South: Winter wheat and oilseed rape fungicides

Overnight frosts are now gone but the crops are ten days behind where they are expected to be. Winter wheat is at GS32 and has been sprayed with Ceandu (epoxiconazole + metrafenone) fungicide. There is little disease on the wheat but very welcome rain of last weekend is going to bring in septoria tritici for sure.

Yellow rust is conspicuous by its absence and, even untreated Oakley which has a resistance of 6 is clean! However, my advice is to take care and apply a good fungicide that will give cover against both yellow rust and septoria, despite the fact that yellow rust is not active when air temperature is above 15 C. Winter barley has flag leaf emerging and should receive the T2 fungicide where T1 was applied three weeks ago.

There is some net blotch present on the lower leaves, but the recent rain could encourage the incidence of rhyncosporium. Use a good fungicide based on a triazole plus strobilurin such as Jaunt (prothioconazole + fluoxastrobin + trifloxystrobin).Another good option is the new IZM fungicide Bontima but I believe it would be better used in mixture with a triazole to boost its curative activity especially on rhyncosporium.Nitrogen programmes on winter wheat should now be completed except about 45kg which should be kept back in the case of milling wheat for protein enhancement. Similarly, the main of the nitrogen should have been applied to oilseed rape but the last 30kg/ha if yield is expected to be above 3.5t/ha. Apply this late nitrogen at early flowering where fertiliser applicators that can be lifted high enough above the crop canopy are available. Oilseed rape crops are at the stage when sclerotinia sprays should be considered if a two spray programme is planned. But if only a single treatment is planned wait until the mid flowering stage. Filan (boscalid) alone or in mixture with a strobilurin such as Galileo (picoxystrobin) would be a good choice.Peas are at the first node stage and have already been sprayed against pea and bean weevil as have the spring beans which are at the four leaf stage. Despite the dry weather pre emergence chemicals such as Cirrus (clomazone) and Nirvana (pendamethlin + imazamox) have worked extremely well in both peas and beans.

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