Monthly Archives: June 2018

June 25th

Hi All,

Apparently we had a bit of a technical glitch when I published this yesterday morning so we are trying again today Tuesday. Apologies for the delay in getting this to you, I blame the heat you know….

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Just one word to sum up this week, Scorchio !

Well as we edge towards the end of June it could go down as the driest June on record in some areas of the U.K and Ireland. Just 1.8mm here since the start of the month and 28 days since the last significant rainfall has cast a very dry shadow but hey it is summer 🙂

Before I go on to cover what will be a very straight-forward forecast for the week I had to include this picture of one of the inhabitants of my small garden. This Blackbird will typically walk up to the back door and look into the kitchen, fixing me with a beady stare that says only one thing…”Where’s my food ? “. Lately I’ve noticed if I resist his steely gaze for any length of time, he’s taken to standing on one leg….you could think that he was playing on the sympathy vote…As soon as I dispense some fat sprinkles and mealworms his way, his other leg pops out and off he trots….Birds are cunning creatures for sure…..:)

General Weather Situation

Image courtesy of Unisys Weather

Image courtesy of Meteoblue

 

 

 

 

 

 

With an opening shot on Meteoblue’s U.K and Ireland map top right, it won’t surprise you that this week needs no daily summary because quite simply it will be dry, bright and pretty hot with temperatures pushing into thirty degrees down south I think. That said, the only rain on this forecast is happening now over the west of Ireland as some heavy showers cross Galway and Mayo, they are few and far between though and will soon fizzle out. Night temperatures are likely to be low teens so that’ll make it uncomfortable enough for sleeping but not the worst we have experienced.

As you’ll note from the Unisys graphic (top left), the plume of hot air extends up from Africa into Ireland and the west of the U.K, so I expect these areas to pick up the highest temperatures with maybe some persistent-to-clear cloud cover across the east of the U.K towards the end of the week. I think Monday to Thursday inclusive will probably cover the hottest days and then we will back off temperature’s a little, more towards the low twenties as we see out the week and head towards the weekend. For some areas of the U.K, like us here in The Midlands, we will go out of June with barely a sniff of rain. You know the story…”It just went round us” 🙂

Weather Outlook

Last week I reported that the high pressure was due to break down the end of this week but now that doesn’t look to be the case even though we may lose some of the really high temperature for the weekend. There is a potential fly in the ointment rain-wise or maybe more aptly, a chance of some redemption if you’re desperate for some of the wet stuff. At the end of the weekend there’s a risk of low pressure developing down in The Bay of Biscay and that could edge up towards the south of the U.K and possibly Ireland on Sunday night / Monday morning bringing rain and possibly thunderstorms at a guess as moist air and warm air meet. That could be the only sign of rain though with unsettled conditions in the south of the U.K early next week before another Atlantic high pressure comes in and returns the weather to dry and settled conditions. I think next week will be cooler though with more in the way of cloud cover but with that low pressure close by it shouldn’t be a scorcher.

Agronomic Notes

Well no surprise this week that the main topic is managing stress (the grass plant’s that is) and the above Meteoblue lifted from Dromoland Castle in lovely Co. Clare provides a great back drop to chat through. It is broadly similar to one from Wales, England or Scotland for the coming week…

Watching Growth Potential becomes key during times like this…

The first point is the high GDD forecast, 96 in all which doesn’t incidentally mean we will have rampant growth. It is this time of year when GDD becomes less useful as a growth forecast model because it has no ‘top out’ figure for temperature, so if it gets hotter and hotter, the model assumes that the plant will grow quicker and quicker. Of course there are 2 problems with this assumption, firstly, as we got hot it is likely that moisture will be growth-limiting and secondly, grass species themselves have ‘top out’ temperatures above which their growth rate drops significantly as they go into survival mode. It does however suggest that a greens PGR application will probably only last 10-12 days at present.

Poa annua would have the lowest ‘top out’ temperature at anything above 27°C, with maybe the annual biotype a couple of degrees lower because of its shallower root system and propensity to seed more maybe ?

Ryegrass tends to get to 30°C and call it a day growth-wise shutting down its systems to conserve internal moisture levels.

Growth Potential as a model for predicting growth works better than GDD during the summer months because the calculation of G.P has an optimum temperature for C3 grasses of 20°C, though I use 18°C because I think it more accurately reflects stress periods such as the one we are entering now. So if the average temperature exceeds the optimum temperature for growth then you will see a decline in the G.P figure and that serves as an indicator of plant stress.

If we look at the Growth Potential part of the Meteoturf above, you can see it declines through the week and that’s because the model is predicting less growth due to stress. So if you enter a week of high day (and crucially) night temperatures and you can see your daily G.P forecast dropping then it is an indicator that plant stress is very likely.

The final part of the Meteoturf is the predicted moisture loss from evapotranspiration, in this case, 31mm. Now that is a significant amount of moisture to lose from the grass canopy over a 7-day period and it means you really have to be on top of your game when it comes to irrigating from your mains system and hand watering of course. This kind of weather tends to highlight any inadequacies in your irrigation system as well.

