups 7 & 3. Mild yellowing of leaf margin may occur.

FRAC Group 7: 

• boscalid (Endura): 6.5 oz/A; PHI 0d, REI 12h. Black rot and Alternaria only.
• fluopyram + tebuconazole (Luna Experience): 6 to 17 fl oz/A; PHI 7d, REI 12h, Groups 7 & 3. Mild yellowing of leaf margin may occur. 
• penthiopyrad (Fontelis): 12 to 16 fl oz/A; PHI 1d, REI 12h. Black rot and Alternaria only. See label for greenhouse use restrictions.
• pyraclostrobin + boscalid (Pristine): 12.5 to 18.5 oz/A; PHI 0d, REI 12h, Groups 11 & 7. Do not make more than 1 application before alternating with a non-Group 11 fungicide.

FRAC Group 9: 

• cyprodinil + fludioxonil (Switch 62.5 WG): 11 to 14 oz/A; PHI 1d, REI 12h, Groups 9 & 12.
• difenoconazole + cyprodinil (Inspire Super): 16 to 20 fl oz/A; PHI 7d, REI 12h, Groups 3 & 9. Apply in sufficient volume to achieve thorough coverage. Greenhouse use for cucumber only. 

FRAC Group 11:

• azoxystrobin (Quadris F): 11 to 15.5 fl oz/A; PHI 1d, REI 4h. Do not make more than 1 application before rotating to a non-Group 11 material.
• azoxystrobin + chlorothalonil (Quadris Opti): 3.2 pt/A; PHI 1d, REI 12h, Groups 11 & M05. See label for tank mix precautions.
• azoxystrobin + difenoconazole (Quadris Top): 12 to 14 fl oz/A; PHI 1d, REI 12h, Groups 11 & 3.
• famoxadone + cymoxanil (Tanos): 8 oz/A; PHI 3d, REI 12h, Groups 11 & 27. Tank mix with an appropriate contact fungicide with a different mode of action. Anthracnose and Alternaria only.
• fenamidone (Reason 500 SC): 5.5 fl oz/A; PHI 14d, REI 12h. Do not make more than 1 application before rotating to a non-Group 11 material. Alternaria only.
• pyraclostrobin (Cabrio EG): 12 to 16 oz/A; PHI 0d, REI 12h. See label for tank mix restrictions. May cause crop injury. 
• pyraclostrobin + boscalid (Pristine): 12.5 to 18.5 oz/A; PHI 0d, REI 12h, Groups 11 & 7. Do not make more than 1 application before alternating with a non-Group 11 fungicide.

FRAC Group 19: 

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

FRAC Group 27: 

• famoxadone + cymoxanil (Tanos): 8 oz/A; PHI 3d, REI 12h, Groups 11 & 27. Tank mix with an appropriate contact fungicide with a different mode of action. Anthracnose and Alternaria only.

FRAC Group M01:

• copper hydroxide (Kocide 3000): 0.5 to 1.25 lb/A; PHI 0d, REI 48h. 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).
• mancozeb + copper hydroxide (ManKocide): 2 to 3 lb/A; PHI 5d, REI 48h, Groups M03 & M01.

FRAC Group M03:

• mancozeb (Dithane F45): 1.6 to 2.4 qt/A; PHI 5d, REI 24h. Some cantaloupe varieties are sensitive.
• mancozeb + copper hydroxide (ManKocide): 2 to 3 lb/A; PHI 5d, REI 48h, Groups M03 & M01.

FRAC Group M05:

• azoxystrobin + chlorothalonil (Quadris Opti): 3.2 pt/A; PHI 1d, REI 12h, Groups 11 & M05. See label for tank mix precautions
• chlorothalonil (Bravo Weather Stik): 1.5 to 3 pt/A; PHI 0d, REI 12h. May cause injury to watermelon fruit. 

FRAC Group NC:

• potassium bicarbonate (MilStop^OG): 2 to 5 lb/100 gal/A; PHI 0d, REI 1h. See label for small volume application rates and greenhouse use instructions. 

