October 15th

Hi All,

Well last week was one week I probably didn’t want to miss when publishing a weather blog but it was unavoidable. Gale force winds, torrential rain and scorching high temperatures were all packed into one week in October together with record high, night temperatures and a 15°C temperature drop from Saturday to Sunday.

Digressing from the weather for a mo’, I did have a good deal of correspondence asking what I was doing on that Monday, in particular a certain James Watson suggested I might be getting married. (ha ha) Nice one James, glad to see your imagination is as over-enthusiastic as ever (like your shirt choice) but clearly not a realistic proposition 🙂

Actually I was competing in the Troutmasters Final at Draycote Water, which is a national competition and quite challenging mentally and physically as I found out.

Bearing in mind the long-held viewpoint (by many) that fishing involves sitting staring at the water and doing nothing for long periods, I think my Garmin readout for the day suggests otherwise. Fly fishing is a different matter because you cast a lot and competition fly fishing even more physically demanding because of the pressure. Don’t normally like blowing my own trumpet (Law of Jante and all that) but I managed to finish a lucky 9th out of 100-odd competitors which I was chuffed with 🙂

OK, enough of the fishing, onto the weather and are we in for another week of gales and rain or is there more of a settled aspect to the job ?

General Weather Situation

After yesterday’s rainfall and much cooler temperatures, Monday continues to follow that trend with a dull, cool and in some places, extremely wet start to the week. There’s a raft of heavy showers moving up across London and eastern counties and further rain north and west of that. Now for Ireland and Scotland it’s the reverse with a cool but sunny start for both as you kick off the week. Through the morning this band of rain will stretch in a line extending from South Wales up to The Humber and it’ll slowly move northwards through the day. East and west of this line you’ll see a dull and cool 2nd half of the day really with the sun not breaking through till we head north of The Pennines. So cool and dull across England and Wales with that central rain belt staying in situ most of the day, contrasting strongly with bright, sunny and dry for Scotland and Ireland. Light southerly winds across the latter but fresh, north easterlies across England and Wales will keep temperatures down to low to mid-teens across all areas. Mild overnight.

Onto Tuesday and overnight that rain clears off into The North Sea to leave a dull, dry start to the day. It won’t stay that way for long as a rain front is set to push into the west of Ireland around late morning reaching Connacht first and then slowly moving eastwards pushing thick cloud ahead of it. Contrast that with the south-east of England which will have a bright, cool and dry day as will most of the U.K, but further north and west we will see more in the way of cloud and less in the way of sunshine. That rain is set to reach Leinster by late afternoon clearing the west as it does so, whilst across The Irish Sea, we see the northerly extremity of that rain reach north-west and Central Scotland by sunset. So not a bad Tuesday for the U.K, cool, dull and wet for Ireland. Temperature-wise, similar to Monday with mid-teens typical, although the wind will swing round to the south over most areas. Mild overnight again unfortunately.

Mid-week and Wednesday sees that Irish rain band move across into Wales and western England overnight so by dawn it’ll be sitting over the West Midlands, but diminishing in terms of rainfall levels as it does so. Away from this narrow band of rain we will see another dull and mild start to the day with maybe some hints of sunshine across The South East, East Anglia and along the east coast of the U.K. This rain band is projected to extend from the Isle of Wight all the way up to The Wash and pretty much sit there all day with more showers joining it from the west and east later on Wednesday. For Ireland, Scotland and northern England, a dry day with some sunshine and plenty of cloud as well from the off with maybe the odd chance of a shower over Ireland. As we approach dusk we see the cloud lift over Scotland and northern England signifying a much cooler night in store with single figure temperatures. Further south over England and Wales, that cloud cover is set to stay so again double figure temperatures but maybe not as mild as earlier in the week. Winds will be light and southerly.

Thursday sees that central band of rain still sitting along the M5 sort of direction and here it’ll be accompanied by thick cloud as well. East, west and north of this, another dry, cloudy day with some sunshine breaking through during the morning. By lunchtime that rain band has finally fizzled out to give a dull, but dry 2nd half of the day across The Midlands. So dry in most places, dull and remaining on the cool side with low to mid-teens the order of the day for the U.K and Ireland. One reason for the extended period of dullness is a change round in the wind to the north-east and an increase in strength pushing cloud in off The North Sea.

