This month’s messages:
It has been wet underfoot since my last time of writing and that has stopped many from travelling for large parts of April. It meant field work concertinaed, with agronomist’s recommendations made and no chance of getting tasks completed. When growers could get on, there was lots happening in the field, with spring crops going in and sprayers on the move, depending on what the farm’s priorities were.
Winter wheat growth stages in Lincolnshire are dictated by drill dates. In the south of the county where blackgrass isn’t a problem and crops were drilled earlier, T1 fungicides will be going on as we speak. In the north where crops were drilled later for blackgrass control, leaf three will fully emerge over the next week (7 May onwards).
Crops are essentially in two camps – those that had a T0 and those that haven’t. Where growers haven’t applied a holding spray and T1s are yet to be applied, they will need to be robust at T1, as septoria and eyespot are widespread after the wet weather. Reports from across Lincolnshire are of limited yellow rust incidence, but be mindful of it in susceptible varieties. Otherwise, highly effective septoria focussed programme should be enough to control the disease this season.
Using Aviator (bixafen + prothioconazole) at 1L/ha delivers 160g of prothioconazole, which is strong on stem-based diseases such as eyespot and fusarium, which is also starting to build. The product will ensure you stay on top of septoria too and you don’t want to be chasing it later in the season like we were in 2012. I should also stress the importance of timing – even where the T0 was late, do not delay the T1 and make sure it is applied to a fully emerged leaf three.
In the earliest drilled crops, we should start to see flag leaves emerge in mid- to late-May, depending on conditions over the next two weeks. At the T2 timing, you are always in a curative situation because leaf two has been emerged and exposed to potential septoria infection for some time. I would recommend Ascra (fluopyram + bixafen + prothioconazole) at 1.2L/ha, which delivers 156g of prothioconazole plus twin SDHIs for the best curative control out there.
OSR crops are variable, ranging from those that are just coming into flower to those that have been in flower for several days. Sometimes the variation is in the same field, so it makes decision making for flowering sprays tricky.
We had a warm period that brought many crops into flower, but it has cooled again. This could prolong flowering and leave crops at risk of sclerotinia for longer. Light leaf spot is also still a threat, so a broad-spectrum prothioconazole-based fungicide is required, with a follow up two to three weeks later. If the flowering period looks like it will be more condensed, one hit of a SDHI-prothioconazole co-formulation might be the best option to see you through, giving both persistency and physiological benefits.
An observation here is Lincolnshire is that there are a wide range of weeds coming through underneath oilseed rape canopies, including blackgrass, due to crops being open for longer and moist conditions. There isn’t anything you can do to control it at this stage, but where there is blackgrass is growing, make a note of location and manage it correctly in follow crop with stale seed-beds and later drilling.
Drilling of sugar beet is late this season and care will be needed with herbicides to adequately control large flushes of weeds and ensure early applications are safe. The herbicide of choice is Betanal MaxxPro (desmedipham + ethofumesate + lenacil + phenmedipham), which has the highest weed spectrum of any product on the market and its oil dispersion (OD) formulation is very crop safe and won’t stunt plants with any phytotoxic effects.