As we march on through July and yet another changeable weekend passes us by you could be forgiven for thinking we may not get a settled summer this year and certainly if I look at the position of the jet stream it does seem that way. It is subtely on the move though and that will allow warmer air into the south of England from time to time and tend to push the more unsettled weather on that familiar diagonal line west and north of the U.K and Ireland. Before this we have our present low pressure system to work its way through and some cooler, unsettled weather.
This is my last blog for a few weeks as I am shipping out to Alaska for some hiking and fishing but bear and moose allowing, I intend to re-commence on August 1st
So how are we looking for the week ahead ?
General Weather Situation
So Monday looks to continue the unsettled weather we saw over the weekend, but at least it made for an entertaining F1 race at Silverstone Already today we can see a raft of showers working across Scotland, the north of England and Wales with the heaviest rain in the north west between Stoke and Manchester I’m afraid which adds to the packet they picked up yesterday. Through the morning this rain will move east and southwards slowly and gradually disippate, though it may not clear eastern coasts till later on in the afternoon. They’ll also be some showers across Ireland but these look set to clear eastwards through the morning to leave a pleasant day there. South of this line of showers it looks to be largely dry, windy but warm with plenty of cloud cover holding temperatures down to the high teens / low twenties. Later in the afternoon, as the showers die out in the north we may see that Welsh rain front sink south into the south west of England. A blustery day with strong drying winds (where it isn’t raining of course :))
Overnight into Tuesday and that cloud base and rain sinks south into The Midlands and Central England so the boot is on the other foot for Tuesday with a drier day for Scotland and the north of England and wetter down south. Ireland looks to also miss the majority of the rain a.m. but this changes through the course of the day as showers are likely to push in late morning to the west and cross country. That rain for The Midlands and south of England looks to intensify during the morning on Tuesday so most areas will get a drop before it exits stage left into The North Sea by late afternoon, though it’ll drag its heels across East Anglia and the south east well into the evening. The same is true in Ireland with that rain pushing eastwards clearing the west and Midlands through the evening but passing over Leinster as it does so. A cooler feel to Tuesday in all areas as the wind swings round to the north west and although it’ll be light to moderate, it will keep temperatures down to the mid-teens for most places perhaps a degree or two higher across eastern Scotland , The North and South East where you may see the sun break through later on Tuesday.
Onto Wednesday after a cool, single figure, July night, with the wind swinging round to the north west you can expect a day of sunshine and showers pretty much everywhere after a dry start to the day. There will be spells of sunshine between the showers but their frequency will increase as we progress through the morning pushed along on a moderate, north westerly wind. These showers will continue to push down all through the afternoon and I can’t see them clearing till the evening to leave a sunny end to the day. Nothing to shout about temperature-wise as you’d expect with a north westerly wind in charge so similar to Tuesday’s. With clearing skies and a north easterly wind, temperatures will drop quickly once the sun is down to high single figures again, brrrrr.
Better news for Thursday with a drier picture across the majority of the U.K and Ireland with clear skies and longer spells of sunshine. Lighter winds as well will allow the temperature to pick up a degree or two to high teens possibly nudging the twenties across the south of England. Dry for most areas then through the whole day, however for Ireland there looks to be a pulse of heavy rain likely to push into Kerry by lunchtime and this will move up country through the course of Thursday afternoon to affect all but the far north of Ireland by tea time. As we close out Thursday you should notice the wind swing around from the north west to the south west and that should signal the start of some warmer temperatures
Closing out the week we see that rain front affecting Ireland sink south and east into Wales and the south west of England overnight into Friday. Through the morning this will slowly try to push eastwards but at this stage it looks only likely to affect the western coastline of the U.K with the heaviest rain across the south west. It will introduce plenty of cloud for the west and this will thicken to give rain up the west coast and into Scotland by late morning. East of this rain front it looks to be dull but dry with perhaps only the east coast of England seeing the sun for any length of time. Ireland looks to stay dull and damp for the course of the day I am afraid. Through the course of the afternoon that rain does move eastwards across Scotland, the north of England and across The Midlands and central regions to give a dull, damp end ot the week for many. Moderate south westerly winds will keep the temperature up through Friday so expect high teens for most areas even under the cloud and perhaps a degree or two lower under the rain fronts.
A sunshine and showers type of weekend is on the cards I think with a rain front pushing in across Ireland, Wales, the north of England and Scotland through Saturday and gradually fizzling out as it pushes across The Midlands and south of England. South westerly winds will keep temperatures up in the high teens, low twenties over the weekend, cooler though across the west and north. We should see a dry end to Saturday with plenty of sunshine but it looks like we will have a re-run on Sunday with a new rain front pushing into Ireland and then heading eastwards on a moderate to blustery south west wind. With this type of weather it is always likely that you’ll pick up more rain in the west and north I am afraid. So is there any end in sight to the unsettled weather ?
So after a pretty uninspiring week for mid-July, how are we looking for the following week ?
Well we look to be staying unsettled next week I am afraid as low pressure continues to keep the warm high from exerting a stable influence on our weather. It won’t be a dire week by any means and for the south of England being closest to the high pressure I don’t think it’ll be bad at all. As usual with a westerly airstream the bulk of the rain will pass across Ireland, the north west and Scotland during the early part of the week. By mid-week, next week though I think high pressure will start to push up and that’ll mean warmer temperatures as the wind shifts round to the south west. So warmer and possibly hot as we head into next weekend. Will it last though ? Cant say but if there’s anytime of the year when a high can dominate it is in July so let’s keep our fingers crossed.
Didn’t we dry out quickly ?
