Vegetarian Newsletter

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1 Vegetarian Newsletter A Horticultural Sciences Department Extension Publication on Vegetable Crops Eat your Veggies!!!!! Issue No. 545 May 2009 Watermelon Fungicides 2009 By: Amanda J. Gevens, UF/IFAS Plant Pathology, Gainesville, FL and Pamela D. Roberts, UF/IFAS Plant Pathology, SWFREC, Immokalee, FL Managing disease in watermelon includes site and cultivar selection, irrigation management, row spacing, and soil preparation. However, once the plants are in the ground, fungicides are an important component of good disease management. The following table includes all of the currently-labeled fungicides for common watermelon diseases in Florida. The list is organized by disease, with products listed alphabetically. Products known to be highly effective have been labeled with an asterisk (*). FRAC, or the Fungicide Resistance Action Committee, was developed to help provide resistance management guidelines for fungicide use. The FRAC codes help identify fungicides by their mode of action and informs if they should be used in consecutive sprays. The FRAC codes for each material are listed in the following table. (A simple way to remember what to use next in your fungicide rotation is to use a labeled fungicide with a different FRAC number or letter.) A good general fungicide program would be: a) inspect transplants for health and quality before setting in the field. b) apply Ridomil under the plastic for damping off (Pythium). c) scout plants on a weekly basis (from transplant to harvest) for disease. d) if diseases (such as Gummy Stem Blight or Downy Mildew) are found, it will be necessary to get on a rotation program with one or more of the fungicides in the following table. e) it is a good practice to tank-mix systemic fungicides with protectants, such as Bravo or Dithane. f) routine applications of chlorothalonil (Bravo) alternated with mancozeb (Dithane) can be made until fruit set.

2 Watermelon Fungicides 2009 Disease Angular Leaf Spot Bacterial Fruit Blotch Belly Rot or Fruit Rot or Rhizoctonia Rot Damping-off (Pythium) *Fixed copper (M1) *Fixed copper (M1) *Azoxystrobin (Amistar, Quadris, Heritage) 2.08F Chlorothalonil (Bravo Ultrex) 6F (M5) Potassium phosphates (Fosphite, Fungi- Phite, Prophyt, Topaz) (33) Thiophanatemethyl (Topsin M) 70WP (1) *Mefenoxam (Ridomil Gold, Ultra Flourish) (4) Potassium phosphates (Fosphite, Fungi- Phite, Prophyt, Topaz) (33) Propamocarb (Previcur Flex) 6F (28) See label Repeated use may cause leaf yellowing See label Start applic. at first bloom; ineffective once fruit reach full size. Repeated use may cause leaf yellowing. See label See label 1 4 hr Make banded applic. to soil surface or in-furrow applic. before seed are covered lb 0 12 hr Use in sufficient water to a.i./a obtain adequate coverage. Re-apply every 7 days. Spraying mature watermelon fruit may result in sunburn of upper surface. See label See label 0 See label Check label for required min. gal/a. Restrictions are for use following copper applic., plant and environmental conditions that restrict use, and compatibility days Apply in sufficient water to obtain run-off to soil 1 to 2 pt/a 0.5 to 1 surface. - 2 days Preplant incorporated (broadcast or band); soil spray (broadcast or band); or injection (drip irrigation. See label See label 0 See label Check label for required min. gal/a. Restrictions are for use following copper applic., plant and environmental conditions that restrict use, and compatibility with other materials fl oz/100 gal 0.6 lb/100 gal days s based on rock wool cube saturation in the greenhouse. See label for use in seed beds, drip system, and soil drench.

3 Leaf Spots, Alternaria, Anthracnose (Colletotrichum), Cercospora, Gummy Stem Blight (Didymella), Target Spot (Corynespora) *Azoxystrobin (Amistar, Quadris, Heritage) 2.08 F Bacillus spp. (Serenade Max, Sonata, Rhapsody) *Chlorothalonil (Bravo Ultrex) 6F (M5) 11 to 15.4 fl 0.18 to 1 4 hr Make no more than with a fungicide with a Apply no more than 2.88 qt/crop/a/season. See label See label 0 0 Do not use product alone. Apply with registered fungicide lb a.i./a 0 12 hr Use in sufficient water to obtain adequate coverage. Re-apply every 7 days. Spraying mature watermelon fruit may result in sunburn of upper surface. Copper (M1) See label Repeated use may cause Famoxadone + cymoxanil (Tanos) 50WP (11+27) Fenamidone (Reason) 500SC *Kresoxim methyl (Sovran) leaf yellowing Only for Alternaria and Anthracnose. Do not make >1 applic. before alternating with a fungicide of a different mode of action. Must be tank-mixed with a contact fungicide. 5.5 fl day Begin applic. when conditions favor disease and continue on 5- to 10- day interval. Do not apply >22 fl oz/season. Alternate with fungicides from different resistance management groups, and make <4 applic. of Group 11 fungicides per season. 4.8 oz hr For Gummy Stem Blight. Follow resistance management guidelines for QoI fungicides. *Mancozeb (M3) 2 to to 2.4 *Maneb (Maneb) 1.2 to to DF (M3) *Pyraclostrobin (Cabrio ) 20WG 12 to to day Apply no more than 24 /season. 5 1 day Spray at first appearance and then at 7- to 10-day Do not use for Gummy Stem Blight where resistance to Group 11 (QoI) fungicides exists. Do not make >1applic. before alternating to a fungicide with a

