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PLANT PATHOLOGY: DIAGNOSTIC KEY [continued]

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  MG Manual Reference
Ch. 4, pp. 3 - 4
[ Diagnostic Key: vegetables | specific vegetables; asparagus, bean, beet, carrot, cole crops, corn, cucurbits, eggplant, lettuce, onion, pea, pepper, potato, tomato | tree fruits| specific fruits; apple, stone, citrus | ornamentals | specific ornamentals; rose family, rose, palm, pine ]


KEYS TO PROBLEMS ON SPECIFIC VEGETABLES

ASPARAGUS Top

SYMPTOMS CAUSES CONTROLS
Tops turns yellow, brown, and die back; orange, reddish, or black pustules appear on stems and leaves • Rust (fungal disease) • Cut tops close to ground in fall and destroy; use registered fungicide; resistant varieties
Shoots wilt, turn yellow, then brown; roots are reddish color • Fusarium wilt (fungal disease) • Destroy infected plants; rotate for 2-4 years; soil pasteurization
• Root rot (fungal disease) • Rotate; remove old plant debris; plant in well drained area
Small spears • Immature plants • Asparagus produces small spears for the first 2-3 years after planting
• Overharvested • Do not harvest late into the season; plants cannot store enough food for following season
• Poor fertility • Amend soil as needed
• Poor drainage • Do not overwater; plant in well drained area
Spears crooked • Mechanical injury from windblown sand or mishandling  
• Insect injury • Control asparagus beetles with registered insecticide
Spears turn brown and soft • Frost injury • Protect spears with mulch when cold temperatures are expected
• Root rot (fungal disease) • Remove old plant debris; rotate; plant in well drained area
Leaves chewed; slime may be present on leaves; no evidence of insects • Slugs (emerge at night and hide during the day) • Use slug bait (either beer or commercial bait)
Spears and leaves chewed or scarred • Asparagus beetles • Turn soil in winter to disturb overwintering pests; protect young plants with cloth netting; use registered insecticide

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