East: Septoria, mildew and rusts lying in wait

A gentle soak is needed. Following an exceptionally dry period with much of eastern England receiving less than 20 per cent of the normal recorded rainfall in March, crops are showing signs of drought stress.

These affects are becoming acute in some spring crops and second wheats on light or poorly structured soils. Dry conditions have hardened weeds, so robust doses of spring herbicides are required, particularly for fops and dims in spring crops and sulphonylureas for the control of brassica weeds and poppies in cereals.  

In cereals, fungicide programmes are well underway as final leaf three emerges in wheats drilled late in September. Dry conditions have restricted the development of septoria and eyespot infection. There is talk of responding to these conditions by reducing fungicide doses. But beware, there is still plenty of septoria, mildew and rust inoculum on the lower leaves. Well timed T0 sprays on rust-susceptible varieties have kept this disease in check.

However, late sprays have often allowed disease foci to develop prior to treatment. This suggests that even in these drier conditions rust inoculum is lying in wait, ready to take advantage of any gaps or weakness in the protectant activity of the fungicide programme.

In wheat, doses should be robust enough to protect emerging leaves for at least three weeks until the next scheduled spray, allowing for wetter conditions and any unforeseen delay in this timing.

In oilseed rape crops, sclerotinia programmes are due to begin. Accurate programming for sclerotinia control will depend on the interaction between temperature and rainfall at flowering. Although rainfall is required for spore release and infection, sclerotinia attack has been surprisingly serious in other dry springs.

Winter bean growth has been generally slow in the dry conditions, but both winter and spring bean crops must be monitored for pea and bean weevil damage. Dry conditions have also limited the residual activity of the pre-emergence herbicides.

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