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  • Writer's pictureMark Hunt

Happy 4th of July !


Hi All,


Well I know, as a 50/50 English / Danish hybrid, I suppose part of me shouldn't be celebrating the America's freedom from British rule, but I can't blame them, especially when you look at the current state of 'affairs'.....


This picture was kindly donated by my good friend, Andy Biggin, an ex-pat living out in Breckenridge, Colorado and I thank him kindly. Looks like they're having very similar weather to us currently and as suggested last week, we seem to be entering into a period of stability weather-wise which may extend a good way into July. I heard some presenter on the radio last week predicting that we would be hitting 30°C + by the middle of this week. Well not quite so don't give up your day job just yet eh ?


It will be thoroughly pleasant though, but someone forgot to factor in wind direction when they looked at the heat charts because with a north westerly wind, that'll keep things pleasantly warm, rather than hot initially. The benefits of an island climate.


June 2022, will go down as a hot one across the world with many countries reporting record temperatures for the month. In England we reached 32.7°C on the 17th of June, but this fell short of the June record of 35.6°C, recorded back in the glorious summer of 1976. I take a look at some detailed June data a little later in the blog and draw some interesting (I think) conclusions on the way our weather patterns are developing....

General Weather Situation


Onto this weeks weather....At first sight the GFS output above for today doesn't look very encouraging but by Thursday (below) you can clearly see why the Daily Express will be trotting out its '100-day heatwave' or equivalent crap headline soon if it hasn't done already 😎

That ridge of high pressure is developing exactly in line with how it was predicted last week, so hats off to GFS for calling this as is....What you can also see is that the leading edge of the high pressure is centred over the U.K and since high pressure systems rotate clockwise, this means that the wind direction will be northerly / north westerly. That's the clue as to why it'll be warm rather than hot initially. As the high pressure develops towards the U.K, that wind direction will have less of an influence and the temperature will build. So we are talking low twenties initially climbing to high twenties as the high pressure system establishes.


The other factor is that because the high pressure is building out to the west of Ireland it means Ireland itself will enjoy a mini-heatwave with temperatures in the low to mid-twenties and no better place to enjoy one :)


The predominantly northern wind direction will also mean that night temperatures shouldn't be too unbearable either which is good for all of us.


Is there any rain on the weather map ?


Weather Outlook


Well surprisingly with high pressure developing, there is, but really only for the north and west possibly early next week, as a low pressure nudges across the top of this dominant high pressure system.


Now this is an interesting sort of weather picture because we have this high pressure developing this week with the hottest temperatures towards the end of the week / weekend and then the heat drops back a bit but then it looks to re-establish again next week.


So as we get to this time next week, you can see high pressure is still pretty dominant, except for the north of Scotland where it is cooler and more unsettled. That ladle-shaped hot air air mass out in The Atlantic is the one to watch because as we go through next week it looks to redevelop but as it does so, it runs into a conflict with a northerly low pressure. Again this results in a northerly wind which will keep temperatures the correct side of pleasant. As you can see from the animated GIF's below, this high pressure system is projected to remain in charge next week so that means pretty much two weeks of good weather to take us well into July :). So I'd say low to mid-twenties sort of territory with reasonably cool night temperatures courtesy of that wind with the odd flirtation into the high twenties across the south of England.


Any sign of a breakdown ?


Well Mystic Megging it, I'd have to look to the 3rd week of July before a BOB potentially comes into play and disrupts the high pressure dominance. That said, it's a long way from then to now so we will see.....


10 day GFS output reproduced by kind courtesy of tropicaltidbits.com


Agronomic Notes


Since this is the 1st blog of July, I'll have a little look back at June but with time ticking on, this one will be a little less detailed than usual.


GDD comparison - June 2022 - The Oxfordshire, Thame, U.K

So June '22 came in with a total of 278 GDD for the month using 6°C as the base temperature. If we look back at our historical data we can see this is towards the upper end of the data set but by no means the highest total for the month with the hottest years showing totals >= 300 GDD. We know we had a really hot spell in the middle of the month (15-17th June) before dropping back into some cooler weather for the latter part of the month.

Y.T.D GDD-wise, we are sitting at a total of 720 GDD for this location at the end of June which again is towards the upper end of the y.t.d totals but by no means the highest, with the record (since 2005) held by 2017 at 864. We are a long way ahead of last year though courtesy of a much better April (remember April 2021 ?)


It isn't all about rainfall.....

So last week I made the case agronomically, that soil moisture isn't just affected by rainfall in determining whether the year has been a wet or a dry one, we also know that E.T plays an ever more important role. I showed last week that y.t.d a number of locations were running at much lower rainfall totals but also with higher E.T levels. The two factors combine to give us a very dry picture so far soil moisture-wise.


When I did some totting up of June stats, I was struck by this combination effect and I got wondering, is there a trend here or has this always been the case.


