Cause The fungus, Rhizoctonia solani (sexual stage: Thanatephorus cucumeris), has been found to cause root rot and crown disease on cilantro in California but has not yet been found to cause disease on cilantro in Oregon. Rhizoctonia solani occurs in Oregon on other crops and may incite root rot on other crops including arugula, beets, snap bean, clover, peppermint, and Brassicas. This fungus also causes damping-off of a wide range of plant species. It overwinters in soil or plant debris and can survive many years as sclerotia or chlamydospores.
Symptoms Leaves turn yellow and then brown and dry as foliage dies. Plants wilt and may die. A brown rot of tissues occurs in the taproot and crown portion.
Cultural control
- Avoid planting cilantro after a Brassica, beet, or other crop that had Rhizoctonia rot problems.
- Practice a 3-year rotation with non-host crops (grains).
Biological control
- Bexfond at 7 to 14 fl oz/A. O
- Prestop WG. 4-hr reentry. O
- Stargus at 3 to 4 quarts/A as a soil drench on 10- to 21-day intervals. Preharvest interval is 0 days. 4-hr reentry. O
Reference Koike, S.T., Daugovish, O., Martin, F. N., and Ramon, M. L. 2017. Crown and root rot caused by Rhizoctoniasolani on cilantro in California. Plant Disease 101:2148.