The problem with the above stated goal is that the cherry gene is dominant and very specifically sizes the resulting tomato to about 1/2 to 5/8 inch diameter. When you cross a cherry with a beefsteak, you get a ping pong ball size tomato. But when you grow the F2 and further generation seed, they segregate with one normal cherry, one normal beefsteak, and 2 ping pong ball size tomatoes. In other words, Purple Haze will always segregate into a small and a large fruited variant.
If you want to develop a large cherry tomato, you would have to start with a tomato that is a stable line and has the desired size. As an example, Pink Ping Pong crossed with Black Cherry would segregate to give a large ping pong ball size black cherry tomato.
Here is how I would go about developing it.
1. Cross Pink Ping Pong X Black Cherry
2. Grow the F1 and save at least 150 seed
3. Grow the F2 and carefully select the plants that produce ping pong ball size black fruit.
4. Grow the selected F3 plants and again back cross to Black Cherry
5. Grow the new F1 plants and save at least 150 seed.
6. Grow the F2 and select the black ping pong ball size fruits and check for flavor.
7. Grow the selected F3 and start weeding out the mediocre flavored fruits.
8. Grow the F4 and pick no more than 3 really good flavored lines to pursue going forward. These tomatoes will be stable for all visual traits but will segregate for flavor.
9. Grow the F5 and these should be very stable black ping pong ball size tomatoes with good flavor. These will be good enough to release as a new variety.
Note that there are 9 steps to the above cross and backcross
DarJones
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