PowerPoint available at https://tiny.utk.edu/ag/vegandfruit Vegetable and Fruit Disease Update Steve Bost Extension Plant Pathologist University of Tennessee scbost@utk.edu
Hot Topics from 2013 Botrytis strawberry Spray program tomato Downy mildew pumpkin Bitter rot apple Orange rust - blackberry
Botrytis Gray Mold in Strawberries Fungicide resistance Surveys of Botrytis in the Carolinas have indicated resistance to Topsin M (MOA Group 1) in all isolates. Resistance to the other MOA groups varied. What to do?
Fungicide resistance testing for Botrytis Clemson University Dr. Guido Schnabel Free service for Southeastern states Instructions for submitting samples: Collecting and Mailing Guidelines for Fungicide Resistance Testing_gs-2 20 to 40 dead blossoms or 150 healthy blossoms. Collected randomly. Or dead leaves, if can t find dead blossoms
OR wait until harvest and submit cotton swabs with spores (too late to help you, but still good info)
Mailing Put the flowers or the 10 swabs in plastic bag. Package with information about the origin of the sample (farm name, state), your name, phone number, and e-mail address. Mail to: Guido Schnabel Clemson University 105 Collings St/220 BRC Clemson, SC 29634 phone (864) 643 7131 When to expect your report: The day they receive the sample you will get an email notification. After notification, results sent to you by email in 7 days (for flowers and leaves if get sufficient spores) or 4 days for swabs.
What to do if you don t get your Botrytis tested? (I.e., I don t know what fungicides will work in my field) Resistance a threat to all mode of action (MOA) groups other than M. Spread out risks by rotating three MOA groups. An M product should be included, alone or as a tank mix with one of the other groups. Avoid Topsin M. Switch has fared well in surveys but resistances to all other than M have been found. Fungicide Captan Thiram Mode of Action Group Topsin M 1 Scala 9 M M Inspire Super 3+9 Fontelis 7 Pristine 7+11 Elevate 17 Switch 9+12
Early blight of tomato very common & very damaging A spray program must be built around controlling it. Programs that rely on the Group 11 s (Quadris, Cabrio, Tanos) have not.
Cultural methods of control are helpful but inadequate. A new spray program was needed. In a trial conducted at Nashville, TN, all labeled fungicides considered candidates for a tomato spray program were compared. Early blight damage on a resistant variety.
Product & rate/75 gal Early Blight of Tomato 2013 Field Trial, Nashville This trial was a search for replacements for the Group 11 fungicides Quadris, Cabrio, and Tanos. Plants were sprayed 3 times at weekly intervals and evaluated 1 week after the 3 rd spray. Fontelis 20 fl oz Inspire Super 20 fl Switch 14 oz 3 lb Bravo 2.75 pt Cabrio 12 oz Tanos 8 oz Quadris 6.2 fl oz Untreated check a a b b b c c c c 0 5 10 15 20 25 30 Leaf area affected (%) The results were used to guide the development of non-strobilurin-based spray programs.
Early Blight of Tomato 2013 Trial, Highland Rim REC Four spray programs were evaluated on trellised, Mountain Glory tomatoes sprayed every 7-10 days, beginning 3 wks after planting. Program Product and rate per acre at application number 1 2 3 4 5 6 7 8 9 10 Early blight % leaf area affected (final) Check none none none none none none none none none none 88.0 a* 1 Quadris 6 fl oz Quadris 6 fl oz Quadris 6 fl oz Quadris 6 fl oz Quadris 6 fl oz 2 23.3 c 57.5 b 3 Fontelis 10 fl oz** + + Kocide Fontelis 10 fl oz + + Kocide Fontelis 10 fl oz + + Kocide Fontelis 10 fl oz + + Kocide Fontelis 10 fl oz + + Kocide 0.3 d 4 Inspire Super 1 pt Fontelis 1 pt Inspire Super 1 pt Fontelis 1 pt Inspire Super 1 pt 0.1 d * Column means followed by the same letter are not significantly different (LSD, P=0.05). ** The minimum labeled rate of Fontelis is 1 pt/acre.
Excellent control of early blight was provided by spray programs containing Inspire Super or Fontelis. Unsprayed check Program 4
Early blight resistant tomato varieties 2013 trials Variety Early blight (% leaf area affected) Davidson Wilson Fruit type Vine habit Mountain Magic 1 25 25 salad indeterminate Matt s Wild Cherry 2 40 45 cherry indeterminate Plum Regal 1 40 45 plum determinate Juliet 2 45 - salad indeterminate Mountain Fresh Plus 2 53 55 large determinate Defiant 1 60 67 medium determinate Iron Lady 1 63 - medium determinate Amelia 2 63 60 large determinate Florida 91 2 65 55 large determinate Plum Crimson 1 65 65 plum determinate Mountain Glory 3 70 - large determinate
Brand Names chlorothalonil mancozeb Bravo Chloronil Echo Equus Initiate Dithane Penncozeb Koverall Roper
Example Spray Program Where bacterial diseases are expected Application no. Product 1 mancozeb + Actigard 2 mancozeb + copper 3 Fontelis + Actigard 4 mancozeb + copper 5 Inspire Super + Actigard 6 mancozeb + copper 7 Fontelis + Actigard 8 mancozeb + copper Notable restrictions: Actigard: 14-day PHI Fontelis: 72 fl oz/a/season Inspire Super: 47 fl oz/a/season See labels for other restrictions. Application no. Product 9 Inspire Super + Actigard 10 mancozeb/chlorothalonil* + copper 11 Fontelis + copper 12 chlorothalonil + copper 13 Inspire Super + copper 14 chlorothalonil + copper 15 Fontelis + copper *The 5-day PHI for mancozeb interferes with harvest. Switch to chlorothalonil when harvest begins. When not using mancozeb, discontinue use of copper if possible. NOTE: If late blight occurs, appropriate fungicides must be added. Fontelis and Inspire Super do not have any late blight activity.
