I would suggest that you destroy the diseased plants and remove all weeds near your garden. The cucumber mosaic is spread by aphids so weekly sprays with an insecticide such as malathion or diazinon will be helpful. My beautiful cucumber leaves have white pencil-like trail lines on them. The pencil-like trails found on your cucumber leaves are caused by leaf miner activity. These insects tunnel their way through to the two layers on the leaf.
Parasites effectively control leaf miners.
Avoid excess spraying with insecticides such as diazinon, which are quite harsh on the parasites. There is a white powdery growth on the upper surface of my cucumber leaves. My plants are not growing as vigorously as it once did. This fungal disease is called powdery mildew. You can control it with copper fungicides, or maneb with dinocap or with benomyl.