Advanced Tomato Workshop

1. Advanced Tomato Workshop Common Tomato Problems Chris Becker

2. Insect, Disease, or Disorder? Tomato Problem Quiz Answers

3. What is a Disease? • A plant disease is usually defined as abnormal growth and/or dysfunction of a plant. Diseases are the result of some disturbance in the normal life process of the plant • Diseases may be the result of living and/or non-living causes.

4. Diseases Abiotic Biotic Biotic diseases are caused by living organisms. Biotic causes of disease include fungi, bacteria, viruses, phytoplasmas, nematodes, and parasitic plants. • Abioticdiseases are caused by non-living environmental conditions such as frost, hail, and chemical burn, nutrient deficiencies.

6. Disease Symptoms Symptoms of disease are the plant’s reaction to the causal agent. • Blight – A rapid discoloration and death of twigs, foliage, or flowers. • Canker – Dead area on bark or stem, often sunken or raised. • Chlorosis– yellowing – Chlorosis is so generic that without additional details diagnosis is impossible. • Decline – Progressive decrease in plant vigor. • Dieback – Progressive death of shoot, branch or root starting at the tip. • Distortion – malformed plant tissue. • Gall or gall-like – Abnormal localized swelling or enlargement of plant part. It could be caused by insects, mites, diseases, or abiotic disorders. • Gummosis – Exudation of gum or sap. • Leaf distortion – The leaf could be twisted, cupped, rolled, or otherwise deformed. • Leaf scorch – Burning along the leaf margin and into the leaf from the margin. • Leaf spot – A spot or lesion on the leaf. • Mosaic – varying patterns of light and dark plant tissue. • Necrosis – dead tissue – Necrotic areas are also so generic that without additional details diagnosis is impossible. • Stunting – lack of growth. • Wilt – General wilting of the plant or plant part. • Witches broom – Abnormal broom-like growth of many weak shoots. • Insect feeding injury is also a symptom used in diagnosis, but not a symptom of disease.

7. Disease Signs Signsare the actual organisms causing the disease. • Conks – woody reproductive structures of fungi. • Fruiting bodies – Reproductive structures of fungi; could be in the form of mushrooms, puffballs, pycnidia, rusts, or conks. • Mildew– whitish growth produced by fungi composed of mycelium. • Mushrooms – fleshy reproductive structures of fungi. • Mycelium – thread-like vegetative growth of fungi. • Rhizomorphs – Shoestring-like fungal threads found under the bark of stressed and dying trees caused by the Armillaria fungi. They may glow in the dark! • Slime Flux or Ooze – A bacterial discharge that oozes out of the plant tissues, may be gooey or a dried mass. • Spore masses – masses of spores, the “seeds” of a fungus. • Insects and/or their frass(excrement) are also signs, although not signs of disease.

8. #1 Aphids • Insect Pests • Have piercing, sucking mouthparts; • physical damage not always apparent • Usually found on underside of leaf • They can reproduce asexually. • Color varies in species • Produce honeydew • Prevention • Insecticides

9. #2 Fruit Cracking/Splitting • An Environmental Disorder • Caused by rapid fruit development • and wide fluctuations in water • availability to the plant. • Mature ripening fruit are most • susceptible, especially when there • is a very dry period followed by • heavy rainfall. • Severity varies greatly by variety. • Prevention • incorporate organic matter, use • drip irrigation, apply mulch

10. #3 Septoria Leaf Blight • A Fungal Disease • Causes numerous small ( about • 1/8" to 1/4" in diameter) brown • spots that develop light tan to • white center as they age • Similar to early blight. Attacks • older leaves – turns yellow, • brown, then withers and dies. • Wet humid conditions favor the • development . • It usually appears after plants • begin to set fruit. • Prevention • use mulch, apply fungicide, limit • wetting foliage / overhead watering

11. #4 Herbicide Damage • Herbicide Damage • Symptoms include downward • rolling of leaves and twisted • growth. In addition, stems may • turn white and split; fruit may be • deformed. • Depending on the level of • exposure, the plant may or may • not survive. • Prevention • Do not apply 2-4-D like herbicides • near the garden • Avoid drift • Prevent contamination by keeping herbicide spray tanks separate from insecticide • & fungicide spray tanks.