Relative Effectiveness of Fungicides against Early Blight Product MOA a group PHI b (days) Max. use/acre/season c Max. no. consecutive apps. Early blight control rating d chlorothalonil M 0 15 lb a.i. (7-14 apps.) no limit 3 mancozeb M 5 22.4 lb (7-30 apps.) no limit 3 Cabrio 11 0 96 oz (8 apps.) 1 0 e Quadris 11 0 37 fl oz (6 apps.) 1 0 e Tanos 11,27 3 72 oz (9 apps.) 1 0 e Priaxor 7,11 0 24 fl oz (3 apps.) 2 5 Endura 7 0 21 fl oz (6 apps.) 2 4 Fontelis 7 0 72 fl oz (3-4 apps.) 2 5 Inspire Super 3,9 0 47 fl oz (2-3 apps.) 2 5 Revus Top 3,40 1 28 fl oz (4-5 apps.) 2 3 Scala 9 1 35 fl oz (5 apps.) 2 2 Switch 9,12 0 56 fl oz (4-5 apps.) 2 3 a MOA=mode of action. Do not rotate products containing ingredients belonging to the same MOA group, with the exception of Group M. Rotation is not required of members of this group. b PHI=pre-harvest interval. c Where presented as a range of applications, the appropriate number depends on the rate(s) used. d Scale of 0-5, 0=no control and 5=excellent control. e Not recommended due to the widespread occurrence of resistant strains.
Spray Program Design Always rotate fungicides with nonrelated fungicides. The always rotate rule does not apply to the multi-site fungicides mancozeb and chlorothalonil. The risk of resistance developing to them is extremely low. Spray to protect, not to rescue. Disease control is better if the spray program is begun before diseases are observed. Pathogen resistance is much less likely to occur if the product is applied to a small population of the fungus than to a large one. DO NOT APPLY FONTELIS OR INSPIRE SUPER TO SEVERELY DISEASED CROPS. It is important that we retain their effectiveness. PowerPoint available at https://tiny.utk.edu/ag/vegandfruit
Cucurbit Downy Mildew
Downy Mildew Applying sprays before infection provides best control for any disease, but is particularly important for downy mildew. Bravo
Fungicide efficacies (0=no control, 5=excellent control) MOA Group Powdery Downy White blight Chlorothalonil * 2 2 3 Mancozeb * 0 2 3 Sulfur * 4 0 0 Quintec 13 5 0 0 Rally 3 2 0 0 Pristine 7+11 3 0 R 3 Quadris 11 0 R 0 R 2 Cabrio 11 0 R 0 R 4 Fontelis 7 4 0 0 Presidio 43 0 3 0 Ranman 21 0 4 0 Zampro 45+40 0 3 0 * These three products do not need to be rotated no resistance problem. R Indicates widespread resistance. THIS IS NOT A COMPLETE LIST OF REGISTERED FUNGICIDES.
Pumpkin Spray Strategies Diseases present None Powdery mildew Downy mildew White blight Strategy Chlorothalonil or mancozeb every 7 to 14 days; scout field. Choose two powdery mildew products and alternate them. Tank mix with chlorothalonil or mancozeb. Choose two downy mildew products and alternate them. Tank mix with chlorothalonil or mancozeb. Choose two non-related white blight products and alternate them. Downy mildew tracking and forecasts: http://cdm.ipmpipe.org/
A pumpkin variety with resistance to downy mildew discovered at Highland Rim REC in 2013. Was by chance. Two fungicide trials, each involving a different variety. Great difference in downy mildew severity between unsprayed Hybrid Pam and Camaro.
Downy mildew on 28 Aug (13 days after initial infection) HRREC Trial, 2013 Hybrid Pam Camaro
Downy mildew on 23 Sep HRREC Trial, 2013 Hybrid Pam Camaro
Camaro A 25-lb pumpkin with resistance to downy mildew and powdery mildew, but its light orange color may not be acceptable.
Bitter Rot Lesions tend to be sunken, with concentric rings of fruiting bodies.
Results of tests on detached fruit At Soil, Plant and Pest Center Best activity Inspire Super Ziram Captan Merivon USE A SURFACTANT
Black Pox Helminthosporium papulosum Captan, Ziram, Topsin M
Orange Rust Rally, Tilt, Orbit, Abound, Cabrio, Pristine