At last a break in the weather over the second weekend of May allowed some spraying to be done and hopefully T1 treatments on wheat to be finally completed. The T1 (if we can still call it that) spraying window has stretched across a period of 4 weeks with opportunities being snatched at numerous points since mid-April.
For those who managed to spray at a normal T1 timing the T2 is now due at a standard flag leaf emerged growth stage. Where T1 treatments were delayed into May, the follow up fungicide is likely to be nearer early ear emergence. There is a lot of interest in SDHI chemistry for the T2 or T2/T3 application, but it won’t be a case of using them in every situation.
They are predominantly septoria fungicides with very good activity on brown rust but a little more variable on yellow rust. We have seen from trials over many years that milling wheats still continue to benefit from the use of strobs at T1 and T2 to improve nitrogen utilisation and increase grain protein – something that the SDHIs haven’t so far achieved to the same extent.
With yellow rust getting going again over the May bank holiday weekend it may be necessary to resort to triazole + strob treatments in the very susceptible yellow rust varieties. Either that or bolster the SDHI with a strobilurin as may also be the case in milling wheats. Whether or not SDHIs form part of the strategy the key to getting fungicide programs right this season is ensuring robust rates of triazole are used.
Final nitrogen top dressings on wheat have also generally been completed. Some upwards adjustments to rates have been made to reflect increased yield potential this season and in some cases, rates have been reduced in large lush canopies where lodging potential is higher. PGR programs have been disrupted by delayed timings and lack of product availability.
Although the focus has been on getting up-to-date in wheat, there have been numerous other jobs backing up. The priority in early May was to get through the oilseed rape crops with a sclerotinia fungicide and in most cases this took priority over wheat T1s. It remains to be seen how quickly flowering takes to finish and there may be some topping up of fungicides towards the end of May/early June, particularly if the weather is wet again and flowering is still going.
It seemed that the majority of the sugar beet acreage was being sprayed over the weekend of 12/13 May. In many cases this will have been the first post-emergence herbicide based on a Broadacre or modified Broadacre type program. Activity on weeds, some of which were getting quite sizeable, will be assessed over the next few days and if necessary another treatment applied on a relatively short interval to try to get on top of large polygonums.