What is the primary disease caused by Fusarium oxysporum in tomatoes?

Fusarium oxysporum is a soil-borne fungus that is well-known for causing Fusarium wilt in tomatoes. This disease is characterized by yellowing and wilting of the leaves, often starting with the lower leaves, and it typically progresses up the plant. The fungus invades the plant's vascular system, leading to water and nutrient transport issues which ultimately can cause the plant to wilt and die. The pathogen can survive in the soil for extended periods and can affect a range of other plants, but in the context of tomatoes, Fusarium wilt is the primary disease associated with this pathogen. The other options, while related to various problems that can affect tomato crops, do not specifically result from Fusarium oxysporum, making Fusarium wilt the correct association for this question.