T2 Strategies revised after CropCheck scores reveal risk

For Julian Gold of Hendred Farm Partnership, Wantage, Oxon, CropCheck is all part of an integrated agronomic approach.

He adopted integrated pest management (IPM) for cereal disease control well before Defra’s announcement to pay £989/year to complete an IPM assessment and put together a plan.

What CropCheck provides is the assurance that the disease control tactics he is to adopt are right for the variety and disease pressure in the field at that time. Using fungicides appropriately being a key part of an integrated strategy.

He places great value in qPCR testing. It provides useable data to help the decision process which can be a little ‘grey’ in his opinion. Variety rating and when it was drilled is a guide but no substitute for what is going on in leaves. He does keep a close eye on the weather, logging temperature and rainfall, plus the amount of N applied and crop biomass. Completing the picture is a study of weather forecasts to see what impact this could have.

That useable data last season revealed established high yellow rust infection in leaves 3 and 2 of Extase and Cranium ahead of T2 applications – CropCheck scores of 23 and 48 respectively. A 0.75 l/ha application of Revystar at T1 had held Septoria, but not yellow rust. As a result, Mr Gold went in with ‘a sniff’ of tebuconazole ahead of T2 sprays with Cranium and added some Comet (pyraclostrobin) to a further application of Revystar to keep the disease in check. He also brought this forward, as Extase was ahead of Cranium in its development.

The results probably took Mr Gold by surprise, as both varieties have good yellow rust ratings, and Extase is a variety thought to be highly resistant to all strains except 19/215. However, it wasn’t just at Wantage that yellow rust was picked up in Extase, positive results came back from Fawley Court, Herefordshire too.

Another to use testing is Mike Ashby of Armston Farm. Mike knows the strengths and weaknesses of his variety roster but growing exclusively milling wheats he also knows the price of a disease taking hold can be high. Therefore, a precise approach to disease management is employed.

The service provides the reassurance that his disease control strategies are appropriate. “Most varieties have a particular susceptibility, so each needs to be managed accordingly. I know the risk as soon as I plant it so decisions are based on this and environmental factors such as the weather and crop development. I’ve found CropCheck data useful to validate what I’m seeing in the field,” he says.

Mike’s approach is to be on the ‘front foot’ with disease control tactics based on prevention rather than cure. Over the last two seasons, CropCheck hasn’t changed any fungicide plans but it might in the future. “It’s an interesting service and to date the results have been in line with my expectations – more, nice to know than particularly illuminating. I’m sure I’ll use the service again this season, although I suspect the data might not throw up any surprises. But ‘nice to know’ is no bad thing, reassurance of any form is always welcome.”

Agronomist Paul Cawood believes the doctrine of a four-spray programme is not always appropriate given the variability we see in disease patterns these days.

Technologies such as rapid qPCR testing and weather modelling allow him to be on the ‘front foot’ with disease control strategies, reacting quickly to the weather extremes we experience now. Coupled with some highly resilient Septoria varieties, his disease approach is now centred around variety, field and market.

With another season of unseasonal climatic conditions, he started leaf testing early on the run-up to GS32. The dry, cool conditions had blunted Septoria pressure out of the winter and the lack of disease was confirmed by a series of low CropCheck scores.

It allowed him to cap T1 spend using a range of fungicide options including Proline (prothioconazole) + Folpet, Zephyr (prothioconazole + trifloxystrobin) or Aviator (prothioconazole + bixafen) dependent on Septoria and yellow rust ratings. Where resilient varieties were in the ground, Paul was able to go a little further and omit a T1 altogether.

He says tools like CropCheck and Sencrop allow him to do his job better. “My role as an agronomist is to recommend the most appropriate solution for every situation. The data provided allows me to adapt strategies to what can be rapidly changing situations. CropCheck gives real insight into what is happening inside leaves, which I can add to other information sources,” he notes.

Testing continued and the run-in to GS39 indicated that Septoria was building after some May showers, as was yellow rust in some varieties. Although Septoria wasn’t visible on leaf surfaces, Paul knew it was only a matter of time so opted for Reystar and Univoq to damp down disease pressure.

But testing revealed yellow rust threatening a number of varieties so he added a strob to boost protection.

The data collected by Paul earlier in the season was also put to good use as it closed. Using azole-based options had allowed for an SDHI to be slotted into the T3 for the more susceptible varieties, so these got a dose of Aviator. “With T3 the last opportunity to see the crop through and with the late disease pressure we experienced last season having the option of an SDHI is welcome.”