Crop Watch: Sclerotinia control up for debate

T1 wheat fungicide applications are nearing completion and timing of sclerotinia protection in oilseed rape is up for debate, according to our Crop Watch agronomists.

In Yorkshire, T1 fungicides were being applied to wheat crops depending on the timing of leaf three emergence, said David Martindale from Arable Alliance. “Septoria tritici levels are high in the base of crops so there is plenty of inoculum present.”

Eyespot was common on susceptible varieties such as Oakley and T1 fungicide choices reflected this, he said. “Thankfully the weather has allowed most T1 fungicides to be applied at the correct time.”

Barley T2 fungicide timing was approaching as awns started to emerge, he said. “T1 fungicides appear to have worked well, despite some high rhynchosporium pressure, so the T2 fungicide should act as a top-up to see the crop through to harvest.”

Oilseed rape crops were beginning to flower, but there was plenty of debate about how best to time sclerotinia fungicide application, he said. “Improved disease forecasting models are helping to provide better guidance, but an element of luck also seems to be required.”

Agrovista agronomist Swaran Bachoo from Hampshire said growers should be considering sclerotinia sprays if a two-spray programme was planned. “But if a single treatment is planned, wait until mid-flowering.”

Winter wheat was at GS32 and had been sprayed with Ceando (epoxiconazole + metrafenone) fungicide, he said. “There is little disease at present, but the very welcome rain is likely to bring in Septoria tritici.”

Most rape crops in Wiltshire received a fungicide at yellow bud, said Dan Dines from Wessex agronomy services. “This will have given some protection against early sclerotinia infection, but a mid-flower fungicide is planned and timing will be guided by crop growth stage and sclerotinia monitoring services.”

T1 applications had been timed well in wheat, yellow rust levels were low and the most prevalent disease was septoria, he said. “It is starting to appear on older leaves. Weather permitting, we will be looking for a gap of no more than three weeks between T1 and T2 fungicides.”

Awns were emerging on forward barley, but crops did not look good, he said. “In light of this and the stress they are under, fewer crops will receive a late PGR this season.”

Nutritional disorders in oilseed rape were causing concern for AICC agronomist Ruth East from Lincolnshire. “Rapid stem extension and failure to take up nutrients, such as boron, are to blame,” she said.

Septoria posed the biggest threat to wheat crops, particularly where inoculum level was high at the bottom of the crop, she warned. “Do not be tempted to reduce rates of triazoles as this is the most difficult disease to control.”

Click below to read the full reports:

Crop Watch North – David Martindale

Crop Watch South – Swaran Bachoo

Crop Watch West – Dan Dines

Crop Watch East – Ruth East

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