Hi All, ,

General Situation

Those of you in the southern half of the U.K will be sweltering under the effects of the Atlantic high pressure that I forecast to influence the weather over the latter half of weekend in the U.K. Yesterday here it hit 30.5°C and on top of 8mm of rain and very high humidity, conditions are challenging, but fear not, because this current weather doesn’t mark the beginning of a heatwave, as those of you in Ireland and Scotland will already testify, where temperatures are mid-teens at best.

This dichotomy in temperature is due to the approach of a weak low pressure which is currently affecting Ireland, Scotland and the North of England and as it moves southwards, it’ll meet the warm, hot air over the south of England and spark off thunderstorms, which will signal the change to fresher conditions over the next day or so.

Thunderstorms are notoriously difficult to predict as their formation starts as a warm updraft of air, the source could be a ploughed field, an empty car park, etc, anything that heats air, so I’m not going to predict specifically where and when they’ll form, but I expect the band to be from the Midlands south and to form from this afternoon and continue over night into tomorrow, with the far South-East possibly not affected till Tuesday lunchtime onwards, with possibly heavy rain in the South-East and East for Tuesday later p.m.

This week low pressure will bring in a fresh feel to the temperature and light showers of rain bubbling up in the afternoon from Tuesday onwards, with the pattern for the week being a dry start and then showers moving in on a North-West wind, with these showers prevalent from Tuesday till Thursday. The showers will be mainly over Ireland, the North Midlands, North of England and Scotland, with the South-East staying reasonably dry most of the week. Temperatures will be mid to high teens most of the week in the South of England and just mid-teens for Ireland, Scotland and the North of England, though warmer towards the end of the week.
The best spray day is definitely Friday, but you’ll probably be able to get away with it most mornings.

As we approach the latter half of the week, temperatures will rise again as another Atlantic high moves in and displaces the low pressure system, but its effect will too be short-lived as another low moves down and pushes showers into Ireland and England for the weekend.

Outlook

The low pressure system that is due to arrive for the weekend will push cooler, moist air into Ireland initially and then the U.K, so plenty of showers around, though no great amount of rain visible at present. Mid-week, next week may push a rain front into Ireland and the North of England, Scotland with significant rainfall.
Winds will be mainly westerly and breezy, but not particularly windy.

Agronomics

The combination of rainfall, followed by high temperatures and high humidity will cause two notable issues, the first is another growth flush, particularly on higher heights of cut and chatting to a few lads in the South-East this morning, they’re amazed at how areas have recovered already from the dry spring.

The second is with respect to disease and this combination of moisture, humidity and temperature will no doubt trigger off alot of Fairy Ring activity, Fusarium and I’m also seeing plenty of Red Thread. There may also be some Dollar Spot about, particularly on the continent where this disease is much more of an issue.

In the past we’ve always associated Red Thread with low fertility, but in my mind this is a bit of a misnomer because when you fertiliser Red Thread-affected areas, all you’re effectively doing is encouraging growth and removal of the fungus on the leaf by cutting, so rather than low fertility being the cause, I think Red Thread activity is mainly down to environmental conditions. Of course it’ll be associated with slow growing grass because less fungi is removed by cutting, but moisture, temperature and humidity are the drivers. We’re also seeing more Red Thread because of the frequent use of PGR’s which by slowing vertical growth and clipping production effectively decrease the rate of fungal removal by cutting, so the fungi is able to develop more. Finally, I think the breeding of finer-leaved Ryegrasses has increased the potential for Red Thread development or more specifically increased its potential to do damage. Light foliar feeds with iron are good ways to quickly and cheaply grow the disease out on outfield and higher-height of cut areas, with the iron also serving the purpose of drying the leaf out.

All the best.
Mark Hunt