Poa annua isn’t always the first grass plant to check out in summer heat

Soil temperature can fluctuate significantly during periods of high air temperature and it is this kind of week when you really notice the negative side of having too much surface organic matter. Organic matter heats up faster than soil and retains heat for longer, once dry it is also very adept at repelling moisture due to the high root system component of thatch so irrigating high O.M turf can be a pretty inefficient process.

So what’s to do in a week like this ?

Plant Leaf N levels

Well firstly keep N levels sensible because if you push too much growth, the grass plant will need to take up more water to support the increase in shoot growth and that’s precisely what you don’t want at the moment.

It is though like most things in life, a balancing act, because we know that running low N levels in the leaf tissue will promote diseases like Anthracnose.

Image courtesy of Bruce Clarke, Rutgers University

Not the greatest image I’ll grant you, but this chart very neatly sums up the relationship between plant N tissue levels and the potential for Anthracnose.

Reading along the bottom ‘x’ axis we have total N concentration of plant leaf tissue and you can see that as we pass below 3.5% (reading from right to left), we dramatically increase the severity of Anthracnose, with 10% at a leaf tissue level of 3.5% and 60% at a leaf tissue N level of 3%.

The message should be clear then, if you’re running low N tissue levels during peak periods for Anthracnose development, you might as well put out a calling card for this disease. By the same token it isn’t about lashing N on, because as I’ve already said this can exacerbate the moisture requirements of the grass plant. The objective is  to achieve a balance in leaf N tissue.

Irrigation

Many of you will have moisture meters and so be ably equipped to know which areas do and don’t require supplementary moisture and how effective your hand-watering is.

You’ll also probably have your own guidelines too, knowing how low you can go moisture-wise before we see plant wilt and footprinting.  If you don’t have a moisture meter, an image like the one above should be a sure-fire warning that you are pushing the plant over the edge moisture-wise and if left uncorrected it will die. Irrigating doesn’t only provide the plant with moisture, it also serves another extremely useful function, that of cooling the soil surface and the plant leaf tissue.

I saw this yesterday at home where I have a flower bed with some really tall Rudbeckia plants (6ft high). They were wilting in the summer heat so I applied some moisture to the leaves to cool down the leaf surface and within 15 minutes they were looking great. It’s the same process when you have a shower, if you don’t dry yourself down properly you’ll note the very welcoming cooling effect on your skin that evaporating moisture plays. So syringing the grass during the middle of the day to wet up the leaf surface can really help well to lower plant stress. Be clear this isn’t irrigating per see, it is applying a fine mist to the leaf canopy to cool the leaf surface and thereby lower moisture loss.

Rolling not cutting

Since we have been dry for much of June, most of you will already be doing this so please forgive me if you think I’m trying to teach you to suck eggs. Missing a cut and rolling instead has been consistently shown to be beneficial to the grass plant during periods of stress and it is worth noting that the Anthracnose work at Rutgers University found no negative relationship between increased rolling and this disease, in fact the opposite. This was held to be because a firmer surface gives a truer cutting height from bench set to actual so you are putting the plant under less stress. Whilst we are on the subject of cutting height, raising it from 2.75 to 3.2mm has also been shown to be beneficial in reducing grass stress and Anthracnose. The use of more rolling as a substitute will also negate any potential loss in green speed. Skipping the clean up cut during stress periods is also a given for me because it is often here where you see the first evidence of plant stress and in particular Anthracnose.

Biostimulants

Some of the research work I am doing currently has shown that certain types of biostimulants (I’m not mentioning which because most of my competitors use a photocopier as a substitute for an R&D department 🙂 ) only produce a beneficial effect when the plant is under stress. So during periods of high temperature stress, biostimulant use is key and applying a good quality product can achieve positive results. If you are making a wetting agent application, combining the two is a 2+2=5 scenario for me. I saw this back in August 2006 when I was doing trial work on wetting agents and biostimulants.

During the trial I progressively decreased the amount of irrigation I was applying to the trial plots as a % of E.T. Once I got to 40% replacement of daily E.T (So on a 4mm E.T day I was applying 1.6mm of irrigation) I began to notice plant stress on most of the plots apart from the one where I had combined a biostimulant and wetting agent application. At the end of the trial (and during a very hot week when temperatures were up in the thirties) I turned the irrigation off completely and just watched the plots go backwards. They duly did but the one that stayed the healthiest for longest had the combination of biostimulant and wetting agent. Seeing is believing…..

Ok that’s it for this week, enjoy the sun, remember to use your sunblock and re-apply to areas where it is likely to be removed through the day.

All the best.

Mark Hunt

 

June 18th

Hi All,

So only a couple of days before the longest day and then we start our inexorable slide towards the autumn 🙁

It always kind of confuses me when we reach this point in the summer, well before summer has actually taken place and the same for the shortest day around the 20th of December. Usually the worst part of the winter occurs well after this date. One cannot argue with the consequences of earth’s rotation though, so I won’t.

