October 5th

Hi All,

Well after the weekend we have just endured I guess there’s only one topic to start the week…..rainfall.

The last 72-96 hours provided a classic example of the behaviour of low pressure weather systems in a jet stream trough.

As I have written about before, the low pressure is ‘trapped’ within the trough and instead of moving across the U.K and Ireland over 18-24 hours (as per normal), it constantly circulates around it’s axes, picking up more and more moisture and depositing it. I have clipped together a series of GFS outputs from Friday 2nd October at midnight, every 12 hours and you can see exactly what I mean….

Now I haven’t caught up with what we got over the weekend, I’m guessing 100 mm + in some locations but we got off lightly when you look at France and Italy that measured record rainfall with 630 mm falling over a 24-hour period. That is 25 inches of rain in old money, 4-months worth for them !

The damage, destruction of infrastructure and loss of life is another wake up call to our climate and how it is changing. Whatever you believe in this respect, the trough and peak pattern of the jet stream is a recent phenomenon that we are having to deal with. Yes, we have no way of knowing if it occurred in the past (because we have only known about the jet stream for the last 80 years odd), but that’s irrelevant in my mind, we have to deal with the here and now.

Jet stream peaks are pushing warmer air higher into northern latitudes and that’s causing a warming of the North Polar Ice Cap and jet stream troughs are causing widespread flooding and extreme snowfall further south. Time to wake up before ‘The Day after tomorrow’ film becomes a reality for our children 🙁

General Weather Situation

So the above GFS output is where we are today, with that low pressure system now out in The North Sea but it isn’t done with us yet and during the 1st part of this week it’ll slowly move up the north east coast of the U.K and in turn drag in some cooler air. So for today that low pressure will drag down rain across the west / north west of Ireland and the U.K as well with a band sitting diagonally (\) down the west side of the country extending through Wales into the south of England. As we move through the morning this will pull rain into more central areas and The Midlands. The eastern arm of that low pressure will hold rain across the north east of Scotland for most of the day. For Ireland, not too bad a morning but during the afternoon that low pressure will pull rain into the west of the country and this will move eastwards as we approach dusk. Between the west and east sides of the low pressure, we may see some dry spells for a time and some weak, autumnal sunshine. This should be across the north of England and the west of Scotland but it depends on how that rainfall moves during the day. Winds will be moderate to blustery and predominantly westerly / north westerly which in turn will mean not bad (mid-teen) temperatures for the U.K & Ireland. Temperatures will be in the low – mid teens.

Onto Tuesday and that low shifts further northward which in turn shifts the wind to a more north westerly and brings rain across Ireland and the south of England / Midlands / Wales for most of Tuesday on and off. The line at this stage is south of The Humber for the bulk of the rainfall with areas north of that and Scotland having a better day on whole though there is still likely to be rainfall along north western coasts. As we approach dusk that rainfall peters out across Ireland, Wales and the south of England. A cooler day than Monday with temperatures just nudging the low teens across most places.

Wednesday sees a much better day for most of us with a good drying wind from the north west and a much lower incidence of rainfall. There will be some rainfall for the north west of Scotland and also the west coast of Ireland. Through the morning we may see some showers push into the west coastline of the U.K and move inland, but these will be few and far between hopefully. Across the south of England and Midlands we may even see that strange yellow globe make an appearance with some sunshine, the same for the north of the country and central Scotland. Duller for Ireland, with some hazy sunshine making an appearance across eastern counties during the afternoon. As we go through the afternoon we see any rain confined to the north west of Scotland and the sunshine extend down the eastern coastline of the U.K. There will be a strong to moderate north westerly wind in situ and this will hold temperatures down in Scotland to low double figures. Further south temperatures will hit 13 -15°C, so not too shoddy really for October.

Thursday sees that weekend low pressure now sitting between Scotland and Ireland with high pressure trying to edge into the south of England. Unfortunately a cheeky, slinky, little low pressure will slip in along the leading edge of the high pressure and this will bring rain for The South West, Wales and The South Coast from dawn. This rain will then move slowly north and eastwards so anywhere south of The Wash may get wet on Thursday morning. Away from this rain front, Ireland and Scotland look to have a good first half of the day on Thursday with some sunshine kicking off the day, but by noon we will see rain push into the north west of Scotland I am afraid. That rain will break down into showers across the western half of Scotland and also across the south of England as we approach dusk. It may just tickle the north west of Ireland during the afternoon as it moves eastwards. Similar temperatures to Wednesday, low double figures to mid-teens in the sunshine if you see it. Winds will be north westerly up north and southerly down south.

