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Generally, conditions in the fields of Lincolnshire are wet and there has been little opportunity for spraying over the last month or so. However, there are plenty of things that can be done to prepare for the spring season ahead.
Most oilseed rape crops received an early phoma fungicide last autumn, but not many received a follow-up spray with light leaf spot activity in November. Very few symptoms of light leaf spot were evident before Christmas, although the SpotCheck initiative has found a few cases where the pathogen was present in more susceptible varieties.
Early February provides a good opportunity to inspect oilseed rape crops and, if necessary, test or incubate leaves to see if light leaf spot infection has occurred. For sampling, take 30-35 leaves at random, ideally across each field, and send them in to ADAS using a SpotCheck sampling kit or incubate them for 24-48 hours. Where it isn’t practical to do every field, take a representative sample from each variety or OSR block to help aid fungicide application decisions.
For any fields that did not receive a late-autumn fungicide with activity on the light leaf spot, a fungicide application should be considered as soon as conditions allow. In these situation, a prothioconazole-based product is recommended, as it has the best activity on the disease.
Cabbage stem flea beetle larvae can be found readily in plant stems, although not quite in the numbers seen last season. Nothing can be done to control this pest now, but ensuring good plant health for the rest of the growing season with a good fungicide programme and adequate plant nutrition will help plants grow away from damage.
The late drilling of black-grass infested land was possible due to the open autumn of 2017 and overall, pre-emergence herbicides went on in good conditions and have performed reasonably well. Use assessments of autumn grassweed control to prioritise fields requiring a follow up contact herbicide treatment such as Atlantis (mesosulfuron + iodosulfuron) or Monolith (mesosulfuron + propxycarbazone).
The most urgent should be where black-grass plants are most advanced. I have seen black-grass still emerging in South Lincolnshire and with no residual left in the soil, these fields will also require attention. Where you have difficult black-grass populations, Monolith is the sensible choice, as it has been shown to provide an extra 10% control over Atlantis.
There has been a general trend to get spring barley crops in the ground as soon as possible in the new year, as crops drilled in mid- to late-March can be a bit of a lottery in the East if we have a dry spring.
Although there is currently a frustration amongst farmers that soils are too wet to start cultivations, remember a compromise is needed in some years when pushing ground to drill as early as possible. Conditions must allow at least a half decent seed-bed where the drill can bury seed, especially where a pre-emergence herbicide is planned, as shallow seed depth can compromise crop safety.