22nd October

 

Hi All,

You get some beautiful sunrises and sunsets at this time of year don’t you ?

This was the scene that greeted me early on Saturday morning at Thornton Reservoir in Leicestershire. Sadly it’s likely to be a thing of the past come the end of this week when we pull down a distinctly Arctic wind and that’ll bring the first taste of winter for all of us I reckon. Some of the weather sites are getting excited about the possibilities of snow on higher ground even across the south of the U.K.

Difficult to believe when yesterday I was walking in shorts in a nice and sunny 18°C, but that change is a coming and  due to us moving from a peak to a trough pattern in the jet stream.

Over the last 9 years, the coming week has typically been one of the mildest weeks of the autumn with 7 out of the last 9 producing temperatures in the high teens and even low twenties, but not this year.

Image courtesy of Netweather

Our old friend the jet stream is responsible for this cold blast and apparently it’s doing the same thing along the west coast of America. You can see its orientation clearly in the Netweather graphic above.

Nature as usual seems to be ahead of the game meteorologically-speaking because yesterday I noticed lots of Redwings and Fieldfares flying overhead and landing on the copious Hawthorn berry crop in the hedgerows. I see there’s also been reports of the first Waxwings (above) into Scotland, Yorkshire and Norfolk. Now they are one sign of winter I absolutely love. I took the photo above of a Waxwing in the winter of 2013, just outside of Loughborough Railway Station. All of these bird species typically spend the summer in Finland and Russia before heading west to the U.K to over-winter in our relatively mild conditions on our berry crop. Maybe they know something we don’t but the signs from nature are starting to suggest to me that we are possibly in for a hard winter…

General Weather Situation

Ok, so we start the week on Monday with a clear cold start (looking out of my office window) and that’s the way we are set to stay today for practically all the U.K and Ireland. More cloud across Ireland and the west of the U.K initially but this will clear through the morning to give long spells of autumn sunshine pretty much everywhere apart from the far tip of Northern Scotland where it’ll stay. It won’t feel warm though as the wind will have a distinctly northern chill about it (though nothing compared to the end of the week) so temperatures across all areas will struggle into the low teens only despite the sunshine.

With clear skies overnight, expect to start Tuesday chilly again over most places though the west and north will pick up some cloud overnight. This is the result of a rain band that is set to push into north-west Scotland during the morning and head south into south-west Scotland by lunchtime. Further south and west of this across Ireland, Wales and England, expect another cold, bright and pretty windy day as those isobars close together and really ramp up the wind strength. Milder on Tuesday due to a north-west aspect to the wind with temperatures creeping up towards the low to mid-teens despite the strong wind. A good drying day.

Overnight into Wednesday we see that rain in situ over north-west Scotland and much more in the way of cloud for all areas to start the day. This cloud will gradually thin to leave a hazy outlook across most areas and plenty of sunshine as well. Across Co. Cavan and the north of Ireland I think it may be slow to clear, the same across the north-west coast of England and Scotland. Not as windy on Wednesday so we keep the mild feel to the weather with mid-teens the order of the day over Ireland, Wales and England and just breaking into double figures across Scotland with that thicker cloud cover.

My the week is flying by and Thursday will probably be the last ‘mild’ day of the week with a cloudier start to the day on the cards. A pronounced west wind as well will keep those temperatures decent but it’ll also be responsible for pulling in some rain to north-west Scotland and a much thicker cloud base to Connacht, Donegal and the west of Scotland to boot. Further south another decent day, more in the way of cloud about but some nice breaks of sunshine as well. So again a good drying day with that moderate westerly wind in place.

Overnight into Friday and we will notice two features of the weather, the first a swing from westerly to northerly in terms of wind direction and the second a strengthening of the wind to strong / gale force. This will have an immediate impact on temperatures in the north with them not likely to make double figures despite a sunny day being on the cards. We will also see a rain front push down quickly across Donegal, Connacht and the north west of England overnight into Friday and this may bring some wintry showers for high ground over The Lakes overnight. It should have cleared by dawn though.That change in direction and strength of the wind will be felt across Ireland, England and Wales and again despite the fact that we should see plenty of sunshine, it’ll feel pretty chilly in the wind. So maybe in the south of England you’ll make it into double figures temperature-wise, but elsewhere 7-9°C is likely to be your best.

