Monthly Archives: July 2018

July 16th

Hi All,

After another scorching weekend, things are due to settle down a bit heat-wise as we see a slow breakdown in the weather. Some areas saw their first rain on Friday evening for 7-8 weeks with torrential downpours across London depositing 50mm in just 2 hours. Elsewhere we have seen rain across Ireland, the north-west of England and Scotland with a vertical band of rain slowly moving across the west side of the country this morning. (It looks like St David’s, Pembrokeshire is getting a proper hammering as I type this at 09.42)

Central and eastern areas though remain parched.

The big question for many will be “Will I see any rain this week ?” and the answer of course will depend on your location. The areas most likely to receive rain this week will be in the north and west and so the south and especially The Midlands may see little more than the odd shower I am afraid. That said the end of the week probably holds the best chance of some sneaky un-forecastable rain for the south of England.

We will see a lot more cloud than of late across the U.K and that’ll help the job temperature-wise with some cooler nights to boot but the breakdown will be slower than first thought because the low pressure is staying up north.

Not every plant dislikes the current weather though, I’ve walked through this Maize crop every week since it was late-planted in the spring and can’t believe how fast it is growing…

General Weather Situation

So we start Monday we that band of rain (/) moving across country and currently affecting the west side of the U.K stretching up from Cornwall through West Wales, up to the north-west of England and east of Scotland. It is a narrow band though and that means it is likely to fizzle out before reaching central and eastern areas which is a pity. As that rain tries to move east it’ll push some cloud up before it and that cloud will keep the temperatures 4-5°C lower than yesterday for The Midlands. Ireland will also see those showers cross-country through the day after a similar day yesterday and much cooler temperatures, down in the high teens. Further south away from the effects of that rain front we will see another hot day I’m afraid with temperatures pushing up into the high twenties. Winds will be light and westerly / north-westerly.

Onto Tuesday and that departing rain front will leave some thicker cloud across the east coast of England and in general we will see a cloudier, cooler day with temperatures down in the low twenties due to the wind aspect and cloud cover. There’s a risk of some showers across the north-west and north-east of England and may be a snap one further south. Ireland looks to have a similar day with any showers confined to Donegal and the north-west. So cooler than of late with Ireland and Scotland in the high teens and low twenties further south courtesy of that north-west wind.

Wednesday sees that north-westerly wind drop and swing more westerly so temperatures will rise again towards the mid-twenties in the south of England. Still plenty of cloud around, some of it quite thick again across the east of the country with Wales and the west coast perhaps seeing the best chance of the sun. Ireland looks to stay cloudy all day but dry. Similar temperatures for Ireland and Scotland in the high teens through to mid-twenties for central and southern areas.

Thursday sees the wind do a full 180° swing down south to blow lightly from the south-east and that’s one of the reasons why any rain later in the week will struggle to affect the south of England. Up north we will see that north-westerly wind push back in, light to moderate and that’ll swing cloud cover across the U.K and Ireland with temperatures dropping a degree or so across Scotland and Ireland as a result. So warmer where you get that wind direction change across central and southern England with temperatures once more in the mid-twenties, cooler further west where you keep that north-westerly air stream.

Closing out the week on Friday we see a rain front push into north-west Ireland / south-west Scotland overnight and this will move in  south-easterly direction across Ireland pushing thick cloud before it. Now currently the odds are that this rain front will not make much progress into Wales and the north of England but it’s been changing on a daily basis so we’ll see. Ireland and Scotland look to be dull with plenty of rain for Ireland but further south it’ll be hotter because the wind will push from the south, so a hot dry day with temperatures in the mid to high twenties to finish off the week across the south of England.

So what’s the outlook for next weekend ?

Well a lot depends on where the winds coming from but currently the odds are that the wind will swing round to the west / north-west across all areas and that’ll push in a cooler, fresher air stream across all areas dropping the temperature significantly on Saturday with high teens likely across all areas. A real north / west / south divide on Saturday with Ireland, Scotland, the north-west and north-east still sitting under that thick cloud so cool and dull here vs. hazy sunshine and cloud further south. Sunday sees warmer air from that close-by, Atlantic high pressure push in over Ireland and the west raising temperatures up to the low twenties for Ireland and Scotland and mid-twenties further south.

Weather Outlook

So next week looks to start warm enough after a hot Sunday but if we are to see a real breakdown of this continued dry spell for many, next week will be the clincher. That’s because we have a deep low pressure sitting north-west of the U.K that through next week is projected to sink down and introduce cooler and more unsettled conditions through the week, starting with the north and west on Monday / Tuesday and then extending south to all parts later in the week. This transition is key because if it occurs it’ll introduce a westerly air stream which will end the blocking action of the Atlantic high and allow low pressure systems to feed in.

