28th September

Hi All,

I think autumn is my favourite season, with the low sun angle bringing beautiful colours to the landscape.

Looking at the temperatures over the last few days one could be forgiven for thinking we have skipped autumn and moved straight into winter !

Yesterday my local reservoir had more than a passing resemblance to The North Sea with waves and temperatures to match. Definitely one of those days when a Sunday morning lie in was definitely the best option 🙂

Two frosts so far this year locally and temperatures down to -5°C in Scotland have certainly marked the passage from summer to autumn.

The culprit was a cold, Atlantic low pressure pushing cold air on a north wind down from Greenland / Iceland.

You can see from the chart below how the barometer plummeted around the 21st of the month and with cold rain falling, it took the soil temperature down from 17°C to 10°C in a matter of hours. Most people got some very welcome rain last week, we managed to miss the majority of it here in Market Harborough with just 4.8 mm for the month. That said, I think we will likely make up for that later in the week. The east of England picked up the Lion’s share of the rainfall with areas of Norfolk receiving 70 mm + last week.

So does winter continue this week or do we see a more ‘normal’ transgression into autumn ?

General Weather Situation

Looking at the GFS output above you can see the cold low that brought us a cool, wet end to last week is now over southern Europe and eyes left shows another cold, northerly low just off Iceland. Well that’s the story of this week in a nutshell, settled first half, wet and cool second half.

So starting off on Monday, not everywhere is dry and settled because there’s a band of rain heading across Ireland currently. Through the course of the morning this will move eastwards into western Scotland and the north west of England but as it does so it will fizzle out, clearing Ireland as it does so. Some of this rain may make it into the west of Wales and The South West by the afternoon and it’ll push eastwards into Central Scotland p.m. as well. East of this rain front we look set for a pleasant autumn day with light winds and sunny intervals. Enjoy it because by the end of the week it’ll be but a distant memory 🙂 Much better temperatures on Monday pushing up into the mid-high teens so all in all a nice day really.

Onto Tuesday and overnight we see that rain band over the western half of the U.K dissipate into a few drizzly showers inland. Thereafter we look to have a dry picture for all of the U.K & Ireland for Tuesday. Freshening south westerly winds across Ireland will herald the arrival of the next Atlantic low pressure system and particularly for those on the west of the country, it’ll be the last dry day this week 🙂 So for most a very similar day temperature-wise on Tuesday with sunshine and cloud pushing us into the mid to high teens for all areas but for the west we pick up a freshening wind whereas across central England, Wales and Scotland, winds will be moderate to light.

Through the course of Tuesday night into Wednesday, Ireland will see rain, some of it heavy push into the west of the country and move steadily eastwards. By dawn this rain will cover Ireland and some of it may be heavy along the south coast / Cork area. As we progress through Wednesday morning this front of rain will push into the western half of the U.K, stretching from The South West all the way up to Scotland and then move eastwards, clearing Ireland by lunchtime hopefully. So a west-east split on Wednesday with central and eastern areas remaining dry till after dark when that rain will eventually reach these areas. Much windier on Wednesday with a strong southerly wind in situ for most areas and this will pull down temperatures to the mid-teens.

Moving onto Thursday and overnight that rain front clears the U.K and pushes out into The North Sea though it will leave some heavy showers behind over central, western areas and across Scotland. As we progress through Thursday morning we will see more in the way of showers breaking out across the west of Ireland consolidating into a broad rain front. Further east we will see the odd shower across North Wales and the like but otherwise mainly dry on Thursday at least a.m-wise. During the afternoon we see more in the way of showers across The Midlands and The South West as the main  rain front straddles Ireland. By dusk that rain begins to move eastwards and during the first part of the night into The South West, Wales. Feeling cooler on Thursday as the temperatures drop into the low teens despite a moderate westerly wind direction.

Closing out the week the low pressure system that first appeared in Monday’s GFS output is now straddled across the south of England so Friday is looking to be pretty wet for anywhere south of The Humber. Less rain across the north of England though we could also see some heavier outbreaks across the east of Scotland on Friday. Ireland looks sunshine and showers on Friday, all in all it is a messy, wet picture with the bulk of the rain across the south of England and some heavier stuff for The South Coast. Winds will be light across the southern half of the U.K hence the slow-moving nature of the rainfall but the trailing edge will pull cooler, northerly winds into Ireland along with some blustery showers.

