For the past 2 years I have grown my tomato plants in a raised bed under my pine trees. First year they did great and got some pine needles in the bed with the new soil. Next year they didn't do nearly so well- could this be from the pine needles - I heard that they could change the soil ph.
Correct Soil for Tomatoes
Lime tomato soils to pH 6.5 to 6.7 -- Home gardens not limed in the past 2 to 3 years will need 2 cups of lime for each plant. The lime should be worked into the soil 12 inches deep.
If your raised beds are under pine trees, they may not be getting enough sun. Tomatoes need a minimum of 7 hours in full sun to produce a good harvest.