One of the things Henry and myself have been chatting about “On the Horizon” is the concept of sub 2c stopping hours.
It’s a concept we’ve developed to help us understand when we start to see weather that is cold enough to slow down the development of Microdochium patch and how variable it is across the country and years.
Whilst pulling some data out about 2021 for the next episode I thought I’d share where we are to date this year in the month of October.
In the below Chart for Sandwich you can see a few things:
- The black line shows the average spread of hours other the month of October in the period 2008 – 2013
- The Orange, Yellow, Red and Green lines are the number of hours at those temperatures in October 2021 (so far)
- The colour is representative of the Microdochium disease pressure used in the Greencast model (which can be found here…. and here……)
As we move in to an ever warming climate the odds are in favour of delivering longer periods in the high pressure zone and less at the colder end of the spectrum where we see the disease slowing down and hopefully stopping.
October has never been a month to deliver many of the “sub 2c stopping hours” so I’m not particularly surprised by the above data.
As we move into November I’d would hope to see more of the lower end temperatures appearing.
Temperature is only one of the environmental factors that needs to be in place for disease development, you also need leaf moisture to enable the the pathogen to develop.
The real concern for me is as we move later into the year, the odds are in favour of higher average temperatures at a time when periods of leaf moisture are at their longest.
This places more emphasis than ever before on keeping putting surfaces clean during this period of the year.