Pests & Diseases
Microdochium nivale hyphae from spores germinating on the leaf surface entering the plant through stomata (left), compared to dead mycelium on a contact fungicide treated leaf preventing infection (right)
If you have the optimum cultural controls in place - and apply the right product, at the right time - it will ensure you get the best possible results and the longest lasting protection.
Application timing
Timing is an essential part of designing and implementing a pro-active disease control programme. Time and time again, we see that prevention of infection is most effective, compared to firefighting outbreaks after they have occurred. Not only is turf quality preserved but, over the course of the season, it has been proven that pro-active prevention can use less fungicide applications than treatment at the signs of disease.
Six steps for disease control • Understand the disease pathogen life cycle
• Create conditions to minimise the risk of infection
• Promote healthy turf growth • Identify risk factors for disease infection
• Time fungicide applications to prevent infection
• Select appropriate fungicide choice for specific disease risks
Understanding how each fungicide active works is important in selecting the appropriate option. Contact fungicides, such as Medallion TL, stick onto the outside of the leaf and stop foliar disease spores from germinating and penetrating into the plant. Contact+ active on the surface is incredibly
effective at preventing new infection from starting but, if disease has already got into the leaf, it can continue to develop and break out as new lesions. Application of any protectant contact fungicide onto a leaf where disease is already active could give disappointing results.
If the disease has only recently entered the
leaf, it can still be hit with a curative fungicide that can get into the plant, such as propiconazole in Banner Maxx or Instrata, before cells are irrevocably damaged. Furthermore, systemic products require the
plant to be actively growing to move fungicide to the point of disease infection, with some systemic formulations being more effective in cool conditions than others. Knowing how a product moves and works in the plant - the biokinetics - is important to select appropriate options for different times of year and conditions. With all curative actives we are still talking
about targeting disease in the early stages of infection, whilst they are developing in cells in the leaf, but before they are visibly seen as lesions on the leaf surface. If you are seeing sporulating lesions on the surface, it’s about damage limitation to stop the spread and working to help turf plants to recover - but it is likely to require repeated treatments and costly intervention. Pro-active treatments to prevent damage should be applied as close as possible to the point of infection risk, but before the infection actually takes place; the rationale is that, as soon as a product is applied, it naturally starts to break down and decline in efficacy, so the longest lasting results can be achieved from application close to infection risk. A lot of that comes down to the
greenkeepers’ skills, experience, local knowledge of conditions and course susceptibility. That can also be supported with technological advances. The Greencast disease forecasting, which uses a combination of local weather data and disease models, validated by STRI, will predict periods of infection risk over the coming seven days. Furthermore, turf managers and
agronomists can look back at historic disease risk and weather data, for any site over the
Curative systemic fungicide activity can still target early stages of disease development in the leaf (above)
118 I PC FEBRUARY/MARCH 2017
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