Spud Special: Dry weather complicates herbicide choices

With no significant rainfall at all in April, so far, along with above average temperatures, the planting of ware crops has continued into mainly good conditions with crops emerging through the ground quickly.


Weeds are also emerging, but in dry conditions I find choosing herbicides a real challenge as the residual element relies on moisture. Without it, it will have little effect, but cost a lot of money.


As a result, I will probably use linuron at the maximum allowed 600g of active plus a low rate of metribuzin, where variety allows, plus diquat or carfentrazone, depending on emerged weed spectrum with a follow up post-emergence application of rimsulfuron.


My choice of diquat or carfentrazone depends entirely on the amount of grass weeds present. Carfentrazone will not touch grass weeds or volunteer cereals, so if they are a problem I can follow up with an application of propaquizafop.


Application technique is also important with a lot of evidence suggesting that a medium/fine droplet size, along with alternating forward and backward facing nozzles, is best.


For those of my clients who can irrigate, timing of the first application will be on the agenda over the coming weeks, particularly if the weather remains dry. Little and often amounts using a fine droplet size will be needed to get moisture to where it is required for common scab control, not easy especially with a rain gun when ridges are dry or cloddy.


Timing of further applications of nitrogen – if required – will also be a topic for discussion, particularly in the absence of rainfall or irrigation. To make use of any available moisture from damp mornings, applying sooner rather than later will be a priority.

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