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Rapid Disease Detection

National Snapshot project

March Week 4 2021

Leaf layer tested: Newest leaf layer, leaf 4 at some sites.

Summary: Despite reports of yellow rust symptoms in some varieties, there are still no positive results of yellow rust in new leaf layers. Septoria tritici is also restricted to the base of plants, with only a handful of positive results, and these being September drilled susceptible varieties.

With cold weather forecast this Easter weekend no immediate change is anticipated.

Septoria tritici:

The divide between the north and west to south and east has disappeared. All sites are currently returning low Septoria tritici pg DNA from the newest leaves. After the disease was found at a number of sites during January and February is has fallen away – probably down to dry and cool weather for much of March and in some cases variety resilience kicking in.

The biggest turnaround is in Perthshire. The newest leaf of LG Sundance (7.9) at Keillor Farm is free of the disease and nearby at Middlebank Farm it has waned in LG Skyscraper (5.1). The disease is still present but readings dipping from 4.8 to 3.081 pg DNA.

At Middlebank Farm, George Taylor is hopeful of not applying a T0, but the crop will get some trace elements and spring herbicide. But a T0 is planned at Keillor Farm. With an eyespot rating of just three LG Sundance is a little vulnerable. This is likely to be a tebuconazole + prochloraz mix as a holding spray until the T1.

Close to 300 miles away at Long Sutton, Lincs the Septoria tritici that was present in Skyscraper (5.1) isn’t present in the newest leaf.

The question for David Hoyles is whether another follow up yellow rust treatment is needed following a pre T0 spray. Just a mile from The Wash the site is buffered from the worst of the frosts and yellow rust is a particular problem. Later drilling adds to the threat but cool weather has thwarted crop development. “In the past I’ve been happy to lose a few tillers on some forward crops, but this season with crops being more backward I want to hang on to every one we have. We’ll be going through with some micronutrition and growth regulation – the question is if the disease ‘bubbles up’ and we need some tebuconazole. Thinner crops and dry, breezy conditions have kept down canopy humidity, and disease. If it stays like this, we might be able to hold off until the T1,” he notes.

Septoria tritici cannot be found at Malshanger Estate, Hampshire either. The disease that was present in both Skyfall (5.8) and Extase (8.0) not detected in leaf 4.

In the past yellow rust hasn’t been a great concern but this season Ian Margettes and agronomist Steve Wood are planning a tebuconazole T0 for Skyfall. This is purely down to concerns over a possible new race and Skyfall’s susceptibility to the disease with its revised rating of three.

The disease control programme for Extase (8.0) will start with the T1. The question around this timing is the use of a multisite. The decision will be made nearer the time but with dry, cool weather during the latter half of March, they might just opt for a higher rate of azole + SDHI, particularly for Extase with its Septoria resilience.

Yellow rust:

New leaves at all sites are clean with no positive results currently.   

 

 

March week 4 results

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March Week 3 2021

Leaf layer tested: Newest leaf layer

Summary: Yellow rust remains undetected in the newest leaf layer at all sites. With Septoria tritici a country divide is developing. At northern and western sites only two fields are free of the disease, and these are both October drilled Extase (8.0). In the South and East disease pressure is generally lower.

Septoria tritici:

LG Sundance (7.9) at Keillor Farm, Perthshire continues to confound. In a week Septoria tritici pg DNA has almost doubled to 21,857. It has also moved on in LG Skyscraper (5.1) at nearby Middlebank Farm, but not to the same degree.

Further south at Scoughall Farm, East Lothian, Septoria tritici is now in the newest leaves of both Elation (4.1) and SY Insistor (6.8). It is no surprise to see Elation carrying more disease but it is not at worrying levels. Despite new leaves free of yellow rust, being a prone coastal location both crops are likely to get a T0 as a precaution.

At Quebec Farm, Leicestershire, Septoria tritici is present in the newest leaves of Gleam (6.1) but not Extase (8.0). With Gleam’s inherent yellow rust susceptibility and a neighbouring field of Skyfall showing signs of yellow rust, it will receive a tebuconazole T0 plus PGR and manganese. Despite being drilled a fraction later, Extase is expected to reach GS30 ahead of Gleam. Under less pressure Extase will receive PGR and manganese but not tebuconazole.

Come further south and east and Septoria tritici is low or unrecorded at all sites, even with susceptible varieties. Here drilling date is having an impact. No variety was drilled before September 25th, with the likes of Skyscraper (5.1) and Parkin (5.5) typically being sown towards the end of October.

Drilling date is certainly a factor at G H Hoyles in Long Sutton, Lincs. Crops went into the ground a month later than normal due to late harvested kale and potatoes. Graham (6.8) and Skyscraper (5.1) are carrying low levels of Septoria tritici on the run up to T0 sprays.

