Not sure if any of you caught a program last night on BBC2 entitled “Will It Snow ?”, but it broadly confirmed the points I made last week ;
1. Long-range forecasting is a very inaccurate science
2. We cannot predict a blocking event in the jet-stream, which is the scenario most likely to bring us arctic conditions for any length of time.
General Weather Situation
Well a pretty settled week coming up, a bit on the dull and dreary side and with a west-east split in terms of rainfall, though amounts for the west will be pretty light compared to last week anyway !.
As you can see from the graphic above, currently we have an Atlantic low moving slowly eastwards and affecting our weather from mid-week to the end of the week with brisk, Southerly / South-Easterly winds, mild temperatures and light showers, mainly for Ireland, the South-West of England and the west side of the U.K. There’s a possibility of some of this rain pushing further into the central region of the U.K on Friday, but amounts will be light.
So in more detail, a dull start to the week for most places, brighter in the west, but even here cloud will soon push in. A weak rain front will push showers into Kerry, the South-West of England and the West of the U.K later on Tuesday and early on Wednesday, but amounts will be light.
On Thursday, Ireland starts brighter, but showers will continue to nibble away at the South-West corner of the U.K (as if you guys haven’t had enough rain), and these may push eastwards into the South of England and South Midlands during the day, but nothing heavy is foreseeable at present. The heaviest rain of the week will arrive into Kerry on Friday morning and this front will push eastwards across Ireland, but it’s likely to stop there and persist through into the weekend.
Temperatures for the start of the week will be typical for early November, low double figures, but as the low pressure arrives from mid-week, they’ll rise a little to early-mid teens and night temperatures will also be higher.
I think we may have the start of a blocking event for next week courtesy of a continental high pressure system. So this will mean a generally cooler spell of weather, lower daytime temperatures and if there’s no cloud cover (as it looks at the moment), a spell of night frosts. There’s no rain on the horizon for next week, aside from a possible chance on Monday in the west.
The topic of interest is definitely the effect of the mild day and night time temperatures over the last 10 days, both from a negative and positive perspective. The chart above shows the trend over the last 3 years for mild temperatures running into November and that is what’s causing high disease pressure and growth rates.
Fusarium activity as predicted last Monday has been extremely high and coupled with the increase in growth and cutting has made control difficult.
Even where products has been applied just prior to this period, there appears to be a delay in efficacy. What’s actually happening here is that the rate at which the fungal population is increasing is faster than the knockdown effect of the fungicide and this means that the disease appears to be still active, even after a fungicide application has been made.
Only when the environmental conditions (temperature and humidity) change in a way that slows the growth of the disease population will you start to see control. Realistically looking at the weather over the next 7-10 days, I don’t expect this to be for another week or so, when temperatures start to drop and growth rates (fungal) slow.
One of the best ways of assessing your current disease activity is to mark the outside of any ‘active’ disease patches with a couple of dots of turf spray paint and then assess over the next few days whether the patch is actually growing outwards past these marks.
Another parameter to assess is whether there are new disease patches occurring in previously unaffected areas, this is a more definite sign that your present fungicide treatment is not achieving control.
The high soil temperatures are also responsible for increased grass growth and this will ultimately affect fungicide longevity because with a cut rate of 3 times per week at the moment and many people saying they could cut every day (it was the same this time last year), alot of fungicide is being removed from the sward by mowing.
For this reason, I’d suggest taking a week off your longevity aspirations for a systemic fungicide. If you applied your systemic fungicide at 1/2 rate, then I wouldn’t expect much more than 2 weeks longevity under these conditions, so in short, not a wise move.
It goes without saying that alongside your fungicide program, it’s equally important to maintain turf hardener / plant elicitor / iron applications and reduce plant leaf moisture levels (by whichever means suits you) during this period of elevated disease pressure.
All the best and good luck !