Zebra Chip Disease of Potato
June 2015
Claudia Nischwitz, Extension Plant Pathologist • Shawn Olsen, Agriculture Agent (Davis County) • Ron Patterson, Agriculture Agent (Carbon County)
Fig. 1. Yellowing and pink-reddish discoloration of potato plant foliage. Image courtesy of http://agresearchmag.ars.usda.gov/2012/feb/potatoes/.
Fig. 2. Brown discoloration of fresh potato tuber
Fig. 3. Brown discoloration of fried potato tuber. Image courtesy of http://www.apsnet.org/publications/apsnetfeatures/Pages/PotatoZebraChip.aspx.
Fig. 4. Adult potato psyllid. (Bactericera cockerelli)
Size: 0.12 inches (3 mm).
Image courtesy of http://www.ag.ndsu.edu/archive/entomology/ndsucpr/Years/2010/August/12/ent.htm.
Fig. 5. Potato psyllid egg. Size: Less than 0.04 inches (1 mm). Image courtesy of Kevin Ong, Texas AgriLife Extension Service, Bugwood.org.
Fig. 6. Potato psyllid Nymphs. Size: 0.08 inches (2 mm). Image courtesy of Kevin Ong, Texas AgriLife Extension Service, Bugwood.org.
Quick Facts
- The non-culturable bacterium Candidatus Liberibacter solanacearum causes zebra chip disease of potatoes.
- Bacteria are transmitted by potato psyllids, (Bactericera cockerelli).
- Bacteria are transmitted throughout the lifetime of the insect and can also infect tomatoes and peppers.
The bacterium Candidatus Liberibacter solanacearum causes zebra chip disease of potato. Zebra chip disease 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%.
Symptoms
The symptoms on potatoes can go unnoticed until the potato tubers are sliced. Above ground symptoms include yellowing and a pink-reddish discoloration of the foliage that could be mistaken for nutrient deficiencies (Fig. 1).
The reddish discoloration is caused by a toxin produced by the potato psyllids. Potato tubers show brown striations when sliced (Fig. 2) that are even more pronounced when fried (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 potato sample in 2013. In summer 2014, another potato sample was confirmed positive.
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 microscope 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).
Management
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 potatoes 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
1 Ag Research Magazine (USDA-ARS)
3 apsnet.org
4 North Dakota State University Extension
5, 6 Kevin Ong, Texas AgriLife Extension Service, Bugwood.org
Related Research
Damping-off is caused by several soilborne fungi including Pythium, Rhizoctonia, Fusarium and Phytophthora species. The fungi kill seedlings that are just germinating and seedlings that have been growing for several days. Powdery mildew is widespread in Utah and affects many vegetables, fruit, and landscape plants. There are several species of powdery mildew fungi, and typically they target just a single host or only hosts in related plant families. Beet Curly Top Virus (BCTV) is taxonomically a Curtovirus in the Geminiviridae family of plant pathogenic viruses. It is vectored, or carried, by the beet leafhopper (BLH) insect. BCTV causes curly top of tomato, a comon disease in Utah and the western U. A short summary of the top insect and disease pests of beans and how they are managed by the backyard gardeners. Big Bud is caused by Phytoplasma species. Phytoplasmas are a unique type of small bacteria that do not have a cell wall. Phytoplasmas are transmitted from one plant to another by phloem-feeding insects such as leafhoppers and psyllids Botrytis neck rot is caused by Botrytis acclada and B. allii. The fungi are specific to members in the Alliaceae (onion and garlic) and can be found in all onion-producing regions around the world. A short summary of the top insect and disease pests of cole crops and how they are managed by the backyard gardeners. Corn smut is a fungal disease that causes swellings (galls) on ears, leaves, stalks, and tassels of sweet and field corn. Smut is rarely observed in Utah and is not considered economically important for grain production. Iris Yellow Spot Virus (IYSV) is a damaging viral pathogen of onions. The disease can devastate an onion field by destroying the photosynthetic area of the leaves of infected plants. A short summary of the top insect and disease pests of leafy greens and how they are managed by the backyard gardeners. The bacterium Candidatus Liberibacter solanacearum infects pepper plants. Candidatus Liberibacter solanacearum is found in all states west of the Rocky Mountains, Kansas, and Texas. The disease was first reported in the United States in 2004. Yield losses Leveillula taurica is a powdery mildew fungus capable of infecting onions, garlic, and over 1000 plants in various genera and species in the western United States. A short summary of the main insect and disease pests of peas and how they are managed by the backyard gardeners. Pink root (Phoma terrestris) is a devastating disease in onion production. The fungus is found worldwide in the soil and can be up 45cm (1.5 ft) deep. A short summary of the main insect and disease pests of tomato and how they are managed by the backyard gardeners. TMV/ToMV is transmitted from handling contaminated tobacco products. TMV/ToMV is also transmitted by handling infected plants. In Utah, Tomato spotted wilt virus (TSWV) most commonly affects tomatoes, peppers, and tomatillos. It has also been found in ornamental plants such as blanket flower(Gaillardia sp.), and zinnia, and weeds. Fusarium wilt and Verticillium wilt are both soilborne fungal diseases that affect many vegetable crops grown in Utah. Both cause similar symptoms in their hosts. The non-culturable bacterium Candidatus Liberibacter solanacearum causes zebra chip disease of potatoes. Bacteria are transmitted by potato psyllids,(Bactericera cockerelli).
Damping-off
Powdery Mildew on Vegetables
Curley Top of Tomato
The Backyard Garden: Bean Pests
Big Bud in Tomatoes and Peppers
Botrytis Neck Rot of Onion
The Backyard Garden: Cole Crops Pests
Corn Smut
Iris Yellow Spot Virus in Onions
The Backyard Garden: Leafy Greens Pests
Candidatus Liberibacter of Pepper
Powdery Mildew on Onions
The Backyard Garden: Pea Pests
Pink Root Disease of Onion
The Backyard Garden: Tomato Pests
Tomato/Tobacco Mosaic Virus
Tomato Spotted Wilt Virus of Tomato & Pepper
Fusarium and Verticillium Wilts of Vegetables
Zebra Chip Disease of Potato