Cause Burkholderia caryophylli, a vascular, bacterial problem. Bacteria enter the plant through wounds. After infection it may take a month for symptoms to show although the bacteria have already colonized the roots and vascular system. Cuttings from symptomless plants can carry the bacterium. Hands, tools, and splashing water can spread this bacterium. Most carnations are susceptible but Dianthus capitatus ssp. andrzejowskianus and D. henteri were found to be resistant.
Most cultivars are highly susceptible but Wiko, Nocto and Sandrosa have adequate resistance.
Symptoms Plants wilt, turn dry, become colorless with roots disintegrating. The first symptom is a grayish-green foliage that rapidly turns yellow, wilts, and dies. Yellow streaks of frayed tissue in vascular areas extend 1 or 2 feet up the stem. When soil temperature is below 63°F, the internodes become deeply cracked. At high temperatures plants wilt. Infected cuttings wilt and die before forming roots. Cutting diseased stems reveals a brownish-yellow ooze. Diseased tissue is sticky in comparison to plants with Fusarium wilt.
Cultural control
- Use culture-indexed plants free of the pathogen.
- Use sterilized soil or use a soilless potting mix.
- Remove diseased plants from production areas as soon as possible, including healthy-appearing plants in a 1.5-foot radius from the diseased plants.
- Clean and wash hands and tools after handling plants.
- Thoroughly clean and sterilize the greenhouse between production cycles.
- Avoid overhead watering, or any practice that keep plants wet for extended periods.
References Kawanishi, T., Uematsu, S., Nishimura, K., Otani, T., Tanaka-Miwa, C., Hamamoto, H., and Namba, S., 2009. A new selective medium for Burkholderia caryophylli, the causal agent of carnation bacterial wilt. Plant pathology 58:237-242.
Onozaki, T., Yamaguchi, T., Himeno, M., and Ikeda, H. 1999. Evaluation of wild Dianthus accessions for resistance to bacterial wilt (Pseudomonas caryophylli). J. Japan Soc. Hort. Sci. 68:974-978.