4 Leaf Spots, Alternaria, Anthracnose (Colletotrichum), Cercospora, Gummy Stem Blight (Didymella), Target Spot (Corynespora) (continued) Downy Mildew *Pyraclostrobin + boscalid (Pristine) 38WG (11+7) Tebuconazole (Folicur) 3.6F Thiophanatemethyl (Topsin M) 70WP (1) Mancozeb + Zoxamide (Gavel) 75DF (M3+22) Azoxystrobin (Amistar, Quadris, Heritage) 2.08 F Bacillus spp. (Rhapsody, Serenade, Sonata) Chlorothalonil (Bravo Ultrex) 6F (M5) *Cyazofamid (Ranman) 400 CS (21) *Cymoxanil (Curzate) 60DF (27) Dimethomorph (Acrobat, Forum) 50WP (40) *Famoxadone + cymoxanil (Tanos) 50WP (11+27) 12.5 to to hr Not for Target Spot. Use highest rate for Anthracnose. Make no more than 4 applications per season. 8 fl hr Gummy stem blight suppression only. Limited to 24 fl /crop/season Spray at first appearance and then at 7- to 10-day 1.5 to lb to to 15.4 fl 0.18 to Begin applications when plants are in 2-leaf stage, and repeat at 7- to 10- day 1 4 hr Make no more than 1 with a fungicide with a Apply no more than 2.88 qt/crop/a/season. See label See label - 0 Do not use product alone. Apply with registered fungicide lb a.i./a 0 12 hr Use in sufficient water to obtain adequate coverage. Re-apply every 7 days. Spraying mature watermelon fruit may result in sunburn of upper surface fl Do not apply >6 sprays/crop. Make no more than 3 consecutive applic. followed by 3 applic. of fungicides from different resistance management groups Use only in combination with labeled rate of protectant fungicide. No more than 9 applic./12 months Apply only as a tank mix with another fungicide. Do not make >2 sequential applic Do not make >1 applic. before alternating with a fungicide that has a Must be tank mixed with contact fungicide.

5 Downy Mildew (continued) *Fenamidone (Reason) 500SC Fixed copper (M1) *Fluopicolide (Presidio) (43) Fosetyl-Al (Aliette) 80WDG (33) 5.5 fl Begin applications when conditions favor disease and continue on a 5- to 10-day interval. Do not apply >22 fl oz/season. Alternate with fungicide from different resistance management group, and make no more than 4 total applic. of Group 11 fungicides/season. See label Repeated use may cause leaf yellowing fl days 12 hrs Max rate is 4 fl lb a.i./a /applic. And 12 fl /season. Apply no more than 2 sequential applic. Before alternating to fungicide 2 to to 2.4 *Mancozeb (M3) 2 to to 2.4 *Mandipropamid 8 oz 0.13 (Revus) (40) lb/a.i./a *Maneb (Maneb) 75DF (M3) *Mefenoxam + chlorothalonil (Ridomil Gold Bravo, Fluoronil) 76.5WP (4+M5) Potassium phosphates (Fosphite, Fungi- Phite, Prophyt, Topaz) (33) 1.5 to to 0.6 of a different chemistry Do not tank mix with coppers. Mixing with surfactants or foliar fertilizers is not recommended. 5 1 Apply no more than 24 /season 0 12 hr Max of 4 applic. during 1 crop cycle. Apply no more than 2 sequential to a fungicide of a different chemistry. An adjuvant is recommended. Do not use in transplant production. 30 day plant back restriction, unless plant appears on label. 5 1 Spray at first appearance and at 7-10-day 2 to Spray at first appearance and repeat at 14-day Apply full rate of protectant fungicide between applic. Avoid late-season applic., when plants reach maturity. See label See label 0 See label Check label for required min. gal/a. Restrictions are for use following copper applic., plant and environmental conditions that restrict use, and compatibility with other materials.

