Watermelon Cantaloupe and Cucumber

Why are my young watermelon leaves crinkled and pale?

Young watermelon plants should be medium green and grow rapidly. Plants which are pale green and have crinkled true leaves are most like suffering from manganese toxicity. Manganese is an essential element for plant growth, but too much available manganese in the soil can cause the plants to stop growing. The problem is closely linked to soil pH. Anytime the soil pH is less than 5.5, there is a potential for manganese toxicity to develop. The cure is to test each field before planting and apply lime to fields with a pH less than 5.5. Once the young plants display symptoms, it is too late to cure the problem.