Now I know when we are going through this process it is a bit like waiting for a delayed train, every time you look at the timing board it’s delayed a little bit more so you wonder whether it will ever turn up.

Honestly-speaking,  this could be the case here, we could have a re-run of this week with the low pressure staying further north and only bringing cooler weather / rain to the north and west, whilst the south and east bakes. Part of the problem is that we are sitting here in the middle of July so we still have heat potential to come, whereas in 1976, this process occurred in late August. I could counter that by saying the run of August weather we have had of late would point towards a greater likelihood of unsettled conditions than heat. Time will tell.

Agronomic Notes

Dormant Turf

Pic courtesy of West Lancashire Golf Club

So in some areas we are into week 8 now without appreciable rain and the effects of continual E.T stress are plain to see.

Above is a pic from the north-west of England, an area normally associated with anything but a shortage of rainfall. This course got 15mm of rain late last week and I think I’m right in saying it is raining there now.  It will however be a while before the grass comes out of dormancy and begins to respond to the change in moisture status and fresher conditions. Brown grass like this is at its very simplistic, exhibiting nitrogen deficiency, because with extremely low levels of soil moisture the grass plant is unable to uptake nitrogen and so sacrifices its leaves to protect the part of the plant that ultimately determines its fate, the crown.

The crown is where it all goes on in the grass plant because it is here where cells divide into root or shoot cells and during spells of prolonged drought this is the area that the grass plant prioritises. So when you are looking at an area of turf like the one above an obvious question springs to mind “Is this turf dead or is it dormant ?”

The survival of the grass plant crown is not only a function of moisture availability, its place within the turf canopy is key and that’s where things like surplus organic matter come in to play. Areas of turf that contain excessive organic matter will cause the crown to be elevated above the soil layer and resident within the surface organic matter layer. This in itself drastically lowers the ability of the plant to survive. Firstly organic matter heats up far quicker than soil and so areas of thatch will literally bake off, dehydrating the crown and killing the plant. An elevated crown is also prone to damage by wear and tear being situated above the soil layer so turf that is dormant with an elevated crown will show more wear damage and soon take on a black appearance as the grass begins to degrade.

Image courtesy of Bruce Clarke Rutgers University

More of a golf green scenario for many but the level of topdressing integrated within the profile will also dictate the grass plants ability to withstand this type of prolonged heat and ultimately survive. I’ve used this picture before but you can clearly see how the crown of the grass plants (in this case Poa but it applies to any species really) on the right are sitting down in the rootzone and so protected from the worst of the summer heat and wear and tear to boot. The plants on the left taken from an area which has received little topdressing are elevated and right in the firing line unfortunately.

So one thing you may notice is that your thatchiest areas on the golf course / sports pitch, etc won’t recover once rainfall re-commences and this is because the crown has died and is starting to degrade. The images above show a healthy white grass plant crown above compared to a tan-coloured crown that is starting to degrade. (in fact you can see fungal hyphae on the crown)

So should you apply fertiliser to drought-stressed turf ?

It may seem a daft question but in some instances (domestic lawn care for example) this one comes up a lot. It really depends on the type of fertiliser because depending on how much rain falls when the drought breaks, you could make the situation worse my desiccating the plant further as moisture is drawn out of the plant towards the fertiliser.

The amount of desiccation is dependent on the osmolarity of the applied fertiliser (whether it be liquid or granule) and this is a function of the salt index of the fertiliser. (the lower the salt index, the lower the osmotic draw from the plant)

If we have plenty of rain then this won’t be an issue but the smart money is on waiting for moisture levels in the rootzone to re-establish and the grass plant to begin growing again before applying fertiliser.

E.T Stress – Where are we now ?

At the end of June I put together two graphics comparing 2018 y.t.d with 2017 in terms of rainfall, Demand E.T and soil moisture deficit.

Two weeks on I thought I’d re-visit this to see how we are doing…

So in the above graph from 2017 you can see we had a period during June for about 16 days when no rainfall was forthcoming, we then got rainfall on the 27th. It went hot and dry again and E.T ramped up but on the 12th July we got rain again, that’s a gap of 14 days. So in terms of crown hydration the grass plant kept getting a little water every fortnight to keep it healthy and viable.

