Basil Downy Mildew Research Results

Basil Downy Mildew Research Results

February 1, 2022

Meg McGrath, Long Island Horticultural Research & Extension Center, mtm3@cornell.edu:

Major findings from three experiments conducted on field-grown sweet basil at LIHREC in 2021 are:

1. No to very few symptoms or signs of downy mildew were found on plants of Pesto Besto (Proven Winners) and several varieties of Prospera (Genesis Seeds), while downy mildew became more severe on the Rutgers DMR varieties than in 2018 and 2019.
2. Fluoxapiprolin (new fungicide not registered yet) was most effective (64% control), Revus was least effective (43%), and 56% control was achieved with the grower recommended program (Ranman + K-Phite alt. Presidio + K-Phite alt. Orondis Ultra).  Efficacy overall was lower than in previous conventional fungicide evaluations likely due to the impact of two hurricanes on application timing, product residues, and/or disease development.
3. None of the biopesticide treatments tested on Rutgers Passion DMR were effective, in contrast with results obtained in 2020, likely at least partly because the resistant variety was not as effective as in the past and because of the impact of storms.

In these experiments incidence of affected leaves (percent leaves with sporulation of the pathogen visible on the underside) was assessed rather than severity because any amount of symptoms renders a leaf unmarketable. 

See basil downy mildew research webpage for more information, results tables, and photographs from these experiments and others conducted in the past.