After the heat of last week, we can down to earth with a bang with some pretty heavy rainfall, The east of Ireland copping a packet to start their Bank Holiday weekend with 84mm falling at Dublin Airport and 54mm in Mullingar !
Here I have to say we needed some rain and we got 12mm on Saturday morning, which you guessed it, filled up my boat and resulting in a very soggy flyfishing session, the term ‘dry flies’ was not appropriate !
We’ve not finished with the rain though and this coming week promises more heavy rain on the cards, with Wednesday and Friday looking a bit grim. It’s courtesy of a low pressure system that has dropped down into a trough in the jet stream. I don’t want to sound alarmist but typically if / when this occurs in August, it usually brings with it some very heavy rainfall.
General Weather Situation
Monday starts the week off dry for most of the U.K and Ireland, except for some lingering rain over north-west Scotland. Elsewhere we’ll have a pleasant day with hazy sunshine and temperatures just touching 20°C after a cool start (with dew). Later in the afternoon, a rain front moves into west Kerry and Connacht to bring rain for the late afternoon / evening. Winds will be light and from the south-west.
Overnight into Tuesday that rain pushes north and eastwards across Ireland into Leinster and also affecting the south-west of England, Wales and the north western coasts of the U.K, including Scotland. As we go through the day, that rain affects a line drawn diagonally north from Bristol to The Wash. South of this it should be another pleasant, dry day with temperatures up in the low twenties, but in the afternoon there’s a risk that some of this rain may sink south to affect London and the Home Counties. That rain over Central Scotland looks to be stuck in for most of the day unfortunately. Temperatures will be a little cooler as the wind swings round to the south, maybe just nudging across the 20°C mark.
As we move into Wednesday, we see the first signs of a slow-moving low pressure weather system that’s due to affect our weather from Wednesday through to the weekend……
So we have a heavy rain pulse moving into the south-west of England, Wales and north-west Munster, south-west Connacht in the early hours. By morning rush hour, this pulse is over the entire south-west of England and Wales and tracking north and eastwards to cover most of the country by late morning. Ireland looks to dry out after this early morning rain to leave a fine day. By the afternoon, that rain is set across England and Wales with Scotland missing the worst and as we approach the evening it clears the west and central areas, but may linger on eastern coasts. Again the wind stays set in the south, moderate in nature with temperatures down on Tuesday under that cloud and rain.
Moving on into Thursday, we have a much drier day on the cards save for some rain over north-west and the Highlands of Scotland. Elsewhere it’ll be a pleasantly warm day with lots of sunshine and temperatures up in the high teens / low twenties.
Clsoing out the week we may, I say may, potentially have a very wet end to the week, courtesy of a pulse of heavy rain up from, you guessed it, the continent. I say may because as we all know, this type of rain is extremely unreliable in terms of amounts and location affected, so keep an eye on your Weathercheck portal closer to the time. At present it’s saying that a rain pulse will push up from France into the south-west of England around morning rush hour and then track northwards with all areas getting rain, but the heaviest looks to be central and western parts, rather than the east of the U.K. Ireland is also likely to get rain later in the morning, pushing into Munster and tracking northwards. This rain front looks particularly heavy and slow moving so flooding is likely and by late afternoon it’ll still only be sitting over The Midlands, so very slow moving in nature. As we close out Friday that rain will have cleared the south of England and Wales and will be affecting the northern and border counties before moving into Scotland late on Friday night / early Saturday morning.
So how does the weekend look ?
Well that slow-moving low will be sitting off the east coast of England so it’ll be dragging down rain into Ireland, Scotland and the west of the U.K on Saturday morning, with that rain pushing eastwards across the U.K in the afternoon, so maybe dry a.m. for the south, but the rain won’t be far away. Sunday again looks the better day, but with a new low lining up to take the place of the departing one, I think the west will be unsettled on Sunday with an ever-increasing westerly / south-westerly wind.
Well as mentioned above, next week looks like starting off very unsettled due to an Atlantic low pressure system that’s rattling in. I expect it to bring high winds and heavy rain to Ireland and the west on Monday and for that rain to spread across country during the day. So windy, from the north-west, unsettled and with frequent showers during the early part of next week and it’ll feel cooler, with temperatures in the high teens only 🙁 From mid-week we pick up some slightly warmer air, so the winds start to drop, the rain eases off and potentially it’ll be a little better, but staying unsettled and cool for August in that north-west wind.
