 Several viruses are known to infect the plant, including seed-borne strawberry latent ringspot virus, parsnip yellow fleck virus, parsnip leafcurl virus, parsnip mosaic potyvirus, and potyvirus celery mosaic virus.The latter causes clearing or yellowing of the areas of the leaf immediately beside the veins, the appearance of ochre mosaic spots, and crinkling of the leaves in infected plants.The shoots and leaves of parsnip must be handled with care, as its sap contains furanocoumarins, phototoxic chemicals that cause blisters on the skin when it is exposed to sunlight, a condition known as phytophotodermatitis.