I just noticed some additional leaf damage to other plants (watermelon and tomato). It seems that whatever is affecting some plants is not impacting the others. Is this herbicide damage, too?
Is there any chance of recovery or do I need to pull the plants? The watermelon plant has several baseball-size (sugar baby variety) growing on it.
From your photos, it looks as if the watermelon may have been subject to herbicide damage. All you can do is monitor the growth of the plant to see if it outgrows the damage.
With the tomato, we cannot see any type of leaf damage. We notice that you have several plants in the container with the tomato. A regular-size tomato needs at least a four-gallon container for best growth. If the tomato is a patio-size, you should be okay. See our publication on container vegetables: http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/HG600%20Container%20....