Monthly Archives: November 2015

November 18th – Mini Blog

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Hi All,

I did say in my last blog that if I got a chance for a mini-update and / or saw a significant change in the weather on the horizon, I’d try and snatch a few minutes to publish a shortened blog.

It was only 8 days ago that I put up a graph showing what happened in November 2010 and reminding us all that it was possible to go from extremely mild to extremely cold on the flip of a coin. At the time there was nothing to suggest that this could happen, now there is……..

There’s a change coming…

Take a look at the two weather graphs below, you can see the cold air (in blue), the yellow air marking the line of demarcation that is the jet stream and the warmer air sitting below it. The projection for this coming weekend is that we are entering into a ‘Trough’ pattern in the jet stream which will allow cold air to stream in from Siberia and winter will start both early and with a vengeance…

Nov20152010comp

Uncanny how they’re so similar isn’t it ?

And just remember 8 days ago there was no suggestion that this was in the offing, so yet again I state my utter conviction that 8-10 days is the limit of our forecasting ability in terms of weather, regardless of what the tabloids and some weather gurus believe…

General Weather Situation (Abridged)

For the rain-ravaged north west, where we have seen more than 10″ of rain fall in a short space of time and currently where we have heavy rain sitting over north west Scotland, I hope this will be the last of the extremely heavy downpours for this week. They’ll still be rain around for sure today and Thursday, but with the cold, it’ll decrease in intensity and of course it’s likely to change to sleet and snow at the weekend.

For all of us the change day is Friday, where we see the wind swing round from the west to the north west and then the north by early doors on Friday for Scotland and the north of England. Those isobars will be packed tight so it’ll be a strong northerly wind to boot and by close of play Friday we will all feel the difference..It looks like Friday will be pretty dry for all of us and bright with it, but that sun won’t be warming anywhere, anytime soon. Close of play Friday I expect the first of the wintry showers to be pushing into the north east of Scotland and across Donegal and north Connacht.

Overnight into Saturday it looks like we will see wintry showers, a mix of rain, sleet and snow depending on altitude push across Ireland and down the west coast of the U.K into Wales / the south west of England. By dawn, central and eastern areas of the U.K should start bright and cold with a penetrating hard frost. For Ireland it looks the same, dry on the east, but wet down the west coast of Connacht and Munster. During the morning those wintry showers will push down from The Highlands into Central Scotland and the north of England by lunchtime with some significant snow I think for The Pennines. As we approach dusk those showers spread more east and south to The Midlands and south of England. Again a mix of rain, sleet and snow expected. Temperatures will barely break freezing and with that strong north wind I expect the windchill to be around -9 to -10°C !!!!! In other words, absolutely Baltic !!!!

Sunday sees a day of sunshine and wintry showers after another overnight frost with a likelihood of more rain, sleet and snow over Scotland and a tendency for most of the wintry showers to be along the east coast this time. Again another day of biting northerly wind accompanied by a significant windchill.

Winter

Weather Outlook

So is this just a blip or a portent of things to come for the winter of 2015 ?

This fast transition from an extended mild autumn to a hard winters day doesn’t look to be a permanent one from what I can see with a change to milder air on the cards next week, though we won’t be going back to the teens anytime soon I think. Even though the Arctic blast is likely to be a short one, I think winter has shown a glimpse of its hand and I expect they’ll be more to come. Hopefully this will be around Christmas and I can retire to Costa Rica on my Paddy Power winnings :)

So next week looks like starting cold, dry and settled for all of us after another frost, though likely not as hard as the weekend’s. Already on Monday we’ll see milder air coming into Ireland and the west of the U.K so here you may escape a frost completely. Through late Monday into Tuesday sees the wind decrease and swing round to the north west and eventually the west bringing those temperatures up as we see more in the way of cloud cover and the risk of light rain for Tuesday, particularly in the west and north later on in the day.

By Wednesday we start to see another change as the wind swings back to the north west and  the isobars begin to tighten so a markedly windier day on Wednesday and that will start to drive rain associated with a north west low pressure across Ireland and the U.K. That sets the tone for the end of next week, extremely windy with heavy rain likely, particularly across Scotland and the north west I’m afraid to say. Further south and east it’ll remain unsettled, very windy and cool with temperatures likely to remain mid-single figures for the time-being.  The end of the week will see temperatures start to tumble again, first across Scotland and the north with some of that rain likely to turn to wintry showers through Friday and into the weekend. By Saturday I think only the west and far south will still be sitting in mild air. It wouldn’t surprise me if we finish off November with another cold, northerly blast.

Agronomic Notes

So life for us and the grass plant is going to feel very different in just a few days, the difference is we know its coming and can plan….

Preparing for cold….

For the north and west, the heavy rainfall will make most of the suggestions in this blog irrelevant so please excuse me on this one. To prepare for cold weather my advice is very simple, leave some leaf on the grass plant and if conditions make it practically feasible just put a light roll on the greens to keep some pace. I would try to avoid a cut on Friday and roll instead to leave the plant protected for what will be an icy wind blast over the weekend.

You have to think of it from the grass plants perspective. Up until this Thursday it has been growing super-fast for the time of year with many end-users feeding back to me that clipping yields have been like ‘cutting in the summer’. That means it’ll have a high nitrogen content in the leaf, a high water content and the leaf epidermis is likely to be thin. (due to a fast growth rate) In other words it’s totally unprepared for extreme cold and we may see some grass loss in areas where the rootzone is saturated and this is followed by sudden, heavy frost.

Our experience of 2010 showed that leaving a slightly higher cutting height benefited the plant during periods of cold weather and that would be my advice for this week.

I’d also stop short of applying anything to the plant leaf on the run up to this weekend because although it’s unlikely with the high winds and rain that you have a spray window, I’m not sure you’ll see a benefit from doing this, it may even count against you.

So let the plant go through this period as protected as possible and by next week it’ll start to get the message that the days of growth are finished for the time-being..You can clearly see this on Meteo Turf with the decrease in daily GDD / G.P…

MeteoTurf181115

Disease Activity

I expect with this severe transition into cold weather that disease activity will come to a pronounced halt as will re-growth in scarred areas. It certainly doesn’t mean that the Microdochium nivale will be ‘killed’ by exposure to hard frost, I don’t believe this old wives tale, but for sure one of the key drivers of disease, that of air temperature, will be exiting stage west for the time-being. With the loss of temperature and grass growth, we will also see a drop-off in uptake efficacy of fungicide A.I’s because the grass plant will effectively ‘shut down’ for the foreseeable. So my only exception to keeping applications to a minimum this week would be if you still have active, aggressive disease and want to get a fungicide application in. I would though keep tank-mixing to a minimum in terms of putting other non-fungicidal materials in the tank. Remember with that cold and severe windchill the plant will easily become desiccated, particularly if the ground is frozen, so you don’t want to be plastering lots of iron onto the leaf just prior to this in my humble opinion, as that may (depending on the type of iron) add to this desiccation effect.

Ok that’s all for now, sorry it’s not the usual full-on blog, but time and tide wait for no man…

Remember to dig out your thermals, buffs and winter hats for the weekend, because boy are you going to need them. That said I expect we will still see the comical sight of some teenagers, oblivious to the weather forecast until they step out of the house, walking around in shorts and a T-shirt in a negative windchill :)

Have fun..

Mark Hunt

 

 

 

 

 

November 10th

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Hi All,

Sorry for being a day late but unavoidable at present I’m afraid. They’ll be a bit of disruption to my blogs this month because I’ll be travelling and therefore it’ll be pretty difficult to put the 4-6 hours in that this blog requires every week. So I anticipate missing the next two Monday’s and starting again November 30th, however if I can squeeze just the weather side in, I will particularly if I see a change on the way.

I get some pretty strange pictures sent in to me from you guys, here’s two that arrived this week…

StinkhornThis one was sent in by Chris Knowles in Germany, a frequent ‘WhatsApper’ and all round good egg :). At first I thought it was something out of a Jules Verne film and that does indeed give a hint as to its name. Officially it’s Clathrus archeri, The Octopus Stinkhorn fungus. Originally a native to Australia and Tasmania before making the jump (and it’s a big one) to Europe, this one was found growing in his rough. It smells exceedingly foul, living up to its name in every sense. Its appearance is meant to resemble decaying flesh (as is the smell) to attract flies…..Strange….