Overall the theoretical moisture deficit from June 1st, 2017 to July 15th, 2017 was -116.1mm

Compare that with the scenario below for this year ;

Quite a different shaped graph with no rainfall since June 1st and consequently an ever-increasing theoretical soil moisture deficit, now at 177.4mm up until the 15th July, 2018, that’s over 7″ in old money.

As mentioned before this cumulative plant stress is likely to result in some plants in less than optimal conditions checking out depending on their crown and of course root status.

Coming back to the beginning of this blog, the reason that maize is still looking good is because it has a very deep root system and so finds it easier to maintain plant moisture status. The same is true of grass plants but of course the functionality of the root system is dependent upon so many other factors aside from just plant species.

I once saw an autumn over-sown Fescue / Rye fairway go under drought stress the following summer and I expected to see the Fescue survive and the Ryegrass check out. When I visited the course, the exact opposite was true, the Fescue was dead and the rye alive.

Upon examination the previous autumn sown rye had got its roots down through an organic matter layer present in the rootzone and into the clay beneath and so had survived whereas the less vigorous Fescue had not penetrated through the organic matter layer and its roots had dehydrated to a point where the whole plant died. Not what you’d normally expect species-wise but an illustration that the local environment (rootzone characteristics, organic matter content, root depth) has a big say in what happens to a grass plant in a severe drought scenario.

Humidity = Disease

One last point is that ‘if and when’ your site does finally receive some welcome rain it may not all be good news. The increase in humidity is sure to kick off some of the more stress-related turf diseases like Dollar Spot and Anthracnose. Be on your guard.

Ok, that’s me for this week, I am on my travels next week but I’ll still be taking time to put the blog together as I know next week is critical from a weather perspective. In a little under a months time I’ll be off to the Alaskan Wilderness once again and taking a sabbatical from the blog till late August as mercifully Upper Camp on the Kanetok River has no WiFi, no phone reception, well nothing really except Tundra, Salmon, Dolly Varden, Trout, Bears and lots of Mozzies 🙂

All the best…

Mark Hunt

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

July 9th

As we now enter week 7 without meaningful rain and an E.T loss over that period that runs to 6-7″ (150-175mm) of moisture, the cracks are starting to show in more ways than one.

As I walked through the parched countryside yesterday I mused that not so many months ago these same paths were almost unwalkable, such was the amount of rain we had endured, now I was staring down at deep cracks in the Leicestershire clay. It’s an oft-used term but we seem to lurch from extreme to extreme weather-wise nowadays.

The last drought / heat of this magnitude was in 1976 and showing my age I can remember it well as the first year of my teens. (showing me age now I know)

Back then it was warm and dry from January onwards, so we went into the summer already on the back foot water-wise. Rivers and lakes dried up, canals became unnavigable (and crystal clear because of the lack of boat traffic Mike :P) and spring crops failed in the fields. That year the weather broke in August and it was quite amazing how quickly things turned around and life returned to normality, the drought quickly forgotten.

2018 doesn’t equal 1976, because we had such a wet run up to proceedings and till now that’s been our saving grace from hose pipe bans and golf courses being treated like a 2nd-rate  citizens when it comes to the pecking order of who can water what. Plants are struggling though, whether it be on the golf course, in the garden or crops in the field. You only have to look at the pitiful state of late-sown spring crops or the amount of re-growth after the last silage cut to see that. Water is a resource that is no longer a given.

Last week at the ETS Conference, the question was posed a number of times…”If our water allocation was cut by 25%, could we survive ?”…I think we could and in the future it is likely in some areas of the country to come to that, such will be the competition for this resource from building and infrastructure.

We as an industry would change and adapt, just like they have in other areas of the world where water scarcity threatens. Management practices and indeed expectations would also have to change from our customer perspective, the latter may be a harder nut to crack judging by some of the comments I hear from you guys in the industry. Of course this thought process will likely disappear from the agenda when the weather breaks and we turn our focus onto the next challenge to our golf course, football pitch, racecourse (delete where applicable), most likely how to implement a satisfactory drainage policy in a wet autumn 🙂

So onto the general weather situation and has that whiff of change I mentioned last week gathered momentum or disappeared and will this be my Michael Fish moment when I forecast exactly the opposite of what will indeed occur  (Thanks Adam :))

General Weather Situation

So Monday starts off pretty much as we left off the weekend, hot dry and sunny for England and Wales with possibly more in the way of cloud over the north and east of the U.K. Quite a difference in temperature though between Scotland and Ireland sitting in the low twenties (lucky you) and down south in England and Wales where we are looking at high twenties again I think depending on your location, wind and cloud cover. The wind will swing round to the north-east through Monday and freshen. That’ll knock the temperatures back a tad in the evening and perhaps bring cooler and more pleasant night temperatures to aid a better nights sleep. (some hope)

