Best grass killer in crops

WEED CONTROL: Agronomist Paul McIntosh discusses weed control for crops like these field peas.
WEED CONTROL: Agronomist Paul McIntosh discusses weed control for crops like these field peas. Contributed

STILL on weed control this week, with some serious complications if you overstep the mark.

We all know our best grass killer in broadleaf crops is generally an active ingredient product called Haloxyfop.

This active is a widely used generic product throughout the world and it comes under the Group A mode of action.

These days it is even being used as part of our solution in fallow sprays for glyphosate- resistant grasses or glyphosate-tolerant grass species.

My concern is that its customary and original use pattern has been for in-crop grass control to be completed by certain crop growth timings, which is often ignored by many of us.

In other words, by in-crop timing I mean when the mung beans or chickpeas are emerged from below the surface and freshly germinated grass weeds become a problem.

For chickpeas, fabas, lentils and field peas the label does state to apply before flowering, and therefore in this use pattern there is no withholding period required.

Unfortunately, many of us have pushed the envelope too far over the years and are applying Haloxyfop product well into the flowering period.

Admittedly, herbicide labels these days are very busy with lots of information and it's easy to overlook these few critical comments of "prior to flowering” when trying to get all the other parameters in line.

On the Haloxyfop labels, a few words beside these above mentioned winter crops state: apply from second leaf, second branch or second node to prior to flowering. It really means what they say.

Prior to flowering is a crucial piece of herbicide application timing as the peculiarity is that these flowers appear to be a herbicide sink mechanism.

By that I mean when flowers are present on our pulse crops and we apply these fop and most likely dim grass control products to our legume crop foliage, it appears to translocate to flowers if they are present.

These flowers then appear to re-translocate this build-up of chemical into developing seed pods and so hence our MRLs are compromised in our clean and green food product.

So do not put your crop or yourself at risk from having Maximum Residue Levels exceed the agreed upon level with our overseas trading partners.

My parting comment is to recommend to not apply this group of herbicide products to flowering pulse crops.

Topics:  agronomist column opinion paul mcintosh

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