Calibrachoa and Black Rot

Susceptibility of Calibrachoa cultivars to Thielaviopsis basicola, causal agent of black root rot disease. Here I screened seven elite Calibrachoa cultivars for their response to T. basicola inoculations in greenhouse.

Calibrachoa is an annual flowering solanaceous ground cover plant, closely related to Petunia, introduced by breeders in 1990s. Production is currently valued at 45 million dollars annually in the US, and close to 1 million dollars in NC. Grown from cuttings in late fall/winter for sale in spring

Thielaviopsis basicola Berk. and Broome (sp. nov. Berkelyomyces basicola), causal agent of Black Root Rot disease. Cosmopolitan soil-borne fungus, distributed throughout temperate areas. Capable of infecting over 15 families of plants, including solanaceae (nightshade family). Sanitation is key to management.

Variation in susceptibility of Calibrachoa cultivars to T. basicola has been reported, but not subjected to comprehensive experimental investigation.

We used 7 Calibrachoa cultivars, grown from unrooted cuttings and inoculated each at time of transplant

We used 1 Thielaviopsis basicola isolate MD1

• Inoculated at rate of 100 chlamydospores per gram of soil

• Non-inoculated plant included for each inoculated plant

• RCBD, 5 plants/treatment, 2 reps

Calibrachoa root rating for Thielaviopsis basicola susceptibility trial yielded the following results: