Are my tomatoes and cukes too close together?

[jal_ut]

If cukes get stressed, they will often get a bitter taste. I don't think this has any thing to do with the particle wood. Yes, as someone already said, keep them watered well. If those are slicers, pick them when they are 8 inches long. If picklers, pick at 4 inches. Often the bitterness is only on the stem end of the cuke. Try cutting an inch off the stem end and see if the rest tastes better. Good luck.