Some of the leaves on my indeterminate Black Krim heirloom tomatoes are curled, yellowish and stunted. I've looked up curly top virus, but the leaves don't get purple veins as was described in a few sources. In fact, they actually look chlorotic, with dark green veins with pale green leaf edges. The lower leaves look fine, the affected plant parts are growing although not fruiting. Any idea what I'm dealing with?