July 1st

Hi All,

Bit of an abridged blog this week with back to normal service next week when I’ll do a monthly summary of June 2019, an interesting month in many ways, so hopefully you’ll bear with me…

What a scorcher Saturday was and with that wind, a pretty high E.T day to boot as well, we measured 5.73mm E.T loss on the weather station at The Oxfordshire (more on that later)

So for this week’s blog  I’m going to do a summary of the week’s weather, rather than drill down into individual days and actually we have a pretty stable weather picture so that kind of works.

Before I do I thought it was interesting to see a snapshot of last weekend, this week and next weekend when you look at it from a temperature and jet stream position perspective…

Thanks to Tropical Tidbits.com for use of the images….

Starting from the top we see the hot air plume as the jet stream forms a peak pattern and pulls warm air up from Africa. This resulted in our hottest day of the year so far and record temperatures in many countries in mainland Europe. This week we are seeing the weather settle down as high pressure asserts itself and we build some gentle heat compared to last weekend. Finishing off with the projection for next Sunday and you can see a trough pattern developing in the jet stream from the east (which is weird) and set to bring cooler, duller weather and some rainfall most likely…

General Weather Situation

So with high pressure in charge this week it’s going to mean pretty consistent conditions with some rain showers around today over Northern Ireland, Western Scotland and northern England. We will have a pretty strong north-west wind in place today and that’ll keep things on the cool side with mid to high teen temperatures likely. Cloud cover will be a feature of this week and particularly along the eastern coastline of the U.K. Tuesday looks a better day with a gentler north-westerly wind, pretty much dry everywhere across the U.K & Ireland except for some rain lingering over the far north-west of Scotland. Temperature-wise I’d expect mid to high teens with the cooler temperatures over Scotland and the warmest across the west and South Wales. Wednesday continues this pattern, bright at first but cloud soon coming in from the east across central areas of the U.K. Cloudy, dull but dry for Ireland as well. Wednesday looks a change day for the wind where we see it drop back in strength and swing round to the north-east / east. Lighter winds will mean a gentle hike in temperatures into the low twenties for the south of England, Wales and Midlands. Ireland and Scotland will still keep that cloud cover although Scotland should enjoy a better 2nd half of the day as the sun breaks through so a couple of degrees down on the temperature here, but dry. A similar forecast for Thursday with the exception of some rain due into the north-west of Scotland and likely to run along The Moray Firth into the north-east of Scotland as well. A much brighter day on Thursday with plenty of sunshine for England, Ireland and Wales and reasonable temperatures in the high teens to low twenties. Light winds as well as it starts to swing back to north-westerly through the day depending on your location. Closing out the week on Friday that rain over north-west Scotland clears through the morning only to re-appear as we go through the early afternoon. Elsewhere remaining dry but Ireland looks to stay cool and dull with some thick cloud pushing in from The Atlantic. Not so for England and Wales with long spells of unbroken sunshine and likely to be the warmest day of the week so far with temperatures pushing up into the low to mid-twenties in most areas. A strong to moderate north-west wind is expected to close out the week so a high E.T day no doubt.

With low pressure pushing in from the north it is no surprise that we have a north-south divide for next Saturday with the south of England hot and sunny with potential temperatures in the mid to high twenties. The same for Wales as well but as we move further north and east we pick up cloud cover and the cooling effects of an easterly wind and The North Sea to keep temperatures in the high teens, maybe low twenties. For Ireland and Scotland, not a bad Saturday with some good spells of sunshine and temperatures up in the high teens and low twenties. Sunday sees more in the way of cloud cover and a developing easterly wind so that’ll mean a cooler day for areas affected by the cloud cover with mid to high teens likely from The Midlands north. Further south and west you should still keep temperatures up in the high teens and low twenties for the west of England, Wales and Ireland.

Weather Outlook

An interesting one next week as we see a continental low pressure (strange for the summer?) out to the east of us and high pressure to the west. Usually it is the other way round. So as we go into next week expect a cooler northerly wind with some showers along eastern coasts through Monday and Tuesday  but drier, brighter and warmer towards the west. By Wednesday the high pressure should be keeping the cooler, more unsettled air to the east of us so drier for Wednesday before an Atlantic low pressure system is projected to usher the high pressure out-of-the-way and introduce cooler and wetter weather for the end of next week / next weekend. Temperature-wise, similar to this week really so high teens and low twenties by mid-week I reckon.

