Suckers are removed from tomato plants to prevent; crowding of the fruit, to increase the size of the fruit. If a sucker is allowed to grow it will produce a stem similiar to the main stem, and the fruit will be extremely crowded and sometimes difficult to pick.
One or two suckers can be allowed to grow if desired, but they should emanate from the area above the first cluster of fruit.
The suckers should not be removed until they can be clearly identified as such. Avoid removing suckers from the main header area due to possibly confusing suckers with the header or a fruiting branch.
Two weeks before the end of the season remove the main header. This will allow the remaining fruit to enlarge and ripen. The plants will often get 4 to 8 feet high, and will need support in most cases.
Durgan- Ontario, Zone "5B"