Why Haven't My Turnips Developed Well?

Are your turnip roots riddled with slimy, winding tunnels?

Is the root flesh of your turnips black but firm, and is the skin rough and cracked?

Is the root flesh black and rotted?

Does the turnip root have dry, sunken spots in it?

Does the turnip root have small, water-soaked spots or pits on the surface?

If the turnip roots are riddled with slimy, winding tunnels, the plant is infested by cabbage maggots. These white larvae feed on roots and transfer bacterial and fungal diseases. Remove and destroy infected plants. Solarizing the soil will help reduce maggot populations in problematic areas.

Black root flesh with rough and cracked skin is caused by Downy mildew. Control this fungal disease by spraying plants with a baking-soda-and-soap spray (1 teaspoon baking soda. 1 teaspoon liquid dish soap, 1-quart water) or copper. Cultivars tolerant to downy mildew include ‘Crawford’ and ‘Scarlet Queen Hybrid.'

Black and rotted turnip roots most likely indicate a bacterial disease - Black rot. Leaves will have V-shaped spots on margins. Destroy infected plants. Spray copper if the weather is wet and if you had problems with black rot in the past.

The most likely cause for these symptoms is Anthracnose. Keep plants dry when watering to prevent spread. You can avoid this fungal disease by planting turnips in cool soil, somewhere around early spring or in fall.

Small water-soaked spots or pits on the turnip root surface are caused by Cold injury. You can protect your plants with mulch if temperatures drop below 30°F.

Some environmental issues might have caused your turnip to develop poorly. Turnips require cool, moist, rich soil with a pH between 5.5 and 6.8. Plant seeds directly in the garden. Turnips grow best between 60° and 65°F. They grow poorly above 75°F but will tolerate temperatures as low as 40°F.