Advances in Botrytis control for flower crops

M.K. Hausbeck, B.R. Harlan, E.I. Brisco-McCann
Flower crops are constantly threatened by the fungal pathogen Botrytis cinerea Pers.:Fr. which causes gray mold or Botrytis blight. Symptoms of Botrytis-caused diseases include leaf spots, blighting, stem cankers, rots of corms, rhizomes, tubers and seeds, and damping-off of seedlings. Blighting may affect leaves, petioles, blossoms, and stems. B. cinerea is ubiquitous, has a wide host range, and causes significant losses at all stages of flower production. This study investigated plant protection products for their ability to limit Botrytis foliar and flower blight under greenhouse conditions. Floral crops known to be especially susceptible to Botrytis blight were inoculated once with conidia from B. cinerea cultures grown on potato dextrose agar for four weeks. Plants were incubated under high relative humidity conditions. Prior to inoculation, plant protection products were applied as a foliar spray using a hand-pump compressed-air sprayer and reapplied at specific intervals. Assessment included the number of leaves and/or blossoms with sporulating B. cinerea and an overall disease severity rating. Data were analyzed using SAS PROC GLM and statistical differences were compared using the Fisher's protected least significant differences test (P=0.05). The results of multiple, replicated trials indicated that the following plant protection products were especially effective in limiting Botrytis blight: pyraclostrobin/boscalid, chlorothalonil, fenhexamid, fluopyram/trifloxystrobin, isofetamid and azoxystrobin/ benzovindiflupyr. Biopesticides were also tested and included polyoxin D zinc salt, Bacillus subtilis, Pseudomonas chlororaphis, Aureobasidium pullulans, extract of Swinglea glutinosa, thyme oil, and Reynoutria sachalinensis. With the exception of polyoxin D zinc salt, when used alone, the biopesticide products did not adequately control B. cinerea. Successful management of Botrytis blight in new floral crops requires integration of the latest research results with sanitation and environmental control strategies.
Hausbeck, M.K., Harlan, B.R. and Brisco-McCann, E.I. (2020). Advances in Botrytis control for flower crops. Acta Hortic. 1288, 231-238
DOI: 10.17660/ActaHortic.2020.1288.35
Botrytis cinerea, ornamentals, fungicide, biopesticide

Acta Horticulturae