July 5th

Hi All,

This week will be a short blog because I’m attending a 3-day internal meeting showcasing our new turfgrass research facility at Throws Farm where I have been working over the last year or so, so time is short today.

Next week will be a special blog for me, in it I’ll do a synopsis of June using all the weather data you have kindly sent in and then I have some news to impart.

The picture above taken at Donington World Superbikes this weekend, kind of sums up the weather. I rode through nice warm and sunny weather and then torrential downpours the next with the roads awash. Only4,000 fans were allowed to attend this outdoor event compared to the 140,000 that will be allowed to attend Silverstone F1 and 60,000 at Wembley, Money talks eh ?

Speaking of football, definitely had to swallow my words regarding England, an exceptional display on Saturday night, brilliant to watch, but now comes Wednesday night. With a Danish mum (sadly departed, she’d would have loved this) and an English dad, I have a real dilemma on my hands. Half of me will be happy whatever the result but in truth I’d love to see England win because after all this is where I’ve lived so its my country. It makes you think though when you are a bit of a genetic tankmix 🙂

So I’ll do a summary of this week’s weather, a look at next week and some agronomic goings on….

GFS Monday 5th July, 2021

General Weather Situation

So as you can see from the GFS output above we have another low pressure system moving in from The Atlantic and this is due to bring us strong winds, cooler temperatures and rainfall for the first 3 days of this week as the low pressure system moves across the U.K. The wettest period looks to be Monday night into Tuesday and by the time we reach Wednesday, the bulk of the rain will have cleared Ireland but still be crossing the U.K. It’ll clear from the south west as it moves north east into The North Sea. By Thursday that low pressure looks to have moved away completely, the temperatures start to recover into the high teens / low twenties and we have a nice dry and warm end to the week as high pressure builds across the U.K. Note the words ‘across the U.K’ because by Friday, Ireland will be picking up a weak Atlantic weather front which will bring rain from the off for the west of Ireland and thereafter it’ll track eastwards.

The U.K isn’t out of the woods yet though because the weekend sees that weak weather front providing an unsettled spell of weather with sunshine and showers and light easterly / southerly winds. Temperatures will remain rooted to the high teens which personally I think is pleasant enough thanks.

Predicted GFS 12th July, 2021

Weather Outlook

So the end of June and beginning of July has seen a pattern of Atlantic low pressure systems push over the U.K & Ireland bringing some really torrential rain in places.

Is this pattern set or is there a chance we will see a transition to hotter, drier weather ?

Well if you look at the GFS predicted output for next Monday it looks remarkably similar to today with an Atlantic weather front pushing cooler and unsettled conditions into our weather picture for the start of next week.  Now this low pressure is predicted to take a more northerly path so the north and west is likely to see more of the rain than the south of the U.K & Ireland. Nevertheless the prediction is for a continuation of the cooler and unsettled conditions for the first part of next week but…….There is an upside because a ridge of high pressure looks to build across Ireland first on Wednesday and then the U.K from Thursday onwards so we will see I think (if the GFS prediction pans out) some warmer and drier weather for the second half of next week. There may be a temporary cooler period thereafter but from the third week of July that heat returns and looks like building again. So warmer / hotter weather is on the horizon. (if you like that kind of thing)

Agronomic Notes

Growth patterns 

Now I will do a more detailed synopsis of June 2021 next week but it’s worth a quick look at how we fared from a GDD perspective for June at our default location of Thame, U.K.

Well we came in at 294 total GDD which ranks as one of the highest GDD totals we have seen (3rd highest since 2010) for the month. Now as we know the GDD model (regardless of which base temperature you use) is flawed because it has no ‘top out’ temperature, that is to say if the temperature goes up, so does the GDD, even when the temperature is too high to support optimum grass growth. Typically this is 27°C plus for Poa annua and 3-5°C more for Lolium perenne. A more accurate measure of plant growth is of course Growth Potential, so if we look at the 30 days of June and we know optimum G.P per day is 1.0, the total representing maximum growth is 30 total G.P for the month. Well this site came in at 25.82 for the month, which represents 86% of optimum growth for June. So the bottom line is if you couldn’t grow grass in June, you need to have a word with yourself in the mirror 🙂

Disease activity

Of course this isn’t the whole story for June and the early part of July because it wasn’t just a good growing month for grass. We had a very dry first half of June for a lot of locations and then the rain arrived with some torrential downpours taking place. This location picked up 51.8 mm over the 17th and 18th with 43 mm falling on the 17th !.

June was a dry month in Ireland as well, particularly for the east with rain arriving in the last week of the month and then making up for it big time in July to date ! This was because the low pressure systems that affected the U.K tended to push up from The Bay of Biscay and so the southern half of the U.K copped it most with Scotland getting off lightly as well.

This combination of temperature, rainfall and humidity has meant June will also go down as one of the highest disease pressure months I can remember with a period over the weekend of the 19th and 20th coming in close to 100% optimum conditions for Microdochium nivale.

Want to know what that can look like on managed-amenity turf, well try this…..

Microdochium nivale at optimum growth rates – June 2021

Now even if we had Iprodione, Tebuconazole and Prochloraz still kicking about, they wouldn’t have been able to hold back this severity of disease attack, absolutely no way. This high disease pressure at the end of June has carried on into July and with the run of Atlantic low pressure systems, high humidity, heavy dew formation and the like, it is no surprise that we have seen plenty of disease making an appearance.

Not just Microdochium.

Smith Kerns model output – The Oxfordshire, Thame – June 2021

The Smith Kerns Dollar Spot Prediction model has been running at > 40% for some periods of the month at this location and that has meant diseases that favour humidity have made an appearance.

These include Superficial Fairy Ring, Fairy Rings (other types), Dollar Spot, plenty of Red Thread.

Take All in Poa annua

We have also seen plenty of Take-All activity as well. No surprise really considering the wet May we all endured and then as we hit a dry June and the E.T began to ramp up, the grass plant called on its roots to uptake optimum moisture and found it couldn’t because of damage inflicted by this pathogen. So then you see the ring-like thinning, sometimes quite ill-defined because of grass composition and not only taking out bentgrass but also Poa annua. If you looked at the damaged roots through a microscope you’d be able to see the black runner hyphae inside the plant root. (see below)

Black runner hyphae of Take All in Poa annua

The above is a Poa annua plant infected by Take All and in my experience sometimes it can recover (just like Anthracnose) by developing new roots at the bottom of the crown if and only if the weather plays ball. So although these periods of unsettled weather can be a pain in the butt, they can also aid recovery.

OK short and sweet this week, I have to go off, change into my smart (?) clothes and do the outdoor tour.

All the best till next week.

Mark Hunt