October sees autumnal conditions set in, and thoughts of summer have all but disappeared. Most renovations will have taken place whilst conditions were favourable, whilst those who have not yet been able to carry out such work will be holding out for temperatures not to drop off too quickly to ensure there is some recovery before winter when growth potential drops to 'low'.
Mornings and nights continue to become noticeably darker and importantly for turf managers, leaf wetness (dew) on the grass plant becomes a management priority.
The weather conditions certainly changed from the start of September compared to the end. Growth potential went from an average of 93% down to 68.5% which certainly indicates autumn has arrived. The monthly accumulation of Growth Degree Days (GDD) had also rapidly depleted compared to the previous month. For more information on GDD follow this link.
In August, GDD was 604, compared to Septembers 378.5 which, is a big difference in just 4 weeks. Average rainfall was 84mm with some regions experiencing more than others and even some heavy deluges.
The average maximum temperature also dropped significantly from 21°C in the first week down to 15°C by the last week in September. Average minimum temperatures also followed a similar drop throughout the month but overall, the average maximum temperature was 17.5°C and the minimum was 9°C.
Base nitrogen requirement dropped significantly throughout the month too. 5.5 kg/N/ha in the first week of September down to just 2kg/N/ha by the last week. In total, 14.5kg/N/ha was the average base nitrogen requirement across the UK compared to 27kg/N/ha in August.
Plant stress has been significantly influenced by the noticeable swing in weather conditions. Early September saw low turf stress across the UK and this has slowly increased as the month went on where we now sit at medium-high turf stress condition.
If you want to take a deeper look into your regional weather for September please click here and to keep up to date with weekly amenity weather forecasts, visit https://academy.agrovista.co.uk/category/weather.
Nutritional inputs will start to reduce inline with the reduction in growth potential. Applying a fertiliser with a nitrogen source suitable for the time of year is key to minimise any disease outbreaks. Following the base nitrogen figures outlines above, applications if around 2kg of nitrogen per hectare will be sufficient. Which is the equivalent of 6.0.12 conventional release granule (4-6 week longevity) applied at 20gm2. Choosing a fertiliser that is going to release nutrients as the temperatures decrease is also needed. Some slow-release technology will release extremely slowly in cooler conditions which may not provide an adequate supply of nutrition to maintain a healthy plant able to withstand pathogen attack. Therefore, it is as important to not under apply at this time of year as it is to not over apply.
Monitoring disease pressure is a main priority for October as cooler, damp conditions are experienced over longer periods during the day. Conditions in October can be ideal for Microdochium nivale outbreaks and predicting when these outbreaks may occur is challenging. Gaining an understanding of what contributes to disease pressure reaching tipping point on your own site allows better informed decisions when selecting and timing any of the applications aimed at counteracting disease pressure These may be, fungicidal, nutritional or plant response applications.
Fungicide technology is only one part of an IPM approach and increasingly it will be the other applications which will become more in focus as tools in which to reduce disease outbreaks and severity. Morning dews can lead to an increase in leaf wetness in October and this additional moisture on the surface can be the perfect vehicle for pathogens. Therefore, utilising dew dispersant technology can be a useful tool.
Expectations need to be set to a realistic level in relation to longevity of the products compared to when using them in cool months when growth potential is low. When frequent mowing is still taking place, the longevity is going to be relatively short, however this can still be long enough to reduce the level of leaf wetness long enough to get through a high disease pressure period.
- Use a programmed approach to maximise plant health, through balanced nutrition of all plant essential elements not just NPK as part of an IPM plan.
- Raise cutting heights to minimise stress with a reduction in stress invoking practices such as top dressing which weaken and damage leaf blades.
- Ensure cutting units are sharp to provide a clean cut to minimise weakened points for pathogen attack.
- Well timed aeration to maintain movement of water away from the surface and down through the profile. (Caution when tining around Leatherjacket hatch periods)
- Reduce periods of leaf blade wetness by removing dews or utilising dew dispersant technology (apply only to a dry leaf)
- Monitor disease forecasts via resources such as Syngenta's Greencast
- Use biostimulants and plant response promoters to maximise plant health.
- Take advice on and construct a preventative fungicide application plan, using historic data, live weather forecasts and site-specific conditions, for applications ahead of when conditions favour the development of disease.
The Emergency Authorisation for Acelepryn for control of leatherjackets has been approved and can now be purchased for use on golf courses, airfields and racecourses only. With extenuating circumstances for some situations (check the label for details).
You can check reported sightings of crane fly species on the Pest Tracker (https://www.greencast.co.uk/turf-pest-tracker) on the GreenCast website. To aid effective timing of treatment, follow Syngenta guidelines (7 point plan) for application one month after peak flight is observed. Where chemical control is not authorised, entomopahogenic nematodes can be applied with warm soil temperatures and available moisture being ideal conditions to get the best out of an application. The entomopahogenic nematodes swim in the water film on soil particles in their bid to search out a larval host, useful information can be found on this link https://www.pitchcare.com/shop/sportnem-t-leatherjacket-killer-5000-m-sup-2-sup.html
With the increased soil moisture content worm activity has increased. There are still no legal controls for earthworms and any product which is applied to directly affect them is done so illegally. Cultural management continues to be the only route currently available which can include a combination of practices such as localised surface acidification, removal of grass clippings to reduce their food source and sanding of surfaces to assist in the drying out and dispersal of casts, leading to less negative lasting impression on the surface from the cast.
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