Controlling Bacterial and Fungal Diseases in Tomato. Sally Miller Ohio State University Department of Plant Pathology

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1 Controlling Bacterial and Fungal Diseases in Tomato Sally Miller Ohio State University Department of Plant Pathology

2 Early Blight Very common disease Leaf spots, stem cankers, fruit rot Often defoliates plants Starts on older leaves and moves up

3 Septoria Leaf Spot Usually appears after mid-july Favored by rainy conditions Spots appear on leaves and stems at any stage of plant growth Plants may lose leaves Tiny, dark fruiting bodies in lesions No fruit symptoms

4 Late Blight Favored by cool, wet conditions All above - ground parts of the plant are susceptible: lesions are brown-black Disease can progress very quickly Early sources of the pathogen: Transplants (?)

5 Timber Rot (Sclerotinia White Mold) Stem necrosis, plant death Favored by cool, rainy conditions Soilborne pathogen, wide host range, long survival of sclerotia No resistance

6 Powdery Mildew Potentially serious problem Already serious in several states Signs are white powdery mycelium and spores on the surface of plants May see plant deformation and death

7 Anthracnose Favored by warm, wet weather Symptoms mainly on fruit Symptoms generally occur on ripe or ripening fruit

8 Buckeye Rot Phytophthora capsici Occurs occasionally in Ohio Requires hot, wet conditions Symptoms occur on fruit; root rot also poossible

9 Botrytis All above-ground plant tissues susceptible Olive-green/grey spores produced rapidly Ghost spots on fruit Primarily a greenhouse problem Favored by cool temperatures, high relative humidity, free moisture

10 Bacterial Canker Very serious disease Causes burning ( firing ) of the foliage, fruit lesions, stunting, plant death Stunting, plant death more often observed under stress conditions Seedborne No resistant varieties

11 Bacterial Spot Spots w/chlorotic haloes and firing of leaves, defoliation, fruit spots Favored by hot, humid conditions and driving rainstorms Seedborne No resistant varieties available

12 Bacterial Speck Foliar symptoms similar to bacterial spot Smaller spots ( specks ) on fruit Favored by cool, humid conditions and driving rainstorms Seedborne Limited resistant varieties available

13 Bacterial Stem Rot/Pith Necrosis Stunting, plant death Pith shows brown discoloration Favored by hot, wet weather Increased by excessive nitrogen fertilization Soilborne No resistant varieties available

14 Tomato Disease Management Use IPM approach - multiple tactics Select best possible site Open (good air movement), well-drained Improve soil quality Organic amendments Cover crops Practice appropriate rotations Rotate away from solanaceous crops at least three years

15 Tomato Disease Management Manage water properly Trickle/drip irrigation better than overhead Use raised beds Choose varieties with best resistance available Mountain series: moderate resistance to early blight (Mountain Pride, Supreme, Gold, Fresh and Belle)

16 Use Clean Seed To control bacterial diseases Tomato seed are acid treated during processing/de-fuzzing Not fully effective in sanitizing seed Other options Clorox treatment (surface sanitation) Hot water treatment (surface & internal)

17 Hot water seed treatment Seed Brussels sprouts, eggplant, spinach, cabbage, tomato Broccoli, cauliflower, cucumber*, carrot, collard, kale, kohlrabi, rutabaga, turnip Mustard, cress, radish Pepper Lettuce, celery, celeriac F Minutes * Cucurbit seeds may be damaged by hot water treatment

18 Effect of Hot Water Treatment on Bacterial Disease in Tomato

19 Disease incidence and yield of organic tomato plants raised from seed treated with hot water or not treated Treatment % Foliar Bacterialmature fruit (T/A) Anthracnose (T/A) Marketable Yield (T/A) Fruit Size (kg/fruit) Healthy immature fruit (T/A) Hot water 2.4 a 0.9 a 3.1 a 23.3 a 1.9 a 10.6 a Untreated 66.6 b 2.4 b 12.6 b 16.7 b 1.6 b 0.9 b

20 Hot Water Treatment -Disadvantages Percent Germination Figure 1. Effect of Hot Water Treatment on Germination of Tomato Seed Florida 47 untreated Florida 47 treated Peto 696 SM untreated Peto 696 SM treated CMM untreated CMM treated May delay or reduce seed germination, especially in old or poor quality seed lots May reduce seedling vigor 0 Day 3 Day 5 Day 6 Days after Sowing XCV untreated XCV treated May reduce seed longevity Height (cm) Figure 2. Effect of Hot Water Seed Treatment on Tomato Seedling Height Not compatible with other seed treatments (pelleting, priming etc.) Florida 47 untreated Florida 47 treated Peto 696 SM untreated Peto 696 SM treated CMM untreated CMM treated XCV untreated XCV treated Too damaging to largeseeded vegetables

21 Seed Treatment Cautions Use new, high quality seed Treat a small sample first and test for germination Treat close to time of planting (within weeks) Treat only once More information: OSU Extension Bulletin Vegetable Production Guide Miller, S. A. and Lewis Ivey, M. L Hot water and chlorine treatment of vegetable seeds to eradicate bacterial pathogens. Ohio State University Extension Fact Sheet HYG

22 Produce Clean Transplants Practice good sanitation in the greenhouse Use new or sanitized plug trays or flats and pathogen-free mixes Sanitize equipment Install solid flooring; raise seedling trays Limit movement of personnel and equipment between greenhouses Clean benches, greenhouse structure thoroughly after the crop

23 Produce Clean Transplants Do not raise exotic or experimental vegetable varieties, or plants from saved seed, in the same greenhouse with commercial seedlings unless all seeds are treated Avoid raising or holding ornamental plants and vegetables in the same greenhouse Exclude insects (may carry viruses)

24 Produce Clean Transplants Maintain conditions in the greenhouse that do not favor disease development Maintain relative humidity as low as possible Good air circulation Proper temperatures Do not overwater Handle plants as little as possible

25 Seedling Treatments for Bacterial Disease Management Objective is to reduce or eliminate bacterial pathogen populations on seedlings Copper/Manzate Bacteriophage - Omnilytics Good results in Florida Apply in overhead irrigation water Other biocontrols, e.g Serenade + Copper

26 In the Field - Cultural Tactics Mulches Plastic or plant-based Reduce splash dispersal of pathogens Protect fruit from soilborne pathogens Row orientation Maximize air movement Minimize leaf wetness periods

27 In the Field - Sanitation Destroy tomato tissue post-season Removes sources of inoculum Remove diseased plants and weeds inseason esp. for late blight, bacterial diseases Sterilize plant stakes between crops Clean tools, equipment frequently Prohibit tobacco use

28 Management with Fungicides Regular program of fungicide application Mancozeb or Manzate or Bravo standard protectants (P) Alternate with Quadris, Cabrio, Tanos or Flint (S) e.g. P-P-S-P-S-P-S-P-P Strobilurin resistance in potato early blight - consider S+P tank mix instead of S alone Include copper material in tank mix with mancozeb or manzate if bacterial spot or speck a concern Other fungicides may be necessary for specific problems: Topsin M for timber rot

29 GH Tomatoes - New Fungicide Registrations Decree Scala Botrytis management