South: Keep watch for slugs despite dry weather

Drilling is now well under way with most OSR in and up and in most places looking quite healthy. Many crops have had a volunteer spray and in some situations this has been mixed with a post-emergence broad-leaved weed spray such as metazachlor/quinmerac mixes.

Wheat is being drilled as we speak intogood seed-beds, with many growers pressing on early not wanting tobe left in the same situation as last year, which isunderstandable. We are possibly coming to the end of a long dryspell in the south and my fear is that once the weather breaks itcould be replaced by an equally long wet one.

People are asking about pre-emergenceresidual sprays in dry weather and generally speaking I would saygo ahead and put them on. They won’t go anywhere and as soon as itrains they will become activated, and until it rains we’re unlikelyto get much weed germination anyway.

The slug risk has reduced considerablywhere it has been dry but it hasn’t disappeared. This is a goodcase for monitoring and perhaps mash trapping. But with all thefocus that is on metaldehyde at the moment I would shy away fromblanket prophylactic treatments.

It’s easy to remember the problems oflast year but we must also remember that this time last year we hadonly just finished combining after a month of foul summerweather.

All the discussions are about what we dowithout IPU and this makes the pre-emergence residuals even moreimportant, especially on non-chlorotoluron tolerant varieties.Often these mixtures work well early post-emergence (ie one leaf ofcrop), but plants are often very sensitive at that stage and somecrop effect may take place especially in overlaps.

But I have yet tosee any serious yield reduction from these early symptoms – it isfar worse to let the weeds get away or have crop effect fromapplications in the spring.

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