Tuesday sees a thicker layer of cloud cover the U.K and particularly over Scotland where it may be thick enough for some mizzly drizzle in places. Down south we will see this cloud cover slowly burn off aided by a freshening north-easterly wind but across the west coasts, Wales, Ireland and Scotland, it may well prevail and that’ll keep the temperature nipped down. In fact for most of the U.K we will be noticeably cooler on Tuesday with that freshening wind keeping temperatures down in the low twenties, a pleasant transition and a cooler night to boot.

Overnight into Wednesday and we see a rain front push into Donegal and the north-west of Scotland but it’ll be short-lived and soon move off again. Again we will see plenty of thicker cloud come off The North Sea and again it’ll hug some westerly regions, particularly South Wales and the east coast of Ireland. That north-easterly wind will be a tad lighter on Wednesday so I think similar temperatures to Tuesday, around about 20°C for Ireland and Scotland and a couple of degrees higher for England and Wales. Remaining dry but again a cooler night for which to contemplate the telly and the next England World Cup match. Have to say, great to see the return of team spirit to our national side, a lack of prima donna’s and the lads enjoying the challenge, at last something positive to focus on amidst the political turmoil that is unfolding currently 🙁

Thursday sees a weak weather front push into Ireland and the west coast of the U.K bringing the potential for rain from The South West up through West Wales, The North West and south-west of Scotland. (Did I say rain ?) Inland from this we will see the familiar pattern of cloud cover burning off and a dry, bright and sunny day for most of England and Scotland with the exception of the west. Ireland looks to be cloudier with perhaps a chance of some rain across eastern counties through the 2nd half of the day. With the wind taking on a more easterly aspect I expect temperatures to ease up a degree or two towards the mid-twenties for those of you seeing the sun, low twenties for Scotland and maybe just the very high teens for Ireland under that thicker cloud.

Rounding out the week on Friday and that familiar pattern again of thicker cloud burning off but I’d say it may be persistent in some central and western areas of the U.K and Ireland. Similar temperatures to Thursday but they’ll start to climb for the weekend so maybe a degree or two up and warmer night temperatures return 🙁 Remaining dry.

So the weekend looks like being hot again although I’m not 100% on this because I think by the 2nd half of the weekend (that’s Sunday to you and me) we will see the wind edge westerly and bring cooler temperatures, initially to the north and west but by the 2nd part of Sunday, hopefully further south, but this may not occur till Monday perhaps. Now this change in wind direction would be one piece of the weather-breakdown theory that may (or may not) unfold over the next week or so and a crucial one in my books. So hot, sunny and dry for the weekend but I’ll be looking for that wind swing on Sunday. One final point is that if we do see cooler air come in, then the beginning of the breakdown will probably be accompanied by thunderstorms.

Weather Outlook

And here I fear a Michael Fish moment looms…..

So looking at Unisys weather the outlook is for the jet stream to drop south and allow low pressure to move in during the early part of next week and move us into a phase of cooler and more unsettled weather with rain. The cooler and unsettled conditions will affect the north and west first before pushing south later into next week.

There I’ve said it, that’s my take following on from my contentious ‘whiff of change’ comment in last Wednesday’s blog…

In order for our weather to change properly we need a number of things to fall into place, with the position in the jet stream the key piece in the puzzle. Since the beginning of June we have sat under a peak in the jet stream that allowed hot air to form below it and a succession of Atlantic High pressure systems to dominate. So the rain has been going up and over us. Iceland is having its wettest summer for years with less than a week of dry days since the middle of April. You’ll also have seen the weather in Russia, cool and unsettled with plenty of rain. That’s the flip side to our current weather coin.

Both Unisys and Netweather show the jet stream dropping south at the end of the weekend and that’ll allow low pressure systems to do likewise with the north initially affected and hopefully further south later into next week rain-wise.

Now there’s a big caveat with my prognosis and it is this….I can’t see a consensus out there from a weather projection perspective so this may well turn out to be a Michael Fish moment on my behalf but the cards in my hand say unsettled conditions are coming so they are the ones I’m playing…..I’ll see you and raise you ten 😛

Agronomic Notes

So if the prognosis is right, we have another week of dry, bright and settled conditions, cooler than of late with that change in wind direction and that’s reflected in the projected E.T figures for this week.

