That looks an awful lot like yellow mosaic virus to me, though hopefully someone will chime in and say I'm wrong. Classic symptoms are patchy yellowing between the veins, stunted growth, and cupped/puckered leaves, and I think all you can do about it is pull up the infected plants and throw them away (don't compost). It's transmitted from plant to plant by aphid, so clearing up any patches of those can help curb the spread of the virus.