Bacterial Wilt (Erwinia tracheiphila)

Striped cucumber beetles transmit bacterial wilt. Symptoms of this disease include dull green foliage and wilting during the day, often with recovery at night. Wilting begins at the tip and progresses down the vine. Leaves eventually turn yellow, brown at the margins, and die back. Cucumber and muskmelon are highly susceptible to wilt; watermelon is not. Seedlings at the cotyledon and 1- to 3-leaf stage are more susceptible to infection with bacterial wilt than older plants; thus, it is especially important to keep beetle numbers low before the 5-leaf stage. Remove and destroy infected plants. There are a few resistant cultivars of cucumber. Spunbonded row covers will exclude beetles and prevent infection. Perimeter trap crops of Blue Hubbard squash, which is highly attractive to striped cucumber beetles, can be used to protect more susceptible crops; the trap crop must be sprayed with insecticide to be effective. Use crop rotation to reduce beetle numbers. Because this bacterium is transmitted systemically by striped cucumber beetles, bactericide sprays are not effective. Striped cucumber beetles must be controlled by appropriate insecticide programs. Scout twice weekly at seedling stage for striped cucumber beetles. Treat when beetle numbers reach the threshold of 1 beetle per 100 feet of row. See the Cucumber, Muskmelon and Watermelon insect control section for more information on striped cucumber beetle.

Cucumber Mosaic Virus (CMV)

Cucumber mosaic virus has one of the widest host ranges of any plant virus. It is known to be seedborne in some host species but it is not commonly seedborne in commercial cucurbit seed. Symptoms of infection include stunting, yellow leaf spots, vein yellowing, malformation of leaves, and a mosaic pattern of light and dark green on leaves. On fruit, the viral symptoms may appear as ringspots or line patterns. More than 40 species of aphids and 2 beetles spread the virus. The abundance of other host plants, their proximity to crops, and the presence of vectors govern the incidence and severity of disease. The use of resistant varieties is the most effective means of control. Reduce weeds, especially chickweed, pokeweed, and milkweed, as much as practical. Practice rotation and plant away from previously contaminated fields. Insecticides are not effective.

Downy Mildew (Pseudoperonospora cubensis)

Pseudoperonospora cubensis only infects members of the cucurbit family and is an obligate parasite. Its survival depends on the presence of living cucurbit hosts, either in climates that permit their growth year-round or in greenhouse culture. The source of primary inoculum in cold climates is windblown sporangia from areas where plants survive the cold season. Generally, cucurbit downy mildew arrives in southern New England  in mid- to late summer. The progress of downy mildew is tracked by the North American Plant Disease Forecast Center (http://cdm.ipmpipe.org/). 

Symptoms of downy mildew include small, angular lesions on the foliage which are confined by leaf veins. These lesions later develop into darker necrotic spots and usually develop grey fuzzy fungal growth on the undersides of the leaves. Physiological specialization occurs in P. cubensis and several pathotypes and races have been described. Spread of downy mildew can occur over long distances by air currents and moves within a field via wind-dispersed sporangia. The main means of control are fungicide applications, the use of resistant cultivars, and cultural practices. Maximum control can be achieved only with a combination of these measures. Use proper plant spacing to reduce plant canopy density and avoid overhead irrigation to minimize the length of leaf wetness periods. Some commercial cultivars of cucumber have good levels of resistance to downy mildew. Watermelon and melon cultivars are available with low levels of resistance. P. cubensis is an oomycete and will not be controlled by the same fungicides that control true fungi. 

FRAC Group 11:

• azoxystrobin + chlorothalonil (Quadris Opti): 3.2 pt/A; PHI 1d, REI 12h, Groups 11 & M05. See label for tank mix precautions.
• famoxadone + cymoxanil (Tanos): 8 oz/A; PHI 3d, REI 12h, Groups 11 & 27. Tank mix with an appropriate contact fungicide with a different mode of action.
• fenamidone (Reason 500 SC): 5.5 fl oz/A; PHI 14d, REI 12h. Do not make more than 1 application before rotating to a non-Group 11 material.

FRAC Group 21:

• cymoxanil (Curzate 60 DF): 3.2 to 5 oz/A; PHI 3d, REI 12h. Must be tank-mixed with a protectant fungicide (copper, chlorothalonil, or mancozeb).