No surprise then that the outlook for the weekend looks unsettled with that low pressure system so close to our shores. Saturday could see some pretty heavy rain for both the west and east of the U.K, ironically leaving central areas with sunny intervals. Through the latter part of Saturday we could see a repeat of heavy rain over East Anglia and The South East dependent on the trajectory of the low pressure system. That heavy rain could extend up the east coast into The North East and east of Scotland. Ireland may start dry but those strong, cold northerly winds will pull rain quickly into the picture on Saturday. As we close out the afternoon on Saturday, that low swings round and pushes the rain back eastwards into central areas, so if you were dry initially, you may not stay that way !

If you take a look at the animated GIF at the top of this spreadsheet you’ll see the low pressure system actually moves from east to west over the weekend, instead of the other way round !

This means the boot will be on the other foot on Sunday with the heaviest rain now across North Wales and strong southerly winds across central areas juxtaposed to northerlies over Ireland where it will be windy, dull and with the bulk of the rain pushing down the eastern half of the country. By the afternoon the rain will consolidate to most areas of the U.K with the east of Ireland picking up the worst from an Irish perspective. Similar temperatures over the weekend, that is low double digits, 11-13°C , with a variable wind direction dependent on your location.

Weather Outlook

Looking at the GFS output above for next Monday you can clearly see the cool low pressure system still in residence as we start next week but also another sneaky Bay of Biscay low tucked below the U.K. So no prizes for guessing that the start of next week looks cool and unsettled with the bulk of the rain across the eastern side of the country. This low eventually departs on Tuesday so this means a drier day for us all though we can still expect some showers around over western coasts pushing inland. Wednesday sees a new low pressure push into the south of Ireland and this will move rain briskly eastwards across the southern half of the the U.K through the course of Thursday before an Atlantic high pressure introduces some drier, more autumnal weather for the end of next week and perhaps beyond. The leading edge of this high pressure will unfortunately pull down some cool, northerly winds through the end of next week as it pushes into our weather picture. As it stand now, the high pressure isn’t projected to last long though as a new northerly low pressure will swing rain into Scotland and the north west on a strong north westerly wind by the time we reach the weekend 🙁

Agronomic Notes

As we move into October thoughts obviously turn to the usual matters associated with this time of year, worms, Microdochium nivale, leaves, dew management, e.t.c

From a disease management, pesticidal perspective, we now have a two-tier system now that the U.K has left the E.U.

Across The Irish Sea, the republic of Ireland has two new fungicides,  Signature Stressgard from Bayer and Ascernity from Syngenta to go alongside the other fungicides they / we have in the U.K & Irish markets. This is because the U.K is no longer recognised as being part of the northern climatic zone used in data generation / recognition across the E.U, so these products have been registered in Europe but not in the U.K. For chemical companies this provides a major headache because they effectively have to generate different data requirements for the E.U and the U.K with the upshot being that the registration process for U.K products will become inevitably slower and more costlier. Over time this may change depending on the stance of the U.K government / legislators but that is our lot for the time-being, like it or lump it. The consequence for now is that for Ireland you have two more (new) A.I’s with which to combat Microdochium , whereas in the U.K, we don’t.

The reason I am highlighting this is firstly for information purposes and secondly because if I’m talking about Microdochium management I will have to make this distinction going forward between the U.K and Ireland.

So here in the U.K, we now have a dwindling range of pesticides with which to tackle Microdochium, sure there are a number of products labelled as such and some of these have parallel import copies, but the reality as we know it is that some of these actives are less effective and some have widespread resistance (Strobilurins), so this leaves us with very few tools to do the job if you’re looking at it from a purely fungicidal perspective.

So I thought I’d chat about this area in today’s blog.

Consider the diagram below ;

 

 

So here is the predicted disease activity level over autumn / winter 2018/19 for a Midlands location according to the algorithm I’m developing with the ever-suffering PV (Paul Vipond) to predict Microdochium nivale. You can see some aggressive peaks of activity but what you’re looking for is continual disease pressure where you have a number of columns > 60%, day after day. In practice this translates to climatic conditions which enable the pathogen to develop more of less uninterrupted during the night and sometimes during the day as well leading to new activity and severe pressure on existing scars.