David Holes will finalise T0 decisions next week – W/C 29/03. “Through the combination of late drilling and three weeks of cool weather in February, there is little Septoria. We will keep an eye on yellow rust - we had to apply a pre-T0 spray following an outbreak early in the season.”

At our most southerly sight of Penryn, Cornwall new leaves are clean in late October drilled Graham (6.8) and Extase (8.0). Agronomist Richard Tresidder, who manages both farms, is still going to include a T0 spray.

5mm of rain fell overnight on March 25th, and showers continued on the 26th. “Disease pressure here can change rapidly and I don’t want to reach the T1 and find established disease. With the current risk low, I can opt for an inexpensive holding spray to keep disease in-check.”

Yellow rust:

As we move towards T0 sprays new leaves remain free of yellow rust. Testing hasn’t found new infection at any site regardless of location.

 

March week 3 results

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March Week 2 2021

Leaf layer tested: Newest leaf layer

Summary: Yellow rust remains in check and Septoria tritici is still not been detected in new leaves at just over half of the sites across UK & Ireland. However, Septoria tritici is progressing week on week in Herefordshire and Perthshire, Scotland. Meanwhile, stronger varietal resistance is proving itself in fields near Edinburgh and York.

Septoria tritici:

For those sites where Septoria tritici is being detected in the first half of March, it is at low levels with disease pressure generally reflecting varietal rating and drilling date. But there are signs at some sites that pressure is starting to build.

One is J P Clay Farms in Herefordshire, qPCR results have revealed a gradual increase in Septoria tritici levels. Manager Mark Wood describes the disease as ‘quite high’ in RGT Wolverine (5.3) and notes it is starting to spike in KWS Extase (8.0). He feels it will be interesting to see how the disease develops on both varieties over the course of the season.

At Grant Reid’s sites in Perthshire the differences between LG Sundance (7.9) and LG Skyscraper (5.1) continue to fascinate. Keillor Farm, Kettins, currently has the highest level of Septoria tritici detected so far this season, at 12.972 pg DNA, higher than any 2020 result.

Despite a resistance rating of 7.9 the disease still appears still to be developing faster in LG Sundance than in LG Skyscraper (5.1).

He believes this might be down to snow insulation earlier in the year. “When we collected samples some of the leaves had visible Septoria. This field is a little higher up the hill and probably had greater snow cover, which might have insulated the crop. But I expect as we move through the season the genetic resilience of LG Sundance will eventually come into effect.”

Further south at Coldstream Mains, Septoria tritici is in the newest leaf layer of Elation (4.1) but not in SY Insistor (6.8). But levels are low and technical manager Craig Simpson and partner David Fuller aren’t overly concerned.

At our site near York, it is a similar picture with KWS Kerrin (4.8) and and KWS Extase (8) respectively. This reflects our understanding that varietal resistance is an important factor when in disease management. 

Yellow rust:

This disease remains in check on the newest leaf layer at all of our sites tested so far this season, likely as a result of the recent cold spells.

March week 2 results

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March Week 1 2021

Leaf layer tested: Newest leaf layer

Summary: We have now moved into weekly sampling and despite a slight increase at some locations, no disease has been detected in the newest leaf layer for the majority of fields tested. Grant Reid in Perthshire and Gareth Bubb in Herefordshire are seeing the highest levels of Septoria tritici levels so far.

Septoria tritici:

Following the cold spells through February, there is still no disease detected in the newest leaf layer at most sites.

On Mark Wood’s farm in Herefordshire, there is a slight increase in Septoria tritici levels from February, with the disease detected on his crops of RGT Wolverine (5.3) and KWS Extase (8.0) however both results remain relatively low with T0 sprays on the horizon.

Which is where Mark is turning his attention to, in particular the need for yellow rust control. He sees Rapid Disease Detection as another tool in the armoury and having a role in T0 decision making.

A twice winner of the ADAS Fungicide Challenge he says fungicide decision making always has a degree of guesswork so having a steer on disease pressure is important. “The sooner you know about disease the better and the results will tell us if we are holding disease and our fungicide strategy is the right one.

On Grant Reid’s two partner farms, results are showing low levels of Septoria tritici on the newest leaf layer of both LG Sundance (7.9) and LG Skyscraper (7.1).

Results from James Howat’s partner farm of R H Mason in Yorkshire are detecting low levels of disease in KWS Kerrin (4.8), whilst the crop of KWS Extase (8.0) drilled on the same day currently in the newest leaf layer.

Yellow rust: After several hard frosts throughout February, it is not surprising to find that there is still now yellow rust on the newest leaf layer at any of the sites. However, several of our technical managers are reporting visible infection on the lower leaf layers of more susceptible varieties. Although the disease has dried up due to February cold spells we will continue to monitor these all closely.

 

March week 1 results

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Return back to Rapid Disease Detection National Snapshot Project home page for more results.