Closing out the week on Friday we have a new rain front pushing into Ireland and the north west of Scotland in time for dawn, this will move across Ireland during the morning rush hour maybe not reaching the east till lunchtime by which time it will have dissipated. That rain over Scotland begins to push eastwards and southwards into north west England during Friday afternoon reaching North Wales and northern England by dusk. Further south we have not a bad day, pretty dry but a good bit cooler with temperatures just nudging double figures / low teens despite some hazy sunshine and a south west wind turning westerly / north westerly later in the day. During the afternoon, we see a new rain front push into the west of Ireland but this will peter out through the course of Friday evening to leave a dull end to the day for all of us.

With low pressure over Norway / Scandinavia and high pressure trying to push in from The Atlantic, we are caught between the two somewhat over the weekend. So this means north westerly / northerly winds, plenty of cloud cover and on the cool side with temperatures just breaking double figures. Saturday will see some showers across Scotland pushing south through the course of the day into the north of England and North Wales / Ireland. Elsewhere we look to be largely dry if a little on the dull and cool side. Some of the showers over North Wales may push inland through the latter  part of the day. Sunday looks dry and cool for all of us with just the odd shower across Scotland and down eastern coasts. That wind will now be northerly and so keeping everything on the cool side temperature-wise despite the lack of rain. So not a bad weekend, a bit dull and cool but mainly dry for most of us.

Weather Outlook

So as we can see from the GFS output above we have high pressure doing its utmost to push into the U.K & Ireland for the start of next week. I’m willing it to do so because I’m off for the week and would like another crack at the Bass 🙂 So next week looks to start ok from the GFS output but the devil is in the detail as rain will push down into the north west of Scotland and Ireland through Monday and into Wales and the south west of the U.K. We may also see more in the way of showers inland. Tuesday sees the wind freshen and move to the north east and that may pull some showers into eastern coasts but otherwise not a bad day if a bit on the dull and cool side. Wednesday look similar, dull, cool and dry for most but by Thursday we see more rain heading into and across Scotland. This rain will push southwards through the course of Thursday / Friday as the wind swings more northerly dropping the temperatures further. Ireland will be closest to the high pressure by the end of next week so maybe some better temperatures and sunshine for you 🙂

Agronomic Notes

August & September GDD summary – U.K Location – Thame

Since I missed out on doing an August summary, I’ll try my best to summarise both months in this week’s blog. August’s very hot weather at the start and middle of the month really had an effect on the y.t.d GDD with a monthly total of 381.5 recorded for our Thame location. To put this in perspective, it is the highest August figure we have recorded since I started this in 2010 and surpasses August 2018 to boot. If you look at the graph above you can see the last 3 August’s have been particularly hot and therefore high from a GDD perspective.

I converted the above figures for August 2020 into the U.S-GDD model where they use a base temperature of 0°C instead of the 6°C that I have adopted and the month of August would return a total figure of 569 GDD. I mention this because if you’re following the U.S – GDD / PGR model and applying Trinexapac-ethyl every 200GDD accordingly, you’d have had to apply every 10 days to keep within rebound tolerances !

Moving onto September, the beginning of the month continued this trend but a cooler end to the month rounded us down to a similar figure (remarkably so) to 2018 and 2019.

Y.T.D from a GDD perspective, 2020 looks to be continuing the trend towards growing total GDD over the last 5 years or so with a y.t.d figure at the end of September of 1754.5. This compares very similarly to 2018 and 2017.

August & September GDD & Rainfall summary – U.K Locations

The above charts really hit home how tricky a month was in the U.K from a growth perspective with really high GDD courtesy of a now long forgotten heatwave in the 2nd week of the month and then the arrival of cooler weather and rainfall from the 3rd week onwards.