Agronomic Notes

A little look at last week….

The top graph is fairly self-explanatory as you can see we ran some pretty high humidity through the night last week after the rainfall on Monday and Tuesday. That heat on Saturday came late in the day and lasted right through into the evening with some locations still at > 25°C after 9 p.m.

The bottom graph shows the respective rainfall and E.T levels for each day and a running total of soil moisture deficit. Now of course your site will be different, you may be more sheltered than The Oxfordshire and consequently run lower daily E.T totals, you may have had more rain as well. What is interesting is that despite 6mm of rain on Monday / Tuesday, they were already running into moisture deficit by 10.00 a.m on Thursday morning because the daily E.T levels were so high. By Sunday evening they were at -19.63mm moisture deficit and with the dry and sometimes windy outlook this week, that deficit is set to grow.

So if you think you dried out quickly last week that’s why and what’s more is you’ll continue on this moisture deficit curve this week with very little rain forecast and some high winds. Meteoturf is predicting 30mm E.T loss over the next 7 days for the south of England which is similar to last week so keep an eye on things soil moisture-wise because the dry-down will continue this week.


Disease activity

As discussed last week, with high moisture and high humidity, just about everything comes out of the woodwork from a disease perspective. Locations that picked up high rainfall over the last fortnight may have seen Waitea Patch on some greens. (above)

Although it resembles Superficial Fairy Ring, I think it is more vivid yellow in colour and tends to favour wetter areas on greens. Ordinarily it fades as quickly as it appears and doesn’t really affect the putting surface so I wouldn’t class it as public enemy no.1 in our climate.

Anthracnose Trigger ????

I’ve had quite a bit of correspondence about the likelihood of Anthracnose as we move into July and whether last week’s temperatures were enough to trigger the germination of spores and subsequent development of the disease. There’s no simple answer here and it really comes down to your site specifics in terms of critically both temperature and humidity, because it’s the combination of both that leads to disease development.

Take summer 2018 for example, sky high temperatures with consistent Anthracnose triggers / high stress and although we did indeed see some disease development, it was nowhere as bad as 2014 / 2016. The majority of Anthracnose we did see was late in the season, from September onwards…

So why wasn’t summer 2018 a high Anthracnose season ?

In my mind it was because of the lack of rainfall and therefore humidity which characterised last summer and thereby prevented mycelium development. (Anthracnose like most diseases is greatly encouraged by periods of plant leaf wetness)

So was last week’s weather a viable Anthracnose trigger ?

Well the conventional wisdom is that you need 3 days of ≥ 25°C for spore germination and then in my mind this needs to be followed by an extended period of plant leaf wetness for the fungal mycelium to develop on the leaf / crown of Poa annua. If you look at the map I think the only area that may have hit both criteria is Scotland because some areas there have had rainfall following the heat of the last week. That said it wouldn’t go down in my books as the strongest of Anthracnose signals.

The other thing is bear in mind with this disease is that the effect of having a good IPM program in place is much more significant. I’ve referenced it before but Bruce Clarke’s work at Rutgers pinpoints very specific IPM factors that greatly influence this disease regardless of fungicide applications. You can read about them here and here

By far the most critical factor in preventing this disease becoming your worst summer nightmare is plant health and specifically leaf tissue levels of nitrogen and potassium. Rutgers recommend keeping the plant leaf tissue N and K levels above 3.6% and 2.0% respectively which in my books is normal nutrition, nothing excessive and certainly not high enough to compromise greens speed. (Especially with good PGR usage)

The only time I see nutrition contribute to Anthracnose is when someone is on a “Let’s see how low I can go on my N” crusade and then gets hit and spends the rest of the summer chucking on N and seed to fill in the damage. It simply doesn’t make any sense to me why we still go down this route and as for the “It gets rid of my Poa annua and does me a favour” line then of course yes it does (temporarily) but what comes back in the voids that are left ? Poa annua and not your fine-leaved, perennial biotype, you’ll get the coarser, annual biotype that’ll stand out nicely for the next couple of years to remind you as it spends most of the year seeding 🙁

A bit harsh maybe but the number one lesson with Anthracnose is that most of the time it can be largely prevented by good non-pesticidal IPM,

OK, off my soapbox, have a good week with a reasonably stable forecast 🙂

All the best…

Mark Hunt