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Coming soon: A new solution for grey mould in berries

Fruit
26.11.2020

Grey mould, caused by Botrytis cinerea, is one of the most devastating diseases in berries. The fungal pathogen affects both flowers and fruit, resulting in significant yield loss and reduction in fruit quality.

The fungi survives on dead or decaying plant matter and in the soil. Spores are spread from this infected plant material or soil, by wind and water, to infect new plants.

Infection mainly occurs through natural openings or wound sites, caused by wind, water, insect pests or cultural management. Botrytis requires at least 8 hours of moisture and relatively high humidity to infect. Optimum temperature range for infection is 18-23°C.

Botrytis infects flowers where it can remain dormant. The plant produces anti-fungal compounds which stop the development of symptoms on flowers and green fruit.  When fruit starts to ripen, sugar content increases. The fungus feeds on sugar and causes rapid fruit decay. New infections can also occur at this stage as ripe fruit is more susceptible to disease.

Symptoms of botrytis on fruit include a soft brown rot extending into the berry and grey fluffy mould. Fruit that are completely rotted can become dry and tough. Cultural practices can be used to reduce the incidence and spread of the disease. Practices such as removal of any dead or decaying plant matter and removal of old infected canes can reduce the risk of new infections. Ripe, rotten fruit are a source of inoculum and should be removed from the paddock. Ensuring adequate airflow around individual plants will reduce the risk of disease development whilst providing protection from frosts. Use of excessive nitrogen can lead to dense canopies, so maintaining good crop nutrition will ensure a healthy crop whilst minimising excessive foliage. Irrigation management can also assist in reducing moisture for extended periods.

A preventative program of fungicides, used with cultural practices, will provide the best protection. The timing of fungicide application is critical to ensure plants are protected in wet conditions and when rain events are forecast. Fungicide use requires careful management as overuse can lead to resistance, thereby rendering the chemical group ineffective. Alternating different fungicides with different modes of action are recommended to minimise the risk of fungicide resistance.

A new fungicide, MIRAVIS® PRIME, is being introduced into Australia early in 2021. Miravis Prime combines two active ingredients pydiflumetofen (Group 7) and fludioxonil (Group 12). With two different modes of action, MIRAVIS PRIME attacks fungi at multiple sites for optimum protection against botrytis.

“Fludioxonil, works as a protectant on the surface of the leaf, whilst pydiflumetofen, moves very quickly into the waxy cuticle giving long lasting protection” advised Syngenta Territory Sales Manager Lisa Dillon.

“Miravis Prime halts spore germination and kills the fungus directly by entering the mitochondria.”

“Miravis Prime is a suspension concentrate and is very compatible with other crop protection products” described Lisa. “Miravis Prime, very importantly, has a one-day withholding period in berries, so it can be used close to harvest to protect against late-season disease. And with one-hour rainfastness, it offers growers flexibility of application when a rain event is forecast.”

Miravis Prime will be registered to control botrytis in berries, with additional control of powdery mildew in strawberries. It will be registered for use in both field and protected cropping. Product registration is expected early 2021. 

For more information, please contact your local Syngenta territory sales manager.

Incidence and severity of botrytis grey mould 10 DAA

Figure 1. Incidence and severity of botrytis grey mould assessed on fruit 10 days after application 2 of MIRAVIS PRIME or Fontelis in strawberries, Woodside, SA (2016).  Fungicides applied at 7-8 day intervals at the recommended label rates. Trial conducted by AgXtra, SA.