Solenaceous Crops II

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Solenaceous Crops II

• Root-knot nematode
• Bacterial Spot
• Blossom End Rot/Sun Scald

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Root Knot Nematode

• CROP Tomato, Pepper, virtually all plants
• PATHOGEN
• Meloidogyne incognita Southern Root-knot
  nematode
• M. hapla - Northern Root-knot nematode
• M. arenaria - Peanut Root-knot nematode
• DISTRIBUTION Worldwide, IL

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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

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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

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Disease Symptoms
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Disease Symptoms
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Pathogen Description
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
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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
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Southern Root Knot Nematode
Not detected Detected Detected on soybean Still
counting
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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

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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.

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Pathogen Life Cycle
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Control Measures

• Use resistant cultivars some populations may
  overcome resistance.
• Practice crop rotation.
• Use of soil fumigants or soil nematicides are
  effective for control.

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Germplasm Evaluation
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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

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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

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Disease Symptoms
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Disease Symptoms
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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.

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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

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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.

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Symptoms and Signs
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Disease Symptoms
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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

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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

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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.

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Disease Symptoms