This week isn’t going to be like our usual high pressure, Indian Summer-style start to September that we’ve been getting used to over the last few years, however there are signs that more stable, drier and warmer weather is on the horizon, but first we have to get through what will be a chilly week with some winter northerlies to keep you company 🙁
General Weather Situation
The Bank Holiday (For England, Wales and Northern Ireland-only I know) passed for many under leaden clouds, cool temperatures and with heavy rainfall and this is because of the now familiar situation we find ourselves in during August of picking up a low pressure trough in the jet stream. This week will see that low pressure off the east of the U.K and high pressure pushing in from the Atlantic, so we are sandwiched in-between. The upshot is where high and low meets it funnels the wind down from the north and gives us a taste of October / November temperatures. I’ve put together a schematic so you can see what I mean…
So Tuesday looks to start off drier than Monday, but it won’t stay that way for long for some areas as rain (light and scattered I think) pushes into the east and south-east of England and further up the north east coast by mid-morning tracking westwards across the country. At the same time we also have some potentially heavy rain over the north of Scotland. By early afternoon this rain has pushed south to cover most of Scotland and at the same time we see the eastern rain moving across the north of England and may reach The Midlands. The areas driest areas look to be South Wales, the south west of England and Ireland (Remember last week I said the boot would be on the other foot this week with the east getting the crappy end of the weather stick instead of the west ??) It’ll feel cool everywhere with similar temperatures across all of the U.K and Ireland, mid-teens the order of the day and the light to moderate winds will be north to north-westerly depending on where you’re situated. If you see then sun then temperatures will creep up to 16-17°C.
For Wednesday we have a drier picture with only light rain sitting over The Borders at the start of the day. This will push down south across The Pennines into northern England during the morning and into North Wales and the north Midlands by the afternoon, but it’ll be light. With Ireland being furthest away from the low pressure system, you’ll be dry again as will The Midlands and south of England. During the afternoon that rain will fizzle out in most areas except the north east of England. With cloud cover across much of the U.K and Ireland, you’ll be lucky to catch some hazy sunshine, but temperatures will stay firmly in the mid-teens due to that continuing northerly / north-westerly wind.
Moving into Thursday we have an increasingly drier picture as that low pressure reluctantly edges east across Scandinavia. Again they’ll be plenty of cloud cover and that cloud may be thick enough for some drizzle / light rain across Connacht and the north of Scotland. Elsewhere it’ll be a dull, cool day with very little in the way of sunshine and because of this it may feel even cooler on Thursday with temperatures sitting between the low to mid-teens. The winds will stay in the north / north-west and will remain light to moderate in nature.
Closing out the week we have a slightly better picture with more in the way of sunshine for some areas of the U.K, particularly the north east and eastern counties. So temperatures may just perk up to 16°C (Gosh Golly) when the sun peeps through the cloud cover. It’ll be another dry day for most areas, however late in the afternoon we can expect to see some rain pushing into The Highlands of Scotland and northern counties of Ireland. Winds will still be north westerly and light to moderate.
So how do we look for the first weekend of September ?
Well more of the same really looks the way of the world with that cool theme continuing, though maybe slightly better on Sunday with more in the way of sunshine for most areas. In particular the west and central areas of England and later on on Sunday, the south of Leinster / Munster maybe will see the sun. It does however look dry on the whole, however a note of caution as there’s a lot of wet weather sitting just off the east coast of England through Saturday and Sunday and it wouldn’t take much of a change in the weather for this to affect eastern coasts. At this stage it is projected to miss but you never know 🙂 Winds will continue to be northerly in nature and that’s why we’ll keep a lid on the temperatures.
So this week was a battle between a westerly high pressure and a reluctant-to-leave easterly low, how is next week shaping up ?
Well pretty good you’ll be pleased to hear..:)
We should have high pressure in situ from the start of week for most of the week so that means dry and warmer with some lovely sunshine and in it I’m expecting temperatures to pick up to high teens, maybe higher in the south of England. Will it last though ? , that’s a tricky one to answer because there is a possibility of a continental low pressure system pushing in during the latter part of the week and that may push rain in from the south towards the end of the week. If it does we can expect rain for the west and south at the end of next week and possibly over the weekend.
Now is the time to look back at August and see what a month it was for turf management and for me I think it was quite difficult because of the combination at certain points in the month of high day and night temperature, high humidity and rainfall that led to high disease pressure.
Looking at the GDD data for The Oxfordshire we can see at first glance that August 2015 looks on balance similar to July 2015 in terms of temperature, but totals always hide a story don’t they ?
It’s like looking at the rainfall total for a month and saying it is similar to the same month last year, but when you look at the pattern of the rainfall you see that it all occurred over 2-3 days ! It’s the pattern of rainfall and temperature in August that tells the real story.
So lets drill down into that data in a bit more detail….
The two graphs above graphically illustrate why the end of August was so hard from a consistent disease pressure period. First off on the bottom graph we can see at both sites they had a massive spike in GDD between the 21st and 23rd of August. (We can also see that the south west location had less temperature spikes in August compared to the Thame location)
To give you an idea this GDD spike was caused by day and night temperatures of 17°C, 27°C and 16°C, 30°C respectively at the Long Ashton and Thame locations.
You can then see a pronounced drop off in GDD caused by the arrival of cooler and wetter weather on the 23rd August when Long Ashton received 37mm of rain ! The rain took a little longer to reach Thame , but even at this notoriously dry location, they received 25mm odd over the course of the next 3 days.
So there we have it, high temperatures, high humidity and rainfall, the perfect witches brew for disease development and that’s why I wrote about disease last week !
Current Disease Conditions
So on the back drop of last week’s high disease pressure what can we expect to see going forward ?
Well with the loss of temperature (and humidity as we go through the week) this week it’ll mean some of the more exotic diseases like Rhizoctonia will fade away, however the cooler temperature-biased diseases will hang around a bit longer I’m afraid.
So I expect to see Microdochium nivale, Anthracnose Basal Rot and surface Algae continue their activity through this week but as we progress through the week we should see a lowering of disease pressure even here as things dry out. This will continue through next week because of the arrival of high pressure so the outlook going forward in my books is for declining disease pressure and that can only be a good thing.
That said with the consistent wet conditions I also expect to see Red Thread carry on its merry march through our turf this coming week unfortunately.
ETS – Etiolated Tiller Syndrome (Ghost Grass, etc)
Thanks to Colin Jones for this picture of an issue that I think is growing in severity year on year. He also sent me a pdf of some of the latest research findings that I highlighted was in progress in a blog 2-3 weeks ago. You can download it here.
In these research findings they appear to be pointing the finger not at a fungal species causing the increase in gibberellic acid production, but a bacteria and that is significant. It means that if you wanted to treat it you’d have to apply not an anti-fungal product, but essentially an antibiotic to your turf ! This has already been used in the U.S (surprise, surprise) to treat an issue they have there called Bacterial Wilt. For me we still have some way to go here to ultimately prove the causal agent, clearly identify the role of PGR’s in its expression and find a solution.
I expect plenty of this around this week after the rainfall of last week and The Bank Holiday, particularly on areas that haven’t had a cut because of the latter.
With the loss of temperature this week and the cooler, northerly air stream I think I’d be continuing to look at low temperature available nutrient forms for the best result, so light rate foliars using ammonium sulphate, potassium nitrate and of course iron will be the order of the day. Similarly if you have to apply a granular product for aeration recovery then this should be following the same line in terms of nitrogen form.
Ok that’s all for this week, time to catch up with my in tray…last time I saw it it was legging for the door 🙂
All the best.