Hi All,

As my mini-update suggested on Friday, we have a change in the weather on the way with the arrival of a warm, high pressure, it’s certainly been a long time coming. When I was fishing yesterday, the owner of Thornton reservoir, (a colourful Welsh character called Ifor), showed me a picture of the woods surrounding the lake taken on the same day last year…all the trees were in full leaf, whereas now they’re barely through..I reckon nature is running 3-4 weeks behind because of the lack of temperature and just as importantly, lack of light levels in April and May to date. We sometimes forget that plants utilise light for energy and during prolonged cloudy conditions, their photosynthetic efficiency suffers. Last year, Ireland and Scotland had extremely low levels of sunshine during the growing season and this affected plant growth significantly, with crops like Maize only reaching half of the height as usual. Grass, I think is a very efficient photosynthesiser and adapts quickly to its conditions (particularly Perennial Poa.) so the effects aren’t as noticeable.

Left image - 'Peak Pattern' December 2011 / Right Image - 'Trough Pattern' April 2012 Courtesy of Meteoblue

We have high pressure asserting itself from the earlier part of this week and that’s going to bring warm, dry conditions for the week, with plenty of sunshine. The question in my mind is whether this heralds the end of the ‘trough’ pattern of weather that we’ve been in since early April or not ?, are we now shifting into a ‘peak’ pattern, which as we know from last year, brings warm, settled conditions and very little rainfall. This is particularly relevant to those currently affected by irrigation bans. We know that the rainfall of the last 6 weeks has seriously benefited ground water and particularly reservoir levels, below is the trend for Bewl Water in Kent, one of the driest areas of the country up until the end of March and you can see it has gone from 40% of capacity to 76% of capacity in 6 weeks.

My feeling is that this change in weather is not the precursor for a prolonged period of dry weather, though the trough pattern looks to have shifted away for the moment. The long-term jet stream pattern looks normal for next week with a more southerly feel to the weather on the cards. (sunshine and showers maybe)

General Weather Situation

Onto the weather, from today we have low cloud cover affecting most of the U.K, blown off The North Sea, courtesy of a cool, north-east wind and a weak band of rain affecting the west coast of Leinster and Connacht, but as the day progresses, this cloud will thin and the sun will break through, raising temperatures from their current low teens to close to 20°C in a short space of time. Tuesday starts with low cloud over the U.K and Ireland, but this will soon burn off in the U.K (but linger in Ireland) to give a beautiful warm, dry, sunny day (remember them ?) with temperatures in their low 20’s and a light easterly wind. The pattern is repeated on Wednesday, but this time the cloud clears over Ireland, so they join in the sun 🙂 . Thursday sees a similar pattern, but with a weak band of rain affecting south/mid-Wales and the north of England, Scotland, mainly on the west coast. Friday is more of the same, but this time there’s likely to be a greater risk of rain, with a band of rain  affecting a diagonal line across Munster and South Connacht, there’s also the risk of some rain for Wales, The Midlands and the south of England in the afternoon, with possible thunder and lightning. For the weekend, the temperature drops a little as the high moves away, but it’ll still be pleasant on Saturday and Sunday.

Outlook

The beginning of next week looks a little unsettled with some rain from the continent likely to affect Southern England early on in the week and some more general rain for the end of the week likely. It’ll still feel pleasantly warm with temperatures in the high teens I think, but with more cloud cover as an Atlantic low pushes cloud in. I think winds will be light and from a more southerly direction than of late.

Agronomic Notes

This section of agronomic notes is largely orientated towards clubs affected by the irrigation restrictions, if this isn’t you, my apologies, but it may be beneficial at some point in the future.

Firstly, I don’t feel there’s a need to panic because although we have a warm week in store, ground water levels are good and I think the end of this week / next week may bring some rain to keep things ticking over.

In the meantime I’d definitely be applying a PGR early  this week to slow growth down and in doing so increase water-use efficiency by the plant. This isn’t a sales gimmick for the cynics amongst you, the research is clear since 2007/8 on the benefits of using Trinexapac-ethyl to increase drought tolerance. Here’s a link to one piece of work by the highly-respected scientist Bingru Huang, have a read if you’re interested.

Drought Responses of Kentucky Bluegrass and Creeping Bentgrass as Affected by Abscisic Acid and Trinexapac-ethyl

Stephen E Mccann, Bingru Huang in Journal of the American Society for Horticultural Science (2008)
It’s important to regulate the plant before it goes under stress, hence my comment about applying early on this week. I’m not suggesting that we’re going into a drought, but if you can’t water or are heavily restricted (no hand watering for instance) then the objective is to help the grass plant through periods of short-term water stress – i.e high temperatures and high E.T.
Other beneficial cultural practices include missing the clean-up cut, raising the cutting height, missing cuts and replacing a cut with a roll to keep green speed up and not verticutting, scarifying during periods of high temperature. All good common sense really, but you’d be surprised people still get it wrong by not paying attention to the weather and the state of play in terms of grass stress. Using smooth rollers as opposed to grooved ones also decreases physical plant stress, but it tends to suit some grass swards more than others in terms of quality of cut.
Research by Huang has also highlighted the benefits of biostimulant usage prior to and during periods of plant stress and it’s clear that use of a bioactive seaweed, combined with humic acid provides a clear benefit in stimulating antioxidant production and thereby decreasing the accumulation of free radicals in the grass plant.
In terms of plant nutrition- it’s well-known that a succulent grass plant at a high nitrogen leaf status produces more leaf / shoot tissue that in turn requires more water to maintain cell turgor. During periods of high temperature it is therefore advisable to maintain a balanced nutrient status in the plant and thereby avoid any flushes of growth (hence the PGR advice). This doesn’t mean no-N, rather balanced N, applied in a ‘little and often’ manner to maintain plant health. Cutting N down to too low carries as many negatives as positives, particularly with respect to disease activity and it’s well documented that Anthracnose, Dollar Spot and from my own experience, the activity of plant-parasitic nematodes is enhanced by a grass plant maintained at too-low an N status. So the rub is to keep the plant balanced from an N status perspective and avoid flushes. The best tools in the box for this are obviously foliar / liquid fertilisers applying low rates of N and of course with these you have the flexibility to tankmix in your biostimulant and PGR at the same time. One last point, it’s also beneficial to apply products with low osmolarity, this is defined as the ability of a material to draw water out of the grass plant. Liquid, foliar, water-soluble fertilisers with a high-salt loading will draw water out of the grass plant by osmosis and thereby deplete the plants internal moisture status, so use low osmolority fertilisers like urea and / or slow-release, liquid nitrogen sources duirng this period. Iron should be used at light rates and preferably in chelated, rather than sulphate form, again because of the lower dessication potential of the former.
None of these measures are high-cost or difficult to implement, the key is in the timing of the implementation and syncing the grass plant into a certain growth habit, in the U.S, they call it pre-stress conditioning, but they would, wouldn’t they 🙂
All the best, enjoy the warmth, I’ll be working in Switzerland this week, where it’ll be a nice 25 – 26°C hopefully.
Mark Hunt