IMG_5144

Another new one for me, this time from Cork, Ireland.

I think, but I haven’t had it confirmed, that it’s a type of Slime Mould, because the colour is exceedingly white and there doesn’t appear to be the usual basal turf damage associated with a pathogenic fungus like Microdochium nivale for example.

Both of these phenomenon are I think symptomatic of the balmy / barmy late season we’re currently  ‘enjoying’…

……………………………………

And so this extremely mild start to November goes on, but we all should remember what happened in November 2010. We started the month extremely mild and then towards the third week we dropped off a cliff and went from very mild to very cold, almost overnight. That set the pattern of what was a hard winter. You can see this on the graph below ;

Nov2010

Now honestly I can’t see that happening this November because at present we have a strong westerly jet stream that is pushing low pressure systems over The Atlantic, you can see this on the NetWeather image below…

jetstream101115

I can’t see any indication that this will change anytime soon, in fact I think November will run through as a windy, stormy, but generally mild month. So at present no repeat envisaged of November 2010, but weather is a fickle beast, its unpredictability well-known, but little understood :)

General Weather Situation

Starting the week on a Tuesday this week we have rain affecting Ireland and the west coast of the U.K. This will be a bit of a feature this week as will the strong winds. The U.K rain stretches right up from the south west, through Wales, The Lakes and up into Scotland. Through the day this rain will intensify over these areas, particularly Connacht I think and some may head inland as showers, blown along by a blustery, but mild westerly wind. Away from these rain fronts I think it’ll be a mild, dull and largely dry day, but there’s always a risk of showers on a south-westerly air stream. Later on in the afternoon, the likelihood of these showers increases over The Midlands and East Anglia. It’ll remain very mild for the time of year with mid to high teens possible.

For Wednesday, we have a similar situation but the rain looks to be a bit more south in its orientation, so principally affecting western coasts,  south of a line drawn from Galway across to Newcastle. Through the late morning / early afternoon we will see this rain push into Scotland and intensify over north west England and Wales at the same time. A little cooler for Wednesday as that low pulls down some cooler air into the mix rather than warm southerly air, so early teens the order of the day and still with a moderate to strong south westerly wind.

For Thursday we have a drier, brighter start after that overnight rain moves through so bright and sunny for many. During the morning you’ll see cloud cover pushing in from the west over Ireland and the west coast of the U.K, but eastern and central areas should stay bright. By lunchtime on Thursday the rain front behind that cloud will make landfall on the west coast of Ireland and push eastwards through the afternoon. Again though its pass is more north easterly and so Scotland will see the worst of this rain by the late afternoon / early evening. Later on Thursday night it’ll also push into Wales. south and east of this, it’ll remain dry and bright, but still a little cooler than the start of the week with low double figures / early teens the order of the day. We will still have those strong to moderate south westerly winds increasing in intensity the more north you go over the U.K and Ireland for that matter. Definitely not a spraying week :(

Closing out the week, Friday looks to be a re-run of Thursday with heavy rain over Ireland and Scotland. In the north it’ll feel noticeably colder and for the first time I’ve noted that some of these showers may be wintry in nature over The Highlands. Through the morning this rain will push into Wales and north western England to round out what will be a pretty wet week for you guys. East of a line drawn by the M5 / M6, it looks to be dry and bright again after a cool start. By the afternoon that rain will be affecting the west coastline of Ireland and the U.K, with drier brighter weather still over central and eastern areas. I think that rain may only stretch 30-50 miles inland so again east of the M6 should be drier.Noticeably cooler for everyone on Friday with temperatures down in the high single figures so more like where you’d expect them to be for mid-November really. That wind will swing round to the west and pull in cooler air as a result. That change in direction and the increase in strength of that wind will peg those temperatures back.

