August 23rd, 2021

Hi All,

As you can probably guess from the picture above I spent another soggy session in a boat at the weekend, not too bad this time as I swopped days on the basis that Saturday’s rain looked worse than Sunday’s. When you look at what happened this weekend it kind of typifies summer rainfall forecasting. A big rain front came through on Saturday, most areas got the rain that was forecast but it arrived later than forecast in some areas and earlier in others !

Sunday looked a dry day and for many it was, save for a line of showers (see above) that pushed down across northern England, through Rutland and Leicestershire and down south (see above). Not forecasted but if you were under them, you got plenty of rain. Guess who lives where the triangle is 🙂 !!

Now for me it wasn’t a great issue, I’m always grateful of summer rain as is my garden and although it changes the fishing dynamic, it’s only temporary and to see the sky full of Martins and Swallows again was beautiful. There’s also a young Osprey at Eyebrook, probably a Rutland Water offspring. I saw him / her hunting 3-4 weeks ago and he / she couldn’t quite master leaving the water with a fish. No such problem now as he/ she has morphed into an adept fisherman / fisherwoman !

GFS output 230821 – courtesy of Tropicaltidbits.com

General Weather Situation

So we enter the last week of August and I can tell you that the coin has flipped nicely on the side of some drier weather, not intensely hot, but dry and with some sunshine as well. As predicted last week we have our own heat plume coming up from The Med this week and as suggested then, Ireland and particularly Scotland will pick up the highest temperatures.

So a pretty straight-forward weather forecast this week as you’d expect with high pressure calling the shots. There will be some temperature and cloud variation though because of the wind direction primarily. There’s not many times that I can remember writing….”So a dry week for the U.K & Ireland across the board” but that’s what it looks like from where I am sitting with temperatures in the low twenties for England, Wales and Ireland. Maybe just a degree or two down on this dependent on cloud cover. Scotland will pick up temperatures into the mid-twenties and not for the first time this year, it’ll be the hottest country in the U.K.  The factor that will make the difference with respect to temperature will be wind strength and direction and for England we have a north east wind set all week which will usher in more in the way of cloud cover during the week so that’ll lessen the sun hours and keep the temperature ‘sensible’. Scotland has lighter winds and so less cloud and higher temperatures. Ireland and Wales are further away from the effects of a north easterly airstream and so they’ll be more in the way of sun hours.

GFS output 270821 – courtesy of Tropicaltidbits.com

The GFS output above shows Friday, 27th of August and you can see how much of a heat plume we are in. It’s a bit like looking at a larva lamp, this plume will detach itself from the main heat across southern Europe and sit across us. I’d also draw attention to the low pressure system over The Baltic, Eastern Europe. This is a slow-moving system and it is likely to bring some very heavy rain and flooding to those areas. You can also see another low pressure sitting down off The Bay of Biscay. Essentially it’ll be between these two low pressure systems how our weather develops next week.  It is an important weekend for me as it’s MotoGP at Silverstone so I have everything crossed that it is a dry one.

GFS output 300821 – courtesy of Tropicaltidbits.com

So the outlook appears to be stable high pressure to see out the rest of the month and provide us with a really nice Bank Holiday weekend. Can’t say fairer than that can we 🙂

Weather Outlook

Well I’m on holiday in early September so what’s the betting the weather breaks up just as I pack up my stuff and shut the car door ?

So the pattern of weather for next week looks stable enough with similar weather at the start of next week to this week until we reach mid-week when that low pressure over northern Europe begins to push a northerly airstream down across the U.K. This means cooler and more unsettled weather for Scotland first (who may want a drop of rain by then anyway). So a cooler showery breakdown may be on the cards at the end of next week starting in the north first but hey that’ll be 10-12 days of nice dry weather and let’s be happy at that.

Agronomic Notes

Disease Pressure

Over the last month or so we have had pretty unsettled conditions, gloomy (as I covered in my DLI info last week), wet and on occasion, humid.

This has meant we have had lots of disease pressure, thatch fungus, Superficial fairy ring, plenty of Take all on Poa annua (as is the MO now when we have a wet summer), Dollar Spot, Anthracnose (of late) and of course Microdochium nivale. You don’t have to be a rocket scientist to predict all of the above when we factor in the weather.

What’s interesting for me being a bit of a disease geek I suppose (5 years of working on disease modelling turns you into one believe me )is how things are changing on the disease incidence and timing perspective. One of the benefits (few) of starting in this industry as a ‘wet behind the ears tyke’ back in 1989 is that I have a database stretching back  over 30 years, so I thought I’d put down my thoughts and observations this week as a bit of a discussion point. This week I’m going to cover Anthracnose…..

Then and now….Anthracnose

Acervuli (spore production bodies) of Anthracnose on Poa annua

Well back in the late 80’s and early 90’s, this was a disease confined to the autumn and winter and it manifested itself solely in the basal rot form so no occurrence in the summer, no foliar blight and to be honest it was very much a disease of minor importance.

I would say it wasn’t till the early 2000’s (ish) that we began to see this disease morph into a summer variant with more aggressive outbreaks of a foliar blight kind. Interestingly over the pond in the U.S, Anthracnose came to prominence as a turfgrass pathogen at around the same time. There’s an interesting article from GCM back in 2012 that covers the history of this disease, you can find it here

Anthracnose Foliar Blight

So here we have a disease that has basically adapted because the pathogen is the same, Basal rot or Foliar blight, there’s no difference in the actual pathogen, just when it occurs and how it manifests itself.

