Fusarium Wilt: Fusarium oxysporum f. sp. melonis attacks muskmelon and Fusarium oxysporom f. sp. niveum attacks watermelon.

Symptoms

• Both fungi contribute to damping-off of seedlings, but most significant losses occur after young plants are infected in the field.
• Plants infected early in the season often produce no marketable fruits.
• Plants that begin to show wilt symptoms at or near maturity produce fewer and lower quality fruits.
• The first symptoms of Fusarium wilt are wilting and chlorosis (yellowing) of older leaves. The wilt is most evident during the heat of the day.
• Plants may appear to recover by morning, only to wilt again in the afternoon.
• Stem cracks and brown streaks often appear near the crown of the plant and are associated with a red-brown exudate.
• Fusarium wilt also causes vascular browning that is visible in stem cross-sections.

Management

• Planting resistant cultivars is the only reliable way to keep infested fields in production.
• Commercially acceptable resistant cultivars exist, but extremely high pathogen populations in the soil can overcome their resistance.
• Therefore, methods to reduce Fusarium populations in the soil also should be employed.
• These methods include extended rotations with crops other than cucurbits and fall plowing of severely infested fields.