12. #5 Glyphosate Injury • Herbicide Damage • White/Yellow discoloration at the • base of the youngest leaflets. • A result of spray drift to the stem • of the plant and/or application • during a windy day. • Herbicide on stem becomes • translocated to the upper leaves. • 1/50th to 1/150th rate can do this • type of damage. • Prevention • Use a shield to limit drift. • Cut off the leaves and observe the • plant

13. #6 Southern Blight • A Soilborne Fungal Disease • Causes yellowing of leaves and • wilting of infected plants. • The stem at the soil line appears • soft and sunken (cankered) and • turns brown to black. • Under moist conditions, a white • fungal growth occurs on the lower • stem near the soil surface. • Favored by moist conditions and • high temperatures above 85 °F. • Prevention • crop rotation, soil solarization, • deep plowing

14. #7 Fusarium Wilt • A Soilborne Fungal Disease • Invades the roots, plugs-up the • water conducting vessels, causes • yellowing and wilting of leaves. • Initially causes a yellowing and • wilting of lower leaves on a single • branch. • Whole plant eventually wilts and • dies. • Prevention • use resistant varieties, crop • rotation, soil solarization.

15. #8 No Tomatoes • Mostly an Environmental Disorder • Plants sometimes drop their flowers • when night temperatures are lower • than 55°F. • When night temperatures above • 70°F, flower production and • pollination are reduced. • Favorable night range for tomato • fruit set is between 58 and 68°F. • Very hot daytime temperatures • coupled with drought is a cause too. • May occur due to excessive nitrogen. • Prevention • Use heat resistant varieties.

16. #9 Tomato Fruitworm • Insect Pest • Also known as Corn Earworm • Caterpillar color varies from light • green to reddish-brown. • Usually has a broad dark stripe • with a light stripe on the body. • Feeds on stem end, entering • inside the fruit of green tomatoes. • Feeding damage leads to watery • and wormy fruit. • Prevention • Hand Remove • Insecticides

17. #10 Blossom End-Rot • A Nutrient Disorder • Caused by a Calcium Deficiency, • Due to improper soil pH, above or • below 6 - 6.5. • Insufficient calcium in soil • Aggravated by changes in soil • moisture – too dry or too wet • Prevention • spray calcium nitrate for temporary • relief, take a soil test, add lime, • keep soil moisture consistent.

18. #11 Catfacing • A Physiological Disorder • Misshapen ugly fruit. • Cold weather at the time of • blossom set distorts and kills • certain cells that should develop • into fruit, resulting in the • deformities. • Most often observed among first- • formed fruit. • Common in the large-fruited • “beefsteak” type tomatoes. • Prevention • none

19. #12 Zippering • A Physiological Disorder • A thin longitudinal scar from the • stem scar to the blossom end. • Series of transverse scars which • resemble a zipper. • This defect happens when the • flower anthers fuse to the ovary • wall of developing fruit • Occurs most commonly when fruit • set takes place in cool weather. • Varieties can vary in their • susceptibility to this malady. • Prevention • None

20. #13 Stinkbugs • An Insect Pest • Feed with piercing-sucking • mouthparts which cause whitish- • yellow corky spots underneath the • skin of the fruit. • On green fruit, damage appears as • dark pinpricks surrounded by a • light discolored area • Commercially, this damage is • serious because they render the • fruit unmarketable. • Prevention • Insecticides

21. #14 Early Blight • A Fungal Disease • Begins on older lowers leaves by • turning them yellow. • Leads to irregular spots that • enlarge to ½ inch in diameter with • concentric rings and a yellow halo. • Plants appear to “fire-up” from • their base • Early season pest; warm, wet • weather favor its development • Prevention • use mulch, apply fungicide, limit • wetting foliage / overhead watering

22. #15 Tomato Spotted Wilt Virus • Virus disease spread by thrips • Infected plants are stunted, may • die slowly. • Dark ring spots form on leaves. • Terminal leaves stop growing, • become distorted and have a pale • purple/bronze appearance. • Fruit exhibit “real cool-looking” • ringspots. • Prevention • Remove suspected and infected • plants immediately, control insects, • use resistant varieties

23. #16 Armyworms • Insect Pest • Caterpillar color varies from dull • green to black. • Older larvae have a broad, light- • colored stripe along the side of • the body. • Feeds primarily on leaves but will • attack fruit making a single or • group of holes or depressions. • Damage is typically superficial but • could lead to fruit to rot. • Prevention • Hand Remove • Insecticides

24. #17 Leaf Roll • A Physiological Disorder • Edges of the leaves roll upward • and inward. • High temperatures, prolonged • periods of wet soil conditions, • and drought may promote • symptom development. • Symptoms are most common • when plants have a heavy fruit set. • Associated with varieties having a • specific gene that favors this condition. • Prevention • Variety Selection, Irrigation

25. #18 Cutworms • An Insect Pest • Active only at night and remain • buried below the soil surface near • food plants during the day. • They emerge to feed at night and • often cut seedlings or small • stems, causing the plants to fall • over. • Prevention • Insecticides, remove grass and • weeds, plow the soil well in • advance of planting, use paper or • plastic "sleeve" over the plant to • protect the stem.

