New option for Botrytis control in cherries

Botrytis grey mould (Botrytis cinerea) has long been overlooked as the cause of serious fruit losses. The industry has consistently battled brown rot (Monilinia spp.). The new registration of MIRAVIS^® Prime fungicide in cherries helps address a gap in available control measures for Botrytis cinerea. It offers optimum protection against the disease.

The challenge of Botrytis

Syngenta Technical Services Lead Dr Brandy Rawnsley said Botrytis cinerea presented a significant challenge. Early infections are sometimes not detected until much later in the crop, presenting serious issues.

"Botrytis cinerea is a weak pathogen. It can only infect through wounds or openings," she said.

"The fungus typically infects ripe fruit. But it can often begin at flowering and lie inactive (latent) until symptoms develop later in the season. Botrytis infection can cause petals to wither and fall. This affects fruit set and results in poor yield."

How MIRAVIS^® Prime works

Dr Rawnsley said MIRAVIS^® Prime contains two active ingredients:

• Pydiflumetofen (Group 7): Moves rapidly into the waxy layer of the plant to provide long-lasting protection
• Fludioxonil (Group 12): Forms a protective barrier on the surface of the plant

As a suspension concentrate, MIRAVIS^® Prime has shown excellent crop safety when used in cherries. It provides exceptional control of Botrytis grey mould.

Best application timing

"The best time to apply MIRAVIS^® Prime is at beginning of flowering," said Dr Rawnsley. "The fungal species Botrytis cinerea occurs across a wide range of crops. Spores are prevalent in many horticultural areas. Protecting flowers stops disease development early in the season before it's too late."

Pre-harvest protection

MIRAVIS^® Prime fungicide can also be used during the period prior to harvest. It offers protection of the fruit during ripening, picking, transport and storage. This gives growers the confidence they will produce premium quality fruit.

"Rain can increase the risk of fruit cracking and grey mould around harvest. The 3-day withholding period of MIRAVIS^® Prime provides an ideal solution when growing for domestic and many key export destinations," stated Dr Rawnsley. "Make sure you check the AusCherrySure app for specific export market Maximum Residue Limits (MRLs)."

Trial results

Most cherries are grown in southern Australia. The registration of MIRAVIS^® Prime was supported by independent trials conducted in Tasmania through the Hort Innovation cherry research and development levy fund (project ST20005).

In one trial, MIRAVIS^® Prime fungicide was applied at two different label rates (60 mL and 100 mL/100 L) on cherries. Applications were made at the beginning of flowering and 11 days later. Aborted fruit were collected from trees and assessed 63 days after the last spray. Results showed MIRAVIS^® Prime provided exceptional control of Botrytis grey mould (Figure 1).

Key findings:

• No disease was detected after treatment with MIRAVIS^® Prime at 100 mL/100 L
• 6% of fruit were infected after treatment with an industry standard
• When applied as a 3x concentrate spray, MIRAVIS^® Prime provided effective control of the disease

These results highlight the benefit of using MIRAVIS^® Prime at the highest label rate for optimum control of Botrytis grey mould.

Resistance management

As with any fungicide use, a spray program should adhere to the CropLife Fungicide Resistance Management Strategy. Although a specific strategy does not exist for Botrytis, there are other Group 7 fungicides that can be used for fruit rot caused by Monilinia species.

"It's important to rotate chemical mode of action groups," said Dr Rawnsley. "This is not only for resistance management purposes, but to change the way a fungal population is targeted. Group 7 fungicides work so well because they target a very specific region in the mitochondria. But because of this, they are considered medium-high risk of fungi developing resistance to them."

Application guidelines

MIRAVIS^® Prime fungicide should be applied preventatively before disease occurs. Application limits:

• A total of two MIRAVIS^® Prime applications can be made to a cherry crop
• No more than a total of three Group 7 fungicide applications in a season

"And remember, the first spray of the coming season shouldn't be a Group 7 if it was the last spray of the previous season. This is regarded as consecutive applications."

More information

For more information visit MIRAVIS^® Prime or speak with your local Syngenta representative about the benefits of MIRAVIS^® Prime in your cherry spray program this coming season.

ENDs

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^{The project 'Generation of data for pesticide applications in horticulture crops 2021 (ST20005) is a strategic levy investment under the Hort Innovation Fund, supported by grant funding through the Australian Government's Access to Industry Priority Uses of AgVet Chemicals program.}