If you look at the chart you can see there was one such block at the end of November and another between Christmas and The New Year. Coincidentally or not, that is the 3rd year in a row (including 2019/20) that we have had high, concentrated disease pressure at this time of year. So from a practical perspective, the weather between Christmas and New Year coincided with high pressure that brought in muggy, mild day and night time temperatures between 8-10°C, no wind, high humidity and almost continual dew formation on the grass plant. Regardless of whether you diligently skipped Boxing Day brekkie to take the dew off, 2 hours later, the grass would have been as wet as before. (unless you’d applied a dew control that is)

So in other words Microdochium nivale was your worst Christmas pressie 🙁

Let’s now consider management of this disease for your facility ;

 

I have created 3 bands across the above chart that seek to show the influence of different parts of an IPM program on disease management.

The level that they do so is of course subjective because different facilities have different disease pressure dynamics – For example, a Links course has less issues from shade (though I have seen some), poor air flow and typically (but not always mind) has a mix of grass species less likely to be susceptible to Microdochium nivale. On the flipside, a parkland course in a heavily wooded location in the south or east of England will have significantly higher disease pressure both from a local perspective (more shade, less air flow, less leaf drying) but also a climatic one (more likely to have humid conditions)

The first band is really down to the practical side of things, organic matter control, aeration, topdressing, rootzone mechanics,  grass species overseeding efficacy, maybe tree removal would fit here as I’ve seen it make a massive difference to disease pressure as a facility (eh Simon :)).  It really symbolises what you are doing (or more precisely these days, have the money and resources to do) to try and tip the balance culturally against disease.  The assumption is that if you are doing these things, your sward is able to ‘tolerate’ a certain level of Microdochium nivale pressure without becoming symptomatic. Of course the flipside of this coin is that if you aren’t (or aren’t allowed to for that matter), your actual level may indeed be a lot lower i.e you will have consistent disease pressure at relatively low climatic pressure.

The second band relates to where you are applying products to change the environment that the grass plant lives in. Dew control is a good example. By applying this type of product your objective is to achieve a drier leaf and in so doing tip the balance away from disease development. Now on this subject a lot of people are obsessed with longevity of dew control, but the reality is say for last years Christmas pressure period, it only had to last 7 days (which most good products will do in the middle of winter with low cutting frequency and low growth levels) to dramatically decrease disease pressure. Either way we know there are a number of products that change the environment that the disease exists in, both outside and inside the plant and in so doing they suppress the growth of the pathogen. This means that we are able to manage a sward to a certain level of disease pressure without showing symptoms of disease. In my example I have put a line at 80%, it may be lower or even higher at your facility depending on your location, disease dynamics, IPM program, etc. I would add that the low – moderately effective fungicides probably fit into this banding as well in my mind. That is to say they do exert a control on the pathogen but are not able to provide effective control under the most severe levels of disease pressure.

That brings us onto the 3rd banding, in the above example I’ve put this at >80% disease pressure. At this point we are saying that the climatic drivers to disease formation are severely tipped in its favour to such an extent that most facilities will see aggressive disease on their grass sward. Rather than just talking about greens, it would also be quite typical to see disease on tees, aprons, fairways, winter season pitches and in  domestic lawn situations. Now even if you have applied a fungicide before a disease peak of this magnitude, you may not see complete control and particularly with the later fungicides at their reduced A.I loadings. This is because the dynamic is tipped in favour of disease development at a faster rate than the fungicide can affect it negatively, remembering it is being driven by climatic conditions. Often it is not till these climatic conditions change that you see control.

There is another factor that we need to consider in this disease modelling dynamic, that of timing….

For instance, if we develop aggressive disease in August or September, then we are likely to be able to grow any disease scarring out really quickly and that in itself may mean you do not resort to a fungicidal application to control it. You will though carry a higher population into the autumn theoretically. That would be an interesting subject for research, i.e if I applied my fungicide early, does it lower the level of disease I see later in the autumn / winter ?. I think it probably does but it doesn’t negate it occurring and that’s the problem. If we see aggressive disease in say November, we are much less likely to be able to grow it out until later in the spring because of short days, lack of light, lack of growth so there’s an argument to use any pesticide applications later in the winter.

Today I have conceptualised (big word for a Monday !) by view on disease development for you. I am not saying it is 100% bang on, but in my mind it helps me and hopefully you to understand the dynamic we / you face at your facility and maybe how you approach disease management ?

It doesn’t just apply to Microdochium, the same is true for other turfgrass pathogens. What I would say though before I sign off is that it is my perspective and as such it is protected by intellectual copyright and not for reproduction / distribution by commercial companies. Fine for you to share within a golf, groundsman, educational environment though 🙂

Have a good week, Tempus fugit for me as I have a spray window to catch this afternoon 🙂

All the best.

Mark Hunt