Onto the all important weekend and it’s getting closer to the time when I hang the fly rods up for the winter, but not quite as I cling desperately hang on to my fishing time :)

Saturday looks very similar to the previous week with a dry start to central areas but rain, some of it heavy is due into Ireland through Saturday morning and further rain will also affect Wales and the north west of England. Up in North West Scotland, that rain will again fall as a mix of rain, sleet and possibly snow at altitude through Saturday morning, so winter has arrived here, if not further south.  Through the afternoon, that rain pushes eastwards on a strengthening westerly wind to bring heavier rain to Wales and north west England, but also inland as well. Through into Sunday and that rain will continue to affect Ireland, Wales, the north west and north of England and Scotland I’m afraid. South and east of this it should die out a bit to give a cloudy day, but still with the threat of showers though central and eastern areas may miss these entirely. In fact these areas may see more in the way of sunshine and in it temperatures will pick up to the mid-teens, so a nice Sunday in prospect for some.

Weather Outlook

So how are we looking for next week ?

Looking ahead I can see us losing the temperate southerly air as we pick up cooler spells of northerly air through next week. So next week looks unsettled with rain for Monday for the west and north, fading through Tuesday when the wind switches temporarily to the north to introduce a chill feel to the weather. Later on Tuesday we see a new low pressure system sweep westerly winds and rain across all areas for Wednesday, again with a cooler feel with a northerly wind. Thursday provides a quiet interlude, but by the end of the week a really large, intense low pressure system is gearing up to push rain and strong south westerly winds into all areas. So cooler next week, potentially milder at the end of the week when we get that new low pressure system moving in, but frequent rain and strong winds are likely, more in the west and north.

Agronomic Notes

Disease Pressure – What we’ve had and where we are going with it…

Microdochium111115

Microdochium nivale on Perennial Ryegrass Sward

As documented at length over the last month we’ve had incredibly high, sustained, disease pressure on all turf areas. I’ve had lots of reports of Microdochium nivale on fairways, outfield turf, tees and approaches running riot and end-users saying it’s the worst they have ever seen it. I agree.

RedThread111115

It is isn’t just Microdochium that’s been active, I took these pictures of Red Thread on a Ryegrass sward last week and it’s the first time I’ve seen it form clumps of mycelium on the leaf margins and leaf tip.

Ok, so we know we’ve had a bad time of it, but how do I see it going over the course of the next couple of weeks ?

Well from a positive perspective I see disease pressure decreasing in some areas as we progress through this week. Why ?, well although we’ve still got mild temperatures over the U.K and Ireland, we also have some areas of the country away from the west and north that is not having the volume of rainfall. Even if it is, there’s another factor present this week that wasn’t present last week, wind. A strong, mild wind is great for drying areas out and you can see how quickly that process is occurring by how soon the roads dry out after rain. There is still heat in the ground (more on that later) and coupled with the strong and mild wind, the grass leaf is drying out much more than it did last week. Now you guys in Ireland, Wales, the west of England and Scotland won’t be in the same boat unfortunately because as we’ve seen from the forecast, there’s a lot of rain heading your way over the next 5-7 days I’m sorry to say.

GP1111231115

So in some areas we have a decrease in one of the drivers for disease and that is leaf wetness.

We will I think also see a gradual reduction in temperature as we proceed towards the third week of November and apart from Sunday’s blip, you can see this map out on the graph above. So that means we are likely to see a decrease in the 2nd driver for disease, that of air temperature.

This is just as well because with the outlook being unsettled with strong persistent winds, the likelihood of getting out to spray is quite low, especially across the north and west of the U.K and across Ireland of course.

Grass Growth

As you can see from the information above, we’ve had some pretty hefty G.P figures of late and that is really driving grass growth. With wet weather, cuts have been less frequent and when you do get out there, it’s quite amazing how much growth there is !

The rain that’s fallen recently has been during mild periods of air temperature, so it’s kept the soil temperature elevated and that too is driving growth. Below is a comparison of where the soil temperature has been on this date over the last 6 years ;

Soiltemp10115years

You can see we are the highest I think we’ve ever been for early November, but as indicated above I expect this to drop back significantly over the next 10 – 14 days after Sunday’s mild upward blip.

Light vs. Temperature – Which one is the stronger driver  ?

It does make me wonder now that our days are getting much shorter (we are only 5 or so weeks away from the shortest day would you believe) how come the grass is still growing at a high rate even though light levels are diminishing ?

