Bacterial Leaf Blight of Carrots

HOSTS

• Carrots
• Parsnips

DESCRIPTION

Bacterial leaf blight is caused by the bacteria Xanthomonas campestris pv. Carotae. The pathogen can reduce the quality and growth rate of infected crops, which can lead to economic losses.

BIOLOGY

Bacterial leaf blight can survive on and be spread by infected seeds and contaminated plant matter. The bacteria can survive up to a year on carrot plant debris, but will not survive in the soil without it. 

The bacteria can also be spread through water, tools, or machinery after coming in contact with infected plant matter. As the disease can be spread by water, areas with heavy irrigation or rainfall are more likely to experience bacterial leaf blight on susceptible crops.

SYMPTOMS

• Brown, necrotic leaf spots with yellow halos usually starting at leaf edges 
• Leaf spots will grow together to cause leaf blight 
• Curled leaves and petioles 
• Gummy, yellow-brown discharge from foliage

GENERAL MANAGEMENT

• Plant certified disease-free seed 
• Rotate with unsusceptible crops every 2-3 years 
• Avoid watering practices, such as overhead irrigation, that result in wet leaves for prolonged periods. Instead, try drip-irrigation or similar techniques. 
• Crop debris should be incorporated into the soil 
• Plow or till plant debris into the soil to speed up decomposition.