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  • Writer's pictureMark Hunt

April 3rd, 2023

Hi All,

Last week I was talking how nature was in full swing with the arrival of spring, despite the inclement weather. Last week I was fly fishing on Eyebrook Reservoir and saw 50-70 House Martins and Swallows hungrily feeding on the hatching midges after their long migration up from Africa. You could hear them chirping happily to each other as they fed, it's just a shame the Trout weren't so co-operative :)

Now some of you may know I am an avid motorcyclist and during the winter I spend long hours in the garage working on some restoration projects. Well it was singular but now it's plural ! :). When it is mild I have the garage door open and all winter a female Blackbird has been joining me in the garage while I work. She's very tame and follows me around the garden as well. So last week I was just about to put up some Willow frameworks in readiness for the summer when I noticed a pair of eyes looking at me from a nest at the end of my Willow sticks ! Guess I won't be using them for awhile !!

Well we are into April, a month that I always think of as a tricky one to maintain turf and just to put a marker down to that effect, we started the week with a -2.0°C frost !

April is nowadays associated with low rainfall, a fact that may come as music to the ears of course managers / head greenkeepers currently whose courses are closed today due to the extremely wet March that we have just. If April runs true to form it'll either be cold / dry or warm / dry and with the SSW event of late February still front and centre, you'd have to bet on the former. Cold and dry is the reason why I always associate April with a tricky rating when it comes to turf management. Growth levels are often low and surfaces dry out but end-users are often reluctant to irrigate because of the temperature of the water. You know the form and to cap it all, normally at the end of the month we have the Poa annua seedhead flush.

The run of rainfall this year has been interesting to behold. A very wet start to the first half of January, then no rain for the next 6 weeks giving us our driest February for a number of years and then March, it starts raining and doesn't stop !

A wet March is actually more of a help than a hindrance in my mind because it will help us through the next month if April turns out to be especially dry. I'll chat that through later in my blog and look at rainfall vs. E.T for this year and last to illustrate my point.

Ok, so let's look at this week's forecast and have a punt at next week. Certainly watching the BBC weather last night they have much higher day time temperatures in this week's forecast than I think we will get. Hmmm....

General Weather Forecast

So this week is kind of divided into 3 parts. The start of the week is characterised by high pressure sitting over the continent and this will effectively shield the U.K & Ireland from the Atlantic fronts that made March such a wet month. So Monday and Tuesday (for a large part of the day) look to be dry with just the odd coastal shower across the west coast of Ireland. Clear skies overnight gave us a frost on Monday morning and this looks to be repeated on Tuesday morning if your skies are clear. More likely in the east than the west I'd say. Now the Beeb have day time temperatures getting up into the mid-teens, but I'd say we are more likely to just nudge into 11-12°C sort of territory. Plenty of sunshine at the beginning of the week as well with light winds as well.

As we move into Tuesday evening, an Atlantic rain front pushes into Ireland and slowly crosses Ireland overnight into the west of Scotland. So Wednesday sees showers and heavier spells of rain for Ireland and the west coast of Scotland, with more rain pushing into the north west of England and Wales during Wednesday morning. More cloud cover on Wednesday so better night temperatures and less risk of frost. That rain front morphs into two heavier, consolidated fronts which cross Ireland on Wednesday and then push into the west of the U.K on Wednesday evening.

That rain front will slowly move eastwards across the U.K on Thursday morning and during the afternoon, so a wet day on Thursday is on the cards. Further west, Ireland and Wales will be left with a showery, unsettled theme. Being slow-moving, this rain could give some significant totals unfortunately on the run up to Easter. Slightly cooler on Thursday with a freshening north westerly wind and temperatures just the right side of double figures.

Closing out the week on Friday we lose that rain with just some coastal showers across western-facing coasts and some wintry showers across The Highlands. A brighter day but temperatures will be capped by a primarily northern wind direction, so again temperatures just nudging into double figures with 12-13°C likely. Not too bad then for Good Friday.

The outlook for the Easter weekend is okay really, sunshine and showers for some and better temperatures from Easter Sunday onwards as the wind direction swings round to a more southerly orientation. Ireland will pick up some rain arriving to the west on Sunday morning and this will then move north east into the north of Ireland and eventually, later on Sunday, the west of Scotland. Some of this rain will fall as wintry showers over elevation. This rain will also affect the north of England and The North West overnight into Easter Monday but should mostly clear by the morning. Further south, it looks like we will see more sunshine and temperatures pushing up into the mid-teens by Sunday afternoon. Similar on Easter Monday, mild and plenty of sunshine with a low likelihood of rain. These milder temperatures will extend north into Scotland and west into Ireland on Sunday and Monday.