For my location the projected E.T loss is 16mm over the next 7 days, whereas last week it was around 26mm, roughly a 40% reduction.

Now last week I tried to explain the relationship between E.T and irrigation demand (badly), but the USGA Record do a much better job with this article on E.T-based irrigation scheduling here

Now of course some of you might say that’s all well and good but how do I measure E.T ?

Well you can purchase a dedicated E.T Gauge / Evapotranspiration Simulator, but that’s the thick end of $400 bucks for a posh one. Alternatively you can get a weather station that also measures E.T (Netatmo doesn’t by the way) or you can use a weather forecast system that includes projected E.T rates as part of the forecast. As you can see from the above, we include this feature as part of Weathercheck. In the U.S, where E.T is more relevant for turf and crop management systems, they have a national network of weather stations that you can check to find out the current E.T rate for your area (or an area close to you).

I looked at Weather Undergrounds network for the U.K and Davis Weatherlink and only found the odd PWS that broadcasts E.T data so clearly we are behind the curve here. The problem here though is that even a forecasted E.T figure will only be an approximation and across your site you will have big variations. For example, a golf green in full sun and with an open-aspect will run a much higher E.T than a green that is sheltered from the wind and say in shade. In turn this means that the former green will run higher E.T’s, higher plant stress levels and so be more susceptible to some of the stress-related diseases like Anthracnose and Dollar Spot to name but two.

Aeration and Stressed Turf

Clearly during periods of weather like this, aeration practices have to be well thought through and sometimes ‘less is more’. If we have grass that is on the edge of wilt for 10 hours of the day (or longer) then cultural processes that impact the leaf like verticutting / grooming, topdressing and the like isn’t in its or your best interests.

Switching to smooth rollers during stress periods has always been a big win in my mind (if budgets allow) because they put less stress on the plant but what of processes like solid tining or even using compact vertidrains with narrow tines.

Again the USGA-Record (a brilliant resource that is free to all) comes to my rescue with a nice article on mitigating summer stress. In it you’ll see there are two sides to the aeration coin. You can read the above article here.

I think this is where we need to read our turf and the weather closely because in these cooler periods of weather and particularly when we have cooler nights, then using small diameter solid tines to vent surfaces has a number of benefits. Firstly, one must remember it is possible to over-water rootzones and effectively you end up causing more harm than good. A saturated rootzone has low oxygen availability and of course as that water warms, it’s ability to hold oxygen decreases even further. So effectively we are simmering our roots if we have over-watered an area and depriving them of oxygen, cue a stressed plant. So water management and more specifically water movement becomes key and critically we need to maintain a balance of air and water in the rootzone and that’s where venting comes in. It allows areas to dry down more effectively, it increases oxygen availability and of course vents potential harmful gas build up. So this week with that cooler period mid-week would I think be a good time to vent your greens.

I have probably related this story before but I think repetition is no bad thing in this case….

During the summer of 2014, we had very high levels of Anthracnose in the UK and I visited one end-user who was particularly badly hit. Now 2-3 weeks previous to the Anthracnose rearing its ugly head, I could see the greens were on their limit from a nutrition and stress perspective and was concerned that we were staring potential Anthracnose issues in the face. That concern was well-placed because indeed we saw the disease affect most greens. I say ‘most greens’ because two were largely unaffected and when I sat down with the Superintendent to chat it through I tried to focus on what was different about those two greens management-wise. We went round the houses as usual but eventually I think we nailed it. Those two greens had been vertidrained in July with a compact vertidrain down to 8-10″, they were the only two as it happens and the benefits to me in carrying out this work before Anthracnose reared its head were clear to see.

As the referenced article above states, less can be more when it comes to aeration during stress periods and I can’t stress this enough however if you are keeping your turf on the healthy side and the weather plays ball then solid tining / vertidraining with small diameter tines in the right circumstances can pay big dividends.

Ok, that’s all for this week and time will tell if this is or is not my ‘Michael Fish moment’, that said Meteoblue’s forecasted max temps for Sunday have just dropped 2°C, so you never know.