Friday rounds out the week with more of the same really with most of the U.K and Ireland starting off dull if a little cooler courtesy of that north-east wind, though The South East may see some sunshine. As we approach late morning we see a band of rain push into the west of Ireland and Scotland and this will slowly progress eastwards over lunchtime and into the afternoon with maybe more rain across south-east Munster and the west of Scotland and not central areas. For England and Wales we will see the sun break through during the afternoon so not a bad 2nd half of the day at the end of the week and with a much lighter, westerly wind, it’ll feel a little milder possibly. So a wet, dull end of the week for Ireland and Scotland and a brighter, hazy, dry end for Wales and England. Similar temperatures to the rest of the week, maybe a degree or two higher across England due to the lighter westerly wind.

The weekend forecast is a bit of a north-south divide with the north of the U.K and Ireland affected by strong winds and low pressure vs. central and southern regions which pick up an Atlantic high pressure system. At this stage I think Saturday will see cloud and rain over Scotland and maybe Ireland for the 1st part of the day before clearing easterly afterwards. It’ll feel warmer across the west first as that Atlantic high pushes in. Further south I think we should miss this rain and instead have a largely dry and dull day with a moderate to breezy south-west wind. I think the worst of the rain for Scotland pushes through overnight into Sunday morning before clearing to give a better Sunday after early rain. Across Ireland I think Sunday may still see some showers across the west but for Wales and England a much better weather picture with warmer winds and sunnier intervals pushing up temperatures into the high teens in the sunshine.

Image courtesy of Netweather

Weather Outlook

With high pressure pushing in from the weekend, next week looks to be a battle of low vs. high where high wins out, so despite the start of next week looking a bit unsettled with strong northerly winds and some rain showers, I think the weather will calm down soon after this and allow high pressure to dominate bringing calm, settled and mild conditions to the fore with light winds. The Netweather graphic above shows a high jet stream position mid-way through next week pushing winder and wetter weather over us before it takes a sharp right and pushes cold air down into Scandinavia and Central Europe.

Agronomic Notes

It’s been a really interesting weather dynamic over the last 7 days or so and one that makes me realise how little we understand about disease dynamics with respect to Microdochium nivale.

I will drill down into it from a weather conditions vs. disease population growth dynamic later but first off let’s look at October 2018 vs. the previous two years to see how it pans out…

Daily Growth Potential Comparison – October 2018 vs. 2017 vs. 2016

What we are looking at here is Growth Potential for this month over the last 3 years and you can clearly see the peaks and troughs. October 2016, was a reasonably cool month with lower than normal G.P figures but last October you’ll remember we had some particularly aggressive Microdochium nivale activity coinciding with the middle of the month and extending on into the third week of the month (red dashed line).

This year we have had two G.P peaks culminating with the one that began last Tuesday and lasted until Sunday when the wind direction changed to north dropped the daytime temperature and G.P significantly.

I have used the projected day and night temps to plot out the projected Growth Potential (faded green) for the next 10 days and you can see we have a couple of daily peaks coming up but we shouldn’t be as bad as October 2017 from a growth perspective.

That is significant because of course growth this late in the season is a double-edged sword isn’t it ?

Firstly it can be very beneficial in growing out disease activity but secondly of course it will also grow out fungicide applications leading to reduced longevity.

Cumulative Growth Potential Comparison – October 2018 vs. 2017 vs. 2016

We saw this in 2017 if you remember, when we had a very warm month with elevated periods of grass growth. I work off a cumulative Growth Potential figure of 10 for a systemic fungicide application based on my observations in the field and in research trials.

Now there’s a fair % of SWAG (Scientific wild-arsed guess – Copyright Dr Jame Beard) here and I accept it is also wholly-dependent on lots of variables, not least your grass species, level of nutrition, PGR usage but above all the effectiveness of the fungicide active ingredient (s). A more effective A.I may go longer, a less effective one, will definitely last less.