Obviously the grass plant needs light to photosynthesise and convert  light energy into carbohydrate, which in turn drives the production of new shoots and root growth. What we can deduce at the moment is that the lower light levels aren’t an issue for some plant species, Poa sp. in particular and that temperature, both air and soil is playing more of a role here than light in terms of driving growth. It may be different for some of the less shade-tolerant species like Bentgrass and Ryegrass, but I suspect not as much as you’d think.

Enhanced Microbial Activity

It must be the case that with the warm soil temperatures, microbial activity is still progressing at a pace so conversion of organic nitrogen to mineral nitrogen is actively taking place. That’s another reason why I think we’re seeing significant grass growth rates because microbial conversion of N is extending longer and longer into the autumn season. So our autumn growth season is also drawing out longer and longer into what used to be called early winter.

What are the consequences of this for shoot and root growth ?

Well I think the grass plant is happy to make new leaf and shoot growth as long as the temperature remains favourable, but it will be a lower rate because light levels are decreasing.

Whilst we are mild I don’t think the grass plant needs to make much root because moisture and nutrient levels are high, so this favours new leaf production instead. It’s only when the ambient air temperature drops and this process slows down significantly that I think the balance of growth changes from leaf to root production. I’d be interested to know if you’re seeing good progressive new root development of late along with your enhanced clip rate ?

Ok that’s all for now, sorry I’m a day late and will most likely miss the next two weeks on this blog but I’ll be back before the end of this month.

All the best.

Mark Hunt

 

 

 

 

 

 

 

November 2nd

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Hi All,

The warmest start to November on record for some of us yesterday with temperaturesIMG_5122 in Wales exceeding 22°C, but if you were in the south of England you were lucky to see half of that as the fog failed to lift for most of the day. This time of year it’s all about leaves isn’t it, no sooner have you cleared them all up, than they are joined by some more…I just about completed this task yesterday when the Air Ambulance had to make a landing in the Rec behind my house. You’ll notice the absence of leaves around the helicopter, guess where they all ended up ?

If you were lucky enough to see the sun and feel that heat I think it felt almost unnatural for this time of year and looking ahead I don’t see things changing anytime soon. It may not only be the mildest start to November, unless the outlook changes soon (and it can do) it may well be the mildest November on record, but we’ll see, plenty of time for things to change yet…..So how are we set for the week ahead ?

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Fog is a major issue as we start Monday, particularly for the south of England, extending up into The Midlands as well. The west side of the U.K and east coast of Ireland should have more chance of seeing the sun earlier, but elsewhere if you have the fog, it may take up until lunchtime or even later to clear and for the sun to break through. So a cloudy, dull start to the day, but with the sun breaking through later temperatures will climb into the mid to high teens. As is usual on foggy days, they’ll be only a light south-easterly breeze to move things along. Pretty much a dry day for everyone save for some coastal drizzle over North West Scotland early afternoon. As we go into Tuesday that fog may well re-appear in some places as the temperature drops.

For Tuesday our dry start to the week comes to an abrupt end as that south easterly wind pushes some rain off the continent and into the south of England by early morning. By the rush hour that rain is into Wales and The Midlands and heading north. Elsewhere it looks another dry day with the best chance of sun along the eastern coast, but in general it’ll be cloudier everywhere than Monday because of that rain front. By mid-morning that rain is into North Wales and northern England and by lunchtime it’ll be into the borders of Scotland. There’s a chance in the afternoon that the westerly end of that rain may intrude into the east coast of Munster and Leinster as it heads north. As we reach dusk more rain is pushing into southern England and tracking north. During the evening the wind swings round to the south west and that’ll push the northerly rain over to the north east of Scotland and the southerly rain will head north east to affect the eastern coast of England. Temperatures will be a little down on Monday because of cloud cover and rain so expect low to mid-teens to be the order of the day and winds to be light to moderate.