26. #19 Sunscald • A Physiological Disorder • Initial symptom is a whitish, shiny • area that appears blistered. • Occurs on green tomato fruit • exposed to the sun. • Injury is more serious during • periods of abnormally high • temperatures. • The killed tissue is quickly • invaded by secondary organisms • and the fruit decays. • Prevention • Control foliar diseases • Avoid heavy pruning

27. #20 Bacterial Spot and Speck • Bacterial Diseases • Introduced on transplants • Attacks leaves and fruit • Favored by warm, wet conditions • Leaf spots can be irregular and • ragged • Fruit spots can be raised or • scabby • Prevention • Use disease-free transplants

28. #21 Tobacco Hornworm • Insect Pest • Large, smooth, green caterpillar of • the Carolina Sphinx moth. • Mature larvae measure 3½” in • length • Has seven or eight conspicuous • white V-shaped markings down • each side and a prominent spike • (horn) on its rear end • Feeds on the leaves, stems and • fruit of tomato plants • Prevention • Hand remove, insecticides, plant • dill a trap crop.

29. #22 Adventitious Roots • A Physiological Disorder • These are adventitious roots or • aerial roots which would grow into • normal roots if placed in contact • with the soil. • They emerge as a result of stress, • particularly water-related stress. • Determined by cultivar, weather • conditions and culture. • Prevention • Maintain moisture, mound • compost around root initials on • the lower part of the plant.

30. #23 Thrips • Tiny Insect Pests • Prefer to feed in flowers, but also • occur in flower and leaf buds and • on leaves. • Feeding on foliage may cause a • bronzing or silvering of foliage. • Eggs inserted in fruit causes • dimpling, and the infested area • may appear white. • Thrips are also vectors of tomato • spotted wilt virus. • Prevention • Insecticides

31. #24 Whiteflies • An Insect Pest • Adults are very small, white and • moth-like; 1/16th inch long. • Feed underside the leaves on plant • sap. • Usually noticed during mid to late • summer. • Numbers are usually not sufficient • to cause damage to plants. • They do excrete honeydew and • may cause sooty mold. • Prevention • Insecticides, sticky traps

32. #25 Spidermites • An Arachnid Pest • They damage plants by inserting • their stylet mouthparts into • individual plant cells and • withdrawing cellular liquids and • contents. • Damaged plants take on a bronzed • appearance. • Affected leaves eventually die and • turn brown. • Tends to be hot weather pest. • Prevention • Horticultural oils and soaps

33. #26 Bacterial Wilt • A Soilborne Bacteria Disease • Most commonly found in low, wet • areas of fields. • Plants wilt and die rapidly without • yellowing or spotting of the • foliage. • It invades and gradually blocks • the vascular tissue (the food- and • water-conducting vessels just • beneath the epidermis). • The pith will turn brown and • sometimes become hollow. • Prevention • crop rotation, soil solarization.

34. #27 Nematodes • Microscopic wormlike animals • found in the soil – 1 mm in length. • Damage plants by feeding on • roots, impairing its ability to • take up water and nutrients. • Cause stunting, leaf yellowing, • loss of plant vigor, reduction in • yields, and wilting. • Causes distinct swellings or galls • on roots. • Non-uniform distribution of • symptomatic plants • Prevention • Soil Solarization, Crop Rotation

35. #28 Flea Beetle • Flea beetles are tiny black beetles that jump when disturbed. • Overwinter as adults and begin feeding in spring. • Feed on the undersides of leaves causing small holes or sunken pits. • Mostly a problem on new seedlings, and if left unchecked, can cause significant • Prevention • Insecticides

36. #29 Leaf-footed bug • Insect pest that feeds on tomato plants during the adult and nymph stage. • Overwinter as adults and begin feeding in spring. • Congregate and feed together during nymph stages. • Prevention • Insecticides

37. #30 Buckeye Rot • Caused by the fungus phytophthoraparasitica. • Starts as a grayish green or brown • spot on fruit that has come into • contact with soil. • Light and dark brown concentric bands appear in the affected area. This firm, leathery rot is characterized by a smooth surface and lack of sharply defined margins. • Prevention • Mulch, prevent fruit from touching the soil.