Candidatus Liberibacter of Pepper

June 2015
Claudia Nischwitz, Extension Plant Pathologist • Erin Petrizzo, Research Assistant

symptoms on pepper
Fig. 1. Yellow discoloration and stunted growth of leaves.
pepper comparision
Fig. 2.
Healthy pepper plant (right). Diseased pepper
plant (left)
Fig. 3.
Yellow discoloration of pepper foliage.
adult potato psyllid
Fig. 4.
Adult potato psyllids and nymphs. (Bactericera cockerelli) Size: 0.12 inches (3 mm)
Fig. 5.
Potato psyllid egg. Size: Less than 0.04 inches (1 mm)
Fig. 6.
Potato psyllid Nymphs. Size: 0.08 inches (2 mm)

Quick Facts

  • The non-culturable bacterium Candidatus Liberibacter solanacearum infects peppers.
  • Bacteria are transmitted by potato psyllids, (Bactericera cockerelli).
  • Bacteria are transmitted throughout the lifetime of the insect and can also infect tomatoes and potatoes.

The bacterium Candidatus Liberibacter solanacearum infects pepper plants. Candidatus Liberibacter solanacearum is found in all states west of the Rocky Mountains, Kansas and in Texas. The disease was first reported in the United States in 2004. Yield losses can reach up to 100%.


The symptoms on peppers include stunted growth, and yellow discoloration of the foliage (Fig. 1, Fig. 2, Fig. 3). The potato psyllids have been present in Utah for a long time but the bacterium was detected for the first time in a in 2013 (potato sample). In summer 2014, pepper samples were confirmed positive for the first time. 

Disease Cycle

The bacterium is transmitted by potato psyllids (Bactericera cockerelli) (Fig. 4). Potato psyllids are very small and look like black, winged aphids on the plants. They are native to North America and found in the Southwestern United States.

Under a dissecting micro-scope the characteristic white bands on their back can be seen. Eggs (Fig. 5) are a light to dark yellow-orange color and can be found on short stalks near the edge of the leaf. Nymphs (Fig. 6) are only visible on the leaves with a strong hand lens. Potato psyllids can acquire Candidatus Liberibacter solanacearum by feeding on an infected plant. The bacterium can also be passed on from mother to offspring. Depending on the number of potato psyllids feeding, a potato plant can be infected within one to six hours. One adult potato psyllid is capable of infecting a healthy potato plant within six hours. Twenty adult potato psyllids are capable of infecting a healthy potato plant within an hour (Munyaneza 2012).


It is important to start scouting for potato psyllids using yellow sticky cards early in the season. Leaves should be inspected on the underside for the presence of psyllid nymphs (Fig. 6 ). The nymphs are very small and can be seen easier with a strong hand lens. If peppers are planted in an area where potato psyllids have been a problem in the past, imidacloprid insecticide can be applied at planting. If follow-up treatments are needed, insecticides containing spinosad or spiromesifen can be used following the label. Once a plant is infected with Candidatus Liberibacter solanacearum, there is no cure for it. It should be removed to reduce the amount of inoculum present in the field.

References and Further Reading

  • Munyaneza, J. E. 2012 Zebra Chip Disease of Potato: Biology, Epidemiology and Management. Am. J. Pot. Res. 89:329-350

Image Credits

4 Department of Primary Industries and Regional Development (Government of Western Australia)
5 © Plant & Food Research (

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