By Wednesday morning that rain will have departed stage east and left behind some dense cloud cover, heavy enough for some light rain and drizzle over most of the U.K and Ireland first thing. As we progress through the morning that rain will be isolated to The Lakes and the south west of Scotland, but there’s more on the way unfortunately. Elsewhere it looks pretty dull again as more cloud is pushed in from The Atlantic, a portent of more rain for all of us. So by mid-afternoon, maybe earlier, we have rain pushing into the south west of Munster and the south west of England and this will quickly track inland. So through Wednesday evening that rain will track across Wales and be reasonably light, whereas the rain affecting Ireland will push across the whole country and be heavy in nature with localised flooding possible. So another mild day, with temperatures in the low to mid-teens but no risk of fog as the wind picks up to a moderate south westerly.

As we go into Thursday that rain has lightened but spread out so Thursday morning looks likely to start showery across all of the U.K and Ireland, but most of the showers will be confined to the western coasts of the former. By lunchtime that rain front has cleared Ireland to leave some sunshine behind and the showers affecting the west of the U.K will tend to track north east into northern England and Scotland later on in the day. So away from the rain another dull day, but with a chance for the sun to break through in the east particularly and if it does the temperature will pick up nicely to the mid-teens accompanied by a brisker south westerly wind.

Closing out the week we have more rain on the radar for Ireland and the south west of England, but this front is moving much faster and clears Ireland by dawn to give a sunny start to the end of the week. Elsewhere we have rain over most areas in time for the morning rush hour, but it’ll be potentially heaviest across the north of England and particularly Scotland. With this being rain from The Atlantic, it’s possible the south and south east may miss most of it to give a dry day on the whole for Friday. By lunchtime this northerly rain should have cleared all but the far north east tip of Scotland to leave behind a nice, sunny day and in that sun temperatures will pick up into the mid-teens for most areas, so a nice finish to the week.

The weekend looks a bit of a mixed bag really with a dry start to Saturday, but rain, some of it heavy, will push into Ireland and the south west of England early doors and move north eastwards inland. Central and southern areas of England may not get this rain till later on Saturday (or may miss it totally) so it’ll be touch and go for fireworks on Saturday night (Note Bro). This rain will still be around early doors on Sunday to give a dull, damp day for many, possibly brighter in the west, but more rain looks like arriving later on Sunday for a repeat showing unfortunately. That makes Sunday a day to sit in and watch Marquez skittle Lorenzo at the first corner while Rossi rides on to seal his world championship…(I’ve just woken up..)

Weather Outlook

Pretty much bang on last week with the projected forecast for this week suggesting the high and low pressures would tilt to give a south westerly air stream and a more unsettled picture, so how are we looking marching into mid-November ? Well similar in a way with that ’tilted’ theme still much in evident but the high will extend it’s influence into the south and east of England so a weather map of two halves for next week me thinks.

For the west and north, you’ll be closer to the low pressure so that means windy and unsettled with rain pushing through across all areas for the start of next week. Thereafter things settle down a bit with that wind and rain very much isolated to north of a line drawn diagonally up from Kerry over to Fife. Further south they’ll still be some rain around but they’ll be less of it and as you head towards the south east, you’ll be closer to the high pressure so more settled, but cooler here and potentially a return to some foggy nights. I can’t see it getting cold though because the air stream will still be south westerly and that will pull mild air up from the continent for the foreseeable. Can’t complain for the middle of November.

Agronomic Notes

First off we’re going to catch up with how the year is shaping up GDD-wise vs. past data…

GDDmonthlycomparisonJantoDec2010to2015image

GDDmonthlycumulativeJantoDec2010to2015image

Now here’s an odd one because you can see that the GDD total y.t.d is 1562 and that’s the lowest cumulative total for the last 5 years, even the year of the cold winter / spring, 2013, had recovered to a higher cumulative total y.t.d by the end of October, so why is 2015 low ?

Well we had a very slow start to the year, but September and October 2015, have come in lower than any other year, so although we’ve had warm spells in both of these months, we’ve also had some colder air flow as well. For certain that’s the peak and trough of the jet stream coming into play…

Comparing 3 sites across the U.K you can clearly see a continuation of the yearly pattern with Long Ashton picking up the more temperate conditions in the spring and The Oxfordshire lagging behind, pretty much on a par with York for that matter. As the summer gets into its stride, we see the central Oxfordshire location ramp up in July and August, so much higher temperatures there than either of the other two locations. For September and October we revert to the same pattern as the spring, i.e with Long Ashton picking up the milder temperatures and York / The Oxfordshire, the cooler, easterly airflow.

