April 19th

Hi All,

Well another dry (ish) week this week and slightly less cool, except for those of you on the eastern coasts of the U.K & Ireland.

I’m surprised there hasn’t been more about it on the media, but April 2021 will surely go down as one of the coolest on record.

Looking at my data from Great Dunmow, I see we are at 12.6 GDD / 1,96 G.P cumulative for April, boy that’s a cool one and equivalent to two good days of growth so far this month !!!.

And also a dry one, with not even a fraction of a mm of rain passing through the Davis VP2 over in Essex, no wonder the ground is cracked and nature looks on hold. It is a year that has got colder the further we have moved into it, with Mid-Feb to Mid-March warmer than Mid-March to Mid-April, now that’s bizarre. Remember though I said we would depart April cool and wet, well that’s a maybe at the moment.

Fortunately that beautiful woodlander, the English Bluebell, is starting to make an appearance, these were in one of the Willow Coppices on the Hambleton peninsular at Rutland. The weekend was just so beautiful and now we are allowed out I think we appreciate more than ever. We also had lots of insects on the wing allowing me to catch my first Trout off the top on a dry fly, that’s my passion 🙂

Today’s blog will be a short one as I’m under time pressure and have to go and get my hands dirty.

General Weather Situation

So as intimated last week, we start this week with high pressure sitting over the U.K, but across Ireland you can see an Atlantic low pressure pushing in which is currently bringing rain across the west of Ireland as we speak. Currently this rain is projected to slowly edge eastwards across Ireland over the course of the day and push into western Scotland later this afternoon, so for the U.K on the whole it looks another dry one to start the week. With light easterly winds and lots of sunshine, temperatures will push up into the mid-teens after a ground frost in places this morning. Now there’s a chance this rain may push into The South West and the western coastline but I’d say it’s a slim one.

Tuesday sees that rain having edged into the western half of Scotland overnight and still sitting over the west and north west of Ireland, but elsewhere we look to continue that dry theme, which across the east of the country is shading into 3 weeks and counting. During Tuesday that rain pushes eastwards across Scotland, dissipating as it does so and stays mainly a feature of the west and north west across Ireland, with just some showers early on making it over to the south and east. Another warm one but with more in the way of cloud cover across the U.K, so that means a milder start ot the day and temperatures nudging through the mid-teens, so 15-17°C likely for England and Wales, cooler across eastern counties and Scotland and Ireland with that much thicker cloud base. Here temperatures will only just break double figures.

Onto Wednesday and a pretty straight forward forecast with the U.K divided into a region south of The Humber estuary which will have plenty of cloud cover and maybe just thick enough for some light rain over central areas, but it’ll be few and far between. If you start with clear skies, it’ll will mean a return to frost on Wednesday I’m afraid. Further north of this line, plenty of sunshine and a little milder than Tuesday for Scotland. The same north-south divide will exist over Ireland with a region south of Connacht sitting in thicker cloud and above that more in the way of sunshine. Warm it will not be on Wednesday as that easterly wind cranks up a notch or two and pushes temperatures down towards the low teens for England, especially eastern counties. Further west, it’ll maintain better temperatures so Wales and The South West will push up into the mid-teens with Ireland and Scotland 10-12°C.

Thursday and Friday I’ll deal with together because they’ll be very little to report with early cloud cover on Thursday clearing to give a bright sunny day over England, Wales and Scotland. More in the way of cloud for Ireland, but that easterly wind will still be moderate in intensity so that’ll peg back temperatures over eastern and central regions with the west and south west warmest again with similar temperatures to Wednesday across the board. So 13-15°C for Wales and Scotland, but England and Ireland stay a little cooler with temperatures in the low double figures at best, though warmer in the south. A dead ringer on Friday, with the exception that the easterly wind will moderate to light and that’ll allow temperatures to pick up to mid-teens in most regions, with Ireland still the poorer cousin temperature-wise, especially across the east. Across the south of England, the sun will be out and I expect temperatures to push into the high teens here, but again we can expect a hard frost to start the day if you finish Thursday with clear skies, hardly brill when it comes to growth.