Over the weekend some of you enjoyed some rain showers but for many we got very little at all and with drying winds its effects were soon gone. That puts us in a prolonged dry period, particularly for the east of the country with <20mm of rain in May and practically nothing to shout about in June either. Here in the Midlands we have had 1.8mm over the last 3 weeks and looking at the outlook we have an Atlantic blocking high pressure developing this week which will push any rain over the top of the U.K. This will make June one of the driest months we have endured for a good few years I reckon. Will we get payback in August I wonder ?

Before I go onto the weather, a quick aside. As many of you will know I love nature and together with the 4 Hedgehogs I now have visiting the garden nightly, I put a number of bird feeders up and some fat sprinklers for the Thrushes, Blackbirds, Robins, Dunnock and the like. Now for a long time it’s been a source of constant frustration to me to see a big fat Squirrel empty the feeders on a daily basis. Catapults and water pistols are fine but when you’re out at work, they can do their worst and you come home to an empty feeder 🙁

Image courtesy of www.lovegardenbirds.co.uk

So I researched Squirrel-proof feeders and found this one accompanied by good reviews ;

It’s called the Brome Squirrel Buster Mini  and I think it works 🙂

If anything heavier than 700 gms hangs on the feeder, the spring compresses and the inner feeder slots into the outer guard, effectively denying the weighty Squirrel access to the contents of the feeder. You can alter the trigger weight if you have thinner-than-average Squirrels visiting 🙂

The instructions say you should hang it 18″ away from as feeder, tree, post, etc to stop the Squirrel hanging over and attacking it from the side.

Mine is about 12″, 30cm away and I am pleased to say that after 2 weeks it remains unmolested by those bloody Squirrels and I now have a thriving number of young birds (Coal Tits, Robins, etc) visiting on a regular basis no longer intimidated by a tree-living Rat.

Ok back onto the weather for the coming week….

General Weather Situation

It’s a north-south and west-east divide for the beginning of this week with frontal systems affecting the north and west whilst the south sits in a period of calm, fine and dry weather. Today we start dry in all places but by mid-morning a rain front will push into the west of Ireland preceded by a bank of thick cloud. This rain will cross Ireland on the back of a westerly wind and push into the west coast of the U.K by late afternoon. Anywhere from Wales up to south-west Scotland will see thicker cloud and rain showers developing through the afternoon with rain pushing into northern England and across Wales this evening. All the time staying west though. The afternoon rain that pushes into Scotland will soon fizzle out through the evening as will most of the rain across Ireland, becoming isolated to the south of the country. East and south of this will see a fine, dry and settled day with varying amounts of cloud. In the sunshine temperatures will pick up markedly into the low twenties for the south of England, high teens, low twenties for The Midlands and mid to high teens further north with Scotland and Ireland slightly cooler under that cloud cover. Winds will be moderate and westerly.

Onto Tuesday and we see a re-run of thick cloud and rain building across the west of Ireland before rain sets in from early doors. This time the trajectory is more north-west and the rain is heavier and so we will see showers develop along the north-west coast through the morning and afternoon. Later in the afternoon that rain over Ireland becomes much heavier across the north-western counties and this rain then pushes across The Irish Sea into Scotland and the north west of England during the evening to give a particularly wet night for the north west. South of this rain event we see England and Wales dry and settled with cloud cover burning off during the morning to give a hot, dry and sunny day with temperatures pushing up into the mid-twenties again across the south of England. Again cooler across Ireland and particularly Scotland under that thick cloud and evening rain with temperatures struggling into the mid-teens.

Onto mid-week in a jiffy and the longest day. Overnight and Central Scotland will see that heavy rain pushing through and out into The North Sea so a dry(ish) start for most on Wednesday with lighter winds.  I say dry(ish) because North Wales and the north of England may still see some rain courtesy of that overnight frontal system as we start the morning rush hour but this will soon fizzle out. It will however leave thicker cloud around for many on Wednesday so a slightly cooler day for the U.K and Ireland, except for the south-east of England which will see clearer skies and hotter temperatures, again climbing into the low to mid-twenties. As I mentioned earlier we have a blocking high developing out in The Atlantic and on Wednesday we will start to see the effects of this high pressure introducing northerly winds into Ireland and dropping the temperature down into the mid-teens.  Further east we will see light westerly winds but these will change overnight to a northerly.

Thursday sees those light to moderate northerly winds in place so a cooler day for sure. That change in the wind direction may just push some rain down the north-east coast of England across into East Anglia overnight but we will see. Other than this we look dry for the whole of Thursday with varying levels of cloud and sunshine. The northerly wind will drop the temperature considerably across the south of England down into the high teens with Scotland and Ireland a couple of degrees lower.

Friday starts off clear and cool after a chilly night where temperatures will drop into single figures. Through Friday we see cloud build, particularly over the north and west and this cloud bank will move south through the day to give a dry but hazy sunshine kind of a day for most of us. Again with a cool northerly wind in situ we will see temperatures locked in the high teens perhaps just breaking twenty degrees across the south of England. Dry again though.

