August 3rd

Hi All,

Bit of a quicky blog this week as time is short today for me.

Friday proved to be the scorcher that they forecast with temperatures close to the mid-thirties (higher where concrete pushed the temperature up further like Heathrow) and some pretty challenging E.T figures to match. On the Davis weather stations I am monitoring, the highest E.T came in at 6.82 mm for the day with a peak E.T loss of 0.76 mm per hour occurring at 2:00 p.m. The E.T though continued right into the evening with the wind and heat not dropping off to past 19:00 p.m. It was a challenging day and I can’t imagine the job superintendents in the States have to do with months of that type of weather, they can keep it 🙂

General Weather Situation

So we have had a change since I put pen to paper so to speak last week with high pressure winning the battle for this week. That means rainfall for the south of England and Wales will be in shorter supply than originally projected. I suppose it is to be expected at this time of year that heat will win the day when we look at the battle between low pressure and high pressure systems. So we are in for another end of week heat pulse as warm air pushes a long way north on Thursday and Friday.

So the beginning of this week looks calm and settled with a pleasant start to the day. Some showers will pop up over Essex and mouch about before heading out to The North Sea and we will also see some showers across the north west of Scotland. Throughout the day we will see some more showers pop up, principally over the north and west but also down the east coast so you never know you may just catch one. Temperatures will be on the cool side for the beginning of the week with a cool north west wind keeping things this side of the twenties for England and mid to high teens for Ireland and Scotland. As we move through the evening, the low pressure that was supposed to affect all of the U.K & Ireland will push in from The Atlantic into the west coast of Ireland and bring rain, some of it heavy overnight into Tuesday. So this rain looks pretty well entrenched for the start of Tuesday across Ireland and soon that rain will move north and east across The Irish Sea into the west of Scotland, north west England and North Wales. The rain looks like affecting the U.K north of The Humber, so south of this will just be cloudy, dry and settled. As we go through the day that rain begins to clear the south and west of Ireland and push heavier rain into the north west of Ireland and western Scotland, some of it will be pretty torrential. So wet in the north and west, dry in The Midlands and south of England with similar temperatures to Monday, high teens maybe just nudging the twenties among the concrete down south. Winds will be from the south west.

By mid-week that rain takes a second bite out of Ireland so another wet start for Ireland, the north west of England and Scotland on Wednesday. This rain will be a little further south orientated so there’s a chance of it affecting West Wales, maybe South Wales in the morning and The South West later in the morning but it will stay confined to the west side of the U.K unfortunately. By the afternoon it should have cleared the west of Ireland but still it will push north and east to continue to affect the west and north west of the U.K, with some heavy totals for Scotland. (though the east may miss most of this). A breezy day with winds from the south west pushed along by that nearby low pressure system and similar temperatures to Tuesday. For Thursday we see a dry start for everywhere and high pressure begin to ramp the heat up down south with lighter south west winds allowing temperatures to push up into the mid-twenties. Ireland looks to have a dry but largely cloudy day after the wet start to the week and Scotland sees a dry day with sunny intervals. As we progress through the day, the wind will push round to the south and that will ease the temperatures up into the high teens for Ireland and Scotland and low to mid-twenties for England and Wales. Closing out the week on Friday we see that heat continue to build with a real east-west split in the weather. Ireland looks to have thicker cloud and some rain over Kerry and along the west coast, with Scotland also seeing some showers along the west coast. The west of the U.K looks cloudier but across England it looks a pretty sunny and hot end to the week (again) with temperatures expecting to peak around the low thirtiess down south and along the south coast with light southerly winds. Ireland could just push into the twenties with Scotland a little cooler with the cloud cover and showers. A sticky night on Friday for England and Wales.

The outlook for the weekend is dry on Saturday with more cloud around for England and Wales. Some showers across the north east of Ireland and Scotland and in the west of Scotland pushing into more heavier rain centrally for a time. As we go through the day we will see a weak low pressure system pull showers down the north east coast of England into the east coast. This ridge of rain will build along the north east coast to give some heavy totals on Saturday night and may push south into the north of England and North east Midlands. There is a risk of thunderstorms across the south and Midlands as the heat breaks down but before it does expect temperatures up in the mid to high twenties. Sunday looks dry pretty much everywhere but cooler and fresher with temperatures dropping away quickly on Saturday evening as the wind swings round to the north west. So a cooler but dry day on Sunday for everyone with temperatures back down to the high teens / low twenties thankfully.

Weather Outlook

So next week looks like starting with high pressure just about in charge so that means warm, settled and dry for the first half of the week anyway with heat building by mid-week again. Ireland could still see some showers in the early part of the week, especially in the west.  As we approach the end of what will have been a pleasantly warm summer week with temperatures in the mid-twenties, we see another Atlantic low projected to push into Ireland and Scotland on Friday and then across all of the U.K on Saturday / Sunday. Now we all know how reliable Atlantic low pressure systems are in the middle of summer so lets not hold our breath, especially down south where its likely to stay dry for the second week in a row.

Agronomic Notes

July 31st, 2020 was officially the hottest day of the year as a temperature of 37.8°C was recorded at the concrete jungle that is Heathrow, it was also the 3rd hottest day ever recorded in the U.K.