If you think that’s a bit poor, wait for the weekend 🙁

Talking about the weekend, well overnight into Saturday we will see that northerly air stream pull in a mix of wintry showers across Scotland, the north of Ireland but also along some north-west and north-east coasts as well. We may be cold enough for a ground frost as well in some sheltered areas. A mixed picture on Saturday with some sunshine but also the risk of rain across all areas particularly for the first half of the day turning to sleet and wintry showers across higher elevations. That wind will be due north on Saturday, maybe north-east on Sunday and despite the possibility of plenty of sunshine on Saturday and Sunday as well, it’ll feel really raw with 7°C likely to be the maximum temperature. It’s all about the the wind chill though with temperatures not much above freezing in the wind further north. Sunday looks a bit cloudier but still we will feel a strong north-east wind and cold day / night-time temperatures. Ireland may just break double figures being further away from that cold air stream but it’ll still feel pretty parky.

Weather Outlook

So after our winter weekend, how does next week look ?

Well that cold theme will continue through to the start of next week with Monday looking cold and wintry with the risk of some wintry showers along eastern coasts and still windy from the north east. Overnight into Tuesday we see some rain and wintry showers push across Ireland and into the west coast of the U.K and we should notice a drop in the wind so to me that means a risk of frost. That risk continues through Wednesday but we then see a Bay of Biscay low come into play and that’ll swing the wind round to the south for Thursday introducing milder and wetter air into the forecast. So I expect a wet and windy end to next week but milder with it.

Agronomic Notes

Microdochium nivale pressure – what else ?

It’s October, it’s been mild and humid so what else is there to start this blog with but Microdochium ?

I mentioned at the start of last week that we had a critical period coming up with lighter winds, high overnight temperatures and the possibility of dew formation and indeed that’s what we got. Consequently we saw plenty of Microdochium nivale activity at the start of last week, Monday and Tuesday in particular.

It wasn’t that straight-forward though because a number of you mentioned a repeated requirement to remove dew from surfaces during the day with it consistently re-forming.

Although we did see dew last week, we also saw a related phenomenon, Guttation Fluid, courtesy of that very wet Sunday (14th October) loading up the soil moisture level.

I took the picture below at 10.15 a.m. on a golf course last Tuesday and you can clearly see the droplets of Guttation Fluid on the tips of the grass plant leaf. (Bloody spellcheck keeps trying to change this to Gas Station !)

So what’s the difference between dew and Guttation Fluid ?

Dew is simply moisture condensing from the atmosphere when we reach 100% humidity. The dew point is the predicted temperature when dew will start to form and when the air temperature drops to the dew point temperature that is what we are supposed to see, i.e dew formation, but it isn’t quite that straight-forward when we are dealing with grass…

What I have noticed is that the air temperature doesn’t have to equal the dew point temperature for dew to develop on grass. This is because the grass leaf loses heat to the atmosphere (particularly on clear nights) and consequently cools down quicker than air temperature. So that means the actual grass leaf surface temperature is lower than the air temperature.

In the weather station readout below you’ll see the air temperature is 1.5°C and the dewpoint is calculated at 0.8°C, so theoretically dew shouldn’t be forming as the air temperature ≠ dewpoint temperature. As you can see from the accompanying image below, the reality was very heavy dew formation on grass. (Thanks Sean for this)

Ok that’s dew but what is Guttation Fluid ?

Simply put, Guttation Fluid is exudate from xylem sap that is forced out of the tip of a grass plant leaf through holes in the tip called hydathodes. Since it consists of xylem sap it contains water, nutrient salts and sugars that are normally transported up from the roots to the leaves of the grass plant. When we have heavy rainfall, water pressure builds up in the roots and then the xylem, forcing water up through the xylem vessel and out of the grass leaf tips. As Guttation Fluid evaporates, you can see white crystals of these salts and sugars forming on the plant leaf tip, initially I thought this was fungus forming but it’s actually nutrient salts evaporating. I snapped this phenomenon on a golf course awhile back, see below ;

Guttation Fluid will reform after removal if the pressure gradient is still present from the roots to the grass leaf tips and that’s why the presence of Guttation Fluid is more of a problem than dew when it comes to disease.  It’s not just the reformation that marks it out as a contributory factor to disease development..