Dry and settled is the forecast for the weekend with varying amounts of cloud and a north to north-westerly wind in situ. This means we will remain on the pleasantly cool side with cloud cover and that wind keeping temperatures down into the high teens. High pressure looks to remain in charge for the foreseeable so dry and settled it is.

Weather Outlook

High pressure looks to start off next week so remaining dry and settled but not especially hot because of the position of the high and the orientation of the wind. Through the course of Tuesday next week the high looks to get pushed south very slowly by a northerly low so we start to see some unsettled weather move into the north of the U.K and perhaps push further south as we go through the week. So I think a dry start to next week but more cloud and some rain making an appearance in northerly areas first and then perhaps later in the week further south.

Agronomic Notes

So last week I mentioned that the third week of May provided the conditions conducive to Anthracnose spore germination for definite and that early May when we also had high temperatures was unlikely to have provided the necessary conditions because the humidity wasn’t high enough during this period.

This assertion regarding the early May temperatures has been proved wrong because late last week saw my first diagnosis of active Anthracnose, mainly foliar blight on Poa annua. If you work it back that’s 5 weeks since the early May high temperatures so the finger points strongly to this period being responsible for triggering fungal growth.

I decided to re-look at my weather data from this period using my own weather station as a source of data.

So here’s the data from May 1st till present day looking at air temperature, rainfall and humidity and remembering that we need a minimum of 25°C for 2-3 days to start spore germination.

So you’ll see two highlighted boxes on the graph above (red dashed lines), the first at the beginning of May when we hit 4 days > 25°C from the 5th and although the humidity wasn’t high during those 4 days it was immediately afterwards because we got rainfall.

If this early May event was indeed a trigger, it appears we don’t require temperature and humidity at the same time to generate fungal growth, rather we need the humidity straight after. You can see for the period of the 19th May onwards, we had both high temperature, high humidity and rainfall so that definitely provided the correct combination of conditions for disease development.

Now this doesn’t mean we will see rampant Anthracnose this year, more it’s one piece of the puzzle. The defining piece is whether the grass plant we manage goes under stress as Anthracnose is a stress-related disease. I believe when a grass plant is under stress it releases hormones (similar to humans) and the presence of these hormones acts as a trigger to disease growth within the grass plant, effectively switching the disease from a biotroph to a necrotroph.

It’s just a theory of mine. Of course the main stress we see during the summer is drought stress and with some areas of the country especially dry it isn’t beyond the realms of feasibility that we will see this disease manifest itself in foliar blight form from now on. Of course the other trick it has up its sleeve is that Anthracnose can also develop as a basal rot during periods of prolonged leaf / crown wetness so it can be of equal issue during a wet summer.

The idea therefore is to minimise stress, maintain plant health in terms of adequate and not deficient / excessive N nutrition and keep doing those all-important good cultural practices.

Other pathogens….

Now sometimes in this job you get sent an image which introduces more than a couple of frowns to the forehead. Such was the case last week when I got this in my inbox…

So kind of vague yellowing, some areas showing stimulated green up around the circumference.

We duly sent a sample off to Kate @ The Turf Disease Centre and I nipped along to have a look at the actual symptoms. What struck me was that the appearance was related to grass species distribution across a green rather than a specific ring or patch. The grass looked like Poa annua to me and if I guessed I’d say it was more of a annual biotype because it was coarser-leaved and seeding still. My first thought was either a plant-parasitic nematode species or perhaps Waitea (because of the pronounced yellowing) / Superficial Fairy Ring. On examination there was no depression in the area, no smell and it was only present on a few greens which had this grass species / biotype present.

Whilst I was at the club, Kate’s disease diagnosis came in and promptly re-introduced that frown to my forehead.

Image courtesy of Kate Entwistle – The Turf Disease Centre

As you can see from the image above the disease was diagnosed as Take All or to give it its proper lardy-da name – Gaeumannomyces graminis var avenae.

So here we have a disease present on Poa annua rather than its more normal host, bentgrass.

Rather than showing as rings of dying turf it seemed to be only affecting specific Poa biotypes. My SWAG (Scientific Wild-Arsed Guess – Copyright Dr James Beard) is that this type of Poa was shallow rooted and therefore particularly susceptible to stress / desiccation. So the combined effect of this pathogen and elevated stress levels (the course had struggled with an irrigation system problem) was enough to tip the plant over the edge and display yellowing (probably as a result of poor nutrient uptake through a compromised root system)

It just goes to show you learn something new every week in this job and goes a long way to explain my well-furrowed brow 🙂

PGR applications on greens and longevity….

Did a little look at the temperatures we have had lately in The Midlands and correlated them to GDD.

Working on the U.S principle of applying every 200GDD (calculated using 0°C as a base) or approximately 130GDD ( (calculated using 6°C as a base), I reckon a PGR application on greens is lasting 12 days at present before we see rebound and that’s regardless of rate. Looking ahead we have some cooler nights from mid-week when that north wind kicks in so this will probably stretch out to 14 days through the next period. The bottom line then is to keep applications tight.

