Solenaceous Crops II Root-knot nematode Bacterial Spot Blossom End Rot/Sun Scald Jan 26, 2009 **Not all images created by J. Bond**

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

Disease Symptoms

Disease Symptoms

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 detectedDetectedDetected on soybeanStill counting

Host Crops in IllinoisRow 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

FemaleEgg 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.

Germplasm Evaluation

Disease: Bacterial SpotCROP: Pepper, tomato, and many other crops

PATHOGEN: Xanthomonas campestris pv. vesicatoria (strain specific)

DISTRIBUTION: Worldwide - IL

PATHOGEN DESCRIPTION: Gram-negative rod

DISEASE SYMPTOMSAffects 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

Disease Symptoms

Disease Symptoms

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

Disease Symptoms

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.

Disease Symptoms