Q.Why are my Big Beef and Beefsteak tomatoes wilting?
I have 15 tomato plants in a raised bed garden. All are thriving except for the Big Beef and Beefsteak, which are wilting from top down. The lower leaves are also turning yellow. These are mature plants, and it started about a week ago. Some fruit has set but it looks small in comparison to other plants. Another Big Beef started from the same seeds, planted in a different bed is also thriving. I thought these varieties were resistant to fungal wilt so am confounded by this. I have grown tomatoes (including these varieties) in this bed for a number of years, with no problems.
Tomato wilt can happen from a fungal wilt.
Make sure you are properly watering and that this is not the reason for wilting plants.
I would also encourage you to practice crop rotation with tomatoes. You mention you have planted for years in the same raised beds. Every 3 years you should plant your rotate any nightshade crops.