FRAC Group 22: 

• ethaboxam (Elumin): 8 fl oz/A; PHI 2d, REI 12h. 
• mancozeb + zoxamide (Gavel 75DF): 1.5 to 2 lb/A; PHI 5d, REI 48h, Groups M03 & 22. Apply preventively. Do not tank mix with other fungicides if downy mildew is the only target pest.
• zoxamide + chlorothalonil (Zing!): 30 to 36 fl oz/A; PHI 0d, REI 12h, Groups 22 & M05. See label for crop injury warning. 

FRAC Group 27:

• famoxadone + cymoxanil (Tanos): 8 oz/A; PHI 3d, REI 12h, Groups 11 & 27. Must be tank-mixed with a protectant fungicide (copper, chlorothalonil, or mancozeb).

FRAC Group 28:

• propamocarb HCl (Previcur Flex): 1.2 pt/A; PHI 2d, REI 12h. Alternate with a contact fungicide (copper, chlorothalonil, or sulfur). See label for greenhouse use restrictions.

FRAC Group 29:

• fluazinam (Omega 500F): 12 to 24 fl oz/A; PHI 7d/30d, REI 12h. 

FRAC Group 40:

• ametoctradin + dimethomorph (Zampro): 14 fl oz/A; PHI 0d, REI 12h, Groups 45 & 40.
• dimethomorph (Forum): 6 fl oz/A; PHI 0d, REI 12h. Must be tank-mixed with another fungicide with a different mode of action. 
• oxathiapiprolin (Orondis Ultra): 5.5 to 8 fl oz/A; PHI 0d, REI 4h, Groups 49 & 40. Begin foliar application prior to disease development. Use higher rate when disease is present. Not for use in greenhouse cucurbits.

FRAC Group 43:

• fluopicolide (Presidio 4SC): 4 fl oz/A; PHI 2d, REI 12h. Must be tank-mixed with another fungicide with a different mode of action.

FRAC Group 45:

• ametoctradin + dimethomorph (Zampro): 14 fl oz/A; PHI 0d, REI 12h, Groups 45 & 40.

FRAC Group 49: 

• oxathiapiprolin (Orondis Ultra): 5.5 to 8 fl oz/A; PHI 0d, REI 4h, Groups 49 & 40. Begin foliar application prior to disease development. Use higher rate when disease is present. Not for use in greenhouse cucurbits.

FRAC Group BM02:

• Bacillus amyloliquefaciens strain D747 (DoubleNickel 55^OG): 0.25 to 3 lb/A (foliar); PHI 0d, REI 4h.

FRAC Group M01:

• copper hydroxide (Kocide 3000): 0.5 to 1.25 lb/A; PHI 0d, REI 48h. 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).
• mancozeb + copper hydroxide (ManKocide): 2 to 3 lb/A; PHI 5d, REI 48h, Groups M03 & M01.

FRAC Group M03:

• mancozeb (Dithane F45 Rainshield): 1.6 to 2.4 qt/A; PHI 5d, REI 24h. Some cantaloupe varieties may be sensitive.
• mancozeb + copper hydroxide (ManKocide): 2 to 3 lb/A; PHI 5d, REI 48h, Groups M03 & M01.
• mancozeb + zoxamide (Gavel 75DF): 1.5 to 2 lb/A; PHI 5d, REI 48h, Groups M03 & 22. Apply preventively. Do not tank mix with other fungicides if downy mildew is the only target pest.

FRAC Group M05: 

• azoxystrobin + chlorothalonil (Quadris Opti): 3.2 pt/A; PHI 1d, REI 12h, Groups 11 & M05. See label for tank mix precautions.
• chlorothalonil (Bravo Weather Stik): 1.5 to 2 pt/A; PHI 0d, REI 12h. May cause injury to watermelon fruit.
• zoxamide + chlorothalonil (Zing!): 30 to 36 fl oz/A; PHI 0d, REI 12h, Groups 22 & M05. See label for crop injury warning. 

FRAC Group P05: 

• Reynoutria sachalinensis extract (Regalia^OG): 1 to 4 qt/A; PHI 0d, REI 4h. Apply to ensure thorough coverage.

