Presentation on theme: "Solenaceous Crops II Root-knot nematode Bacterial Spot Blossom End Rot/Sun Scald Jan 26, 2009 **Not all images created by J. Bond**"— Presentation transcript:
Solenaceous Crops II Root-knot nematode Bacterial Spot Blossom End Rot/Sun Scald Jan 26, 2009 **Not all images created by J. Bond**
Root Knot Nematode CROP: Tomato, Pepper, virtually all plants PATHOGENS: Meloidogyne incognita – Southern Root-knot nematode M. hapla - Northern Root-knot nematode M. arenaria - Peanut Root-knot nematode DISTRIBUTION: Worldwide, IL
Pathogen Description Parasitic Roundworms Early juvenile and Male stages are vermiform Extreme Sexual Dimorphism Female nematode is pear-shaped with egg masses attached at maturity
Disease Symptoms -above ground: plants are stunted with some yellowing and severely affected plants may wilt - root system: galls are formed on primary and secondary roots; galls become large and are very obvious
Sedentary endoparasite Males can be rare, reproduction by amphimixis and parthenogenesis Life cycle is 3 weeks to several months depending on environment, 4-5 cycles per growing season 400 μm Pathogen Description
Uses its stylet to pierce cell walls to excrete enzymes for infection and feeding After feeding for a few days, females release eggs in gelatinous matrix Pathogen Description
Southern Root Knot Nematode Not detected Detected Detected on soybean Still counting
Host Crops in Illinois Row Crops Corn, Soybean, Wheat, Oats, Barley, Sunflower, Canola, Buckwheat, Pasture Grasses Vegetable Crops Asparagus, Beans and Peas, Beet, Carrot, and Parsnip, Cole Crops (Broccoli, Cabbage, Collards, etc.), Cucurbit Crops (Cucumber, Melons, Pumpkin, Squash), Lettuce, Spinach, and Other Greens, Onions, Garlic, and Leeks, Potatoes, Sweet Corn, Sweet Potatoes, Tomatoes, Peppers, and Eggplant Fruit Crops Apples, Blueberries, Brambles (Blackberries and Raspberries), Grapes, Peaches, Strawberries Virtually all ornamental plants
Conditions for Disease Development: - the nematode has a wide host range; it can also survive as dormant eggs a few months. - warm temperatures and light sandy soils are conducive for development.
Pathogen Life Cycle
Female Egg mass
Control Measures Use resistant cultivars; some populations may overcome resistance. Practice crop rotation. Use of soil fumigants or soil nematicides are effective for control.
Disease: Bacterial Spot CROP: Pepper, tomato, and many other crops PATHOGEN: Xanthomonas campestris pv. vesicatoria (strain specific) DISTRIBUTION: Worldwide - IL PATHOGEN DESCRIPTION: Gram-negative rod
DISEASE SYMPTOMS Affects leaves, fruit, and stems On leaves lesions begin as small water-soaked spots that remain small and become necrotic with a chlorotic border. Lesions may be sunken on the upper surface and raised on the lower surface. On fruit raised, dark colored lesions are wart-like in appearance On stems and petioles lesions appear as elongated necrotic spots or streaks Heavily infected leaves turn yellow and drop resulting in severe defoliation
Conditions for Disease Development Bacterium is seedborne and can survive in infected crop debris Many strains attack both tomato and pepper. Disease is enhanced by overhead water, heavy dew formation, and high temperatures.
Control Measures Use pathogen-free seed and disease-free transplants Crop rotation Resistant cultivars are becoming available, but may not be resistant to all strains Copper and copper + maneb sprays reduce damage Rain shelters may reduce disease severity during heavy rainfall periods
Physiological Disorders BLOSSOM END ROT - Calcium deficiency and water imbalance DISEASE SYMPTOMS AND SIGNS: A water-soaked lesion develops on the fruit lobe near the blossom end. The lesion desiccates, turns tan or brown, and becomes leathery in appearance. Saprophytic fungi and soft rot bacteria may invade the lesions.
Symptoms and Signs
Conditions for Disease Development Soils with low calcium levels Excessive or deficient soil moisture and high temperatures Excessive nitrogen levels and root damage by cultivation enhance blossom end rot development
Control Measures Application of limestone to low pH soils and gypsum (calcium sulfate) to high pH soils with low calcium levels. Good water management and proper nitrogen applications Avoid cultivation near the plant that causes root damage
Sunscald - Fruit exposure to direct sunlight DISEASE SYMPTOMS AND SIGNS: Pod wall tissue looses turger and rapidly dehydrates forming a papery, bleached lesion on the side exposed to the sun. Discoloration may occur later as secondary organisms invade. CONDITIONS FOR DISEASE DEVELOPMENT: -bright sun and exposure of fruit due to limb breakage by wind, cultivation, or harvest Mature green fruit are most susceptible. CONTROL MEASURES: - care in harvesting and cultivation not to damage the plants. - selection of cultivars with good foliage coverage.