The California Citrus Quality Council (CCQC) is providing additional guidance on how to comply with the Korea and China export protocols.
CCQC is advising the industry that the risk of Septoria infections is high in most counties at level 4 due to atmospheric rivers except for Kern, Fresno, Imperial, and Eastern Riverside Counties that accumulated to Level 2 (Kern, Fresno) or 0 (Imperial, Eastern Riverside) since Jan. 5, 2023. With additional rainfall this week and next week, Fresno, Kern and Tulare counties are predicted to be at 3 or higher, and this supports the forecasted risk and recommended fungicide applications by April 7, 2023, and growers should apply a third fungicide application for all late season Navel and Valencia oranges and lemons harvested after April 7, 2023. Imperial and Eastern Riverside Counties remain at low risk and no fungicide application date has been set for these counties.
China and Korea
If citrus groves are being managed jointly to meet the China and Korean protocols, then an application of copper or a copper alternative such as oxathiapiprolin (Orondis®) or mandipropamid (Revus®) are needed to maintain eligibility for both export markets. Fungicides listed in the GAPS for Phytophthora brown can be mixed with fungicides listed for Septoria Spot. The copper model is at level 4 (highest risk) and the P. syringae model is at level 3 (highest risk) except for East Riverside and Imperial, due to the high rainfall and cool temperatures conducive to brown rot.
Also, the forecast for additional rain events over the next 10 days means that it could be difficult to make the needed applications using air-blast sprayers because grove conditions are so wet. CCQC has consulted with UC Riverside’s Dr. Jim Adaskaveg, and he is providing the following recommendations:
- Attempt ground applications as soon as groves can support equipment.
- Use aerial applications including helicopters if ground applications are not possible. Aerial applications have been made in past high rainfall years with high success.
- Fungicide such as Abound® or fungicide mixtures such as a Quadris Top®, Luna Sensation®, and Priaxor® can be used to protect fruit over extended times. This will maximize the protection of fruit from Septoria spot. Copper, as well as alternatives to copper, forPhytophthora brown rot management (e.g., Orondis®, Revus®) can be mixed with fungicides for Septoria spot. Follow the labels of each fungicide.
- Increase monitoring for Septoria spot and submit samples to the NAVEK lab.
- Postharvest sorting and grading: remove all fruit with spotting or mechanical injuries. Lots containing ice-marked fruit as shown in Category IV F-J in the GAPS should not be shipped to Korea and should be diverted to other markets.
- Postharvest – sanitize fruit with sodium hypochlorite (100-200 ppm).
- Use postharvest fungicides that have anti-sporulation activity on Septoria Spot such as the highest rated Graduate A+®, Mentor®, and TBZ (Alumni®).
- Packers might consider using phosphonates (potassium phosphite) as a postharvest treatment for Brown Rot protection with the understanding that MRLs might not be available in some markets. It should be noted that there are preharvest phosphonatefertilizer labels available, and such uses could be referenced in the event of a phosphonate residue detection. If phosphonates are used postharvest, that block should be also treated preharvest.
- Fruit should be stored at 3-5°C (37°-41°F) no longer than a week after packing. Lower storage temperatures can cause injuries and exacerbate the disease. Long term storage should be at 5°-6.6°C (42°-44°F) for oranges and warmer for lemons such as 10°-13°C (50°-55°F).
Please contact CCQC President Jim Cranney by telephone at (530) 885-1894 or via e-mail at firstname.lastname@example.org if you have questions or need additional information.
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