FRAC Group P07:

• fosetyl-Al (Aliette WDG): 2 to 5 lb/A; PHI 12d, REI 24h. Do not tank mix with copper products or apply in a spray solution with a pH less than 6.0.
• phosphorous acid (Fosphite): 1 to 3 qt/20 gal; PHI 0d, REI 4h. Do not apply to plants that are heat- or moisture-stressed. Do not apply directly to plants treated with copper within 20-day interval. 

Phytophthora Blight and Fruit Rot (Phytophthora capsici)

Symptoms of this disease can occur at any stage of development. P. capsici may cause damping-off of seedlings. On mature vines it causes water-soaked lesions that later darken and girdle the stems, causing plant collapse and death. Foliar symptoms include chlorosis, water-soaked lesions, and leaf death. Lesions will usually begin as small spots with an olive-green border that quickly become necrotic. P. capsici cannot be managed by fungicide applications alone; successful disease control is achieved only by a season-long effort to manage water and other cultural practices. The single most effective way to control this disease is to prevent its movement into clean fields by equipment, humans, or infested water. Plant susceptible crops (tomatoes, peppers, eggplant, all cucurbit species, and beans) in well-drained fields with no history of this disease. Plant non-vining cucurbit crops on raised beds, avoid planting in low areas where water puddles, and improve drainage by sub-soiling. Promptly disk under small areas where the disease appears, along with a border of healthy-appearing plants. Avoid working in wet fields and minimize compaction.

FRAC Group 11:

• famoxadone + cymoxanil (Tanos): 8 to 10 oz/A; PHI 3d, REI 12h, Groups 11 & 27. Suppression only. Foliar or fruit phase only. Tank mix with an appropriate contact fungicide. Do not make more than 1 application before rotating to a non-Group 11 material.

FRAC Group 21:

• cyazofamid (Ranman 400 SC): 2.75 fl oz/A; PHI 0d/1d, REI 12h. Addition of a surfactant improves effectiveness when disease pressure is severe. Do not make more than 1 application before rotating to a non-Group 21 material. Observe a 30-day plant back interval for crops not on label.

FRAC Group 27:

• famoxadone + cymoxanil (Tanos): 8 to 10 oz/A; PHI 3d, REI 12h, Groups 11 & 27. Suppression only. Foliar or fruit phase only. Tank mix with an appropriate contact fungicide. Do not make more than 1 application before rotating to a non-Group 11 material.

FRAC Group 29:

• fluazinam (Omega 500F): 12 to 24 fl oz/A; PHI 7d/30d , REI 12h. 

FRAC Group 40:

• ametoctradin + dimethomorph (Zampro): 14 fl oz/A; PHI 0d, REI 12h, Groups 45 & 40. Begin application before disease development.
• dimethomorph (Forum): 6 fl oz/A; PHI 0d, REI 12h. Must be tank-mixed with another fungicide with a different mode of action. 
• oxathiapiprolin (Orondis Ultra): 5.5 to 8 fl oz/A; PHI 0d, REI 4h, Groups 49 & 40. Begin foliar application prior to disease development.

FRAC Group 43:

• fluopicolide (Presidio 4SC): 4 fl oz/A; PHI 2d, REI 12h. Must be tank-mixed with another fungicide with a different mode of action.

FRAC Group 45: 

• ametoctradin + dimethomorph (Zampro): 14 fl oz/A; PHI 0d, REI 12h, Groups 45 & 40. Begin application before disease development.

FRAC Group 49: 

• oxathiapiprolin (Orondis Ultra): 5.5 to 8 fl oz/A; PHI 0d, REI 4h, Groups 49 & 40. Begin foliar application prior to disease development.

FRAC Group P05: 

• Reynoutria sachalinensis extract (Regalia^OG): 1 to 4 qt/A; PHI 0d, REI 4h. Apply to ensure thorough coverage. 

FRAC Group P07:

• fosetyl Al (Aliette WDG): 2 to 5 lb/A; PHI 12d, REI 24h, Group P07. Do not tank mix with copper compounds. Tank-mixing with surfactants or foliar fertilizers is not recommended. Use the high rate when Phytophthora blight is active.
• phosphorous acid (Fosphite): 1 to 3 qt/20 gal; PHI 0d, REI 4h, Group P07. Do not apply to plants that are heat- or moisture-stressed. Do not apply directly to plants treated with copper within 20-day interval. 

