Today is Saint Swithin’s day and as the saying goes, whatever weather we have now will stay for the next 40 days…
‘St. Swithin’s day if thou dost rain
For forty days it will remain
St. Swithin’s day if thou be fair
For forty days ’twill rain nae mair.’
So will Saint Swithin be correct? No I don’t think so. My feelings are that we have this weather pretty much for the next 2 weeks, with this week remaining dry and very warm. During next week I think the heat will slowly decrease (from the north first) until the end of the week when the jet stream will sink south and allow a low pressure system back into the picture for the end of July. As you know forecasting beyond 7 days is tricky, but that’s the way it looks at the moment, as usual, I’ll keep you posted although next week’s blog will be a short one because I’ll be in France on my hols.
General Weather Situation
As mentioned above, we have a pretty stable weather situation this week, with dry, warm / hot weather for most of the U.K. and Ireland, and the only variables being cloud cover and the chance of thunderstorms coming out of the heat as it builds. I won’t even begin to try to predict where these may be because a thunderstorm starts as an updraft of hot air and the catalyst for this can be any area that reflects heat, be that a car park, the roof of a building, the top of my head :), etc. so absolutely impossible to predict.
The hottest day looks like being Wednesday potentially so that’s likely to feature the highest probability of thunderstorms kicking off in the later afternoon, particularly in the south-east / south of England. Any rain this week will be confined to north-west Scotland for the early part of this week and here the cloud cover will keep temperatures confined to high teens, low twenties. There’s just a chance of some pretty localised rain in the north of England on Thursday and some parts of the south, but this will be one of those it’s raining 2 miles down the road, but not at your golf course / sports pitch scenarios, so very localised. Lastly, the night temperatures will sit in the mid-teens, so at least refeshing for those in pursuit of a good nights kip 🙂
The weekend looks set fair and dandy for all of the U.K. and Ireland, with Scotland warming up a little from the lower temperatures of the week so, the pattern will be early mist, cloud cover burning off around mid-morning with sunshine taking over.
It is looking like staying settled and dry through to next week, but the key will be the end of next week; around Thursday 25th July if we are going to see a change to the stable, hot, dry and high pressure scenario that we currently have. As it stands, the projections suggest that the jet stream will drop south towards the end of next week and, if this occurs, we’ll see a low pressure system push in for the end of July that will bring rain. As mentioned above, we’ll need to see the signal a lot clearer than it is now for me to be anywhere near certain that this will happen, but I’d say I’m 60% sure on it at present.
Well I guess the main topic of conversation has to be irrigation, hand-watering and syringing. The most important aspect is balancing mains irrigation through sprinklers, with hand-watering and for sure the best approach is to apply between 50-60% of E.T loss by irrigation and then ‘top up’ on hotspots with hand-watering. Obviously there’s a huge amount of variability inherent in that statement depending on rootzone type, greens aspect (shade vs. open) and design (contouring) and this often presents a problem for understanding your irrigation requirement because no one size hat fits all.
If we look at the E.T loss since the start of the hot spell (and remember this followed what was a very dry June for some), we can see that the golf club in question has lost 36.7mm of moisture through evapotranspiration. (E.T)
So just to keep the grass healthy, we need to apply roughly 50% of this E.T loss by irrigation, that means 18mm or so. Now that’s the rough basis for irrigation requirement, your situation will undoubtedly differ, you may find you can water to replace 40% of E.T and anything above that gives too much water to the low spots on greens and so making up the rest with hand-watering is the best option.
Some people mention hand-watering and syringing in the same breath, but they are not the same. Hand-watering is to replace a moisture deficit in the soil, usually on a hotspot present on a raised surface, mound, ridge, etc, whereas syringing is applying a light spray of water straight onto the foliage of the grass with the intention of cooling the leaf tissue and slowing moisture loss to the atmosphere. Syringing is very popular in the States where temperatures are often much higher than we currently have and they stay for longer. That said, I think there is a place for syringing under the current conditions, but ultimately it’s a function of manpower and getting out between the golf, both of which can be tricky. You can argue that hand-watering also provides a syringing function as well because you are wetting the plant in the process of irrigating the rootzone in a localised fashion.
The same advice as last week. I’d be applying low amounts of N by foliar / liquid means using low-salt / no salt liquid feeds (so those that are very safe to use when it’s hot) and during these conditions, I’d also drop out my iron and replace with it a biostimulant in the same tankmix as the liquid feed. Make sure beforehand that it’s tankmix compatible and suitable for foliar application. (i.e you will get a benefit from it, with no nasty surprises!) If you’re applying a soil surfactant / wetter instead, I’d also be popping in a biostimulant to the tankmix, with the same concerns / considerations as above.
Currently we have low amounts of disease present, but that’s not to say disease isn’t an issue because areas that showed Superficial Fairy Ring, Thatch Fungus, Fairy Rings or Take All previously, are taking a lot of work currently to stop the areas from drying out (as the first three on this list are nearly always hydrophobic in the first place). That list also includes areas affected by plant parasitic nematode damage because these often behave in pretty much the same way, due to the fact that the root system has been damaged and is therefore less efficient at taking up water. You can get to a point (especially when you have 4.0mm+ E.T days !) twhen the grass plant cannot take up enough water to keep itself alive through the damaged root system (i.e it is losing more water by E.T than it can replace) and it’s in this situation that syringing can be of great benefit by lowering E.T loss and cooling the plant tissue.
I guess if the weather does map out as suggested we’ll have had 3 weeks of hot, dry weather, following on from a dry June, so I’d suggest that disease pressure through August from Anthranose Foliar Blight may potentially be an area of concern, especially if your course / facility has a past record of this disease (so background spore levels may be high). I’ll chat about this more next week, hopefully sitting out in the French sunshine sipping a Cafe au lait 🙂