Boothmans Agriculture agronomist Charles Starkings.
Anearly application of an appropriate protectant fungicide at T0 (GS30) especially on mildew susceptible varieties is critical this season in lightof current weather conditions, forward crop status and varietal susceptibility.
Growershave not faced a bad mildew year for a few seasons, but with more susceptiblewheat varieties such as KWS Santiago, KWS Kielder, Leeds, Conqueror, Solsticeand Claire in the ground along with barley variety Cassata and the oat varietyGerald, following favourable autumn conditions for the disease extra vigilanceand early spraying will be essential.
Mostgrowers were drilled up in the autumn in good time, says Boothmans Agricultureagronomist Charles Starkings. Warm weather then helped establishment so by theend of the year crops were forward and lush a perfect breeding ground formildew.
Mildewrisk is too high to ignore this spring. The disease can take more than 20% ofyield if not treated early, he says.
Earlyonset of mildew can be far more damaging to yield than the later flag leaftiming infection. When the crop is still tillering and at the start of earformation (up to GS31) is when mildew is most damaging, explains Mr Starkings.
Thesecond half of March is the typical winter wheat T0 timing when most cropswill be ready for the first fungicide spray. If mildew and/or yellow rust arebad before then we might consider an earlier application. Protecting new growthand avoiding plant stress which can restrict rooting and ear formation at thisearly timing is essential. An application of a long lasting protectantfungicide such as Justice (proquinazid) at a rate of 150ml/ha giving up tosix weeks protection should keep mildew out of the crop during late tilleringand up to the point when a second fungicide spray might be required ifconditions are very favourable to disease development.
Proquinazidis the top protectant fungicide, he says, and even in the absence of disease ithas plant physiological effects that far outweigh the cost of the chemical.
AtT0 we also add in 2l/ha of Fezan (chlorothalonil + tebuconazole) for septoriatritici and yellow rust protection/control, he says. Depending on soil typemanganese can be added as well as a PGR or herbicides if appropriate.
AtT1 Mr Starkings says that Aylora (penthiopyrad + chlorothalonil) mixed withprothioconazole gives excellent septoria tritici and eyespot control and providedit follows Justice the prothioconazole tends to be enough to keep on top ofmildew.
Ifyou have missed the T0 Justice timing then T1 does give you an opportunity toclean up mildew although the potential yield loss will have already beencaused. In this situation at T1 we would also use a morpholine or metrafenoneto the mix to knock down mildew, he explains.