The weather has allowed a good cereal drilling window this year and majority should soon be complete. The conditions have been favourable, with plenty of moisture to allow for good germination. However, this has led to slug issues, particularly on heavier land. Crops with cloddy seed-beds and high previous crop residue following oilseed rape should be carefully monitored up until the crop has reached 3-4 leaves.
Cooler nights, heavy dews and scattered showers have assisted with pre-emergence applications, which can be seen on emerging weeds. This will also help with persistence of the actives.
Aphids are being found in cereal crops and Rothamsted Research insect survey bulletins suggest bird cherry-oat aphid numbers are increasing, so crops without Deter (clothianidin) dressing will need treating from the 2-leaf stage, with a follow up four weeks later. Those that have the dressing, a follow up treatment will be dictated by drilling date and seed rates. Ensure to check the arthropod buffer zones before application as these vary for certain products.
Winter oilseed rape crops are variable, with some earlier drilled crops producing very large canopies that will require growth regulation management. However, the wet weather during late August/September led to a large area of rape being drilled later. These crops have struggled with slug and flea beetle damage, which leaves a concern with under-developed root structures going into the winter. These smaller crops have had foliar stimulants containing phosphites at 2-4 true leaves, to encourage root growth and produce stronger plants before the colder winter weather begins.
Attention now turns to phoma and light leaf spot control. It is important to check the disease resistance scores of the variety grown – consult the AHDB guide if you are unsure. Phoma lesions are being found at threshold and applications are being made, along with growth regulation where it’s required. Phoma can move 5mm/day at 15C, so to prevent the disease travelling to the leaf axial and causing stem cankers later on smaller, backward crops should be prioritised.
Light leaf spot has traditionally been an issue in the more northern regions but is now a more widespread problem. It favours cool wet conditions with symptoms appearing from early November. With concerns over triazole resistance, ensure a preventative approach is adopted with varying chemistry groups. Refinzar (penthiopyrad + picoxystrobin) has proven a useful product in this anti-resistance strategy, as well as enhancing root growth.
Plants with sufficient growth will also receive an autumn boron and magnesium application.
Crops treated with clethodim (Centurion Max) for blackgrass has given good control, which will now allow a well timed propyzamide application later on in the season. At the time of writing soil temperatures are still too high (12C). Ensure they drop below 10C before treating.