Lots to talk about this week…..
GDD / Growth Potential Spreadsheet – Data Entry Issue
We have a slight issue with the spreadsheet we provided at the start of this year to record GDD and GP figures. The August tab on the spreadsheet doesn’t allow you to enter minimum temperatures, so needs a slight, simple tweak. The instructions are ;
1) Open the Log file in Excel
2) Select the August Sheet
3) Click on the ‘Review’ tab
4) Click on the ‘Unprotect Sheet’ button
5) Save the Spreadsheet
That should do the trick, any problems, just drop us an email in the usual way, thanks to Graham for highlighting this issue
A number of you have asked about some of the abbreviations I use in my blog, so Paul has inserted a tooltip which highlights the abbreviations in blue and if you pass over them with your mouse cursor when you’re reading the blog, it’ll open up an explanation of the abbreviation as you do so, very clever, cheers Paul….
Disease Activity – Anthracnose
After the very hot and dry (for many) July, we now have a familiar August breakdown in the weather with rain, some of it heavy. In my mind this creates a perfect storm for Anthracnose and indeed I’m starting to see / hear quite a few reports of this disease. Last week I was doing some moisture readings on a golf course to look at fluctuations with respect to green situation / organic matter levels, etc and interestingly I found one area affected by Anthracnose Basal Rot. The area was a low point on a green and the moisture readings were around 40.0% (they’d had 8mm rain the previous night), whereas other areas were in the low twenties.
It highlighted to me how useful a moisture meter is from a diagnostic perspective, ok we don’t need a moisture meter to tell us that a low spot will have higher levels of moisture, but it certainly helps to quantify how much more moisture that area was holding and of course if you change irrigation strategies, you can monitor the effect much easier, rather than sticking your finger in the air and saying, it’s drier 🙂
Going back to Anthracnose I expect a high incidence of the disease this August bearing in mind the rainfall we’ve had / going to get and the heat in July. From a prevention perspective, good balanced nutrition is key, so either light and frequent foliar N applications or a light rate, summer granular fertiliser are the order of the day. Work in the U.S found nutrition was key to controlling / preventing Anthracnose, almost as effective as applying a fungicide and a lot cheaper !
Anthracnose – Remedial Action after the event
If you already have signs of Anthranose, then the normal path is to apply a fungicide, but personally I think it’s one of those diseases that by the time you see it, it’s too late for a fungicide to be effective because the base of the plant is already infected and dying off, so chances are you’re going to lose that grass plant whatever you do. A fungicide will merely ‘ring fence’ the affected areas. To get quick recovery from Anthracnose, you need to lightly aerate, raise the cutting height if practical, fertilise and topdress, as well as dropping your PGR rate to allow the plant to grow back / tiller across the affected areas. Don’t be taken in by the “It doesn’t grow upwards it’ll tiller better with a PGR” spiel because I don’t think it’s true, particularly for Poa annua.
Incidentally there’s been no correlation with increased rolling and Anthracnose activity in USA research, in fact they found less disease in the more rolled plots…Why ? because the rolling is firming the surface which means the actual cutting height is more similar to the bench set height, rather than is the case where a softer (un-rolled) surface allows the mower to sink in a little and cut shorter than the bench height. (Thereby applying more stress)
Moisture Meter Readings
Not the greatest of pictures I’ll admit, but it shows 2 different designs of moisture meter side by side sampling turf. The Delta-T model is reading 29.9% and the Spectrum 28.2%. Now obviously there’s variability in turf even on supposedly homogenous rootzones, but I consistently found that the Delta-T was reading 1.5 – 2.0% moisture higher than the Spectrum and I think it’s because of the different rod lengths between the two meters.
The Delta-T Theta Probe comes fitted with 60mm rods as standard, whereas the Spectrum can be 38mm, 75mm, 120mm or 200mm depending on the spec at purchase. The one I was testing against had 75mm rods.
This isn’t a case of right or wrong in terms of the product or manufacturer, just a note that if you’re comparing readings with the guy next door, then if you’re not using the same meter, they probably will be different. Also I’d say that this practice is pretty irrelevent anyway because what matters is how your greens perform at an ideal moisture level and that ideal moisture level is specific to your course, rootzone, grass species, green situation.
Anything we can measure in turf invariably results in a d*** measuring exercise in my humble opinion, so I’d suggest concentrating on what works on your course, taking and learning from your own observations accordingly 🙂
And more disease….