Ok that’s it for this week…

All the best…

Mark Hunt

June 11th

Hi All,

It’s not difficult to see the effects of the very strong grass growth in May this year. Anyone who uses the roads will have noticed the tall grass growth around junctions and roundabouts that makes it impossible to see approaching traffic clearly. If like me, you spend a little time blatting about on a motorbike, you’ll have felt especially vulnerable in this case. Of course we have local cutbacks in budgets that must take some of the blame but for sure with the last 3 May’s showing a trend for increasing GDD, it must be a difficult task deciding how and when to target your limited grass cutting resources in this area.

It’s all change this week with a move to more unsettled conditions and a westerly airflow after 4 weeks of north / north-east dominating the weather. That means cooler, fresher even, some rain for sure, probably more for north and western parts initially and more consistent night temperatures. Let’s put some detail on it for the coming week.

General Weather Situation

A dry start for Monday for most, but there’s going to be some rain around with a thicker cloud base over Central Scotland likely to bring drizzle to the party and then later some heavier, more localised rain. As we go through the morning the heavy mist burns off to produce a warm, sunny day with temperatures rising rapidly into the mid-twenties for the south of England. Ireland looks to continue a nice run of weather with a dry, warm and sunny day. By late morning however we will see some rain showers push in to the north-west, north and possibly South Wales, The South West and north of England. This doesn’t really move much and if anything becomes lighter and more dispersed through the afternoon, as does the cloud cover. Now with moisture and rising temperatures we are sure to see some showers kick off later in the afternoon and the advice as always is look at your rain radar. Temperature-wise, mid-high teens for Scotland under that cloud cover and pushing up to the mid-twenties across the south of England. The wind will remain north-easterly through Monday.

Tuesday looks a cooler one with more in the way of cloud about for all the U.K and Ireland. It’ll be reluctant to burn off as well on Tuesday so that’ll keep the temperatures down a tad on Monday. Maybe the south-east of England will see the best chance of this occurring and if it does, here temperatures will push up into the twenties again. Dry again on the whole though late in the day you’ll feel that north-east wind start to shift to south-east and then by the time you next awake it’ll be south-westerly.

Onto mid-week already, how time flies when you are enjoying yourself. So everywhere will wake up to south-westerly airflow on Wednesday and with it arrives the first rain front from the Atlantic pushing into the west of Ireland early in the afternoon. East of this across Ireland and the whole of the U.K, you’ll have a dry and cooler start with plenty of cloud cover in situ. That rain over the west of Ireland will be heavy at times crossing Ireland through the course of the evening, maybe not reaching Leinster and the north-west coast of Scotland until midnight. So dry, cloudier and a little cooler for everyone on Wednesday, temperatures in the high teens, possibly nipping into the low twenties down south.

By dawn on Thursday morning that rain front will be into the west coast of the U.K bringing potentially heavy rain to Western Scotland, the north-west of England and North Wales. Ireland meantime will see lighter rain showers to start their day. By the start of the morning rush hour the rain will have moved across all parts of the U.K towards the east coast, lessening in intensity as it does so. By mid-morning the rain should have cleared Ireland and be more broken up across western coasts, with the heaviest now across the east and south-east of England. For some areas this will be the first rain for two weeks or so. By the afternoon that rain should have cleared east to leave a sunny and warm end to the day for many, though still with the risk of showers across the north and south-west coasts of Scotland.Temperature-wise, pretty similar to Wednesday, despite that rain, so that’s high teens for most and maybe nudging twenty degrees again down in the south of England. Winds will be moderate to blustery and south / south-westerly.

Friday sees us end the week with a dry (ish) picture for most places though with plenty of cloud cover courtesy of a weak rain front that’ll push some showers into the west of Scotland, the north-west and west of Ireland later on Friday morning. South and east of this we look to have a cloudy but largely dry day with some hazy sunshine. By lunchtime that rain will be into Donegal, Connacht and the west coast of Scotland but it’ll be slow to move inland during daylight hours when it is joined by another rain front. Scotland though may see some rain push into central areas for the second half of the day. Temperature-wise, mid-teens under that cloud and rain and high teens, maybe just nudging twenty degrees in the south of England. Winds will be light to moderate and south / south westerly.

With rain fronts coming in from the west late on Friday it’s no surprise then that the outlook for the coming weekend looks unsettled with rain fronts and thick cloud crossing Ireland and the U.K during Saturday. Sunday looks much the better day of the weekend with lighter winds, hazy sunshine and largely dry, save for some showers across the north-west of Ireland and Scotland possibly.