What significance is this to turf management you may ask ?, well there’s plenty of information we can glean from this.

For example, we know The Oxfordshire will have suffered the highest stress levels of the three sites. If we look at potential grass growth and therefore cutting requirements, Long Ashton comes in 9% higher than The Oxfordshire and a whopping 25% more than the York location, worth knowing and worth budgeting for….

3SiteGDDOctoberytd

Looking across the Irish Sea we see a similar pattern for the year and the month of October,  though as always, milder in Valencia, because that’s where the south-westerlies arrive first.

IrishmultisitedataOctytd

If you compare within the Irish sites you can see some pretty big differences with Claremorris in the beautiful county of Mayo, having a cool year with the lowest GDD monthly figures for each month, 20% down on Dublin or Cork for example. Apart from Claremorris, the sites are very similar through the spring with the exception of Valentia and this follows the same format as the U.K sites i.e the south west picks up the more temperate air and there’s nowhere more south west than Valentia !!!!! Through the summer Ireland is cooler as we know and seldom reaches the dizzy heights of the south east of England, but that means less stress lads, so we can smile about that one. For the autumn the Irish and U.K sites are very similar with Valencia and Wexford showing similar GDD information to central and south western U.K.

Looking at October as a month for grass growth and disease activity…

As is becoming the norm now for the U.K and Ireland, October (probably alongside August) represents one of the highest disease pressure months we have to deal with. So although it hasn’t been the warmest October according to GDD, why do we see such high disease pressure ?

Well there are two main factors driving disease, air temperature and leaf wetness or more specifically, longevity of leaf wetness. If you look at the Growth Potential figures for October from the sites we have data for, you see a clear pattern where sudden increases in air temperature drive up the disease pressure…

GPOct2015sites

GrowthPotentialUK3SitesOct15

If we look at the peaks in Growth Potential for both the U.K and Ireland, we can see 5 clear peaks through October when the G.P increased rapidly. Not only will this drive grass growth, but it’ll also drive fungal disease development and that means Superficial Fairy Ring (Think how many mushrooms there still are about in the fields), Red Thread and public enemy number one – Microdochium nivale.

So when we’re in a peak situation like the last weekend, the balance is tipped very much in favour of disease development. You’ll also be cutting more regularly because the grass is still growing vigorously so the efficacy of any fungicide application will be limited on two fronts ;

  1. Removal of active ingredient in grass clippings…
  2. Ability of the fungicide to slow down the growth of the fungus enough to stop it becoming pathogenic..

So it’s more than likely that you’ll have seen this type of scenario somewhere on your turf surfaces when you came in this morning…

MNivalke

The above image was taken from my front lawn (unfortunately) but there’s only one area affected and that’s the part of the lawn that sits in shade…

This brings me onto factor 2 in the disease-driving equation, that of leaf wetness or specifically the period of leaf wetness…

I know it’s not great for me to say this but we’ve had a perfect storm of late that is driving disease development. Sudden increases in air temperature, heavy dews and of course some heavy rain as well which has increased the moisture content in the ground and led to the formation of guttation fluid. I’ve talked about this before but it’s the droplet of solution that’s secreted from the tip of a grass leaf when soil moisture levels are high and conditions are favourable for dew and guttation fluid formation. Notice I used the term ‘solution’ and not ‘water’ for guttation fluid and that’s because this guttation droplet is full of nutrients and sugars, whereas dew is just water. I took this picture last Thursday after an overnights rain..

Guttation

You can clearly see dew along the leaf margin, but also the droplets right on the tip of the grass plant. This is guttation fluid and right back in 1968 scientists in The States linked the presence of guttation fuid with disease development, in that case it was Dollar Spot.

So let’s look at the weekend over a 24-hour period and analyse when conditions were favourable for dew and guttation fluid formation…

MaxTempHud011115

So what are we looking at on the graph above ?

Dewpoint

Well, firstly let’s talk dew point, a term often banded around, what does it mean ?

