May 3, 2016
Sam Patchett Blog: Difficult Spring Spraying
With little let-up in the weather into early April, Sam Patchett sees many northern growers fast running out of grass weed control options and facing increasingly difficult spring spraying compromises.
It’s been unrelenting. Again, things were drying out nicely in the run-up to Easter. Then everything went pear-shaped and intermittent rain, sleet, hail and wind ever since has kept our sprayers firmly shed-bound.
I can only hope that by the time you read this we’ll have seen a big change for the better. Unlike our excellent T20 world cup cricket performance, though, the immediate prospects give us little reason for optimism.
Having received a good amount of their early top dressing, our winter cereals have picked-up surprisingly well. However, so has the black-grass, which is fast getting too big for comfort.
As we go into the second week of April we’re also still waiting to apply any of our T0s to manage the large amounts of Septoria threatening September-drilled wheat crops, in particular. The mild winters we’ve been having make it important for us to steer away from varieties without the best Septoria resistance and, wherever, possible hold-off on drilling until mid-October to reduce early disease pressure.
There are three key questions of the moment for our wheat management. How long is it before we abandon the idea of a T0 ? How do we adjust our T1 plans if we have to do without it ? And how do we square the need for increasingly urgent disease, weed and insect control, plant growth regulation and trace element nutrition with the desire to avoid overly complicated and stressful tank mixes ?
Where we can’t get our T0s on before the third week of April we’ll be switching to Plan B. This will involve more powerful SDHI, triazole and multi-site protectant combinations at T1 and the addition of trinexapac-ethyl to chlormequat for more robust growth regulation.
We don’t want to include mesosulfuron-methyl/iodosulfuron-methyl herbicides with most of our fungicides. So, we’ll be focussing on broad-leafed and meadow grass control alone at the stage, leaving the worst black-grass infested patches for spraying-off later on. Drastic this may seem, but most of the plants will probably be beyond reasonable spring control at this stage anyway.
To help with disease control, give ourselves extra flexibility in dealing with the conditions and ease the tank-mixing burden, we also have to option of bringing our T1s forward a little and going back in with a T1.5 a couple of weeks later. This will allow us to give a timely chlorothanil top-up, split the PGRs and save further complicating our T1 with foliar trace elements. It will be very much a matter of horses for courses, adapting our programmes closely to individual crop needs – and, of course, the weather.
Thankfully, life is less complicated with our winter OSR. I’m not quite sure how, but most of our stem extension sprays went on in good time and, driven by day length, the more forward crops are just starting to flower. Having said that, many vary from ankle to knee high in the same field.
Despite looking hard for pollen beetles, we can’t find many about. So, other than our later crops, it looks most won’t need treatment again this year. Again this year too, continued cold nights may allow us to hold off on our flowering treatment so we might be able to avoid a second spray in many cases.
We’ll be using the combination of boscalid and metconazole we’ve found gives extra activity against light leaf spot control and valuable flowering synchronisation, helping to maximise light interception over the critical period from mid-flowering. This will be especially useful with our more variable crops.
The diabolical spring weather means we have a lot of spring crops still to be drilled and it’s getting rather later for the cereals, in particular. We’ll be upping seed rates to compensate, including well-placed nitrogen in the seedbed wherever possible and applying micro-nutrients at the 2-3 leaf stage at which we’ve found some of the best responses.
Time is still on our side for the relatively large amount of linseed waiting to go in; especially as we know cold seedbeds mean flea beetles will have most of it and pigeons the rest. Patience, firm, fine seedbeds with sufficient moisture and good sowing depth control will be our watchwords here.
You can email Sam your comments and opinions via email@example.com.