Weather Outlook

So next week looks like starting unsettled with low pressure in charge and this may potentially bring some strong winds and rain across the north and west of Ireland and Scotland through Tuesday. Further south we look to hold onto some drier weather courtesy of high pressure that pushes the low further north so not a bad week at all once the unsettled conditions have departed. At this stage I don’t think it’ll be ridiculously warm, pretty similar to what we have had, low twenties that kind of thing but with a low north of us and high across the south, they’ll be quite a contrast in temperatures as you move north. It could then quite possibly be a dry June as this weekend is the only rainfall on the radar for south and central U.K at present long-term. Time will tell.

Agronomic Notes

Ok, so a week later than normal, here’s our round-up of how May 2018 shaped up across the U.K and Ireland from a growth perspective.

May 2018 – GDD Analysis – Location – The Oxfordshire, Thame, U.K

After the dismal spring that we ‘enjoyed’ up until the middle of April this year, May 2018 came in as a very good growth month indeed, second only to May 2017 in terms of total GDD. In fact the last 3 years have been the 3 highest consecutive GDD totals for May, which kind of makes you wonder doesn’t it. A very good growth month isn’t great news for everyone because keeping outfield areas under control has been an issue but on the back of memories of a truly depressing March and first part of April, I think we will take it 🙂

It’s no surprise that cumulatively for the year we are well behind 2017, courtesy of that Sudden Stratospheric Warming Event in late February this year and unless we get a barn-storming July and August and / or a warm autumn, I can’t see us setting any records for total GDD this year.

May 2018 – GDD / Rainfall Analysis – U.K Locations

The locations show a very similar rainfall pattern across the entire U.K with the east side of the country the driest I think. (Lincolnshire I know was around 18mm for May)

More to the point with the torrential downpours of late May, most places received 50% of the total months recorded rainfall over a 24-hour period and in some extreme cases, all of their months predicted rain in a 3-hour period ! 🙁

May 2018 – GDD / Rainfall Analysis – Irish Locations

Now it’s not often that you see Irish rainfall totals lower than totals from the U.K, but looking at the easterly locations of Dublin and Johnstown Castle, Wexford, we can see 16.8mm and 33.2mm respectively.

That is one dry month from an Irish perspective !

Even 60.4mm in my beloved Co. Mayo is a pretty dry month, but looking back at last year, it was pretty similar, May 2017 was a dry month as well.

GDD-wise, Limerick looks to take the prize for being the warmest location otherwise all locations are very similar, just like most of the U.K ones, which indicates settled and consistent weather conditions throughout most of the month of May.

We also see the same pattern in rainfall totals with those thunderstorms at the end of May contributing 1/3rd of Cork’s rainfall over a 24hr period and 4 days of rainfall contributing 2/3 of it. In other words, a dry month in terms of number of days with no rain and then a small number of days with high daily rainfall courtesy of storms.

Monthly totals don’t tell the whole story…..

On balance May 2018 looks a pretty nice month from a turf management perspective but the storms at the end of the month brought a tricky combination of high temperature, highly localised rainfall and high humidity.

You can see this in the two graphs below from Swindon and Cork, featuring daily GDD and rainfall….

So in both locations we can see some real peaks at the end of May with daily GDD exceeding 12 (in my books this constitutes a growth flush) accompanied by high daily rainfall totals.

I didn’t manage to analyse how much nitrogen was contained in the rainfall that we had during those storms at the end of May but the fact that they were accompanied by lots of lightning suggests that it may well have been in the region of 1-5kg / N / Ha / inch of rain.

What happens here is that the energy contained in lightning is high enough to break the bonds of nitrogen oxide molecules present in the atmosphere (remembering that air contains 78% nitrogen) allowing it to combine with oxygen to form nitrate N (NO3) which is plant-available. So we get a lovely green up after a thunderstorm in part because grass receives a dilute liquid feed.

In the past I have measured amounts of nitrogen in rain water and then done the calculation working on the fact that 1″ of rain represents 254,000 litres of water over a hectare (shocking mix up of units there which I put down to my split parentage of Danish-English).

If you then measure the N content of the water, you’ll get a figure in mg/l so you can just multiply up to get kg / N/ hectare. I have worked out that if you have a total N figure in mg/l, then you multiply it by 0.254 to convert to kg / N/ Ha / per inch of rainfall.

So in the past I’ve typically measured 0.75-1.0kg / N/ ha per inch of rain (25.4mm odd) but during some trial work in Ireland way back in 2007 / 2008, I measured nearly 5kg / N / Ha (per inch of rain) that was deposited in some August storms. (Some of you will remember it because most of Dublin was flooded and the flood water was cascading off Croke Park Stadium roof like a waterfall !)

Agronomically what we saw at the end of May / beginning of June was a surge in growth, particularly in Poa-dominated swards and a ‘puffy’ turf habit indicating a succulent leaf and a fast growth rate.

This made it difficult to keep green speeds sensible at the end of May, beginning of June because the grass growth rate was so high and the sward was soft.

It also made it very easy for fungal pathogens like Microdochium nivale to attack the grass plant and that’s why we saw such aggressive Microdochium across swards during late May / early June.  A combination of a thin leaf epidermis (because of fast growth rate) and long periods of elevated plant leaf wetness (because of high humidity)

I also think this surge of growth was too much for PGR to hold back as I had a number of reports of excess clipping yield even when a PGR had been applied.

