Parsnip Canker

Before planting parsnips, you should know about parsnip canker. Carrots, dill, parsley, and sunflowers may also get this disease.

Healthy parsnips (Jeffery Martin) Public Domain

Parsnip canker is an infection of Itersonilia perplexans and several other fungi that can reduce your crop by as much as 80%. But it is preventable.

Symptoms of parsnip canker

Like other cankers, symptoms include dark, mushy areas on parsnip crowns and shoulders. These areas may be black, brown, orange, or purple and typically have pale green halos. Lesions may also occur on the underside of young leaves.

Parsnip canker management

When growing parsnips, many gardeners mound soil over the crown as the plant grows in a practice known as hilling. Hilling in the UK has been shown to expose pathogens to predators, reducing the chance of infection. Unfortunately, this practice spread pathogens to neighboring plants in Australian gardens. I suspect it has something to do with temperature and humidity differences, but I am only guessing.

Other steps you can take to prevent parsnip canker include the following:

• Invest in certified disease-free seeds and seedlings.
• Plant seeds later in the season.
• Space plants no closer than two inches apart.
• Furrow irrigation reduces the chance that fungal spores will splash onto healthy plants.
• Employ crop rotation.
• Manage carrot rust flies whose larvae predispose plants to infection.
• Keep burdock, Chinese aster, and chrysanthemum away from susceptible crops, as they may carry the disease.
• Compost crop debris at the end of the growing season.

Foliar sprays of fixed copper may help treat the disease if applied early enough. And you can cut out the bad bits and enjoy the rest of the root.

Parsnips have a lot to offer, and they are easy to grow. The ones you might find in the grocery store are never as sweet and crisp as those you can grow in your yard.