August 27th

Hi All,

After a cracking MotoGP weekend at Silverstone it’s back to the day job 🙂

Last year the event was cancelled because the track became dangerously flooded as temperatures struggled to hit the teens. This year it was one of the hottest rounds of the year as temperatures exceeded 30°C. The vagaries of the jet stream are to blame and coming up this week we will again see a transition from peak to trough again with a very different weekend coming up I’d say….

General Weather Situation

So as we start the week on a Tuesday we can already see the first signs of change as a line of heavy showers is crossing Ireland and another is feeding up from The Channel Islands into The South West and Wales. Away from these showers we are enjoying a lovely dry and warm start to the shortened working week with light winds and temperatures already in the low twenties but they’ll be more cloud cover for most. So yet again we have this diagonal divide with rain showers pushing up across central and western areas of Ireland and then more moisture coming up from the continent. It’s the latter that may spark off a thundery breakdown later across western England / The Midlands as moisture and warm air meet. So a pleasant day for most areas of the U.K away from the developing front across The South West and Wales. Temperature-wise, it may not be quite as hot as yesterday but for central and eastern areas expect it to be nudging 30°C. Across the north and west it’ll be much cooler with temperatures in the low twenties with the threat of thunderstorms and more cloud cover. Scotland looks to have a pleasant day with warm temperatures and only the far north-west of Scotland picking up rain. For Ireland we have a west-east divide with west Munster and Connacht picking up plenty of rain bu east Munster and Leinster remaining largely dry. Windier from the south for Ireland and that will be a growing feature for the U.K with light winds giving way to moderate southerlies later on Tuesday.

Onto Wednesday and that rain front over the west of Ireland has moved eastwards crossing Ireland by the morning rush hour and pushing into north-west of Scotland overnight. Through the morning that front will push into the north-west of England / Wales and move eastwards bringing rain and cooler temperatures with it. Further north we will see that rain for western Scotland push eastwards across central and eastern areas through Wednesday afternoon. Ireland looks to enjoy a drier day with pleasant conditions through the day and only some showers moving into the west later on Wednesday evening. So again the eastern side of the country looks to stay warm and dry but temperatures will be much lower with a near 10°C drop for some areas. Even then we will still be low twenties so we can’t complain. Through Wednesday evening that rain continues to move eastwards into The South East and East Anglia, accompanied by a fresher south-westerly wind.

Thursday beckons and that rain front has cleared the U.K overnight and is on its way to my Motherland, Denmark. So Thursday looks like a reasonable day with a quiet start for the U.K. Across The Irish Sea though and you’ll already be feeling some cooler conditions and a strengthening wind as a new Atlantic low pressure system wheels in…Initially this will bring rain to the west of Ireland, Connacht particularly and also western Scotland and through the course of the day will push north and eastwards into western Scotland, clearing most of Ireland as it does so. Further south for England and Wales we will see the bottom of this low pressure bring rain across The Lake District but this will soon move off. So a north-south divide with calm and settled conditions for most of England and Wales with sunny intervals and plenty of cloud cover and a strengthening westerly wind. So Ireland and Scotland both see rain affect the west of the country initially but for Ireland it looks like the east will stay largely dry. A different story for Scotland as that rain pushes eastwards across central and eastern areas through the 2nd half of the day. Mid to high teens for Scotland and Ireland depending whether you are rain-affected or not and high teens to low twenties for England and Wales. Again a moderate to strong westerly / south-westerly wind for Thursday.

Closing out the shortened week on Friday and we have a similar picture with rain, some of it heavy pushing into the west and north-west of Ireland and streaming north and east into Scotland first off. Later through the course of the morning that rain will sink south and east across half of Ireland, Scotland and the north-west of England. England and Wales again will miss the worst of it with a dry settled day here with temperatures in the low twenties and plenty of sunshine. Through the 2nd half of the day that rain intensifies over Ireland and Scotland bringing some very heavy downpours and flooding on Friday night / Saturday morning I think. Some again a tale of two halves…cool, wet with strong winds and heavy rain for the west and north-west of Ireland, most of Scotland and the north-west of England and dry and settled with moderate winds for England and Wales.

With low pressure close by you can imagine for some areas the coming weekend may be unsettled. So Saturday will see that low centred close to the north-west of England so I expect a very wet period overnight into Saturday for The Lakes and north-west of England. This band of rain will clear Ireland to leave a cool but largely dry day for Ireland with western showers later and instead the rain will sink southwards into Wales, The Midlands and affect a line stretching from The South West all the way up to The North East. Scotland will continue its wet and unsettled theme with some heavy rain for central areas. Tricky to say if that rain will reach The South East / East Anglia before fizzling out later in the day. Staying mild across England with temperatures still in the high teens / low twenties but elsewhere a shift to a north west wind will pull those temperatures down into the mid-high teens. Sunday promises to be a cooler day with more in the way of cloud cover, a north-westerly wind and plenty of showers rattling down across Scotland, Ireland and Wales, later pushing down into England.

