Lipid-Based Natural Food Extracts for Effective Control of Botrytis Bunch Rot and Powdery Mildew on Field-Grown Winegrapes in New Zealand

Abstract

Synthetic controls of crop pathogens are increasingly associated with harm to the environment and human health, and pathogen resistance. Pesticide residues in crops can also act as non-tariff trade barriers. There is therefore a strong imperative to develop biologically based and natural product (NP) biofungicides as more sustainable alternatives for crop pathogen control. We demonstrate the field efficacy, over multiple seasons, of NP biofungicides, NP1 (based on anhydrous milk fat) and NP2 (based on soybean oil), on two major diseases of winegrapes—Botrytis bunch rot (Botrytis) and powdery mildew (PM). The NPs were integrated into a season-long integrated disease management programme that has produced chemical-residue-free wines. Efficacies for Botrytis control on three different varieties were: 63–97% on Chardonnay, 0–96% for Sauvignon Blanc and 46–58% on Riesling; with 65–98% PM control on Chardonnay and Riesling. NP2 exhibited the significant control of Botrytis latent infections, making it a viable alternative to mid-season synthetic fungicides. Disease control was significantly better than the untreated control and usually as efficacious as the synthetic fungicide treatment(s). Yields and wine quality in NP-treated crops were normally equivalent to those in the synthetic fungicide treatments. The results indicate that NP-mediated disease control of Botrytis and powdery mildew can be obtained in the vineyard, without synthetic fungicide input.

Pre‐infection efficacy of resistance inducers against grapevine powdery mildew

“…Unlike priming, current knowledge regarding the tested PRIs does not consider any possible direct antimicrobial activity. The epiphytic nature of the pathogen and the well‐known activity of other natural compounds applied directly to PM colonies (Crisp et al., 2006; Moyer et al., 2016; Wurms et al., 2021) leads us to not exclude the possible direct effects of the PRIs tested in this study. This should be confirmed in future research studies.…”

“…Unlike priming, current knowledge regarding the tested PRIs does not consider any possible direct antimicrobial activity. The epiphytic nature of the pathogen and the well-known activity of other natural compounds applied directly to PM colonies(Crisp et al, 2006;Moyer et al, 2016;Wurms et al, 2021) leads us to not F I G U R E 4 Severity of powdery mildew sporulation on leaf disks collected from grapevines that were treated with the plant resistance inducers listed in Table 1 (light grey) or remained untreated (dark grey) and then artificially inoculated with Erysiphe necator in the laboratory at 1 to 12 days after treatment (DAT). Bars are the averages of three experiments and 15 leaf disks that were inoculated; whiskers represent the standard error.…”

A Review of Cultural Practices for Botrytis Bunch Rot Management in New Zealand Vineyards

“…Leaf removal affects the fruit zone microclimate creating less favourable conditions for B. cinerea establishment. This is achieved by exposure of bunches to sunlight, increased air movement around bunches [ 59 ] and through significantly improved spray deposition of botryticides and biofungicides on bunches [ 11 ]. Canopy management trials incorporating leaf removal were conducted on Chenin blanc vines in California in 1984 and 1985 [ 55 ].…”