Trellising and Training Tomatoes (cont)
By: Shepherd Ogden
Why Trellis Indeterminates?
Another reason to trellis -- a reason that's applicable all over the United States, but especially in humid areas of the East and Northwest -- is that it keeps the fruits and foliage off the soil, and it allows air to circulate around the plants, reducing the likelihood of foliage blights.
Trellised tomatoes are also easier to protect from pests than plants that trail on the ground. Aphids, whiteflies, hornworms, and even field mice are more visible and more easily controlled when you don't have to battle them in a tangle of ground-hugging vines.
In the Southwest, a tomato may be better off if it trails below the level of drying winds, but then irrigation is necessary, and unless you provide water through tubing rather than sprinklers, you may still see blight and mildew.