MANAGING BACTERIAL DISEASES OF VINE CROPS. Sally Miller Department of Plant Pathology The Ohio State University

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1 MANAGING BACTERIAL DISEASES OF VINE CROPS Sally Miller Department of Plant Pathology The Ohio State University OPGMA Sandusky, OH January 22, 2013

2 Bacterial Diseases of Vine Crops Melon Disease Cucumber Squash Pumpkin Watermelon Seedborne Angular leaf spot Bacterial fruit blotch Bacterial leaf spot Yellow vine decline Bacterial wilt Bacterial rind necrosis

3 Bacterial Disease Cycle Infection Infested seeds or infected plant or greenhouse source Splashing Alternative hosts + previous diseased hosts Residues in soil Non-seedborne After Gaby Briceño Seedborne

4 Angular leaf spot of cucurbits Cucumber most susceptible but all cucurbits may be affected Favored by moderate temperatures and high moisture

5 Xanthomonas Bacterial Leaf Spot

6 Bacterial Fruit Blotch Mainly an economic problem on watermelon Can affect other vine crops First symptoms are water-soaked spots on lower sides of cotyledons R G O Brien and Christine Horlock Major symptoms are dark olive green spots on surface of fruit

7 Bacterial wilt of cucurbits Transmitted by cucumber beetles Cucumbers most susceptible but other cucurbits affected Plants infected early likely to wilt and die

8 Yellow Vine Decline n Serratia marcescens n Leaves turn yellow, phloem discolored (honey yellow), plants collapse Squash bug eggs n Transmitted by squash bug

9 6-Step Integrated Management Program 1. Use clean seed 2. Choose a resistant variety 3. Use pathogen-free transplants 4. Choose the best site and rotate 5. Use appropriate cultural practices 6. Use crop protectants as needed

10 1. Use Clean Seed Use certified seed Pathogen-tested Does not guarantee pathogen-free Treat seeds Hot water or Dilute Clorox Always pre-test

11 Seed Treatment with Bleach Then dry seeds in a single layer. Plant within 2 weeks.

12 Hot Water Seed Treatment

13 Sanitizing Treatments to Reduce Bacterial Spot on Pumpkin Seeds 2012

14 2. Choose a Resistant Variety Check with seed suppliers or Cornell Vegetable MD online tables Tolerance means partial resistance Consider other disease problems and market requirements when choosing a variety Few options for resistance to bacterial diseases in vine crops

15 Resistance to Bacterial Diseases in Vine Crops Disease Cucumber Squash Pumpkin Watermelon Melon Angular leaf spot ++++ x x x x Bacterial fruit blotch NL NL NL NL NL Bacterial leaf spot NL NL NL NL NL Yellow vine decline NL NL NL NL NL Bacterial wilt + (1) x x x x Bacterial rind necrosis NL NL NL NL NL NL = Not listed in VegetableMDonline Tables

16 Resistance of Cucumber to ALS Cultivar Foliar AUDPC Fruit incidence (%) Classy R d y 0.2 d Slice More cd 1.0 bcd Talladega dc 6.7 a bcd 2.9 a Thunder a-d 7.2 a Thunderbird R a-d 3.7 ab Stonewall T abc 4.7 a Sassy R abc 0.7 cd Green Slam abc 0.3 cd Indy R ab 4.6 a Intimidator R a 7.5 a Speedway R a 4.5 a

17 Resistance to Bacterial Spot-Pumpkin Charmed Solid Gold Data: Jim Jasinski et al. OSU

18 3. Use Pathogen-Free Transplants The goal is to keep bacterial populations low on seedlings Use new or sanitized plug trays/flats and pathogen-free mixes Sanitize equipment and tools regularly; install solid flooring/raise seedlings from floor Restrict movement of personnel, tools and equipment between greenhouses Thoroughly clean and sanitize house after each crop

19 3. Use Pathogen-Free Transplants Prohibit the production of exotic or experimental varieties unless seed was treated Scout regularly and destroy plants with symptoms and surrounding flats Apply one or two copper treatments and one application before plants leave GH Minimize moisture dry growing Use only municipal or well water avoid surface water unless it is treated to kill bacteria

20 4. Choose the Best Site and Rotate Site selection Well-drained Good air movement Sunny Rotate rotate rotate Rotate out of the cucurbit family ALS- 3 years Xanthomonas bacterial spot 2 years Bacterial fruit blotch 3 years Bacterial wilt 3 years

21 5. Use Best Cultural Practices Avoid handling plants when they are wet Sanitize hands, boots and tools between fields Clean and sanitize equipment between fields Maintain reduced-stress growing conditions Well-drained soil Appropriate fertilizer (adequate but not excessive N) Regular irrigation if needed Improved organic matter content cover crops, compost Destroy weeds (especially in the cucurbit family) in and near production fields

22 5. Use Best Cultural Practices Remove wilted/dying plants early in an epidemic to reduce amount of inoculum present Destroy foliage and vines as soon as possible after harvest to help manage yellow vie decline Bacterial wilt diagnostic test

23 Use Barriers to Protect Plants from Cucumber Beetles Treatment Row cover + pyrethrum Untreated control % bacterial wilt 0.0 a 13.3 b

24 6. Use Crop Protectants Scout regularly for cucumber beetles; apply insecticides once thresholds have been exceeded. Pumpkins: apply insecticides after seedling emergence if threshold of 0.5 beetles/plant (cotyledon stage) or 1 beetle/plant (1-2 leaf stage) is exceeded At-plant (e.g. Admire) or foliar insecticides as soon as plants emerge and on 5-day intervals until cucumber beetle infestations subside. Apply copper on a 5-7 day schedule beginning early after transplanting/emergence if conditions are conducive to disease Apply Actigard preventatively on 7 day schedule

25 Effect of Antibacterial Products on Bacterial Spot of Pumpkin Nine applications Data provided by Jim Jasinski, OSU

26 Thank you Acknowledgments Ohio Vegetable and Small Fruit Research and Development Program OSU Vegetable Pathology Lab Jhony Mera, Fulya Baysal-Gurel, Melanie Ivey, Xiulan Xu, Xing Ma, Nagendra Subedi OSU NCARS Matt Hofelich OARDC Wooster Farm Bill Bardall OSU Muck Crops Rick Callendar OSU Vegetable Pathology Lab