Powdery Mildew (Podosphaera spp. and Golovinomyces spp.)

The white, powdery fungal growth that gives this disease its name appears as white spots on both upper and lower leaf surfaces. These spots may coalesce to cover larger areas or entire leaves. Older leaves are typically affected first. Begin scouting for powdery mildew at fruit initiation. Fungicides should be applied at the first sign of disease. Thorough spray coverage is essential. Powdery mildew fungi tend to become resistant to systemic fungicides in FRAC Groups 1 and 11. This has resulted in the removal of these classes of fungicides from recommendations, with the exception of Pristine which is a combination product. Resistance to the DMI fungicides (Group 3, e.g., Rally, Procure) is also widespread; use these products at the high labeled rate only. The most effective contact fungicides are sulfur, mineral oil, and chlorothalonil. Begin applying fungicides when powdery mildew is at a low level (less than 1 of 50 old leaves with symptoms on either leaf surface); do not begin using mobile fungicides when disease is widespread. A 7-day interval is recommended once disease is observed.

FRAC Group 3:

• difenoconazole + cyprodinil (Inspire Super): 16 to 20 fl oz/A; PHI 7d, REI 12h, Groups 3 & 9. Greenhouse use for cucumber only. 
• fluopyram + tebuconazole (Luna Experience): 6 to 17 fl oz/A; PHI 7d, REI 12h, Groups 7 & 3. Mild yellowing of leaf margins may occur. 
• flutriafol (Rhyme): 5 to 7 fl oz/A; PHI 0d, REI 12h. See label for restrictions for watermelon.
• myclobutanil (Rally 40 WSP): 2.5 to 5 oz/A; PHI 0d, REI 24h.
• triflumizole (Procure 480SC): 4 to 8 oz/A; PHI 0d, REI 12h. 
• triflumizole (Trionic 4 SC): 4 to 8 fl oz/100 gal.; PHI 1d, REI 12. Foliar spray only. See label for surfactant recommendation. 

FRAC Group 7: 

• boscalid (Endura): 6.5 oz/A; PHI 0d, REI 12h. Suppression only.
• fluopyram + tebuconazole (Luna Experience): 6 to 17 fl oz/A; PHI 7d, REI 12h, Groups 7 & 3. Mild yellowing of leaf margins may occur. 
• penthiopyrad (Fontelis): 12 to 16 fl oz/A; PHI 1d, REI 12h. See label for greenhouse use restrictions.

FRAC Group 9:

• cyprodinil + fludioxonil (Switch 62.55 WG): 11 to 14 oz/A; PHI 1d, REI 12h, Groups 9 & 12.
• difenoconazole + cyprodinil (Inspire Super): 16 to 20 fl oz/A; PHI 7d, REI 12h, Groups 3 & 9. Greenhouse use for cucumber only. 

FRAC Group 13:

• quinoxyfen (Quintec): 4 to 6 fl oz/A; PHI 3d, REI 12h. Muskmelons and watermelons only.

FRAC Group 19:

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

FRAC Group 50:

• metrafenone (Vivando): 10.3 to 15.4 fl oz/A; PHI 0d, REI 12h.

FRAC Group BM01:

• botanical extract (EcoSwing^OG): 1.5 to 2 pt/A; PHI 0d, REI 4h.

FRAC Group BM02:

• Bacillus amyloliquefaciens strain D747 (Double Nickel 55^OG): 0.25 to 3 lb/A (foliar); PHI 0d, REI 4h.

FRAC Group M01: 

• copper hydroxide (Kocide 3000): 0.5 to 1.25 lb/A; PHI 0d, REI 48h. 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 M02:

• sulfur (Microthiol Disperss^OG): 2 to 25 lb/A; PHI 0d, REI 24h. Sulfur can injure plants, especially at temperatures above 90° F.

FRAC Group M05:

• chlorothalonil (Bravo Weather Stik): 2 to 3 pt/A; PHI 0d, REI 12h. May cause injury to watermelon fruit. 