Have a good week, keep up the sunblock and good luck to England on Wednesday night, we will all be rooting for you (well everyone except The Celts that is 🙂 )

All the best

Mark Hunt

 

July 4th

Hi All

Happy 4th of July 🙂

A late blog this week because I’ve been up at the European Turfgrass Society (ETS) Conference since Sunday. This year it was held in Manchester and they had some really good Turfgrass researchers from around Europe and the U.S sharing their findings across a number of subject areas. (You can see the program from this weeks event to get a flavour of the type of talks here)

Some of the gems of wisdom I gleaned I’ll discuss in next week’s blog as they are both relevant to current conditions and also interesting to boot. I presented a paper on the role of phosphite as this is a contentious subject at present. Fortunately our company is involved in some pretty high level research in this area which I hope will benefit not just the U.K, but European and possibly U.S Turfgrass industries going forward. Won’t be putting it on the blog though because of the Rank Xerox brigade 😛

Now you don’t need to be a rocket scientist to know that June 2018 checked out as a very dry month and for some areas, the driest since records began in 1901. We had 1.8mm here in Market Harborough and I reckon that’s par for the course not just here in Central England but also in Ireland and Wales as well. Scotland started dry and warm, had a wet middle of the month and has then been dry for the last 10-14 days.

In terms of meaningful rain, our last here was on the 30th of May, so that’s well over a month without rain. Some areas of the continent are just as dry as we are…..

Now having said that as I type this blog I can reveal IT IS RAINING SOMEWHERE IN THE U.K AS I TYPE ! (Shock horror)

Image courtesy of Netweather

As you can see Avon and some parts of South Wales extending along the M4 are getting appreciable rain and some other storms are kicking off close to the M1 (Please, please come to Market Harborough 🙂 Footnote – They bloody didn’t ).

I reckon the latter have been created by hot air updrafts emanating from the large distribution warehouses around Milton Keynes and Rugby.

It’s not just the long run of hot days that has been unusual, nor the lack of rain, it is the nature of the E.T loss in June that has caught my eye. We have had a predominantly north-east wind in place for 2-3 weeks and that has meant it has remained windy not just through the day but overnight as well. This has really ramped up the 24hr E.T figures and I’ll be speaking about this later in the blog.

General Weather Situation

So I’ll start my forecast from Wednesday afternoon because that’s when I’m putting this blog together. As mentioned earlier we have some rain around across The South West and South Wales and also some cloud building across North London and Essex. Some of this cloud could thicken to give localised rain don’t you know but where and when is a job for your radar app and not my forecast. Elsewhere it’s another day in paradise with hot, bright sunshine, a little cloud cover and temperatures climbing into the upper 20’s across the U.K, with Scotland and Ireland on the low side of twenty degrees. (Lucky you) A bit more in the way of hazy cloud around in places which will just make things a little more bearable and light winds as well compared to late.

Onto Thursday and that cloud cover may well remain across Ireland, Scotland, The Lakes and the south and east of England. In places you’ll start and remain bright on Thursday as that cloud cover burns off but it wouldn’t surprise me if for the second day running we see some rain showers bubble up during the early afternoon across The South West, possibly South Wales and the south of England. The reason for this is a low pressure across The Bay of Biscay is feeding some moisture into the hot air system but sadly it’s mainly confined to the south of the U.K. Similar temperatures to Wednesday really with mid to high twenties depending on cloud cover for England and Wales and a tad lower for Ireland and Scotland. We may also see the wind swing round to the north.

Closing out a short week (or a long one for me as it started on Sunday) we do it all again on Friday with plenty of cloud starting the day and in places this may be reluctant to burn off till the afternoon. I think we are less likely to see rain bubble up down south on Friday but you never know. Similar temperatures again for Friday, low to high twenties depending on where you’re located and a freshening north-westerly wind likely to ramp up the E.T again.

For the weekend I think we will see the heat start to build again towards the high twenties and even I think pushing into the low thirties on Sunday possibly in places. We will also see a return of that north-east / east wind I am afraid. Hopefully our Celtish contingent will excuse a slightly partisan reference to the England football team to whom I wish all the best to on Saturday. Nice to see some passion in our game for once. That said, the standard of play acting is shameful from some of the teams, come to a road, BSB, WSB or MotoGP race lads and man up is all I can say 🙂

Weather Outlook

Now I confidently predict that this part of the blog will be receiving more scrutiny than usual this week as we enter our 6th week without rain (and longer than that in Scandinavia)

So next week looks like starting off very similar to how the week ended with long spells of bright, sunny weather and high temperatures. Less in the way of cloud cover compared to the end of the week possibly and depending on who you believe, that’s the way we look set to stay with a blocking high pressure in The Atlantic. I say this because 2 weather models beg to differ from this continued drought prognosis.