6 Downy Mildew (continued) Phytophthora Blight *Propamocarb (Previcur Flex) 6F (28) *Pyraclostrobin (Cabrio) 20WG *Pyraclostrobin + boscalid (Pristine) 38WG (11+7) Trifloxystrobin (Flint) 50WDG *Mancozeb + Zoxamide (Gavel) 75DF (22+M3) Cyazofamid (Ranman) 400SC (21) Dimethomorph (Acrobat, Forum) 50WP (15) *Fluopicolide (Presidio) (43) *Mandipropamid (Revus) (40) 1.2 pt/a Begin applic. before infection; continue on a 7- to 14-day interval. Do not apply >6 pt/season. Always tank mix with another downy mildew product. 8 to to Do not make >1 applic. before alternating to a fungicide with a different 12.5 to to 7 mode of action hr Not for Target Spot. Use highest rate for Anthracnose. Make no more than 4 applications per season Begin applic. preventatively and continue as needed alternating applic. of Ridomil Gold Bravo on a 7-10-day interval. 1.5 to to Begin applic. when plants are in 2-leaf stage, and repeat at 7-10-day 2.75 fl Do not apply >6 sprays/ crop. Make no more than 3 consecutive applic. followed by 3 applic. of fungicides from different resistance management groups. 6.4 oz 3.2 oz Must be applied as a tank mix with another fungicide active against Phytophthora Blight. Do not make >2 sequential applic fl lb a.i./a 8 oz 0.13 lb/a.i./a 2 days 12 hrs Max rate is 4 fl /applic. And 12 fl /season. Apply no more than 2 sequential applic. Before alternating to fungicide of a different chemistry hr Max of 4 applic. during 1 crop cycle. Apply no more than 2 sequential to a fungicide of a different chemistry. An adjuvant is recommended. Do not use in transplant production. 30 day plant back restriction, unless plant appears on label.

7 Phytophthora Blight (continued) Powdery Mildew Potassium phosphates (Fosphite, Fungi- Phite, Prophyt, Topaz) (33) *Azoxystrobin (Amistar, Quadris, Heritage) 2.08 F See label See label 0 See label Check label for required min. gal/a. Restrictions are for use following copper applic., plant and environmental conditions that restrict use, and compatibility with other materials. 11 to 15.4 fl 0.18 to 1 4 hr Make no more than with a fungicide with a Apply no more than 2.88 qt/crop/a/season. Chlorothalonil (Bravo Ultrex) 6F (M5) lb a.i./a 0 12 hr Use in sufficient water to obtain adequate coverage. Re-apply every 7 days. Spraying mature watermelon fruit may result in sunburn of upper surface. Copper (M1) See label Repeated use may cause Horticultural Oils (JMS Stylet Oil, Sporan, Neem Oil) *Kresoxim methyl (Sovran) *Myclobutanil (Nova, Rally) 40WP (3) *Pyraclostrobin (Cabrio) 20WG *Pyraclostrobin + boscalid (Pristine) 38WG (11+7) *Quinoxyfen (Quintec) (13) leaf yellowing. See label See label - - See label for specific application techniques required oz hr Follow resistance management guidelines for QoI fungicides. 2.5 to 5 1 to Apply no more than 1.5 /crop. Observe 30-8 to to to to 7 day plant back interval Do not make >1 applic. before alternating to a fungicide with a 0 12 hr Not for Target Spot. Use highest rate for Anthracnose. Make no more than 4 applications per season. 4-6 fl - 3 days 12 hr Do not make more than 4 applic./season. Rotate fungicide chemistries to avoid resistance development. *Sulfur (M2) See label Do not use when temps. are over 90 F or on sulfur-sensitive varieties. Tebuconazole (Folicur) 3.6F 4-6 fl hr Follow label for resistance management guidelines. Limited to 24 fl /crop/season.

8 Powdery Mildew (continued) *Thiophanatemethyl (Topsin M) 70WP (1) *Trifloxystrobin (Flint) 50WDG *Triflumizole (Procure) 50WS (3) Spray at first appearance and then at 7- to 10-day 1.5 to to Begin applic. preventatively and continue as needed on a 7-14-day interval. Do not apply >1applic. before alternating with a non-strobilurin fungicide. 4 to 8 oz 2 to 4 oz Begin applic. at vining or first sign of disease, and repeat at 7-14-day

2007 Indiana CCA Conference Proceedings

2007 Indiana CCA Conference Proceedings Managing Foliar Diseases of Cucurbits in Indiana Daniel S. Egel, Extension Plant Pathologist Southwest Purdue Agricultural Center, Vincennes, IN 47591 (812) 886-0198 egel@purdue.edu The purpose of this