_3.jpg)
Botrytis is a common fungus with airborne spores always present in the environment. The pathogen can attack all parts of the plant and has a wide host range.
At this time of year, the fungus may be particularly problematic within primrose, dianthus, senetti and hardy nursery stock, especially following prolonged periods of high humidity.
What are the symptoms?
Symptoms of early Botrytis infection can include ghost spotting on flowers and fruit, appearing as pale white rings. Late infection symptoms can include the presence of pale to dark brown lesions and/or a soft decay and a dense, furry grey-brown mould. While outdoor crops usually become infected after a sustained period of mild and wet weather, high humidity and poor airflow are ideal conditions for Botrytis to flourish in indoor crops.
How can Botrytis be controlled?
Cultural controls can prevent the onset of disease. Maintaining good nursery hygiene will significantly improve control. Tasks such as removing plant debris, weed management and sterilising the growing area are fundamental building blocks of an IPM programme for Botrytis.
Proper irrigation management can also help to reduce the risk of Botrytis infection. In addition, plants should not be allowed to sit wet for extended periods. For protected crops, good airflow is essential, with plants spaced adequately and vents and fans utilised as appropriate.
Regular crop walks and monitoring of local environmental conditions will help with early disease detection.
Using biopesticides and protection products
The targeted use of biopesticides can allow growers to get ahead of infections and mitigate subsequent crop damage.
Careful and considered use of these products in a preventative manner can avoid serious infection from taking hold, which reduces the requirement and volume of pesticides used. Therefore, this approach is more cost effective and can greatly reduce yield loss. However, if Botrytis persists within the crop, a conventional pesticide may be employed.
Plant protection products such as Taegro and Romeo should be considered in a Botrytis IPM programme in ornamental plant production.
Taegro works by colonisation, which is the process by which the active ingredient, often a bacteria or fungus, will colonise the surface of a leaf and compete against pathogens for both space and nutrients. Applying such products preventatively will mean that any invading spores will find it more difficult to establish on a crop, improving the performance of an IPM programme. This mode of action tends to be broad spectrum, controlling several foliar diseases. Many bacterial products also produce antimicrobial metabolites as they divide and spread across the leaf surface, which will add an additional layer of protection, helping to actively push back against incoming pathogens.
Romeo works by inducing plant defence responses which are triggered by the active ingredient mimicking a microbial attack on the plant and activating a cell signalling cascade. The product induces defence genes including those involved in the jasmonic acid and ethylene protection mechanism against necrotrophic pathogens (which kill host cells and live on the contents), such as Botrytis. These metabolic changes induce physical changes in the plant, including the stimulation of phytoalexins (antimicrobial compounds) and strengthening of the cell walls and leaf cuticles.
Stock up on information
Both of these modes of action need to be carefully considered in an IPM programme. Taegro and Romeo need to be applied preventatively or at low infection levels to maximise efficacy. As such, it is suggested that weather forecasts, sensor data and crop walks inform application timing.
Using these types of products reduces reliance on conventional chemistry, in turn reducing residues and resistance risk. Biopesticides also allow for the effective use of conventional chemistry in high-risk periods where products have a limited number of applications.
If you would like to better understand how to integrate preventative biopesticides into your IPM programme, please contact our Technical Team on 01903 256856 or email technical@fargro.co.uk