Everywhere went into growth mode and it was a real problem to keep on top of for the best part of 7-10 days and get a dry cut. No more was this the case than in the south west of England where they picked up some really heavy rainfall at the end of the month. Bristol recorded > 150 mm between 25th – 29th August and continuing the wet theme, has already recorded nearly 200 mm in October in the first 4 days !

September as we can see was a much drier month, in some cases (Market Harborough) we were sitting at 2.0 mm for the month right up until the last day when it rained. So a pretty stressy month on the whole and that has meant a number of stress-related maladies have come out of the woodwork over the last few weeks.

Remarkably consistent GDD across Wales and England for September with Scotland (Fife) showing a 20% lower reading, which is normal.

August & September GDD & Rainfall summary – Irish Locations

A similar picture in Ireland in terms of a very wet August followed by a drier (but not dry by any stretch of the imagination) September. Again very similar GDD across August apart from Killiney, but elevation is playing a part in these readings (or Mick’s put the temperature gauge in the beer cooler :))

September shows a roughly 25% reduction in GDD vs. August for Ireland but in the U.K that figure is closer to 35-40% because of the higher temperatures reached during August courtesy of a continental heatwave.

I look at these stats and think how how tricky it is to maintain a golf course with the combination of temperature and rainfall during the summer, be that high temperature heat stress, elevated growth levels, high daily rainfall and / or disease management with a cooler, wet August.

It’s difficult sometimes to explain this to the punter who often has a selective memory (did it rain yesterday then?) and doesn’t really understand the job in hand anyway. (and probably doesn’t care)

Autumn maladies

Last week saw quite high humidity and overnight temperatures in the U.K & Ireland and this lead to an increase in Microdochium nivale activity, especially through the first part of the week. Lots of copper blotches forming on greens and on higher height of cut areas, plenty of visible mycelium. The culprit was overnight temperatures > 13°C coupled with high humidity, high levels of plant leaf wetness and heavy dews.

You can clearly see the disease spike in the stats below from our disease prediction output ;

You can also hopefully see this pressure drops away this week though we still see some at the end of the week as that high pressure nudges humidity upwards.

Die Back from Anthracnose Foliar Blight

The peak in humidity also saw a resurgence in the activity of both plant parasitic nematodes and above all, Anthracnose.

As I have commented upon before this disease has the unusual and highly irritating / stress-inducing habit of coming and going in terms of activity. One minute areas will look like they’re recovering, the next they look on the back foot as more plants show symptoms. The reason is because the disease is already well-advanced in the grass plant before you see symptoms and so any attempt at curatively controlling it (from a pesticide perspective) is actually pretty pointless in my mind other than to serve the purpose of ring-fencing neighbouring plants. This it may do but stopping the disease symptoms in its tracks, it won’t. So when we see higher levels of humidity, plant leaf wetness and the like, this encourages the already-present disease to grow and so plants which were infected but didn’t necessarily show symptoms, now do so. It is without doubt a really painful disease not just because of the afore-mentioned characteristic but also because it tends to occur in August and September which are very popular golf months (particularly the latter and particularly under Covid), so golfers notice it and its affect on playability.

Why do I see advancing symptoms despite spraying with a fungicide that is labelled for control of Anthracnose ?

As mentioned above, the disease is already present within the grass plant before it becomes symptomatic (displays symptoms) and well advanced in the formation of spores. In fact when you or I notice the black structures (Acervuli) at the base of the plant, it has already produced spores. So applying a fungicide will not affect this process because none of them on the market today act late enough in the disease cycle of Anthracnose to prevent this. Protecting neighbouring plants, possibly, reversing symptoms on affected plants, not at all likely.

Since Poa tends to be the plant species most affected here in the U.K (but not everywhere), a good practice is to lightly aerate the patches and apply some pre-chitted (to save time) bentgrass seed into the affected area and hope you get some germination and recovery before temperatures say bye bye later in the autumn. Topdressing helps the plant fill in thin / bare areas so if conditions allow you to lightly dress affected greens, I would do so, but again the windows for this area are less and less likely as we go through October. This is an ongoing problem because the heavy rain of the last few days has made moving topdressers about on many golf courses and applying topdressing impossible to achieve without rutting greens surfaces.

Challenging times for us all, talking of which I need to wrap this up as I have a 15:00 conference call and little or no prep done, video conferencing has a lot to answer for !

All the best.

Mark Hunt