So how does the weekend look ?

Well similar to the last one, a bit greyer on Saturday with more in the way of cloud coming off The North Sea, but Sunday looks brighter with plenty of sunshine and staying dry. Temperature-wise, we look to be 13-15°C I’d say across most areas but for Ireland, that keen east wind will continue to the theme of the week with cool temperatures across eastern counties, warmer across the west. Just at the end of the weekend, we may just see the odd shower sneaking across The Pennines.

Weather Outlook

So is there any sign to a change in the weather and more specifically, any rain for the U.K ?

Well it all depends on the behaviour of the Bay of Biscay low pressure highlighted into the projected GFS image for next Monday. At the moment it has its rain sitting over France and Belgium but as we know, continental rainfall is a tad unpredictable so maybe it’ll push up further north into southern England. If not then next week looks to start dry with one high pressure slinking off to be replaced by another one homing in from The Atlantic. Now mid-week we could see some rain into Scotland and the north of England as the leading edge of this high pressure pulls down northerly winds and some showers from the bottom end of a northerly low. If this does occur it’ll happen from mid-week onwards. The change we are looking for then will be towards the end of next week as the winds turn more south westerly and we see a large Atlantic depression push in bringing cooler and unsettled weather for…..the end of April. If this does occur, expect me to be smugger than a smug thing in Smugland……ahem.


Agronomic Notes

You don’t have to be a rocket scientist to look at the chart above and pull out some pretty damning stats for why in some respects, April 2021 is a tricky month to grow grass.

As long as I’ve been typing this blog, I’ve always said April is a crap month to do so and I stand by that statement.

So we can see we have had so far….

  • No rainfall
  • 50.62 mm of moisture lost by E.T
  • 7 frosts so far this month
  • A total of 12.62 GDD in the month – Bear in mind 4-6 GDD per day represents good growth, so that’s a total of 2 days growth in the last 21 !
  • A total G.P of 1.9 for the first 18 days – Bear in mind, optimum growth per day is 1.0, so we have 1.9 / 18 = 10.55% of optimum growth !

You can dress it up anyway you want but the eastern half of the U.K has been hit hard by the predominantly eastern airstream with a lack of both moisture and temperature extremely growth-limiting.

That is why the traditional aeration slots of March / April need to be confined to the bin along with the calendar. I mean January and February were better than we have been this month for growth and that is saying something. I really hope because of lockdown and the situation with Covid that most clubs used this time to do the work that normally they would have done in March and April because this year more than any you can see the benefit of doing so. The reality is even in the hardest winter there are invariably periods when you can remove organic matter and / or vertidrain long before the so called spring appears on the horizon. You then have the work done before moisture and / or temperature become growth-limiting. Now I know the last 3 winters have been really wet with precious few drying days but in some parts of the country (invariably the drier parts), it’s possible to aerate early and reap the benefits. The areas where it isn’t possible like the north and north west aren’t the areas most prone to drying out in the spring. We will see that when we look at April’s stats sometime in early May.

In some respects you can argue that if you have got your house in order, you surfaces back and your irrigation system fired up and ready, then you don’t need the growth and you are in a good place. Forget your 5L can of PGR, Mother Nature is giving you this one for free 🙂

You could also argue that this weather is great not only for the punter but for maintaining large areas that normally would be flying out of the ground by now with clippings around your ankles. Outfield is surely pretty straight forward at the moment with growth limited by moisture and temperature. Straight-forward for some maybe provided you haven’t got worm cast-affected fairways from the winter or grub damage and you need some recovery.

