- Widespread distribution. On citrus including grapefruit, kumquat, lemon, lime, mandarin, orange, pomelo and tangerine, as well as other genera in the citrus family. An important disease.
- Bacterial spots on both sides of leaves and fruit causing them to fall early. Fruit unsightly. Spots up to 10 mm, with haloes on the leaves. Cankers cause twig dieback.
- Worse on grapefruit, lemon, lime and sweet orange.
- Spreads in wind-driven rain, water splash, and nursery plants. Enters through natural openings, wounds (e.g., leafminers). Survival is in leaf litter, and weeds.
- Cultural control: ensure nursery is canker-free; keep out of orchard when leaves wet; plant windbreaks around and between rows; Valencia orange and mandarin tolerant.
- Chemical control: 2-3 copper fungicide sprays 3 weeks apart, beginning when fruits are about 5 mm diameter.
Pacific Pests, Pathogens, Weeds & Pesticides
Citrus canker (091)
Photo 1. Spots - blister or craters - caused by citrus canker, Xanthomonas citri. Note the spots are surrounded by a yellow halo or margin, and that the leaves are not distorted as they are by citrus scab, Elsinoë fawcettii.
Photo 2. Close-up of the pustules formed by citrus canker, Xanthomonas citri, showing yellow haloes.
Citrus bacterial canker
Xanthomonas citri (also known as Xanthomonas citri pv. citri, and Xanthomonas citri subsp. citri).
AUTHORS Helen Tsatsia & Grahame Jackson
Information from CABI (2020) Xanthomonas citri (citrus canker). Crop Protection Compendium. (https://www.cabi.org/cpc/datasheet/56921); Citrus canker (2020) Department of Agriculture, Water and the Environment. (https://www.agriculture.gov.au/pests-diseases-weeds/plant/citrus-canker); Citrus canker (2019). Business Queensland. Queensland Government. (https://www.business.qld.gov.au/industries/farms-fishing-forestry/agriculture/crop-growing/priority-pest-disease/citrus-canker); and Plant Biosecurity and Product Integrity (2017) Citrus canker. Department of Primary Industries. NSW. Australia; and from Citrus canker (2019) Agriculture and Food. Department of Primary Industries and Regional Development. Government of Western Australia. (https://www.agric.wa.gov.au/citruscanker/citrus-canker). Photo 2 Kohler F, et al. (1997) Diseases of cultivated crops in Pacific Island countries. South Pacific Commission. Pirie Printers Pty Limited, Canberra, Australia. Photos 3-5 Richard Markham, ACIAR, Canberra.
Produced with support from the Australian Centre for International Agricultural Research under project PC/2010/090: Strengthening integrated crop management research in the Pacific Islands in support of sustainable intensification of high-value crop production, implemented by the University of Queensland and the Secretariat of the Pacific Community.