Unisys shows a low pressure forming south-east of the U.K around this time next week and then slowly pushing north and east to bring cooler and perhaps unsettled conditions next weekend. Now it is and should be viewed with a big ‘IF’ because we had the same this time last week and the low has never moved northwards rather it has remained in The Bay of Biscay. Metman James is erring on the side of continual blocking and that’s probably where the smart money resides but I like to give a bit of hope to us all that may be struggling with poor irrigation systems and the highest, prolonged E.T stress we have had for a good few years.

So maybe just maybe we will see a change towards the end of next week….I will do a mini-blog at the end of the week if this signal remains in situ and if it doesn’t then I’ll revisit my hunch next Monday as per usual with a despondent shrug 🙁

Agronomic Notes

Since this is the first blog of July we can take a long, hard look back at June 2018 and crunch some pretty dry and parched weather stats.

Thanks to Wendy for taking the time now she’s back from yet another holiday (arf arf) to compile this info. Thanks also to the usual band of contributors, cheers everyone 🙂

GDD Comparison – U.K Location – Thame

This is kind of when recording and comparing historical weather data really comes in handy because I was staring at June 2017’s GDD monthly figure of 329.5 and trying to think back to last June and whether it was hot or not ?

I then remembered we had a particularly hot spell on the run up to Wimbledon (Good luck lads for the tournament by the way) when temperatures soared into the low thirties. So June 2018 isn’t the highest monthly GDD we have measured at 314, but it comes in just a tad behind 2017 and maybe it is significant that the last 2 years have been the highest ever ???

Cumulatively we are catching up fast after our cold, wet and tardy start to 2018…wet ? you remember wet don’t you ? We have now overtaken all the previous SSW-event years and I wonder where we will be in a months time ?

GDD & Rainfall Comparison – U.K Locations

No great surprise here with very consistent GDD across England but significantly lower GDD and higher rainfall for our Scottish location.

Aside from a smidge more rain for Bristol (most of which fell on the 2nd of June !), you can see how dry we are with 2 locations recording no rainfall at all ! That said I reckon half of my monthly total was courtesy of the sprinkler irrigating my Netatmo Rain Gauge !!!! The high GDD figure for my location comes down to sensor location in that it picks up the afternoon sun directly so I get some pretty elevated afternoon temperatures !

What these stats don’t show is the other side of the coin for a hot, dry June and that is extended plant stress due to consistently high E.T.

GDD & Rainfall Comparison – Irish Locations

So we see Ireland comes in with a very consistent GDD figure across all locations, except Limerick which is higher than the average. The consistency of measurement points to the stability of the weather situation that has affected not just Ireland, but the U.K and Continent as well. Rainfall-wise we can see the west of Ireland has had more rain than the east, as per usual, but even for the west these figures are pretty low and reflect precious little significant rain in June. What I mean by that is that most of the rain in the Irish stats occurred either at the beginning of the month of June for the east of Ireland (literally the 1st day of June was the last rainfall for some of the locations !) or the amount of rain that fell in the middle of June across the west was compromised very swiftly by E.T rates. (evaporated off before it wetted the ground)

June 2018 vs. June 2017 – Focussing on Evapotranspiration (E.T) and Rainfall

So I am using data from The Oxfordshire to compare June this year with last year and it makes for interesting reading. First off let us define E.T as the amount of water lost from the grass plant by transpiration (through the stomatal pores) combined with water lost from the soil by evaporation.

Now E.T in weather stations is usually calculated using a complicated equation known as the Penman-Monteith Model (PM). I’m not going to go into this in too much detail but the equation takes into account a number of factors to calculate the potential water loss from the plant and soil surface but of course it is an estimation. There are a lot of variables when it comes to calculating actual E.T (E.Ta) using the Penman-Monteith model and normally you have to multiply the calculated value by a crop coefficient (Kc). This is because the model assumes the crop has a height of 12cm and I think we’d all agree that we aren’t cutting quite that high 🙂

To look at it very simplistically, the PM model tends to over-calculate water loss by E.T and so if you irrigated to replace the water loss calculated by the PM model, you’d have a saturated surface. So the common practice is to water at a % of daily E.T. In my experience I found that irrigating to replace 60% of calculated E.T loss was a good starting point and that if this was reduced to 40%, I saw plant stress symptoms develop. Now of course things have moved on at a pace when it comes to irrigation because we know most end-users only apply a % of their requirements through mains irrigation and then hand water to supply the rest on areas that are known to need it. How do you know where those areas are and how dry they are ? Well the increasingly popular method is to use a moisture meter to identify dry areas and evaluate irrigation efficiency (hand watering or mains applied) Moisture meters really come into their own at times like these.

