Last week I talked about this week’s weather being a battle between low and a high pressure and of course when these two meet you tend to get wind and strong wind at that. Scotland in particular received some huge winds over the weekend for the time of year with 115mph measured over The Cairngorms. Down south we were breezy and hot so we ran some very high E.T over the weekend, more on that later.
This week is going to throw some more curve balls weather-wise with some particularly cold night temperatures for the time of year, down in single figures. There’s likely to be a ground frost over The Highlands of Scotland as a cool north west wind pushes cooler air south. By the end of the week though, temperatures are set to climb again as high pressure pushes in.
General Weather Situation
So another week of north / south divide when it comes to the weather..
Monday sees showers already pushing across south Munster and Leinster and the north of England with heavier rain over north west and central Scotland. South of this we have a dull and breezy start for many with high cloud and mid-teen temperatures. Through the morning we will see those showers die out over most places leaving them dry but with a strong north west wind in place that’ll still push showers into Donegal and feed another stream into North Wales and the north west of England. Not as warm as the weekend because of the north west wind pegging temperatures back to hgih teens and that’ll be the story of the first part of this week. As we close out the day the skies clear and we will see the temperatures drop markedly to high single figures, in other words a chilly night for this time of year. (But at least it will be more comfortable sleep-wise !)
Tuesday sees a continuation of that cooler feel to the weather but we should start dry and bright over most areas. The exception being north west Scotland and England where the cloud cover will be thick enough for some rain along the coast. During the morning cloud cover will build from the north and this will push showers down across The Highlands of Scotland into more central regions and later in the afternoon, northern England. South and west of this we look to have a dry, pleasant day with a slightly lighter, north west wind allowing temperatures to climb to the high teens, so not bad at all. Again that cloud cover is likely to clear over The Midlands and southern England to give a cool end to the day as night temperatures drop again.
OK onto Wednesday and the main feature of the day is a rain front that is projected to push into north west Scotland by the morning rush hour and bring rain to most areas of Scotland through the morning accompanied by a strong north westerly wind. Ireland looks to miss the majority of this rain but you will get much thicker cloud cover which may be heavy enough to give some light rain over Connacht / Donegal during the morning. For Wales and England we look dry and bright initially but as we progress through the morning into the afternoon, we will pick up more cloud cover and that’ll herald the arrival of rain for northern England as those Scottish showers push south. A little bit of uncertainty as to how far south those showers will go but they may reach The Midlands by tea time. For Scotland we look to be mid-teens only under that rain, but for the south and west we should be high teens again.
Thursday looks like being a re-run of Wednesday with showers and heavier periods of rain affecitng the north west of Scotland and these will push south as we go through the morning. Ahead of this rain we will see thick cloud across most of Ireland, Wales and northern England, some of it heavy enough for some mizzle. The south of Ireland and England should stay fine and dry with long periods of sun and here you’ll see temperatures start to edge up into the low twenties through the latter part of the day, but still accompanied by that north west wind. Those showers will edge down the north west coast of England during the afternoon / evening but the north east should miss them.
Closing out the week we have high pressure beginning to exert its influence from The Atlantic so we will see a better day for many with that rain finally being pushed out of Scotland during the morning to leave a fine, clear picture just about everywhere so plenty of sun and warmer temperatures for Friday. That rain will however stubbornly persist over the far north west of Scotland I’m afraid. With lighter, more westerly winds I’d expect the temperature to climb into the mid-twenties over the south of England but for Ireland and Wales it should still break the twenty barrier. So a dry, warm and bright end to the week is on the cards.
Looking ahead to the week we should see a very warm one across the south of England and some good temperatures for Ireland and Wales as well, however for Scotland I’m afraid that north west rain band is likly to sink south again to affect central Scotland through Saturday morning 🙁 We may also see some rain push into Connacht and Donegal for the second half of Saturday. That warmth may be high enough to trigger off some thunderstorms. Sunday looks a better day for everyone, drier over Scotland once that overnight rain clears and so dry, bright and warm again for Ireland, Wales and England.
For the start of next week I think we will see high pressure in charge but it’ll start to get squeezed by another northerly low pressure system, so by Monday afternoon I’ll think you’ll see the wind swing round to the south and pick up strength. That old adage “Back to the wind, low to the left” works here because that low will be tracking in from the north west through Tuesday and that’ll bring rain across Ireland, Wales, the north west of England and Scotland on Tuesday morning / afternoon. This unsettled weather will push slowly eastwards to cover all areas by Wednesday next week I think so maybe the first rain for a while for the south of England. Thursday should see that rain clear through and more off into The North Sea and the weather should then settle down for to sunshine and showers thereafter with a westerly airstream I reckon.