Weather Outlook

Next week will be characterised by high pressure sitting out to the east of the U.K & Ireland and Atlantic fronts trying to push in. This will mean a continuation of showers across Ireland and the west of Scotland through Tuesday and Wednesday. Some of these showers will push into the north west of England and Wales. Further south should stay on the dry side with south easterly winds keeping reasonable day temperatures. Tricky to say if we will be frost-free, that will be entirely dependent on cloud cover, my hunch would be that a south easterly wind will bring in cloud cover and keep night temperatures up. As we progress further into the week, high pressure will exert itself and this will give a drier picture across Ireland and Scotland. Nothing too special temperature-wise, similar to this week really.

Agronomic Notes

So first up let's talk about that rainfall pattern this year and whilst currently it might seem a pain, if we do endure a dry, cool April, it could be a godsend.

So first let us look at the respective rainfall and E.T figures for a location in South Birmingham in the first 3 months of 2022 and 2023. The difference is the theoretical soil moisture deficit / surplus.

In 2022, we had a more typical weather pattern, that is to say a wetter February than March with 149.2mm falling for the first 3 months vs. a combined .ET of 79.06mm. So from a simplistic point of view, 149mm of rain fell and 79mm of rain was evaporated from the soil and plant, leaving us +70mm at the end of March 2022. That said, we can see in March 2022, we had more E.T than rain so we were already heading into a deficit situation this time last year.

In 2023, the opposite is the case. We had 196mm of rain vs. 60.76mm of E.T, so our surplus is 135.24mm. With February 2023 being such a dry month, we actually had more E.T than rainfall, so we were in deficit, however the rainfall of March took care of that and we are very much in surplus at the end of March 2023.

So my point is, yes we have had more rain, but since it fell in March rather than in February, its effect will hopefully carry us further into the year before we hit a deficit situation in early summer. Obviously that depends on what happens in the next quarter but looking at it from a topping up water tables vs. month of the year, it is a positive. Of course if you're closed and everything is sopping wet, you might think otherwise !

Here's a graph showing the soil moisture deficit / surplus situation in 2022 and 2023 for the first 3 months for the same location. Note how in 2022, the graph is already heading downwards, whereas in 2023, it isn't.

Disease Pressure

Last week I touched upon the fact that we had a period in the third week of March when the Smith Kerns showed some positive values indicating a low level of disease pressure. The positive values were recorded from the 21st to the 25th. I have since had reports of disease appearing in greens from the 29th of March onwards from a Microdochium perspective. Now at the time we also had some really mild day time temperatures so we experienced a reciprocal increase in growth at the same time as the disease pressure so I am hoping that any effect on the sward was temporary.

As you can see from the graph above using data from Flempton Golf Club (thanks Kim !) , the Smith Kerns then returned to zero values suggesting disease pressure had reduced but actually for a short period overnight on the 28th / 29th March we picked up a very rapid rise in temperature and relative humidity and that kicked off disease growth. I have highlighted this period on the graph below using data from the same location.

What this illustrates is that the Smith Kerns Model isn't flexible enough to accurately pick up these short-term increases in air temperature and humidity that simulate rapid mycelium growth of Microdochium nivale because it is based on a 5-day rolling average of air temperature and humidity. This isn't a criticism of the model, it works great for the disease it was intended for (Dollar Spot) and we are extremely fortunate to have it available to use, rather it illustrates how Microdochium nivale is a different 'animal' from a disease dynamics perspective. The Smith Kerns Dollar Spot Probability Model (to give it its full title) also works on the basis that Dollar Spot is inactive below 10°C, but we know Microdochium nivale starts to become active above 0°C, so that's another reason why the model won't pick up this disease at certain points of time. Microdochium nivale also only needs relatively short periods of time for it to cause damage to the leaf and that is why from a disease modelling perspective, it is a tougher nut to crack.

Hopefully you saw some but it grew out quickly in the latter part of last week.

O.K, that is me for this week's blog, obviously next Monday is a public holiday so hopefully I'll try and squeeze a blog in sometime next week. I hope you have a lovely Easter and indulge in plenty of Chocolate and exercise :) !

Mark Hunt

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