So let’s look at the stats for June 2018 vs. 2017 and the irony is that the total monthly water loss by E.T was actually identical at 111mm in 2018 and 2017, uncanny but that’s where the similarities end.

The rainfall totals were different with 39.2mm falling in June 2017 vs. 2.4mm in June 2018.

So in June 2017 (above) we started the month with a net deficit of moisture but rainfall on the 5th, 6th and 7th of June took the soil almost back to a neutral level in terms of moisture levels. Thereafter the soil dried out progressively with the next significant rainfall on the 28th June halting the process. Now of course I’m simplifying the situation because I’m assuming I start the month with neither a soil moisture deficit or surplus. (Bear with me though)

By the end of June 2017 we had a theoretical deficit of -72.4mm.

Now let’s look at June 2018 at the same location…

You can see a clear difference with an increasing daily soil moisture deficit from the 1st of June right through to the 30th June and a total figure of -104mm.

So if we were irrigating to replace 60% of E.T in June 2017, we would require 43.4mm of water  vs. 62.4mm in June 2018, that’s 43% more water.

Longevity of E.T stress

There’s another more significant difference though and it relates to the longevity of continual E.T pressure on the grass plant.

In 2017, we can see that continual E.T pressure didn’t really start until the 11th of June and with the arrival of rain on the 28th June, this process was halted.  So the longest period of continual E.T stress in June 2017 was 18 days.

Compare that with June 2018, when the continual E.T pressure started at this location on the 1st of June and continued throughout the month unchecked, so that’s 30 days of continual E.T pressure and of course we know that the process is still ongoing in July.

So both months might have had the same E.T level but the result in terms of higher levels of plant stress in 2018 are certain to be more severe in my books. This is due to the longevity of the stress period and the fact that there’s been no respite for the plant.

Consequences of continual high E.T stress

I believe that we will see more disease development on our turf surfaces as a result of these elevated levels of continual E.T stress but in general I don’t think we will see this till the arrival of rainfall and increased atmospheric humidity.

Principal among those diseases will be Anthracnose and Dollar Spot because they’re stress-related.

Use of PGR’s during stress periods

I get a lot of questions on this front when conditions are as they are so I used my ETS attendance to canvas opinion with the guys that have looked at this. The consensus is that continual applications of Trinexapac-ethyl at the label or sub-label rate are on balance positive with respect to grass plant health. In particular the use of ‘little but often’ TE (and it would have to be little and often with current temperatures to avoid the rebound) has been shown to decrease plant moisture loss and thereby lower stress. It’s logical that if you decrease leaf shoot production then you decrease net water use by the plant. There’s also the potential to increase plant rooting by taking the emphasis off top growth. I’m not particularly sold on this one, never have been but maybe during certain conditions (high E.T stress) the effects are more obvious. Now of course we come to the age-old question of rate and I know there’s plenty of viewpoints on this one. We know Poa annua is one of the most susceptible species to this type of stress (particularly the annual biotype) and the most-affected by TE.  So using a higher-than label rate of TE during drought stressed conditions is likely to increase Poa annua stress. Fine if that’s your objective, not so fine if it isn’t.

Biostimulant usage

I believe that the use of a combination of seaweed and humic acid at this time of year is beneficial to plant health, particularly when the plant is under stress, be it abiotic or biotic.

It is quite likely that use of these products outside of stress periods imparts less benefits but I think they do come into their own when we are faced with situations like the above. The objective is keeping plant health in balance with nutrition and not producing too weak or too lush a grass plant. It is though a tricky balance.

How high is our E.T at the moment and how does it compare to the United States for instance ?

One of the researchers presenting at the ETS was based in California and some of you will know they are enduring an extended drought scenario. In his own words “Our drought is bigger than your drought” 🙂

The researcher put up some weather data that showed their E.T losses per month can be as high as 200-250mm at their peak, that’s an average of 6.5 – 8mm per day !

So where are we in the pecking order of E.T ?

Well I borrowed this Twitter snippet from the venerable Ian Kinley @ Royal Porthcawl G.C.

You can see his weather station is recording a 24hr E.T of 7.64mm, so we are right up there currently. Any advance of 7.64mm ?

I should also point out that minutes after posting this clip they duly picked up a nice and steady 3mm of rainfall (let the slagging begin)

Ok that’s it for this week, sorry for the lateness in the day and week for sending this out. I’m off for a nice walk around a reservoir (possibly with a rod and bag) on the look out for some late-rising Trout 🙂

All the best.

Mark Hunt