See:
Carnation (Dianthus caryophyllus) - Fusarium Wilt
Cause Several Fusarium spp. or Rhizoctonia solani fungi that survive in plant debris. Both Fusarium and Rhizoctonia has been found in samples sent to the OSU Plant Clinic. Wounding, poor sanitation, and high nitrogen fertility favor disease development. Warm temperatures and high humidity favor infection of Fusarium. Warm, moist, poorly drained soil favors infection of Rhizoctonia. These diseases can reduce the number of flower shoots and plant productivity.
Symptoms Fusarium-basal rot, basal stem rot, branch rot, and stub dieback may all occur. Basal rots develop reddish-brown spots at the base of plants. Infected stubs may dieback but there is no vascular discoloration beyond the rotted area. Later roots and stem base may be rotted and discolored. Plant may go on to die. Orange masses of conidia in sporodochia may occur on the rotted stems and branches.
Rhizoctonia-cuttings may suddenly die. Plants have a grayish-green color and wilty foliage. Stems at the soil line have a lesion with a brown border and leaves become yellow. Stems look dry and shredded.
Cultural control Good sanitation and cultural-par actives will help avoid these diseases
- Use culture-indexed plants free of the pathogen.
- Use sterilized soil or a soilless, well-drained potting mix.
- Remove plant debris during production and thoroughly clean and sterilize the greenhouse between production cycles.
- Lower greenhouse humidity below 85%. Heat and vent to expel moist air to reduce humidity.
- Space plants to allow good air circulation.
- Water such that plants are not wet for extended periods of time.
- Maintain adequate fertility for moderate plant growth.
Chemical control Soil drenches along with cultural controls help protect healthy plants from Rhizoctonia.
- Chipco 26019 FLO at 13 fl oz/100 gal water. Use 1 to 2 pints of this solution per sq ft. Group 2 fungicide. 12-hr reentry.
- Empress at 1 to 3 fl oz/100 gal water can be used for seedlings. Group 11 fungicide. 12-hr reentry.
- Heritage at 1 to 8 oz/100 gal water plus a non-silicone-based wetter sticker. Group 11 fungicide. 4-hr reentry.
- Medallion WDG at 1 to 2 oz/100 gal water. Use with oils or adjuvants may damage plant. Group 12 fungicide. 12-hr reentry.
- Spirato GHN at 1 to 2 fl oz/100 gal water. Use with oils or adjuvants may cause plant damage. Group 12 fungicide. 12-hr reentry.
Biological control Use in conjunction with other control tactics such as thorough sanitation.
- Asperello T34 (Trichoderma asperellum strain T34) at 0.35 oz/35 sq ft of substrate before potting. See label for details. 12-hr reentry. O
- RootShield Plus Granules (Trichoderma harzianum Rifai strain T-22 and T. virens strain G-41) at 1 to 3 lb/cubic yard soil mix. Some California nurseries report it helps, but efficacy in the Pacific Northwest is unknown. No restrictions on reentry required when soil incorporated. O
- Bio-Tam 2.0, Tenet WP, or Obtego (Trichoderma asperellum and T. gamsii) at 0.5 to 1.5 lb/cubic yard of substrate. See label for details. No restrictions on reentry when soil incorporated. O
Reference Wolcan, S.M., Malbran, I., Mourelos, C.A., Sisterna, M.N., Gonzalez, M.P., Alippi, A.M., Nico, A., and Lori, G.A. 2018. Diseases of Carnation. In McGovern, R.J. and Elmer, W.H. (eds.) Handbook of Florists' Crops Diseases. Springer Int.