The dewpoint temperature is the temperature at which the air can no longer “hold” all of the water vapour which is mixed with it, and some of the water vapour must condense into liquid water. The dew point is always lower than (or equal to) the air temperature.

This took me awhile to work it out and more than a bit of head scratching on my part (little wonder I’m thin on top then eh? :)) but essentially what we’re saying here is that if the air temperature remains higher than the maximum temperature at which dew will start to form, (Maximum dew point temperature), then no dew forms. Once the air cools below the maximum dew point temperature then water vapour in the air condenses to form dew on the grass plant.

This is really neatly shown on the 24-hour graph above.

Look at the period between 15.00 and 17.00 hrs on 31-10-15 (circled in red), we can see the air temperature is higher than the maximum dew point temperature and so no dew forms. You can also see that as a consequence of this the humidity drops as well because the water vapour in the air is not condensing (the formation of liquid water drops from water vapour)

Once we reach 18.00 hrs, the air temperature has dropped below the maximum dew point temperature and so water begins to condense in the atmosphere, the humidity increases and dew forms on the grass surface by condensation. If we follow this right through into the next day, at no point does the air temperature exceed the maximum dew point temperature and so dew can form all the way through the day. As a consequence, the humidity never drops despite the fact that it’s become day.

Taking the 24 hour period as a whole from 12.00 hrs on the 31st October through to 12.00 hrs on the 1st of November, it looks like there was only 3 hours in that period when the air temperature was high enough to prevent dew formation.

So the plant leaf is sitting wet for 21 hours of a 24-hour period.

Even if you removed the dew at say 7 a.m. on Sunday morning, it and guttation fluid would have re-formed again soon after because the air temperature sat lower than the maximum dew point temperature.

Let’s summarise…

We have very high disease pressure currently because ;

  1. The disease population is growing at a very fast rate because of sudden increases in air temperature and long periods of leaf wetness that facilitate the formation and movement of fungal mycelium across the plant leaf…
  2. Fungicide efficacy is also compromised currently because clipping yields are high due to high G.P levels promoting strong growth so expect less longevity from your fungicide application…
  3. The rate of development of new growth that won’t be covered by any contact fungicide is also high because of a high G.P. So this is growth that has occurred after you have sprayed your contact fungicide and unless that contact is root-absorbed it won’t protect newly-emerged grass.

The proof of the pudding here is the amount of active Microdochium nivale present on non-sprayed areas like lawns, winter season pitches, golf tees, approaches and fairways. It is everywhere you look at the moment.

What’s to do ?

Well obviously we have to try and meet the disease pressure head-on, but our fungicide options are limited because of a low number of different active ingredients (Lots of product names, but not a lot of choice when it comes to active ingredients and even less when you talk about effective active ingredients)

  1. Try to ensure the plant leaf is as dry as you can so remove the dew from your greens as early as you can and if practically feasible repeat the exercise on the shady / poor air flow greens as these are likely to be the ones where the leaf sits wettest. (And dew will re-form)
  2. Make sure that your fungicide applications are appropriate and for me that means using a Triazole-based systemic and mixing in a contact like Iprodione to try and maximise the number of effective active ingredients that are present to suppress fungal growth
  3. Use iron, preferably as acidifying as possible to try to dry the leaf out and acidify the leaf surface which we know will reduce the rate of growth of Microdochium nivale. This option is relatively low cost but can be very beneficial particularly on outfield areas where spraying of a fungicide is either not permitted (on the continent typically) or not cost-effective. Personally I’d try and intersperse fungicide applications with iron rather than just apply together because that way you are spreading out the suppressive effect of the applications over time, rather than applying all of the materials at the same point.
  4. Keep your grass plant healthy, don’t starve it because a weak plant is just as likely to get disease as an over-fertilised plant, so try and sit between the two. Like everything in life, a balance is key. (Easy to write, hard to achieve)

Meteoturf021115

Looking ahead with the slightly cooler temperatures and some wind from Tuesday onwards, our disease pressure has dropped from the high of the past weekend, but it’s likely to increase again as we approach the end of the week..

Ok, this started out as a short blog, I hope it proves useful to you :)

All the best…

Mark Hunt