November 4th, 2024

Hi All,

Last week I attended the Saltex show at the NEC, thanks to everyone that came to see Ben and I on the stand (Peter was on a well-earned break) . I did a short talk with the meteorologist Jim Dale of British Weather Services and to all attending I think it was a bit of an eye opener.

Jim is the author of a number of books on the weather and regularly takes on the climate sceptics on the subject of climate change. He gave the audience a 15-minute resume on why climate change is real and how we need to understand what is happening to our weather. It was my job to follow this and it was a tad difficult to bring it down to a turf-based discussion.

The tragic events in Valencia, Spain recently have clearly highlighted Jim's point about climate change. Heating oceans are super-charging storm systems in a process called Cyclogenesis pushing more energy, temperature and water vapour into slow-moving storm systems with horrendous consequences. We no longer talk about a month's worth of rain in a day. The people of Valencia (and all our thoughts are with them) experienced a years worth in a single day.

Above is a snippet from one of the Davis weather stations in the area, in old money that's 16.44 inches of rain in a day with a rain rate of > 16" per hour. That's difficult to imagine. The storm system that brought that rain was what they now called a COL (Cut-off low), I called them tear drop low's recently because they detach from cold, northerly weather and then move almost independently of our normal air flow. If they come into contact with warmer seas, they gain energy and moisture, with sometimes devastating and tragic results.

The devastating rainfall that central and eastern Europe experienced in September was due to a COL, the rainfall we experienced at the end of September was due to a COL, the rain Spain experienced likewise. You can read all about the real reasons why this rain occurred on Netweather's excellent website here.

For the U.K, we saw this process in Storms Babet, Henk and Ciaran last year and any that vector over The Bay of Biscay are the ones to keep an eye on. My so-called BOB's, Bay of Biscay low pressure systems.

For now talk of storms and the U.K weather are pretty irrelevant because we continue to sit in an Omega Blocking pattern, with high pressure centred over the U.K and the jet stream way, way north of us. You can clearly see the column of warm, humid air that is presenting us continuing issues from a disease perspective as day and night time temperatures sit way above where they usually are for this time of year.

Nature is adapting to climate change even if we aren't. As I walked around Rutland Water's beautiful peninsular yesterday, I was struck by the total absence of winter thrushes in the trees and fields. Redwings and Fieldfares would normally have pitched up over a month ago to feast on our berry crop, but with warm weather persisting in Scandinavia, they have no need to do so and are absent.

General Weather Situation - w/c 04-11-2024

As detailed above, this week we have high pressure sitting over us and so we will continue our run of dry, warm and humid weather, indeed as we reach mid-week, this week, another column of warm air will push up across the west of the U.K and Ireland bringing us high teen, day-time and mid-teen, night-time temperatures. So calm, settled conditions with light winds and high night and day temperatures are the forecast for this week.

As we progress through the week, that peak in the jet stream will slowly edge eastwards across Scandinavia and that will allow cooler weather to move into the west first and then across most of the U.K in time for the weekend. Not massively cooler, but we will lose that warm, mid-week peak. Now normally we would then see more unsettled conditions push in from The Atlantic, but the projections are showing another high pressure system will build over the weekend, keeping those Atlantic low pressure systems at bay and maintaining our dry, mild and humid start to November.

At the end of the week, the closeness of Atlantic low pressure systems will trickle in some rain across Ireland and the west / north west of Scotland across Saturday / Sunday and some of that rain may drift further south but it will be few and far between.

Weather Outlook - w/c 11-11-2024

So for next week we will start with a continuation of that high pressure dominating our weather, but as we progress through the week, that high pressure gets squeezed from the east as a slow-moving low pressure system pushes in from France / Germany during mid-week. This has the potential to introduce unsettled weather / rain to the south east, south and south west of England and Ireland for the latter part of next week. Further north it'll be a continuation of that high pressure weather pattern, so calm, settled and dry. This low pressure then stops south of Ireland and eventually slot into the south west airflow we normally see at this time of year. So for next weekend, we start to pick up cooler, windier and more unsettled conditions across Ireland and the west. This may then move across the U.K thereafter.

Agronomic Notes

Last week, I talked in my blog about how the Omega blocking event we were sitting under was a calling card for mild, humid air and overnight plant leaf wetness. In other words, ideal for the encouragement of foliar pathogens like Microdochium nivale.

Normally at this time of year we would be seeing no positive hits from the Smith Kerns Dollar Spot probability model as temperatures drop lower than the temperature range of the disease model itself, which is 10°C-35°C. As you can see from the graph above, we are still motoring on with continued disease pressure broken only by some cold weather in mid-October. With the forecast for this week and indeed next looking to continue that pattern of weather, it is a statement of the obvious that the disease pressure will continue.

There are some positive flipsides to this coin though. Mild temperatures mean we are maintaining a decent daily G.P level into November so we will get some regrowth from any significant disease pressure. Good growth at this time of year is anything around 0.4 G.P.

For autumn-sown seed, high soil temperatures will continue to push on very good establishment and growth, so that's another positive.

Last week, I was reading the Greenkeeping Facebook page and an anonymous poster asked whether greenkeepers were still continuing PGR applications ?

It is a good question and in reality if we are adapting to our changing climate, a very pertinent one. In my mind although temperatures are still conducive to growth as we can see from the daily G.P above, the characteristic of that growth is different, light levels are on the slide at this time of year.

If we look at the Daily Light Interval (DLI) chart above, we can see that the current weather and its almost seemingly never-ending cloud is contributing to a pretty low level of plant available light as denoted by DLI, measured in mols per m2. The dotted line is the minimum sufficiency range for Lolium perenne, the one for Browntop Bentgrass is probably somewhere around 20 mols per m2 and Creeping Bentgrass likely to be higher still.

So we can deduce that light levels are low but growth levels are continuing if we look solely at air temperature and that means to me that the growth habit of grass will be different. If you grow a plant in low light, it stretches towards the light and becomes elongated. That stretching of the plant extends the distance between leaf nodes (where leaves originate) and potentially creates thinner cell walls. Thinner cells walls means it is easier for fungal disease to penetrate the grass plant and also it may be less able to withstand wear. I have proof for this theory it just a logical deduction on my part.

So if we consider that the growth aspect is likely to be elongated vertically with low light levels and the plant is still growing, then it makes sense to me to continue with PGR applications later into the season. Maybe just half rate and of course the application interval will be extended as growth levels are lower. Every 130 GDD @ 6°C base temp is currently once per month, but of course that will change as we move deeper into the winter (winter??).

On a final note, I wold be wary of tank-mixing that PGR with a fungicide unless you have prior experience or your supplier specifically suggests that it is possible based on their research. In the past I have seen significant phytotoxicity with mixing some fungicides and PGR's together, so be warned.

OK, that is me for this week, tempus fugit and all that....

All the best.

Mark Hunt