High Evapotranspiration (E.T)
The combination of strong winds and high day temperatures over the weekend have really dried surfaces out come the start of this week and with little or no rain on the horizon for the south of England this week, this will prove a testing week I think. That said we will be aided by the cooler night temperatures. Over the latter part of last week and the weekend I observed wilt on greens height turf and this is a signal that the plant is under moisture stress. It’s most evident when you look at foot traffic across a green and the fact that foot-printing occurs with the foot print evident after the golfer has departed. This suggests that the grass plant has insufficient moisture in the leaves to maintain their structure and is an indication that the moisture status of the plant is critically out of balance.
So use footprinting as a sign that all is not well moisture-wise with your grass plant regardless of what your moisture meter reading might say. I mention this because turf will dry out from the surface first (because it’s closest to the warmer air) and because the surface contains the highest concentration of organic matter (and this dries out quicker than rootzone) it can be misleading to rely on a moisture content 60mm or so below the surface. (depending on the probe depth you’re using)
When we see this form of wilt on managed-amenity turf we know that the leaves are moisture deficient and therefore the grass plant cannot take up enough water through the root system to overcome this deficiency. This may be because the rootzone is dry, the plant’s root system is shallow or a combination of the two. So hand watering on these areas is a must if you want to avoid a loss of plant integrity. What I mean by that is if the grass plant wilts we know it has insufficient moisture to maintain the internal structure of the leaf. (I liken it to a balloon losing air, when it is fully inflated it has a hard surface, but as the air pressure declines so does the integrity of the surface) If this is state is un-corrected, the structure of the leaf will eventually be compromised to a point where even watering will not reverse the symptoms. It is then we see die back on the plant, loss of leaf density and sward thinning. It’s common to see this first on raised areas of turf, mounds, ridges and areas adjacent to bunkers that get sand splash.
I haven’t got the E.T readings from over the weekend but I’d estimate that over Saturday and Sunday we lost 10 – 12mm of moisture from the turf canopy so if you’re in this morning and thinking, “Crumbs we are dry”, then you know why. Even if you compensated with irrigation over the weekend you’d have to have a very good irrigation system (close head spacings) to apply a uniform pattern in the strong westerly wind we endured, bearing in mind that the wind continued overnight.
This week provides a good opportunity to get the turf back to full turgor status as we have lower projected E.T figures (see Meteoturf above) because of the cooler north west wind, so my advice is use it wisely before we see temperatures rise again at the end of the week. None of the above is of course applicable to Scotland this week 🙁
Dip in Uptake
You can see from the Meteoturf output above that the Growth Potential (G.P) is forecast to be down to 0.6 ish on Tuesday and Wednesday this week because of the cool night temperatures forecast for Monday and Tuesday nights. This is likely to give a dip in uptake particularly on Poa annua-dominated greens following on from the weekends high temperature and strong winds. You may see a delay therefore in response from a selective herbicide application or a foliar / liquid fertiliser on outfield if you had the hot, dry and windy weekend that some of us did. Some of you guys that are aerating will probably notice this in terms of slower recovery from hollow coring / solid tining but hopefully with the warmer temperatures later this week, things should still pan out nicely.
So far I’ve only had a few reports of Anthracnose foliar blight doing the rounds with no repeat (as yet) of the 2014 outbreak, but it’s early days yet. For me this disease needs a cool and moist weather pattern after high temperatures to provide optimum conditions for disease development and we haven’t seen that so far. In recent years we’ve had troughs in the jet stream that has allowed low pressure to dominate August’s weather but it is sitting just high enough to keep the worst at bay. (Though Scotland and the north of Englnad are on the receiving end for this reason). That said we are only finishing the first week of the month so there’s plenty of time for things to change and change they may do. (I have a hunch the end of the month may be cool and wet)
After last week’s rain and high humidity there’s been plenty of Microdochum doing the rounds but with the drying turf surface at the end of the week I expect this to grow out reasonably in the south and west of the U.K & Ireland, though Scotland is I think likely to see higher disease pressure from Microdochium and Anthracnose this week with their more unsettled outlook. The same is true of Fairy Ring but unlike Microdochium I expect this to hang around because of the dryness of the soil (in some areas)
Quite a bit of plant parasitic nematode (PPN) activity as well because this pathogen tends to attack plant roots and so by damaging the root system you compromise the ability of the plant to maintain sufficient moisture status. The affected grass plant often then shows the symptoms of dry patch because the poorer rooting causes it to dry out quicker. You also often see yellowing in the basal leaves of the grass plant which can at first sight resemble Anthracnose. If the plant detaches easily from the sward then it’s likely to be this disease, if it doesn’t, then it may be PPN damage.
I know I’ve talked about this before but a give away in these situations is to look closely at the plant leaf and see if you can observe green and white banding. If so, then you can assume that PPN’s are the culprit. Lowering plant stress and promoting new roots by light aeration are key to managing the situation.
Ok that’s it for this week, have a good one and don’t forget the extra layer in the morning, you may need it this week 🙂
All the best.