I’ve plotted out the cumulative G.P for the last 3 October’s, workeing on applying a fungicide on the 1st of October and then seeing how many days it takes to reach a cumulative G.P of 10, the results are interesting…

So what we see is that in both October 2018 and 2017, the predicted systemic fungicide longevity is pretty much identical at 14 days, whereas in October 2016, this extended to 26 days because it was cooler. I’ve plotted out the cumulative G.P for the next 10 days and you can see the good news is any application made now should be lasting longer because we are set to be cooler than October 2017 for the second half of the month 🙂

Disease Dynamics

Now let us consider the dynamic of systemic fungicide control vs. fungal population growth.

First off when we apply a systemic fungicide there is a lag period before it is present in sufficient concentration to combat fungal growth. Now the more effective the active ingredient, the shorter this lag period because lower doses achieve better control, quicker and vice-versa. Once in the plant, there is then the ever-present dynamic between rate of fungal growth vs. rate of population reduction by the fungicide A.I.

Now two of the most important factors affecting fungal growth are plant leaf wetness and temperature and last week was so-so interesting when we look at the dynamic between these factors.

On one hand we had really high air temperature at night which for sure was promoting fungal growth, but on the other hand we had a really strong wind and not only was it strong, it was warm, so it was drying the grass leaf. This resulted in very little dew formation and so we didn’t see lots of disease, in fact some sites reported no Microdochium activity at all. Others noted disease ingression from the 10th of October, but more so on the 12th, when the night-time temperature was > 15°C and the humidity increased as well.

We were on a real knife-edge though and depending on your site dynamics you may have seen no disease if you manage an ‘open-aspect’ location or you saw varying levels with the difference noted between shadier and open-aspect greens.

I have used the output from 2 different weather stations, one sited in a reasonably open location, the other in a sheltered one. The geographical locations are different but you can see in the open-aspect location how the humidity just hovered below 90%, enough to avoid aggressive disease, whereas the other sheltered location recorded a much higher level of humidity.

I have circled the night-time temperatures in both graphs and you can see the high air temperature during the night of the 12th / 13th of October, however if you look at the humidity you can see if tops out above the 90% mark in the sheltered location but stays under it in the open location. This was due to the effect of the wind reducing humidity in the open site location.

That night-time temperature on the 12th / 13th October was a record for October in many locations and here in Market Harborough we didn’t dip below 17°C all night !

Tipping of the balance

If you were in a location where the humidity increased on that night above the critical value and you picked up +17°C, you would have seen Microdochium nivale activity no matter whether you had an effective fungicide down or not. The difference of course would have been the severity of the damage but for sure the balance would have tipped very much in favour of fungal population growth to the detriment of fungicidal control, no question.

Disease activity outlook for the coming week….

Well again we have an interesting dynamic, quite different from last week.

OK, it depends entirely on your location and that’s where trying to generalise on this blog does me no favours but the dynamic this week is one of cooler night temperatures but critically lighter wind speeds which will allow for higher humidity levels and hence dew formation. If I look at 6 different locations across the U.K, I think that Tue night / Wed morning represents the highest likely disease pressure this week. After that the temperature at night should drop off nicely and the wind speed will probably stay high enough to decrease dew formation.

High soil temperatures means there’s still time to get recovery on worn areas…

After the very dry (and already forgotten in some quarters) summer, we have a lot of thin / worn and bare areas on golf and outfield turf alike. Last weekend in Leicestershire marked our first decent rain that will have wetted down through the profile so is it worth continuing renovating these areas ?

Definitely so in my books because we are retaining plenty of soil temperature necessary for seed germination and we have soil moisture as well. I remember awhile back we had a very dry summer and autumn to such an extent that a lot of clubs didn’t renovate bare areas till early November. They overseeded as well and I thought it was a waste of time but it wasn’t because those areas got away before the winter and recovered quicker the following spring.

The graph below shows where we are soil temperature-wise vs. previous years…

Ok a long blog for this week, that’ll teach me to take a week off 🙂

All the best.

Mark Hunt