FRAC Group NC:

• mineral oil (JMS Stylet-oil^OG): 3 to 6 qt/100 gal; PHI 0d, REI 4h. Thorough coverage of leaf surface is necessary.
• potassium bicarbonate (Kaligreen^OG): 2.5 to 5 lb/A; PHI 1d, REI 4h. Cucumber and watermelon only.

FRAC Group P07:

• potassium dihydrogen phosphate (Nutrol): 10 to 20 lb/A; PHI 0d, REI 4h. See label for greenhouse use restrictions.

FRAC Group U06:

• cyflufenamid (Torino): 3.4 oz/A; PHI 0d, REI 4h.

Scab (Cladosporium cucumerinum)

Scab is a significant problem for watermelon and muskmelons, as well as summer and winter squash, and pumpkin. Symptoms of this disease appear on both the foliage and fruit. On foliage, symptoms are greyish-brown lesions with a yellow halo. Depending on the severity of infection, the disease can also cause leaf deformation. Fruit symptoms appear small at first and can grow into larger, dark pockmarks. As the disease progresses, lesions on fruit can coalesce and become entry points for secondary infections. Resistant cultivars of cucumber are widely available. The pathogen can live on infected crop debris on or in the soil and may be seedborne. Rotate with non-cucurbit crops for 2-3 years. Select sites with well-drained soil and good air movement for rapid drying of foliage and fruit. Avoid overhead irrigation and dense plant canopies. Fungicide sprays may not be effective during extended cool, wet weather due to the short disease cycle of this pathogen.

FRAC Group 19: 

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

FRAC Group M01:

• mancozeb + copper hydroxide (ManKocide): 2 to 3 lb/A; PHI 5d, REI 48h, Groups M03 & M01. Some cantaloupe varieties may be sensitive.

FRAC Group M03:

• mancozeb (Dithane F45 Rainshield): 1.6 to 2.4 qt/A; PHI 5d, REI 24h.
• mancozeb + copper hydroxide (ManKocide): 2 to 3 lb/A; PHI 5d, REI 48h, Groups M03 & M01. Some cantaloupe varieties may be sensitive.

FRAC Group M05:

• chlorothalonil (Bravo Weather Stik): 2 to 3 lb/A; PHI 0d, REI 12h. May cause injury to watermelon fruit. 

FRAC Group P01:

• acibenzolar-S-methyl (Actigard 50 WG): 0.5 to 1 oz/A; PHI 0d, REI 12h. For suppression only.

Seed Decay

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

FRAC Group 4:

• mefenoxam (Apron XL): 0.085 to 0.64 fl oz/lb seed; REI 48h. For Pythium damping-off protection.

FRAC Group 12: 

• fludioxonil (Maxim 4FS): 0.08 to 0.16 fl oz/100 lb seed; REI 12h. For protection against seed- and soil-borne fungi.

FRAC Group BM02: 

• Bacillus amyloliquefaciens strain D747 (Double Nickel 55^OG): 0.01 to 0.4 fl oz/100,000 seeds; PHI 0d, REI 4h.

FRAC Group M03: 

• thiram (Thiram SC): 4.5 fl oz/100 lb seed; REI 24h.

Watermelon Mosaic Virus (WMV) and Papaya Ringspot Virus (PRSV-W)

Symptoms of WMV and PRSV are similar and include stunted growth, leaf malformation, mottling, vein clearing, and marginal chlorosis. On fruit, symptoms appear as mottling and bumpy warts or blister-like areas. PRSV also causes target-like ringspots on fruit. Several aphid species transmit these 2 viruses in a non-persistent manner. Seed transmission of WMV is considered a possibility but remains unproven; PRSV is not considered to be seedborne in cucurbits. Remove and destroy affected plants. Control weeds. Grow resistant or tolerant varieties. Insecticides are not helpful for control.  

Zucchini Yellow Mosaic Virus (ZYMV)

ZYMV was first discovered in the United States in the early 1980s. Symptoms include severe malformation, blisters, necrosis, and severe plant stunting. On the fruit, the virus causes knobby areas and prominent deformation. Symptoms may vary with host species, cultivar, environmental conditions, and virus strain. The virus is transmitted in a non-persistent manner by aphids. It is also seed-borne. At this time, no weed hosts have been identified. For management strategies, see WMV and PRSV above.