Daily G.P – Great Dunmow Essex – April 2021

Can’t exactly see the reason why I’d be needing a PGR when I look at the G.P stats above but let’s be clear, when this weather does break and break it will, outfield areas in particular will likely shoot out of the ground. We have had first week of May’s before when we have gone from a daily G.P of 0.2 to 1.0 overnight and that has moved everything on at a real pace with no chance to apply a PGR because it was cool, windy and unsettled. So maybe something for the hit list if budgets and resources allow is applying a PGR and iron to higher-height-of-cut areas that are difficult to maintain, when and only when we can see a weather break on the way ?

On this site we are up to a total GDD since January 1st of 115.9 and the Poa annua var. annua constituent of the sward is seeding strongly, mainly because it’s been dry and windy with high E.T levels. I expect it to be well into the beginning of May before its perennial biotype cousin follows suit, but it’ll be very interesting to note just when in May this happens. Normally we have an up and down January to the end of April and we always end up seeing the Poa seedhead flush in the first week of May. Will the dry weather push it on earlier as stress and not temperature acts as the catalyst or will we see a mid-May – mid-June Poa seedhead flush this year ?

It is going to be interesting….

Irrigation and nutrition

I’ve seen some discussion on this subject and certainly on the location above, if I hadn’t have been irrigating since last week in earnest, I would be picking up a P45 sometime pretty soon (but at least I could fly fish my days away eh ?). Granted it is difficult with golfers out now but I would try to irrigate during the warmer part of the day if it’s at all possible. On some sites I know this is a practical impossibility and so it’ll be down to hand-watering the dry spots as and when you can. I did some Delta-T’ing last week and on one course the first (flat) greens came in between 20-45% vmc (the latter near a collar dam I would add). Walking up to the top end of the course I was greeted with 9-11% and a footprint showing wilting grass, a clear need for hand-watering in this case and / or maybe I need to cut out the Pain aux raisin 🙂

With moisture meters we are so much more in control of our irrigation than we were in the old days when irrigation was measured in minutes and not ml. The bit we don’t have a good handle on is local E.T rates though. As I’ve spoke about before, E.T is a function of many factors, not least temperature, relative humidity, wind strength. solar radiation and the like. To accurately measure E.T, you really need a weather station that is recording these parameters and then converting them to an E.T figure to do the job properly.

Look at the daily E.T stats above, the 17th and 18th April recorded 3.61 and 3.63 mm respectively. I applied the equivalent of 4 mm irrigation on the 17th and it took till 8 a.m yesterday (19th April) to dry down to the same level as on the 17th (measuring at 25 mm depth mind which is a lot shallower than most moisture meters). So effectively I’m irrigating at 4 / (3.61 + 3.63) = 55% of my E.T over the course of the two days. Now that’s pretty tight I’d say but currently I have a lot of root, no compaction and no wear (because it is a trial area). I’ve always looked to irrigate at 60% of E.T as a good yardstick and on this site, it isn’t far out. The problem is if I try to apply 2 mm per day, I get poor coverage (especially when the wind gets up) because you are limiting the applied irrigation to a low number of passes of the head. Putting 4mm on at once negates that.

Now when you look at the lack of growth stats above you could argue that applying nutrition is pretty ineffective.

Again here there’s tweaks you can do by applying foliar nutrition when we have a non-frost start to the day and temperatures are on the rise. Cool-temperature available N forms are the go-to and no need to apply any more than 4-6 kg of N per hectare because the plant is still temperature-limited for a good chunk of the day.

Below is a graph of the calculated Growth Potential every 15 minutes through a 24-hour period on the 18th April, you can clearly see how there’s a period of the day when the plant is able to grow provided it is not moisture-limited of course…

Growth Potential every 15 minutes on 18th April, 2021 – Great Dunmow

So as we can see the period from 11.30 a.m. to 19.00 a.m. is great for plant growth with sufficient air temperature for uptake, good levels of light (the DLI – Daily Light Interval = 44 for this day, well in excess of the requirements of a cool season grass species) and only soil moisture the possible limiting factor.

That’s why irrigation and foliar fertilisation are key for months like these….

OK, off to the day job, all the best everyone.

Mark Hunt