Botector trials highlight improved botrytis control

Botrytis affects many crops and for soft-fruit growers it is arguably the greatest disease threat of the season. Under optimum conditions (18-23^oC) infection can take only a couple of hours while in other situations an overnight dew will be enough. With the disease able to take hold so easily, protecting crops requires constant vigilance.

In 2021 trials by crop advisers and research specialists Agrii, found that June-bearer strawberries that received five applications of Botector, a biological fungicide containing Aureobasidium pullans, were found to have a far lower incidence of botrytis than those receiving the industry standard programme.

Disease was assessed at seven days after picking and storing at ambient temperatures. A disease incidence of 15% compared with 48% for the industry standard programme, the findings were described at the time as compelling evidence of the potential that biological fungicides can make to protecting crops.

New studies have shed light on how this remarkable performance was achieved. According to Neil Obbard, Agrii fruit agronomist, it is the ability of the Aureobasidium pullans epiphyte to effectively outcompete the Botrytis cincera on the host plant that gives it the edge.

“The epiphyte in Botector effectively utilises the ‘founder effect’ - it gets their first and dominates. Research shows that used in a preventative manner, it colonises the plant to create a shield that the Botrytis fungus can’t penetrate,” Mr Obbard says.

This new understanding has led Agrii to review strategies for crop protection in order to better utilise Botector’s contribution to crop protection.

“Across all classes of fruit, we are reliant on a limited array of fungicides for botrytis control, and we see that the use of Botector as a protectant reduces disease pressure but also supports the efficacy of the conventional fungicides used in the programme,” Mr Obbard says.

Crops are most at risk from Botrytis infection at flowering so ensuring suitable protection before and after this time is central to producing a quality crop.

“Our early understanding of Botector led us to see its one-day harvest interval as a means of protecting crops in the lead up to harvest. But we now see it as useful in supporting the more targeted use of conventional fungicides as part of an integrated programme based on risk,” Mr Obbard says.

Disease monitoring across Europe has found Botrytis cinerea populations with reduced sensitivity to multiple fungicides, namely fenhexamid, boscalid and cyprodinil. Applications of Botector have been found to support the efficacy of conventional fungicides helping to protect fruit quality while reducing overall fungicide use.

Crop protection programme

Reference: SanAgro, 2018

Fungicide treatments

Reference: SanAgro, 2018

Resistant Botrytis isolates recovered from crops during the trial

Reference: SanAgro, 2018

“Against strains of botrytis found to demonstrate reduced sensitivity to some popular fungicides, we found that initial applications of Botector supported the efficacy of the subsequent applications. We have examined this in strawberries where botrytis can be an issue during white bud and flowering and again in the lead up to harvest, by replacing one of the planned fungicides with a Botector and then monitoring the incidence of disease that emerged,” Mr Obbard says.

“This finding presents a range of benefits to the grower. It promotes the more targeted use of conventional fungicides while improving the protection delivered against a disease with the potential for considerable damage, especially at the flowering stage when the crop is at its most vulnerable.

“An advantage of Botector is that isn’t any more expensive than a synthetic fungicide, but it is under-utilised by the majority of the industry,” Mr Obbard says.

Crop protection programme

Reference: SanAgro, 2018

Fungicide treatments

Reference: SanAgro, 2018

Resistant Botrytis isolates recovered from crops during the trial

Reference: SanAgro, 2018

“Against strains of botrytis found to demonstrate reduced sensitivity to some popular fungicides, we found that initial applications of Botector supported the efficacy of the subsequent applications. We have examined this in strawberries where botrytis can be an issue during white bud and flowering and again in the lead up to harvest, by replacing one of the planned fungicides with a Botector and then monitoring the incidence of disease that emerged,” Mr Obbard says.

“This finding presents a range of benefits to the grower. It promotes the more targeted use of conventional fungicides while improving the protection delivered against a disease with the potential for considerable damage, especially at the flowering stage when the crop is at its most vulnerable.

“An advantage of Botector is that isn’t any more expensive than a synthetic fungicide, but it is under-utilised by the majority of the industry,” Mr Obbard says.

“Against strains of botrytis found to demonstrate reduced sensitivity to some popular fungicides, we found that initial applications of Botector supported the efficacy of the subsequent applications. We have examined this in strawberries where botrytis can be an issue during white bud and flowering and again in the lead up to harvest, by replacing one of the planned fungicides with a Botector and then monitoring the incidence of disease that emerged,” Mr Obbard says.

“This finding presents a range of benefits to the grower. It promotes the more targeted use of conventional fungicides while improving the protection delivered against a disease with the potential for considerable damage, especially at the flowering stage when the crop is at its most vulnerable.

“An advantage of Botector is that isn’t any more expensive than a synthetic fungicide, but it is under-utilised by the majority of the industry,” Mr Obbard says.