Phenological Aspects of Strawberry Growth Influencing Gray Mold Development in Annual Systems

Abstract

Strawberry (Fragaria xananassa) plant phenology was evaluated at two sites in North Carolina in order to assess the relationship of plant growth and the development of gray mold fruit rot (Botrytis cinerea). Site 1 consisted of three cultivars: Camarosa (CA), Chandler (CH), and Sweet Charlie (SC) from a single nursery; site 2 consisted of cultivar CH obtained from three distinct sources. Weekly records were kept of leaf senescence, leaf emergence, flowering, and fruit set, as well as a monthly whole-plant analysis. Leaf senescence and emergence was uniform for all treatments, with >90% of transplant foliage senescing between November and December. Analysis of leaf area and plant weights reveal an increase in dry mass beginning in February and continuing through April. Although first bloom appeared in December, primary floral development occurred in late February for cultivar SC and in March for cultivars CA and CH, with blooms continuing through late May. Marketable yield was lower in cultivar SC throughout harvest, with the exception of early fruit development in March. Non-marketable yield varied, with increases in gray mold following periods of heavy rainfall. Statistical analysis of all data shows no consistent differences in plant growth or disease among treatments. Analysis of foliage revealed latent infections on transplants as the primary source of gray mold inoculum. Patterns of plant growth and corresponding disease development found in this study provide tools necessary for phenology-based control practices for the integrated management of gray mold.