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  • Writer's pictureMark Hunt

November 7th

Hi All,


A short blog this week as I'm off to do 3 talks in 3 days at the BIGGA autumn educational conferences and need to get my self sorted !



I am looking forward to it but after a very busy Saltex week last week, I'm going to need a rest.


Thanks to everyone that dropped by and also for pointing out my typo in the last paragraph of last week's blog (cheers Pete !😊 ).


A reminder that the disease pressure was high last week was served up to me on the stand as the turf I picked up to make the EM Node display came complete with active Microdochium ! ....How realistic do you it want eh ?😊


Next Monday, I'm having a little shoulder work, a legacy of my 'ambition exceeding my talent' on a motorcycle, so the blog will probably be a bit later in the week and in it I'll be doing my usual look back at the previous month.



If I didn't need reminding from looking at the turf on our stand, It is already clear though that October was a pretty aggressive disease month. If you take one thing from this week's blog, it is (unfortunately) that I can see the trend towards a high disease pressure autumn continuing into November as we develop a classic Omega blocking pattern this coming weekend (see below).


You can clearly see the Omega (Ω)shape in the graphic below ;

So we have a finger of high pressure extending up across the U.K & Ireland, sandwiched between two low pressure systems, one out to the east on the continent, one out in The Atlantic. Thankfully it won't be as long-lasting as it looked on the GFS last week, but it will still be a challenge....


All GFS images courtesy of www.tropicaltidbits.com


General Weather Situation - w/c 7th November


A definite week of 2 halves this week with the first half dominated by a very active low pressure system that is already pushing into Ireland and due to bring strong winds and heavy rain over Monday to Ireland and the west coast of the U.K before pushing eastwards across all areas overnight into Tuesday. So wet and windy through Monday and Tuesday but remaining on the mild side with temperatures in the low to mid-teens.

Through Wednesday we see more rain but it tends to affect the western coastline of the U.K & Ireland and possibly along the south coast as well, meaning inland we have a drier picture, but it'll remain windy.


As we move into the second half of the week we see any rain become confined to the north of Ireland and the western half of Scotland. For Scotland, that rain may be heavy for the second half of the week, especially across the west and central regions. Further south, it remains breezy, mild and sunny, which is a blessing as it'll be good drying conditions. As we get to Friday and Saturday, the wind turns more southerly and begins to drop and that'll represent probably the biggest disease pressure period, extending into the weekend. For Ireland, you'll continue to see showers for the latter part of the week and these will continue into the weekend as Atlantic rain fronts stack up out west. So rain moving across Ireland later on Saturday after a largely dry day and continuing into Sunday with a wetter day for the second half of the weekend. Across The Irish Sea we look to have a nice weekend, largely dry, south winds and sunshine, with temperatures in the low to mid-teens I think.




Weather Outlook - w/c 14th November


Next week's weather patterns looks a tad complicated with the Omega block in the jet stream projected to slowly drift off to the east and allow Atlantic fronts to push in. The complicated bit is courtesy of a BOB (Bay of Biscay low pressure system) that's lurking south of the U.K at the start of next week. I can see Monday starting dry for some but those rain fronts across Ireland will be pushing eastwards into western areas and then across the U.K on Monday. The BOB will likely feed moisture from the south into this weather thematic during Monday / Tuesday, though at present this looks to be a narrow band of rain sitting across the west of the U.K. Across The Irish Sea we have a new Atlantic low that will push rain and strong winds into Ireland on Wednesday. This low will then push eastwards bringing wind and rain across the U.K from Thursday next week. Owing to the fact that the low is butting up against a slow-moving high on the continent, it won't just move across the U.K & Ireland quickly, it will be stuck in place, so I expect strong winds and heavy rain to last from Thursday through to at least Saturday, with more showers on the Sunday. Thereafter, another low pressure is on the way with tightly packed isobars and heavy rain.


Man, is the weather / climate on 'even up mode' or what rainfall-wise !


Agronomic Notes


So a shorter than usual blog this week because of my forthcoming jaunt around the U.K.


Microdochium nivale pressure


So this autumn we have started off with some pretty strong disease pressure, commencing at the beginning of September and serving up a repeat dose at the end of October. This weekend will see another peak I think as mentioned earlier in the blog.


The graph below shows 3 locations across the U.K & Ireland and the Smith Kerns Dollar Spot Probability Model (SKDPM) from the beginning of September. (Shannon data starts at the beginning of October).


As mentioned in previous blogs, the SKDPM is used by many as an approximating model for Microdochium nivale, which it does pretty well during the milder periods of the year. The problem comes as it drops colder when the model returns zero values because the lower temperature threshold for Dollar Spot activity is set at 10°C and unfortunately Microdochium is able to grow from 0°C.


Hence the need for a Microdochium-specific model.

We can see the peaks of disease activity clearly in the graph and if you take 20% SKDPM as a baseline for the commencement activity (shown as a black line), the level of activity becomes quite apparent. You can also see how the location in the south of England (Sevenoaks) is showing the highest level of activity, followed by Dumbarton and then Shannon.


Diary of a Microdochium nivale scar....


The image above shows a classically bad, Microdochium nivale scar and it represents a time-phased story of how Microdochium infection can develop across a sward.


This picture was taken in early February.


Below is a description of how this Microdochium nivale scar developed ;


A & B - Initial infection in October that spread quickly with mild, humid overnight conditions and heavy dew. This has recovered well by the following February.


C - December outbreak after Omega blocking event fed up humid air on two separate occasions and facilitated new pathogen growth from the outside of area B. Since fungal diseases spread outwards, the highest population is nearly always on the outside of the disease scar. This is the hardest area to achieve control by a pesticide. This area has shown limited recovery due to the lack of growth days since this period of activity.


D - In January, we had a few mild days and this initiated further disease activity from the outer edge of C into area D. Again this has not had time to recover by early February when the picture was taken.


So this is why it is vitally important to stop the Microdochium nivale establishing an active population in the autumn. 100% that is a much easier statement to write than it is to achieve from a practically perspective, given the lack of spray windows and effective pesticides available.


One thing that does work in our favour though (and it is the flipside of the milder weather that encourages disease) is that we also see good growth during these periods, so the grass is growing out the disease. This recovery potential means damage incurred in say early September will be able to be grown out by early November. As we progress into the winter, this recovery potential is on the wane though as you would expect.


Warm and humid means good grass growth as well as disease...


You can see this in the graph detailing Daily Growth Potential at the 3 locations utilised above ;


So in early September, we were at optimum growth levels, so even though the disease pressure was high, we should have been growing out the disease as fast as it developed. The caveat to this is obviously down to nutrition levels and PGR usage.


We picked up some more recovery growth in early October and then at the end of the month as well. I can't remember ever seeing a G.P level approaching 90% of optimum (0.9) so late into the year. Even Scotland was approaching 70% and the milder climate of Ireland shows with nearly the same level of growth as that of the south of England.


This is the other side of the disease coin and means at least we can hopefully grow out our early autumn disease outbreaks. The more damaging ones in my view are those that occur in late November but typically in December and typically over the Christmas period. (the law of sod)


OK, that's it for this week, tempus fugit and all that.....


I hope to touch base with some of you over the next 3 days and now need to brush up on my presenting skills.....now where did I put them ??? 😃


All the best...


Mark Hunt








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