After the heavy rain across the south of England through the last week of June, it was amazing how things dried out so quickly last week in that neck of the woods and that’s not surprising because we did pack in some E.T. (see graph below)
From the graph above you can see the total rainfall last week at this location was 2.2mm, whereas the total E.T was 40.5mm, leaving a deficit of 38.3mm. So after the heavy rain and saturated rootzones we saw at the end of June, we then went to a situation where the same rootzone experienced high E.T stress and dessication.
Feast to famine in terms of moisture levels. There were two things that I think added to the scenario where greens in particular dried out very quickly ; The first was a grass plant that was overly-reliant on moisture following the wet June so it gets used to having its feet wet and when they suddenly dry out it takes awhile to compensate. Secondly if you were sticking a moisture meter into your greens you’d have seen reasonable readings at the 50-60mm depth you were likely to be sampling at (remembering that you only get an accurate reading if the probe is fully inserted) but the likelihood is that the surface of the rootzone (0-25mm) was much drier.
This is because organic matter is naturally concentrated in the surface of the rootzone and usually declines as we go deeper (unless you have a buried thatch layer that is from a previous period). Organic matter as we know consists of mainly dead and decaying roots and these are naturally hydrophobic in their nature (because when they were part of a living plant they were used to transport water) so when they dry out they become water-repellent. Organic matter dries out much quicker than rootzone and so when we see these rapid transitions from wet to dry with signficant E.T, it is the surface that dries out faster and puts the plant under stress. It’s also where the majority of roots are…
Hypoxia and its effects on grass growth
In The Midlands and particularly the south of England during late June we had some significant rainfall events with 60-70mm common over a 48 hour period (22 / 23rd June) and it is clear that this caused some issues growth-wise. The north west of England currently is in the firing line for heavy rain and so this next paragraph is pertinent to you guys as well. When a rootzone becomes saturated, water fills the vast majority of the pores that exist in the rootzone and since water contains less oxygen than air, this scenario can become growth-limiting for the grass plant. Dovetail in the fact that the warmer the soil, the less oxygen the water contains, so a state of hypoxia (oxygen deficiency) can occur rapidly at this time of year.
If we are fertilising heavily prior to and during a period of hypoxia, the grass plant will try to grow quickly in response to the presence of available nitrogen and so will use up soil oxygen levels much quicker. This can result in loss of grass cover and sward thinning, particularly on areas of turf that are compacted and likely to hold lower oxygen levels than normal. You often see this manifest itself with some of your sward population yellowing / bronzing off and it is likely that the affected plant species has shallower roots and so is more prone to rootzone saturation / hypoxia. It goes without saying that areas with high surface organic matter will suffer most as well during these weather events.
One of the best mid-summer aeration jobs you can undertake is to vertidrain (IMHO) using a compact machine, narrow tines and minimal heave. It really helps to let the whole profile breathe, free some of those anaerobic gases and replace them with fresh oxygen. This will help the grass plant much more than anything out of a bag or a bottle.
In 2014, I visited a course which suffered badly from Anthracnose but for two greens and when we looked into why, it was these two greens that had been vertidrained in late July prior to the main Anthracnose period. In my mind the grass plant was much stronger on those treated greens and less likely to go under stress and that proved key in the months ahead. Now some of you will be reading this with saturated rootzones and the rain hammering outside so I appreciate getting out on the course isn’t practical, but when you do dry out, it would be top of my list of things to do.
PGR usage during cool wet summers
When we have periods of cool weather and heavy rainfall events I think we have to be cautious with our PGR applications in terms of rate and frequency. Now some of you reading this will dismiss it as paff I’m sure because you’re happily applying twice label rate at half the recommended frequency and your surfaces are excellent, well fair play if it works for you then fine, but it doesn’t and won’t work for everyone.
If we look at June the average air temperature was between 14-16°C for the month and if you correlate that with GDD using the U.S model of 0°C for the base (because that’s where the research has been done on PGR’s and GDD), you can see that the PGR longevity was 13 days during June. (working on their basis of applying every 200GDD at 0°C base)
So broadly speaking if you are applying PGR every fortnight at label rate (200ml per fortnight, 400ml for the month) then you are spot on the money. If you are applying at higher rates and tighter frequencies then it is extremely likely that your PGR applications will be overlapping and so the plant will be growing under the combined effect of two or possibly three PGR applications…
So let’s say you were applying 400ml every week, then on the above basis your PGR applicaitons will be overlapping for a good 7 days and during which the grass plant will be growing under the effect of 800ml of PGR. Now we know that PGR affects different grass species differently with Poa annua var. annua the most affected, var. reptans just behind it, then bentgrass and least-affected of all, Ryegrass. So with overlapping PGR applications I’d expect to see a loss of sward integrity on mixed stand areas, particularly if……You throw in a spot of hypoxia late June when low soil oxygen levels will be further limiting growth and you have a recipe for a sward that’s going backwards and poor turf quality. Some of you I know saw that.
So all I’m saying is don’t get carried away with your PGR applications just because you did it last year and it worked well. Every year is different and this one is particularly challenging on that front so time your applications carefully and wherever possible try to maintain correct levels of surface organic matter and soil oxygen. (Along with everything else you have to do that is…:( )
WIth moisture and then temperature it is not surprising that we see some of the diseases that like this combination. In particular, Superficial Fairy Ring is doing the rounds with bleached areas of turf in the ring signalling moisture stress due to localised hydrophobicity. Wetting agents, tablets, hand-watering seem to sort these pretty well as does Azoxystrobin if you want to throw a fungicide at it that is….Unlike other forms of Fairy Ring, these ones come in quickly and are usually present in surface organic matter so target your watering / treatments accordingly.
Ok that’s it for this week, Tempus Fugit and all that…must remember to pack a large tube of toothpaste because my mum has advised me that if a bear comes for you they’ll prefer the toothpaste to me. Can’t see that myself but if it keeps her happy
All the best