Anthracnose Trigger ?

Now that the gliche in Weather Underground has been fixed I’ve been able to look at some different sites across the U.K and Ireland to determine if we had the correct combination of conditions to trigger spore germination. You’ll remember from past blogs that with this disease it is air temperature around 25°C for 2-3 days combined with high humidity around 87.5%. (marked red below)

So I’ve down a lot of data trawling, one of those jobs that you start and then wish you hadn’t because it has taken hours to sort.

Now the data below comes with lots of caveats, not least that I’ve lifted weather station data from around Ireland and the U.K and so much depends on where that weather station is situated. It also depends on whether the location received one of those heavy storms as well to generate the humidity.

Caveats aside, It does at least give a flavour as to which areas have had the necessary temperature and humidity combination for Anthracnose disease development to be initiated.

Now you’ll remember that even if this particularly disease is initiated it doesn’t necessarily follow that you’ll see symptoms develop later in the summer because the plant has to go under stress, usually from high temperature / high E.T. This data does serve as a line in the sand though that some areas have been warm and humid for long enough to start the ball rolling. If we do get high temperature stress in the future then I’d expect to see symptoms from the beginning of July onwards, perhaps more so toward the middle / end of July.

Ok my head is frazzled, that’s it for this week, time for a cup of Earl Grey and a lie down….

All the best…

Mark Hunt

 

June 4th

Hi All,

Another topsy-turvy weather week passes with some cracking thunderstorms and rain coupled with heat and humidity. You could see the cloud formations building as we went through the day as updrafts funnelled hot air from the ground and pulled in cool air and precipitation. I snapped this one over Hallaton in Leicestershire whilst out for a yomp enjoying the beautiful countryside. As usual though when you get this type of rainfall formation it was very hit and miss.

Things looks to settle down this week as we lose some of the heat and humidity courtesy of the return of our old friend, the north-east wind and cloud cover.

General Weather Situation

So Monday starts off as a drab, dull one across many areas as that switch round from west to north-east wind rolls into play. Here in The Midlands, I can accurately report it occurred at 7.20 p.m. last night as I was fishing the evening rise at Eyebrook (which had only just started) and then the wind swung round completely, the temperature dropped 5°C in a fraction and the fish promptly shut up shop 🙁

With this wind in situ, it’ll be the familiar picture of eastern coasts staying dull and the best of the brightness out west across Wales, The South West and Ireland. Maybe not today for The South West though as we see a risk of rain spreading into this area through the morning together with some drizzle and light rain for south-west Scotland. Elsewhere that cloud will keep the mockers on the temperature for most of the day occasionally allowing the sun to break through across South Wales and most of Ireland. So temperature-wise, a bit of a drop from the mid-twenties of the weekend down to mid-high teens for areas of the U.K under that cloud and lifting to low twenties where you see the sun, so more to the west and for Ireland.

Tuesday sees much of the same, plenty of cloud around initially but this will break from the west to give long spells of sunny weather and pleasant temperatures for most areas. Ireland looks to see some rain showers through the day, more down the middle of the country and probably accompanied by some thunder as well if the heat gets up. By the afternoon, that cloud cover should be confined to eastern coasts and the north of Ireland as well allowing temperatures to rise nicely into the high teens, maybe touching twenty degrees for Ireland. Winds remaining light to moderate and from the north-east.

Wednesday sees almost a carbon-copy re-run of Tuesday, starting off dull with plenty of cloud cover and then the sun burns this off from the west allowing temperatures to rise significantly. We may hang onto that cloud cover again across The North East and Western Scotland but otherwise dry and sunny is the forecast. For Ireland we see the familiar pattern of a warm, dry sunny start to the day triggering off some thunderstorms later in the afternoon and into the evening. These are more likely to be western-orientated. The wind will be as is, north east and light to moderate. Temperature-wise, 18 – 22°C depending on cloud cover.

Thursday sees another predominantly dry day but with a thicker cloud mass over the east of the U.K. So a better chance of seeing the sun and some decent temperatures across Ireland, Wales, The South West and west coast of the U.K. Again that cloud cover may be stubborn to clear from the east of the country and we may see a re-occurrence of those thunderstorms across the west of Ireland possibly. Similar temperatures to Wednesday, 18 – 22°C depending on cloud cover with that north-east wind keeping things pegged down on the pleasant side of warm.

Closing the week out on Friday we have pretty much an identical day to Thursday, cloud cover across the east, clearer and warmer across the west, you get the picture by now I am sure. The only potential fly in the ointment may be the risk of continental rain drifting into the south-east of England late on Friday evening. Similar temperatures to Thursday, 18 – 22°C depending on cloud cover. Kind of a boring weather week really.

