Potato Brown Rot

If you squeeze a potato and a pale ooze comes out of its eyes, it has brown rot.

Also known as bacterial wilt of tomato and potato and southern bacterial wilt, potato brown rot is not the bacterial wilt that infects cucurbits or the brown rot of stone fruit trees. Instead, this disease targets the nightshade family, infecting eggplant, peppers, potatoes, and tomatoes. Oddly enough, bananas, ginger, and olives are also susceptible.

Tomato plant infected with southern brown rot (Don Ferrin, LSU, Bugwood.org) CC BY 3.0

Potato brown rot symptoms

If oozing eyes wasn’t enough, downward leaf curling, vein darkening, and severe wilting may also occur. While these symptoms look similar to Fusarium and Verticillium wilts, those fungal diseases travel slowly and uniformly throughout an infected plant. Potato brown wilt symptoms move fast. Young tomato leaves may look limp. Tubers infected with brown rot feature a pale brown ring under the skin, less pronounced than ring rot. If the flesh inside that ring is reddish, your spud has pink rot. 

​How plants catch potato brown rot 

The pathogens responsible for potato brown rot (Ralstonia solanacearum species complex) thrive in hot (>85°F), humid conditions. They can remain viable in water for 40 years (under ideal conditions) and in the soil for up to two years.

Tomato plant infected with potato brown rot (Clemson University - USDA, Bugwood.org) CC BY 3.0 US DEED

Bacteria enter plants through wounds and natural openings and move to the xylem, where they reproduce, clogging veins and killing the plant.​

Managing potato brown rot

Chemical treatments are ineffective against potato brown rot, and serious infections require soil solarization, so prevention is your best bet. These tips can help prevent potato brown rot in your garden:

• Choose a site with good drainage.
• Start with certified pest- and disease-free seed potatoes, preferably resistant varieties.
• Quarantine all new plants.
• Space plants 2 to 3 feet apart.
• Clean and sanitize garden tools regularly.
• Keep weeds in the nightshade family away from your potatoes and tomatoes.
• Employ a 2- to 5-year crop rotation or one fallow year between these crops.
• Remove infected plants and toss them in the trash.