They are rarely a serious problem. With care, the very small brownish larvae can be lifted out with the point of a knife. Leafminer injury is sometimes a point of entry for disease-producing organisms. Crop protectants are available for control. Young plants emerge, become chlorotic, and die back to soil level while roots appear normal.
Problem appears intermittently along the row.
Some parts of the row not affected. This condition is typical of triazine herbicide injury and most often results when cucumbers are planted after corn that was treated with a triazine herbicide.