Watermelon problem, such as the situation in the picture, what's wrong with the teacher?

Cucumber Fusarium wilt mainly harms the base, nodes and petioles of stems and vines. In the late stage of the disease, it cracks and secretes yellow gum. Spray iprodione, difenoconazole, copper hydroxide, fluquinazol, cuprammonium chlorate, azoxystrobin, pyraclostrobin and picoxystrobin in time at the initial stage of the disease. The compound of prochloraz and copper can also be used for diseased stems.