Emerger delivers a ‘step-forward’ in weed control

Launched with little fanfare and a modest request that growers trial it in a range of situations to see for themselves how it might fit their conditions, the performance of Bayer’s new herbicide Emerger (aclonifen) has largely exceeded expectations.

Initially approved for use as a pre-emergence spray in potatoes, Emerger has since gained several extensions of authorisation for minor use (EAMU) as a pre- and post-emergence herbicide for use in stem and root vegetables, herbs, and alliums.

Norfolk independent agronomist, Martyn Cox trialled Emerger across a range of potato crops in combination with other active substances.  The partner products chosen depending on soil type, variety grown and weed spectrum.

“Emerger has been a welcome introduction. It has delivered good control of a range of broadleaved weeds, including fat-hen and annual mercury, weeds where the post-emergence product, rimsulfuron struggles to have an impact. We did not have black-grass where it was used but we know from trials in cereals that it has activity,” says Mr Cox.

Herbicide performance is usually reduced on soils high in organic matter and ridge stability on these soils can compromise the effectiveness of residual products, also regular weed flushes test persistence.

“The control achieved by the Emerger mixes has been a step-forward and I am delighted with what has been achieved. Across a range of varieties and in situations where it has previously been difficult to manage weeds, I have seen a level of control that is close to that seen only on mineral soils,” says Mr Cox.

After seed spacing and nitrogen rate, another issue an agronomist must consider is metribuzin tolerance. 

“Our Emerger-treated crops were clean until the plants met along the row and this helped on varieties such as Sagitta, where post-emergence options are limited.

“Where metribuzin cannot be used, on sensitive varieties or sand soils, we found that tank mixes including Emerger gave improved control of our problem weeds compared with previous standards. We found that Emerger is a useful partner with both metribuzin and prosulfocarb depending on the weed spectrum, soil type and variety, the three-way mix being effective, even with low rates of metribuzin.”

Options for post-emergence weed control in crop are often limited, but the effective performance of Emerger at the pre-emergence stage has relieved much of the pressure.

“Rimsulfuron can be used on most of our crops but is weak on fat-hen.  In an ideal world, we would be able to use a low dose of metribuzin around 10 days after emergence but with an increasing number of Innovator crosses appearing, or the tolerance status of new varieties unknown, then having an effective pre-emergence herbicide is a reassuring introduction. 

“The introduction of Emerger is one of those rare occasions when a new product exceeds expectations. It has taken a difficult situation involving high organic matter soils where variety choice prevents the use of the best post-emergence herbicide available and resolves it effectively,” says Mr Cox.