P-687 - Beyond Leaf Spots: Elucidating strawberry crown infection caused by Neopestalotiopsis

Neopestalotiopsis causing fruit rot and leaf spots has become a significant problem in Florida strawberry. During the past seasons, strawberry plants exhibiting stunting, purple discoloration of the leaves but no leaf spots were diagnosed as Neopestalotiopsis affecting the crowns. In this study, the ability of Neopestalotiopsis to infect strawberry crowns was evaluated through crown and root inoculations using Neopestalotiopsis isolates from different lineages and aggressiveness phenotypes. Selected Neopestalotiopsis isolates from each group were evaluated separately in crown and root inoculations at 10⁵ conidia/ml. In another experiment, isolates from each group were mixed and inoculated at 10³, 10⁴, and 10⁵ conidia/ml. Results showed aggressive isolates reached 75 to 100% disease incidence (DI) (stunting and purpling of leaves) at 55 days after inoculation. However, the incubation period (IP) was shorter for root (< 7 days) than crown ( >14 days) inoculations. Non-aggressive isolates also caused crown infection, but DI was < 20% and IP was >24 days. In the second experiment, aggressive lineages had highest DI and lowest IP at the highest conidial concentration, but DI was still >60% at 10³ conidia/ml for both inoculation methods. For non-aggressive isolates, DI remained below 25% for all inoculum concentrations and methods. Our findings confirmed that aggressive lineages of Neopestalotiopsis can infect strawberry crowns and indicate that infection may occur via root or foliage, with similar symptoms being produced regardless of the infection route.