In a recent webinar, Jim Adaskaveg, University of California, Riverside professor and plant pathologist, discussed some recently registered fungicides to manage phytophthora and other fungal diseases of citrus. Orondis was registered in 2018, Presidio in 2019 and Revus in 2020.
Adaskaveg said Orondis and Revus each contain a new active ingredient with a different mode of action and provide a new level of efficacy against phytophthora brown rot. Both are long lasting, even with high rainfall, and include foliar use on their labels.
Orondis can be used for soil chemigation or berm treatments, Adaskaveg reported. Presidio can be used for orchard soil only, and Revus can be used for container soil treatments in nurseries. They should always be applied to wet soils with additional water to move the fungicides into the root zone.
WHEN TO APPLY
Adaskaveg discussed the optimal times to apply fungicides for fungal disease management. Those times are:
- For phytophthora brown rot, October/November and January/February
- For phytophthora root rot, spring root flush and fall root flush
- For septoria spot, October/November and January/February
- For anthracnose and greasy spot, from five weeks to one week pre-harvest. Management of anthracnose and greasy spot are generally effective with preharvest applications prior to warm, wet weather.
MORE OPTIONS COMING
Adaskaveg reported that several new pre-harvest fungicides are being developed and registered, including Quadris Top, Priaxor and Luna Sensation.
He added that treatments such as peroxyacetic acid-based sanitizers just prior to harvest reduce postharvest decays and improve decay management in the packinghouse.
For post-harvest use, the new synthetic fungicide Exp-2020 is pending registration. It has high activity against green mold and sour rot, Adaskaveg stated.
His presentation was part of the Citrus Research Board of California’s 2023 Citrus Growers Educational Webinar Series.
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