My gut feel is that we are seeing higher E.T levels than we have in the recent past, whereas summer rainfall is as variable as it always was...


So it was time to do some number crunching and see if June as a month verified this hunch or not....


Now I know you guys are going to read this and say, well that's fine for that location, but what about here ? Well the simple fact is I don't have historical E.T and rainfall information for anywhere other than my default location at The Oxfordshire and it's only because of Sean's willingness to both recognise the importance of this data and allow me to share it, that I have that. Don't get me wrong, there's a lot of historical rainfall info out there but in the absence of accompanying E.T, it's a bit, well, incomplete.


So are there any trends we can see from 2005 onwards when I started this work ? (geez that makes me feel a tad ancient)

So here's the yearly E.T and rainfall for June using data from The Oxfordshire. If we look at the last 10 years we can see that 7 of them have exceeded 100 mm per month, which I'd classify as representing moderate to high stress, with 120 mm per month indicating high stress (4 mm E.T per day) on Poa annua in particular. This June we hit 115 mm for the month which is close. Now this is just a snapshot since 2005, but I'd say you can see a tendency towards higher E.T levels in June as a month in the most recent years.


If we split the data set down the middle, the average monthly E.T for 2005-2013 is 84. mm vs. 103.7 mm from 2014 - 2022, that's a 23% increase.


If we do the same with average monthly rainfall for June, it works out as 54.5 mm for the period 2005-2013 and 53.04 mm for 2014 - 2022. Pretty much the same.


So no real trend in rainfall but a suggestion of a building trend towards higher E.T.


If we look at the difference between rainfall and E.T per year for the month of June, this is the picture we get ;

This brings some balance I think to the whole thing and as you can see June '22 is showing a moisture deficit of 60.4 mm, which is significant but by no means close to some of the driest June's we have experienced when we experienced high E.T, but also very low rainfall (2018 and 2015 for example).


So to get a complete picture, we have to take rainfall and E.T together and that's where I think we are not seeing the whole picture nationally, be that England, Wales, Ireland or Scotland. One conclusion is clear though, it is unusual to have a June when the water table is topped up !


Agronomic consequences going forward...


Now we are running into a period of high temperatures complete with a consistent wind element, which by my take means consistently high ET. By definition this infers sustained plant stress. Now if we take account that we had at least one, if not two Anthracnose trigger events so far this year, then I think it's safe to assume that this pathogen will remain front and centre in summer 2022.


I covered some of the Anthracnose agronomics last week but rather than painting a gloomy 'woe is me' sort of picture, I'd like to spin the other side of the coin if I may...


We know there's a lot of bentgrass going into greens nowadays, be it Creeping or Browntop and we also know for the former that it has a high PAR (photosynthetically active radiation) requirement compared to Poa annua.


Earlier in the spring I made the point that there had been very few days bright / high PAR enough to hit the minimum sufficiency DLI (Daily Light Interval) requirement of 30 m mols per m2 per day for creeping bentgrass. By inference, this tipped early spring '22 growth firmly in favour of Poa annua. Last month I started a comparison of DLI levels between central England and Scotland and continuing this into June now shows a much higher frequency of high PAR / DLI days as we would expect / hope as we approach the height of summer. (even though the days are already getting shorter :( )


In central England, 26 out of the 30 days exceeded this threshold and in central Scotland, the figure was 18 out of 30 days. Interestingly the total amount of PAR light for the month came in at 1327 m mols per m2 for C.England and 1004 m mols per m2 for Scotland, so although they are getting more daylight hours in Scotland, they also have more unsettled, cloudy weather with lower PAR light levels overall.


Tipping the balance


So in plain English, the balance tipped nicely in favour of bentgrass last month and with a naturally higher, endophytic resistance to Anthracnose in bentgrass vs. Poa annua, it means the more bentgrass content, the lower the risk / severity of Anthracnose damage. Now we do have other pathogens like Take All to consider and I think its fair to say we see more of this around nowadays than we once did. This I put down to a higher bentgrass content in greens, collars and approaches but also widespread resistance to the once effective, Strobilurin chemistry.


This in a nutshell is our 'ying and yang' sort of balancing act over the course of a year, plant species-wise. There are times when climatic conditions favour Poa annua and times when they favour Agrostis sp. We need to accept this and tailor our agronomic practices accordingly.


For the immediate future, it's about minimising stress, keeping the plant healthy from a PGR, biostimulant and maybe pigment perspective (?) and just applying common sense. More rolling than cutting and I'd be hesitant about lateral aeration (verticutting and the like) until we are through this mini-heatwave. There are plus sides in that the lack of soil moisture will mean rough, semi rough areas, fairway and outfield areas will be nicely manageable as I think they have been so far this year.


So I'll leave you with that positive picture just before I go and pack the campervan and take advantage of this as well !!...Mullet or Bass, Mullet or Bass, difficult decisions nowadays !


All the best.


Mark Hunt



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