Applying strobilurin fungicides allows milling wheat crops to make more effective use of nitrogen, helping them maintain optimum yields and meet protein targets, according to trials by distributor UAP.
Last year’s results in Solstice wheat reflected trends seen during previous trials, Chris Bean, the firm’s technical manager, says.
The trials were set up to investigate whether applying strobilurin fungicide had any impact on a wheat crop’s ability to use available nitrogen, he explains. “We’d seen some evidence of strobilurins having a positive effect on nitrogen uptake during a trial in 2000 on Consort when using pyraclostrobin.”
In these trials three different rates of N were each treated with a fungicide programme of Prosaro plus Bravo only at T1 and T2, a strobilurin (Jenton) added at T2 only, and a strobilurin (Jenton) added at both T1 and T2.
Last year, the N rates were based on what RB209 recommended for the field situation (140kgN/ha), and then two rates based on what UAP’s in-house N calculator suggested for a feed wheat (240kgN/ha) and a milling wheat (340kgN/ha) for that field.
The result was increased yields from strobilurin-treated plots compared with triazole only at the higher N levels, Mr Bean says. The biggest increase – 1.3t/ha – was when two strobilurins were used in conjunction with 340kgN/ha, while just adding a single strobilurin at the flag leaf timing added 0.8t/ha in the 240kgN/ha plots.
Disease control probably played a part in the increase – brown rust was present – but the same trends were present in previous years’ trials, when rust was a non-factor, Mr Bean says.
Protein levels also increased at the two higher N levels when a strobilurin was included.
A clue to the better performance in the strobilurin plots is the increased numbers of ears recorded, Mr Bean suggests. “Where we used two strobilurins there was a significant increase. We know Solstice can be a shy tillerer in the spring or quickly lose tillers if the conditions are not favourable, so it could be that the strobilurin helps the crop absorb more N more quickly.”
It also could explain why, in previous trials, the best response has come from T1 and T2 sprays, rather than T2 and T3.
The results of the trials mean Mr Bean will be recommending two strobilurins on most of his Solstice area.
UAP will be testing the principle on feed wheats this season. “In a non-milling situation I would put a strobilurin on at T2 and you could potentially justify one at T1 as well.”
This year’s trials will also sample plots after harvest to see how much N is left in the soil to ensure more is not being left to leach away.