Lot’s of Waitea, Superficial Fairy Ring, Thatch Collapse, Plant Parasitic Nematodes, etc doing the rounds at the moment and with the recent and forecasted rainfall I’d expect a big hit of Etiolated Tiller Syndrome (ETS). I’ve covered all of these diseases in my recent blogs so I won’t be repeating myself, don’t worry 🙂
Wendy has kindly updated the GDD data for the year, so we can see how it compares…
You’ll note that July 2014 had a very high GDD, similar to 2013 and much higher than previous years, however we know that this isn’t the whole picture for July because of the heat and E.T levels, so let’s look at those now…
High E.T = High Plant Stress
Looking at some of the statistics for July 2014, we can see that it was an extremely high E.T stress month, particularly the last 3 weeks. Using Sean’s data from The Oxfordshire, we can see the following ;
Month& Year Total E.T Loss Rainfall Moisture Deficit
July 2013 109.7mm 39.4mm -70.3mm
July 2014 135.6mm 36.4mm -99.2mm
I’ve charted out the month this year so you can see how the rainfall and E.T stress panned out ;
Effectively the moisture deficit was 99mm in 2014 and 70mm in 2013, so it shows just how hard a month it was in some (but not all) locations.
The consequences of this type of weather are many ;
Firstly, it really highlights how well or how badly your irrigation system is at coping with this sort of water replacement requirement.
Secondly all the consequences of this type of weather, be it dry patch, stress-related diseases like Anthracnose or Plant Parasitic Nematodes, come home to roost in the intervening weeks.
Growth Potential Models
I mentioned last week that I thought the optimum temperature for calculating Growth Potential (GP) at 20°C was inaccurate for Poa annua surfaces over here in the U.K. Micah Wood, one of the key academics involved in the Growth Potential Model was kind enough to drop a comment detailed below on the blog ;
“I think it is a great idea to adjust the optimum temperature in the growth potential equation to match the observed turfgrass growth. That is the whole point, really, to generate a number between 0 and 1 that is representative of the influence that temperature has on allowing or not allowing growth. Jason Haines in Canada has worked with GP adjusted with optimum temperature of 18 for his Poa annua greens. A blog post on that is here:
So I looked at two sets of data for July, one from Long Ashton Golf Club, courtesy of James Braithwaite (cheers James) and the other from Sean at The Oxfordshire (Ta Chuck) and then charted them out looking at the maximum and minimum air temperatures during July and the GP calculated using 18 and 20°C. The results are interesting to say the least ;
Firstly, looking at Long Ashton G.C, you can see there is a moderate dip in both GP models at the beginning of the month, (6th, 7th, 8th July) but it’s a much sharper dip for the model based at 20°C, compared to the model calculated at 18°C. I didn’t see a pronounced shut off in growth during this period, so I think the model based at 18°C is a more accurate description of observed turf growth. Towards the end of the month 20th-24th, we can see another dip in the GP trace, but here the dip is much more pronounced on the GP model calculated at 18°C, with a near 30% reduction in growth potential. Again I think this is an accurate portrayal of actual events because we did see growth of Poa annua shut down during this period.
Looking at The Oxfordshire, the graph is much more variable, with more peaks and troughs than Long Ashton and that’s because of the very open nature of the site at The Oxfordshire. It heats up very quickly because there’s little shade preventing this occurring and it loses heat to the atmosphere at night more quickly as well. You can see that when the minimum temperatures for early July at Long Ashton were rarely below 10°C, at The Oxfordshire, they dropped to 6°C. In contrast, the maximum temperature recorded at Long Ashton was 30.2°C on the 25th July, it reached 32°C on the 23rd of July at The Oxfordshire.
So use of the Growth Potential model for me is showing two things, firstly that we need to modify the optimum temperature to 18°C to give a more accurate portrayal of observed turf growth and that by highlighting dips in GP when temperatures were high, it gives us an expression of applied plant stress and so provides a predictive measurement for the consequences of that stress, like Anthracnose for example.
So we’ll see in the next 7-10 days whether those two dips towards the end of July were sufficient enough to generate increased disease activity from Anthracnose or not…Please keep me posted on what you see out there because without your feedback this blog is limited in its effectiveness.
I’m off to sunny Denmark for my annual family gathering, so hopefully I’ll miss that bloody great low pressure system…good waves though 🙂
All the best…