Away from the capital we typically saw temperatures in the mid-thirties and wow did it feel warm. It reminded me of fishing down on the River Ebro in Spain for Catfish. Early afternoon the wind would whip up and really push the heat up with the day usually ending in thunderstorms which I know some of you got last Friday. Looking at a couple of sites you can see how the heat and E.T built over the day.

The pattern is for the E.T to peak significantly earlier than the temperature with 14:00 p.m. peak E.T and in the above case 16:00-18:15 p.m peak temperature. As you can see from the graphs E.T started to build from 07:00 a.m but really got into its stride from 10:00 a.m so if you were irrigating it is likely that your soil moisture content stayed reasonably good until late morning when the plant would have started to go under temperature and moisture stress.

I have also charted out the soil and air temperature for the day to see how the two compared after last weeks analysis showed the soil temperature higher than the air temperature at times.

So on a really hot day we can see that the soil temperature @ 25mm depth more or less mirrors the air temperature. Now I’ve worked on 27.5 °C as a threshold temperature for Poa annua, it’s a bit gut feel really because there’s very little work published that specifies clearly a threshold point where Poa annua growth begins to decline. I don’t think I’m that far off on this one. Working on this basis we can see that by 10:45 a.m. onwards, Poa would have pretty much shut down into water conservation mode and so very little growth and uptake would have taken place. So if you knocked a product application on the head because of the heat on Friday, it was absolutely the right thing to do in my mind.

Negative reaction to PGR usage

I’ve had quite a few people this summer note some yellowing soon after applying a foliar liquid with PGR tankmix combination. Most times this only stays for a few days then clears up but to me we have to think about not only PGR frequency of use but also rates. One of the negative effects of the Covid lockdown has meant a shortage of staff and therefore less frequent applications to greens. Many clubs have had to apply monthly rather than fornightly and this has meant doubling up on the usual PGR rate from 200ml to 400ml per hectare. Of course there are clubs and people that advise to go much higher than this on greens but you’d have to ask yourself why ? If you need to regulate growth to that extent then maybe you need to look at your other inputs ?

Higher rates of PGR but also normal rates of PGR applied to a grass plant that is under stress will promote a reaction, typically some yellowing and reduced response from a liquid fertiliser and iron for instance in terms of green up and growth / clip rate. If you’ve seen that and you’re wondering what the reason is, then why not drop out the PGR and see how the sward reacts. I think different sites behave very differently to PGR applications, one persons 200ml may be anothers 100ml on fine turf. . Grass species composition, soil moisture levels, irrigation efficiency, etc on fine turf and also on outfield turf like tees, approaches and fairways all come into play when it comes to application rate.

Sometimes I think that Mother Nature serves up a very good PGR on its own without us meddling. Now if this sounds like I’m not a fan of PGR’s, that’s not accurate, they are great turf management tools. What I am saying is have an open mind to rates, look at how your surfaces react or are reacting and cut your cloth accordingly. Above all don’t get caught up in the social media hype of “I apply 1 litre to my greens fortnightly and they’re excellent” diatribe. Make your own mind up from application and observation at your site.

When you look at the weather Scotland and Ireland have had recently, with low pressure dominating and plenty of rainfall, then here you’d have a completely different climate / PGR equation. Maybe you’re getting too much clip rate on outfield with the consistent rainfall and intermittent high temperatures and so buttoning them down makes perfect sense. It’s horses for courses.

Disease Pressure – Ireland & Scotland

Now you lads are probably looking at the graphs above as the rain hammers down and thinking…I wish….. 30°C !

It is difficult sometimes to write this blog when one part of the U.K is up against it with heat and E.T stress and another part of the U.K (and Ireland) are having a summer of rain and warm rather than hot temperatures. I’d take the latter any day by the way because high temperatures and people flocking to the beach is very much over-hyped. That said as I took my first swim in the sea this year off Holkham beach this weekend just gone, it was absolutely beautiful, I love Norfolk.

A negative side of the moisture and warmth coin for Ireland, the north west of England and Scotland-alike is a heightened level of disease pressure with Microdochium nivale and Anthracnose both popping up their ugly heads in recent weeks. It is a well-known fact that here the disease pressure can start a good bit earlier than down south where a course superintendent might identify October as the beginning of the ‘disease season’. Sometimes August will see Microdochium kick off in earnest but of course with growth levels still good, we should grow this out as quick as we see it. Maybe that’s another reason to err on the side of caution when it comes to PGR usage because growing out a summer disease like Red Thread, Dollar Spot and Microdochium nivale will indeed be hampered by an over-regulated sward.

Above is a disease prediction schematic for Microdochium nivale based on Kanturk as a location for this coming week. We can see significant pressure culminating with the weekend and next Monday as high disease pressure days. With fewer fungicide options available to us, I’d really be looking to manage this without a fungicidal hit and try and balance plant health and growth instead. Easy for me to say, harder for you guys to do. The other line of thought is to knock the population back now with a fungicide to reduce the severity of later outbreaks. It is an area where more research is definitely needed particularly as the tools in our toolbox start to look a bit few and far between.

OK that’s all for this week folks, time to get the sprayer out and do some more trials 🙂

All the best.

Mark Hunt