Black Root Rot of Strawberry
Black Root Rot (BRR) is a disease complex on strawberry, meaning that one or more organisms can be involved in the infection, including the fungi Pythium spp., Fusarium, spp., Rhizoctonia spp., and several species of nematodes. It is a common disease in N.C. and the main reason growers fumigate in the southeastern region. In annual systems, the disease builds up over time and typically reaches a peak of damage at peak harvest. However, early damage causes plant stunting apparent within 1-2 months after planting. BRR can cuase yield reductions up to 20 to 40%.
In matted row systems, BRR is generally more severe in older plantings, especially during dry weather due to poor root systems and close to harvest. Infection usually sets in the first fruiting year and worsens the following year. Black root rot is enhanced by stresses like poor soil drainage, cold, drought, flooding, soil compaction and repeated freezing of roots. The disease typically occurs in areas with matted row production and limited rotation. Diagnosis of black root rot is difficult because of the many different organisms that may be involved. On some farms, the disease may be predominately caused by Pythium spp., whereas on other farms, Rhizoctonia spp. may dominate the complex. Multiple other fungi may be associated with the problem, In many cases, the Pratylenchus (root lesion) nematode is associated with BRR but this has not been a consistent observation in North Carolina and surrounding states.
- Symptoms and signs