There is a big difference in the consequences though because Foliar Blight occurring in August for example is a painful disease. It often lingers, sometimes it appears to get better, other times worse and recovery is slow. If you look at the picture above which is of Foliar Blight Anthracnose, it is a fair bet that some of the grass that is affected will die, some will sit there for any number of weeks and some that at present appears unaffected, will become affected. The problem is that Foliar Blight Anthracnose tends to occur in August and so during a period of high play (particularly this year after lockdown) and of course it is even more of a problem when you consider that the following month, September is one of our busiest months for golf. In short, you’re at summer cutting height and frequency, you don’t want to push recovery with N and get slow greens, so you’re between a rock and a hard place. And so it lingers…The other reason why it’s more of a problematic disease is that by the time you and I notice the symptoms on the turf it has already produced more spores. And so it continues….

I find it interesting that Anthracnose rose to prominence as a disease either side of The Atlantic at roughly the same time….We are looking at different climates and climatic zones so it is unlikely to be solely down to climate that has driven its rise. I remember Bruce Clarke (Rutgers) saying during one of his excellent GCSAA Cool Season Turfgrass Pathogen classes, that 10 years ago, Anthracnose didn’t make the top 10 pathogens reported back by superintendents. Over a 5-year period at the start of the 2000’s it rose quickly to the no.2 spot, second only to Dollar Spot. The question is why ?

Well if you look at the BMP’s that you need to have in place for Anthracnose, they include adequate nitrogen / potassium fertility, a cutting height > 3.2 mm and a free draining profile, without of course surface fibre build up.

Therein lies the rub because we know over recent years there has been more pressure for faster greens, lower cutting heights and nutrition levels have lowered from an N perspective. Throw in more climatic stress (heat plumes and the like) and you have a sometimes deadly combination of abiotic and biotic stress. Turfgrass stress is the main driver behind Foliar Blight and I think the increase in this disease is purely down to an increase of stress on the grass plant, both man-made and natural (climatic). Surface organic matter build up is a big contributory factor as well because if you have a concentration of surface fibre AND it is poorly ameliorated with topdressing, then you effectively have a surface on your greens that will hold water when it is wet, heat up faster (than the same amount of O.M ameliorated with topdressing) when it is hot and thereby increase stress on the grass plant.

Comparison between exposed crown of grass plant on left vs. ‘protected’ topdressed crown on right

When we measure surface organic matter (SOM) levels one area that we miss just by looking at a % figure is the ‘nature’ of that fibre.

Now before we got into the very worthwhile practice of measuring SOM by %, we used to cut a plug and test the depth and nature of the organic matter, well I did anyway 🙂

So I’d cut a plug and use a knife to work my way up from the bottom of the plug until I felt resistance. This signified the bottom of the thatch layer, I’d then lightly compress this and measure it. Ideally I’d be looking for 8-12 mm of fibre, not more and nearly as importantly, not less either. Next I’d try and pull the fibre mat apart. If it was very tight and required considerable effort, then it was normally a sign to me that the fibre layer had little topdressing incorporated through it or sometimes it had heavy amounts but they were applied infrequently resulting in the inevitable ‘Victoria Sponge’ effect.

Another give away was lateral or bridged rooting within the fibre layer, indicating that the grass plant’s roots were unable to penetrate down the profile through the SOM layer. The core pictured below is a classic with a thick matted surface layer of organic matter, bridged rooting and the tell-tale give-away of good roots down an aeration hole !

Compressed, matted fibre with precious little topdressing through the profile, note the good rooting far left down an aeration hole…

Now just imagine what the environment is like in the surface from both an agronomic and playability perspective. Soft, poor draining greens for sure that will hold surface water and during the heat of the summer, heat up faster than the air above them because SOM is a vector for heat. There’s another likely consequence as well in that greens with this level of SOM will have a lower actual cutting height because when wet the mower will sink into the greens. So a 4 mm bench set = 2 mm or less actual. When you then factor in that cutting height or a low cutting height is one of the driving BMP’s behind Anthracnose, maybe this is a another contributory factor ?

Throw in more environmental triggers, less effective chemistries and the development of resistance to the chemistries we have got that have a label recommendation for Anthracnose and there you have it. A real witches brew….

If we look at the prospect that climate models point to more extremes of heat and rainfall and the recent Met Office data showing this is now a trend in our climate rather than a future eventuality, then we could venture the opinion that this disease is with us for the foreseeable.

Happy days….

Finishing on a positive note, I did a quick ‘look see’ on disease pressure this month from a Microdochium nivale perspective and you can see it’s been quite formidable with a lot of peaks > 80%. This is for a Central England location but if anything I’d say Ireland has had more pressure, Scotland and Wales, slightly less.

Fortunately we have had good growing conditions (see G.P graph below) and that’s why it hasn’t manifested itself too widely (unless of course your greens are low N and weak) with the disease presumably growing out as fast as it occurs…

With the change in the weather to a more settled, high pressure aspect we can see how the projected disease pressure decreases through this week as the grass plant dries out and climatic drivers tip away from Microdochium nivale.

Always good to end on a positive :)……

All the best.

Mark Hunt