Weather Outlook

No surprise then that next week looks to start off cool and unsettled with rain showers pushing through most areas, likely the north and west getting most of them. As that low pressure moves off we look to have a brief lull in the proceedings with quieter winds and a largely dry day on Tuesday before more rain pushes in with a new low on Wednesday and Thursday. By the end of next week things look to quieten down a tad but low pressure is lurking over the continent so that may bring some rain to southern parts later next week / weekend. Cooler with a westerly / north-westerly air flow and temperatures mid to high teens at best I’d say.

Agronomic Notes

At this time of year I tend to look at September as the beginning of autumn with summer on the wane. This summer has been very different from last year with a low-lying jet stream giving us more rain, less heatwaves and arguably less stress, both plant and human I’d say 🙂

So I am sitting here wondering just what kind of autumn we are going to get from a temperature and rainfall perspective and of course a disease perspective as well ?

So I decided to have a look at the last few autumns from a G.P and rainfall perspective using data from The Oxfordshire, Thame. Now I appreciate it’s one location and particularly when you look at this last week’s weather you could say autumn has already started for the west of Ireland and Scotland 🙁

Here’s how the data looks..

Looking at the G.P data you can see how often October is often a continuation of September in terms of temperature with October 2014, 2017 and 2018 proving to be good growth months. Unfortunately as we know October isn’t just a good growth month for grass but also for fungi and one in particular, Microdochium nivale. That 2014 data may well prove to be significant because summer 2014 and summer 2019 have followed each other very closely.

November is often the ‘drop off’ month when we lose day and night temperature and show significantly less growth than October, for grass and fungi alike. Only in 2015 when we had an autumn of continual mild weather and rainfall did we maintain high G.P levels through November and December alike. December for me is the month where in recent years we have experienced some very aggressive Microdochium activity but the total monthly G.P stats don’t tell the whole story as on first sight it looks like a low G.P month.

So I dug further and charted the daily G.P stats from 2014 for the period Sept – Dec..

If you look at the graphs above you can see some pretty pronounced G.P peaks throughout October, November and into December. Nowadays I’d consider it quite normal to have high disease pressure right through to Christmas and beyond with often two or three clear periods of activity through December.

A G.P peak isn’t always bad news from a disease perspective..

So we can see the trend for milder air later into the year is clear and pronounced.

If I had another life I’d chart this back year on year and see exactly when we started to see this pattern emerging, my own guess is from the early 2000’s onwards. A peak in daily G.P isn’t always bad news from a Microdochium perspective because sometimes it reflects a run of windy, mild weather typical of an Atlantic low pressure. During these conditions we don’t often see very aggressive disease activity. Autumn 2015 was once such season when we saw a continual run of Atlantic low pressure systems right through to Christmas and beyond. It brought us mild and wet weather which was a headache from a cutting perspective (particularly on outfield turf on heavy soils) but it didn’t bring us high disease pressure on fine or outfield turf.

Why ?

Well I have a number of theories on this front, firstly I don’t think the spores of Microdochium nivale survive well in this type of weather. I also think you see less dew formation and maybe the fungus itself is sensitive to strong / high wind levels…who knows for sure ?

Mild, wet and windy also allows regrowth in areas of turf that have been damaged by Microdochium earlier in the autumn so if you’re lucky you can grow out some early scarring later in the season and be in better shape for the spring.

Where peaks in daily G.P are a problem is when we have mild day and night temperatures coinciding with low wind, high humidity and heavy dew formation. This can be a really dangerous set of conditions and so it proved between Christmas and New Year in 2018.

How does this help us prepare for autumn 2019 ?

Well we know the type of weather conditions that are conducive to this disease and we know that dew dispersal (whichever way you end up doing it) is extremely effective in reducing disease levels so one of my first priorities in planning my autumn Microdochium program would be dew dispersal and how I’m going to do it. Maybe allocating more resources to this task, maybe in the order of greens that I remove the dew from starting with my worst Microdochium greens first or maybe trying to incorporate some new agronomic practices to remove the dew for longer (whether mechanical or surfactant-based or a mixture of both) A good number of clubs have blowers now for debris management, how about using these to quickly remove dew, I know some of you are already doing so…

In the next few blogs I’ll take a look at pesticidal and non-pesticidal options for Microdochium management, but for now I’ll wish you all the best and enjoy the short week (for those that have it)

Mark Hunt