Since shipping qualities vary among cultivars and change with advancing maturity, harvesting operations should be coordinated with your buyer's requirements. Experience in selecting fruits for harvest is highly desirable and they should be cut from the vine, not pulled. Watermelons are not adapted to long storage and should be consumed within 2 to 3 weeks after harvest. Watermelons should be protected from sunburn by prompt field handling after harvest and shading while waiting for shipment. Cultural Program Watermelons require moderate amounts of fertilizer and these amounts must be determined by soil test.
Watermelons respond better to split applications of nitrogen and potassium fertilizer.
In addition, watermelons have specific micronutrient requirements which must be met as well. Many nematode, insect, and disease pests affect watermelons. Some of these pests such as fusarium wilt cannot be controlled by spraying. Resistant varieties in conjunction with rotation to land that has been out of watermelon production for at least 8 years is an effective control measure. Other serious diseases include anthracnose, gummy stem blight, cercospora leaf spot, alternaria leaf spot, and downy mildew which can be controlled with fungicide sprays.