Integrated Pest Management in Watermelon

1. Integrated Pest Management in Watermelon Camilla B. Yandoc

2. Watermelon Pests • Insects & Mites • Weeds • Diseases • Nematodes

3. Common Insect Pests Cutworms Rindworms Sweetpotato whitefly Aphids

4. Aphids & Whiteflies • Downward curling & crumpling of leaves (aphids) • Honeydew excreted by both insects attracts sooty molds • Both are efficient vectors of plant viruses

5. Cutworms & Rindworms • Cutworms: reduce young watermelon stands • May feed on leaves of young seedlings • Rindworms: general term for worms that feed on rind (fall armyworms, corn earworm, cutwroms and loopers • Foliage & stem damage • Eat away irregular patterns of the rind

6. Occasional Insect Pests • Cucumber beetle • Mites • Mole crickets • Wireworms • White-fringed beetle • Leafminers • Thrips

7. Occasional Insect Pests • Root maggots • Flea beetles & fleahoppers • Leafhoppers • Plant bugs • Grasshoppers • Melonworms & pickleworms

8. Insect Damage • Foliar damage (holes) • Stem damage • Root damage (wilting, stunting & death of plant) • Fruit damage • Drying up of leaves (sucking insects) • Leaf spots, mottling or discoloration

9. Insect & Mite Management • Sampling • Establish ETL • Recognize & identify beneficials Important Practices:

10. Aphid Control Biocontrol lady beetles, syphrid fly larvae,lacewings & tiny wasps cultural control reflective plastic mulch Stylet oil sprays (interferes with virus transmission)

11. Sweetpotato Whitefly Control Monitoring use of traps Cultural control planting location & sanitation Weed control control alternate hosts Chemical control alternate different classes of insecticides

12. Cutworm & Rindworm Control Mechanical control (cutworm): thorough soil prep Chemical control(cutworm): broadcast application of approved insecticides before planting Chemical control(rindworm): spray before worms > 1/2 in length, spray all of exposed fruit

13. Control of Other Insect Pests Chemical control insecticide sprays for flea beetles, leafminers, mites, mole crickets,wireworms, fleahoppers,leafhoppers, plant bugs,grasshoppers, melon worms and pickleworms

14. Control of Other Insect Pests Cultural control avoidance (white-fringed beetles), plowing & deep turning of crop litter before planting (root maggots), overhead irrigation (mites)

15. Insect & Mite Management Cultural Practices • Reflective mulch • Planting location/timing • Sanitation • Weed control • Overhead irrigation • Plowing & turning in crop debris

16. Diseases • Reduce crop yield & quality • Poor disease control due to delayed accurate diagnosis & delayed implementation of control measures • Disease control consists of a sequence of properly timed control measures (cultural, mechanical & chemical)

17. Anthracnose Damping-off Fusarium wilt Root & Stem Diseases • Gummy stem blight • Fusarium rot

18. Root & Stem Disease Management Gummy stem blightpostharvest plow-down of debris, crop rotation, fungicidal sprays, use fungicide treated seeds Anthracnoseresistant varieties, fungicidal sprays, clean seeds,sanitation Fusarium wiltresistant var.,healthy transplants,crop rotation, soil fumigation, delayed thinning

19. Foliar Diseases Anthracnose Cercospora leaf spot Downy mildew

20. Other Foliar Diseases • Alternaria leaf spot • Bacterial leaf spot • Watermelon mosaic

21. Foliar Disease Management Cercospora leaf spot sanitation (removal of crop debris, diseased vines & weed hosts), crop rotation, fungicide sprays Downy mildewfungicide application, resistant var., avoid irrigation, reduce canopy density

22. Foliar Disease Management Alternaria leaf spot protectant fungicides Bacterial leaf spot avoid overhead irrigation, sanitation, protective sprays (copper sprays)

23. Foliar Disease Management Watermelon mosaic stylet oil application to interfere with virus transmission & insecticides to control aphid (vector)population

24. Fruit Diseases Anthracnose Bacterial rind necrosis Bacterial fruit blotch

25. Other Fruit Diseases • Bacterial leaf spot • Blossom-end rot • Speckle • Watermelon mosaic

26. Fruit Disease Management Bacterial fruit blotch plowing infested soil, elimination of inoculum sources, field rotated out for 3 years or more, copper sprays (Kocide DF Kocide 2000), use of high quality transplants

27. Fruit Disease Management Anthracnose resistant varieties, fungicides, use clean seeds Bacterial rind necrosis use less susceptible cultivars

28. Fruit Disease Management Blossom end-rot soil testing & liming, irrigation during fruit development (preventive), foliar Calcium application (curative)

29. Disease Management Cultural Practices • Sanitation • Healthy transplants • Resistant varieties • Crop rotation • Weed/Insect vector control • Liming & irrigation

30. Disease Management Chemical Control • Fungicide sprays • Soil fumigation • Fungicide seed treatment

31. Weeds • Compete with the crop for nutrients, sunlight, water and space • Serve as alternate hosts of nematodes, viruses and insect pests

32. Weed Management Cultural, Mechanical & Chemical Control • Polyethylene mulch • Cultivation • Soil fumigant • Hoeing & disking • Herbicides

33. Economically Important Nematodes • Root-knot nematodes (Meloidogyne spp.) • Sting nematode (Belonolaimus longicaudatus) • Reniform nematode (Rotylenchus sp.)

34. Nematode Damage • Root galls interfere with normal water & nutrient uptake • Reduced size of root system limits availability of water & nutrients • Aboveground damage: stunting, wilting & chlorosis • Roots attacked by nematodes are predisposed to secondary invasion by root rotting plant pathogens

35. Nematode Management Cultural Practices • Planting location • Resistant varieties • Crop rotation • Land preparation • Use of clean & healthy transplants

36. Nematode Management Chemical Control • Fumigants • Non-fumigants • Chemigation

37. A Grower’s Pest Management Tactics: • Insect control: chemical insecticides • Weed control: mechanical control (cultivation) • Disease control: resistant varieties & chemical fungicides, removal & destruction of diseased seedlings

38. What Growers Do in the Field… • Scout for presence of insects and diseases (major pest problem) • Watch the weather and spray accordingly (follow recommendations) • Some spray protective fungicides even when weather is dry (for insurance)

39. What Growers Do in the Field.. • May spray 1 or 2x a season for aphid control, some never spray because insect problem is minor • Follow recommendations for tillage & crop rotation • Plant in soils without RKN problems

40. What Growers do in the Field • Fusarium Wilt control: crop rotation, use of resistant varieties, scouting for diseased transplants and removal of infected transplants • Gummy stem blight & Downy mildew control: fungicide sprays based on weather(likelihood of disease occurrence) or presence of spots

41. References • Zitter, A.T., D.L. Hopkins, and C.E. Thomas (eds.). 1996. Compendium of Cucurbits Diseases. APS Press. • Maynard, D. N. (ed.). 1992. Watermelon Production Guide for Florida. Florida Cooperative Extension Service & IFAS • Mr. Melvin Poole (Gainesville watermelon grower) • Mr. Gerry Brinen (County Extension Office)