roundup hub ux review

Ensuring Physical Compatibility and Crop Safety

For pre-em herbicides, physical compatibility between different products is not usually a concern but crop safety is. The more chemistry applied, the more chance of crop effects. Depending on the actives in the mix, 3–4 actives is a sensible guideline for wheat tank-mixes; 2–3 in barley. However, conditions make a big difference to what is safe.

“First of all, it’s soil type, you are less likely to get issues on loamy or heavy soil. If you’ve got light stony ground that’s a red flag for me. If you can apply them closer drilling, you’re less likely to get issues. Leaving it just before it’s about to pop through the ground is high risk.”

Good firm seedbeds with consistent drilling depth between 3cm–3.5cm is ideal and puts the germinating crop out of the range of soil mobile herbicides. Make sure there is no heavy rainfall forecast soon after spraying as this can move chemistry through the soil to the crop.

“Even where we see some crop effects, they are usually transitory and don’t have any noticeable effect come harvest, but we understand no one wants to take chances. If you are in doubt, sequence rather stack. Put the main part of the programme on at the true pre-em timing and follow up with different chemistry 2–4 weeks later. Sequencing also helps to extend the duration of protection so there aren’t any real downsides.”

Importance of Timely Application

Correct timing makes a huge difference to pre-em performance. The standard guidance is that applying at the true pre-em timing within 48 hours of drilling gives more consistent results.

In the field, things aren’t always so simple, especially when delaying drilling into October. Farmers often prioritise drilling, so the pre-em gets delayed. “It’s a challenge to get everything done: Drill, probably roll, then spray all within 48 hours when there are many other fields waiting for the same.”

“Have you got the tractors or the drivers to do it all at short notice? And farms with outlying land often have to compromise somewhere. But a one-week gap between drilling and pre-em is too long really, anything less than that is probably ok, but it is best to aim for 48 hours.”

If you know delays are likely, product choice can help, in trials coforms of metribuzin + flufenacet + diflufenican has much less drop off in control compared to straight Liberator. Tri-allate also needs careful consideration if you are relying on a contractor with an applicator to apply it. Is the potential for a delay in application worth it compared with an alternative you know you can apply at the correct time?

Balancing Efficacy and Cost

The overall efficacy of the programme versus the cost is the most important factor for farmers. With so many situations and combinations of products there is no single correct choice. Added to that, it is best to vary programmes between seasons for resistance management.

“Liberator plus Proclus is a solid base; it has good efficacy on all grass-weeds and many broad-leaved weeds as well. It immediately gives you three different modes of action in the programme, so it ticks a lot of boxes.”

“Adding more actives on top whether it is in the metribuzin co-forms, prosulfocarb, tri-allate or pendimethalin can all improve efficacy but also cost. It’s all about finding the right balance.”

Mr Oakley points out that cinmethylin is another strong contender, but its cost does force you to put a lot of faith in one active rather than a diverse programme. But it is a different mode of action so will help with long-term resistance management.

Full details of the performance of different products and programmes against a range of weeds will soon be available.

Glyphosate Stewardship

Resistance Management

Framework for success

Maximise Performance -Attention to detail is essential for resistance management