As mentioned earlier, in a droplet of Guttation Fluid, we have everything a fungus needs to live and as far back as 1968, the formation of Guttation Fluid was linked with increased levels of foliar diseases like Dollar Spot.

So we last week had a wet grass leaf, a combination of dew and Guttation Fluid, high overnight temperatures, high humidity and low wind levels.

In other words perfect conditions for Microdochium nivale development.

Not surprisingly that’s what we saw with very high levels of disease noted across the U.K early last week. Ireland and Scotland had a much lower disease pressure because they were colder, brighter, drier and had less humidity. I have used some disease prediction models I am developing to map out disease intensity this autumn and I think it makes interesting viewing.

So you can see last week we had moderate to high disease pressure culminating in a peak on the night of the 15th, morning of the 16th of October. On this date you may have noticed lots of mycelium development on the grass leaf particularly on untreated areas like approaches, tees and outfield turf.

The previous last peak of this magnitude was way back on the 27th August, but it is unlikely you would have noticed the same phenomenon and that is because of growth levels and evapotranspiration. Back at the end of August we were at optimum growth and so even though we had high Microdochium pressure we didn’t see the same level of disease on the turf surface because it was growing so fast plus E.T levels would have been higher. (drying the leaf down quicker)

Fast forward to last week and although we had some growth peaks, we also had some growth troughs in G.P, which indicate slower grass growth and therefore more significant damage potential from Microdochium nivale. Also E.T levels were low last week so the grass leaf stayed wetter for longer, further increasing disease intensity.

So that’s hopefully a pretty broad explanation as to why last week presented some significant challenges from a disease management perspective.

On the plus side I think we are already learning the lessons of ‘life after Iprodione’ with many clubs putting in place good systemic fungicide programs interspersed with non-pesticidal, disease-suppressant sprays. In addition the important take-home message of reducing the interval between sprays during this month when growth is still significant (despite the troughs) is also providing better efficacy in terms of disease control.

All in all I think we are well-advanced in the process of observing, learning and adapting to the new environment of disease management without the safety net of contact, curative fungicides. That can only be good news for our industry.

In recent weeks it occurs to me that I’ve talked a lot about fungicide efficacy and not a lot about Best Management Practices but that doesn’t mean I see this as secondary, far from it. The reality is that of the contributing BMP’s to better disease management, I believe surface organic matter is the most significant.

The days of getting by without doing sufficient aeration to reduce surface organic matter levels in the top 25mm are behind us, those that think they aren’t are in for a wake up call.

Sure there’s always a reason not to do it, like there’s never a good time to take a holiday when you have a high workload ( 🙂 ), but with the twin challenges of climate and legislation our industry cannot be complacent in this area. I 100% understand the commerciality of running a business and the negativity surrounding aeration but the flip side of having heavy scarring from October to April and poor surfaces (that will not justify a high round cost nor recover till late in spring) has to be considered in the mix as well. Like everything in life it comes down to willing partners working to find compromise and good two-way communication, something incidentally the Brexit process looks to be bereft of 🙁

Next week I will focus on this area specifically looking at aeration dates vs. recovery vs. disease pressure but for now I’ll sign off with having a quick look at the coming 7-10 days from a disease management perspective.

So looking at the disease projection matrix in terms of the forthcoming early winter blast, it’s no surprise that we see very little disease peaks on the horizon over the next 7-10 days. Dove-tail this lower disease pressure with a low weekly GDD / G.P projected total and it’s further good news for fungicide / non-pesticidal mix longevity as well.

So if you’ve got this far with good surfaces, you can relax for a little while but we must remember that in the last 2 years early December has given us a pretty nasty sting in the tail disease-wise, so we shouldn’t be complacent.

Until next week, all the best.

Mark Hunt