The very mixed weather with continuing low temperatures has meant that crop growth stages have been all over the place, but generally later than usual for the time of year. This has created problems for agronomists and sprayer operators in gauging spray timings and intervals between applications along with all the rest of the spring work.
The awns are coming out on winter barleys and with low disease levels the T2 spray may be an opportunity to shut the gate. The ramularia risk prediction is medium to high due to the level of leaf wetness and this should be factored in to the decision as to which actives to use. Prothioconazole and chlorothalonil will do a good job however, SDHIs have also performed well under high ramularia pressure.
Having a sclerotinia monitoring site in Scotland this season is an additional weapon in our quest for Integrated Pest Management in the oilseed rape crop. There have already been positive petal tests at this site so we shall have to be on our guard. Winter oilseed rape crops are in full flower so the decision as to whether we adopt a one or two spray approach to sclerotinia control now hinges on the length of the flowering period. Strobilurons, azoles and SDHIs all have useful activity so a robust mixture of actives should perform well and reduce the likelihood of fungicide resistance developing.
Winter wheat growth stages are probably the most variable ranging from some crops that have only just had their T1 spray to those that are 3 to 4 weeks since they have had a fungicide. Decisions, decisions? Only those crops with high disease pressure, which are the exception, will require mid T1/T2 protection.
In general there is a lot of potential in wheat crops this year and there is no doubt of the value of a good T2 spray. This is the place for a robust SDHI (ie. 75%+ dose rate). If using a straight SDHI then remember to include a healthy level of azole in the mix to assist in reducing the risk of fungicide resistance.
In potatoes there is no shortcut to effective blight control. Be aware of any sources of infection (ie. dumps etc.) and monitor them closely, taking action if required. Start your blight protection programme early and maintain a tight spray interval (ie. maximum seven days). Ensure that you achieve good coverage of the growing points and vary the active ingredients according to the stage of growth and weather conditions. Although you may have a plan for the season be prepared to change it if Mother Nature intervenes.