So the outlook for the weekend is more of the same I think but we have a Bay of Biscay low pressure close by as we go through the weekend so there’s a chance that may feed up some rain into the south-east later in the weekend. We will see. We may see the wind change from north-east to easterlies which will tickle temperatures up a little but at the same time may increase the risk of rain drifting over from the continent. Otherwise it looks dry, sunny and pleasantly warm on the whole with temperatures in the high-teens / low twenties depending on cloud cover. No complaining here.

Weather Outlook

So next week looks very similar to this week, well at least the start of it does but we still have the low pressure lingering south of us to potentially muddy the waters somewhat. At this stage the projections are for that low to stay south of us and that means any rain may just be along the south coast of England, Ireland. So a weak high pressure stays in charge for the early part of the week and things look to stay settled until Thursday that is when all the models point to a change in the weather to a more Atlantic-orientated air stream which will push in at the end of next week bringing strong winds, cooler temperatures and rain I think to most areas starting with the north and west first and then moving southwards in time for the weekend.

Agronomic Notes

Normally being the first blog of the month I do a monthly GDD summary but that’ll have to wait till next week when I have some more GDD summaries in from around and about the U.K.

Disease Pressure

Over the last week we have seen quite significant disease pressure on many turf surfaces prompted by rainfall, high temperatures and above all, high humidity. The chart above shows a readout for May from my location and you can clearly see the 100% humidity peaks on the 24th, 25th, 26th, 27th, 30th and 31st.

Looking at surfaces last week there was a good amount of Microdochium nivale apparent, not just on greens but also collars, complexes, approaches and even fairways. Fortunately with high daily Growth Potential as well, this was being grown out as fast as it was appearing and already you could see new growth in the affected areas, especially off green.

The chart above from The Oxfordshire (thanks Sean) reinforces the end of May period as being the main culprit behind increased disease pressure with the 26th, 27th and 28th of May representing continual high humidity.

There were other factors driving this disease development including very mild overnight temperatures with the minimum temperature at my location exceeding 13°C  from the 28th May onwards right through to last night when we didn’t drop below 14.9°C at all. Dew formation as well was very heavy on some mornings leading to extended periods of leaf wetness.

So we have a witches brew of high overnight temperature, humidity and dew and that will always drive disease.

…………………………….

Other diseases kicking about have been Superficial Fairy Rings and some Etiolated Growth, particularly on the clean up strip cut on greens.

We have come to a bit of a dead end with this disease of late in terms of finding a way forward. In the U.S it is pinned on a bacterial (rather than a fungal) infection of the grass plant but in all the samples I have taken we have failed to either observe the bacterial streaming synonymous with Etiolated Growth or isolate any one of the identified causal bacterial pathogens.

You can kind of look at this both a positive and a negative really because if we had identified a bacterial pathogen there isn’t anything we could do about it other than nipping down to the doctors for some antibiotics and plastering Streptomycin on 🙂

I can’t understand why it shows up so clearly on the clean up strip cut either, right on the margin between the green and the collar cut ? Ideas anyone ?

Anthracnose Trigger

Last week I talked about the potential for the weather during May to have given us high enough temperatures to initiate Anthracnose Spore germination. The question is whether we also got the humidity as well to give the fungus a chance to grow on the leaf and initially infect the plant. When you look at the fact that May’s weather was so variable in terms of rainfall and also temperature it is likely that in some parts of the country we hit the required threshold values for both temperature and humidity whereas in other parts we didn’t. Scotland for example has been really warm and when I can access some local weather station information (Weather underground appears to have changed its API access so you can’t look at historical data currently) I’ll be able to determine if this area of the country may have got an early Anthracnose trigger or not.

PGR efficacy or lack of efficacy ?

I’ve had some reports of pretty poor performance from PGR’s applied lately in terms of not suppressing growth particularly well. I’m not sure if this is anything to do with the product though because when you look at the end of May, the growth level has been really high with 6 out of the last 7 days of May showing a Growth Potential > 0.9. It could just be that with a high growth rate the amount of regulation afforded by Trinexapac-ethyl hasn’t been as significant as usual.

Looking at the temperatures in May and putting them into the U.S GDD model for PGR usage, it looks to me that a greens application of TE should have lasted around 14 days no problem so I don’t think it is a case of the A.I breaking down in the plant overly-quickly.

……………………..

Acelepryn Insecticide

As mentioned last week it looks like the above product from Syngenta has received Emergency Use approval in the U.K. As I understand it the rate will be 0.6 litres per ha and it will only be used as a preventative treatment. Product supplies are likely to be limited and the cost will be significant per hectare, that said I think it is excellent news for our industry and I commend Syngenta for pushing this through and giving greenkeepers and groundsmen-alike an option now for grub control depending on the area they are maintaining of course. Full details of the E.U approval and product will no doubt be available on Greencast in the future (I bet Dan’s busy writing it as we speak 🙂 ). For some background reading, you can find a link to the U.S product technical sheet here

Please bear in mind this is the U.S tech sheet and it is only provided to give you a heads up, nothing more.

Ok that’s me for this week, all the best for the coming week.

Mark Hunt