11 December 1999



Red light

Notable absentee at Brighton was the much-lauded pre-em blackgrass killer, JV485 from the Monsanto/Bayer link-up company Twinagro, following problems with registration. Consensus was that prospects for commercialisation were looking bleak. This molecule took star billing at the last event.

Green light

However, new cleaver herbicide Boxer (florasulam) from Dow AgroSciences did make it through registration. Boxer was given its official green light just prior to the conference. Growers should be able to buy Boxer, and Boxer mixtures/formulations in time to use it on cereal crops this spring – watch out for more detail in a forthcoming issue. In brief, its a low dose, highly active early spring product, so it will be competing in the Eagle/Lotus type slot, rather than pitching against Starane with its later application window.

Waiting in the wings

There are more molecules with cleaver activity in the pipeline. Cyanamid has picolinafen, which will probably make its first UK appearance as a mix partner for the companys best selling herbicide Stomp (pendimethalin) – a "Super Stomp", perhaps? Picolinafen gives cleaver control a headstart, because it works well in an autumn mix thanks to low dose, high activity and rapid kill. It also boosts other gaps in Stomps repertoire, such as speedwells and pansies. The company suggests that picolinafen may eliminate the need for spring cleaver control in some cases.

This molecule is likely to appear as a partner to other autumn cereal herbicides, depending on the commercial deals which were no doubt under way in private rooms at Brighton. For IPU fans, it will give an alternative option to those Panther-type DFF mixtures, with the added advantage of cleaver control. Cyanamid is confident of a bright future for this molecule; it has a good environmental profile and is not a soil residual. Following crop restrictions are not expected. Target for commercialisation is autumn 2001.

Cleavers also take a bashing in potato crops. From Bayer, theres flufenacet, which is being developed as a mix with metribuzin as a pre-em herbicide. Results look promising, with control of a good range of broadleaved weeds as well as cleavers: black bindweed, redshank, groundsel, fools parsley, fat hen, mayweed, as well as some useful activity on grass weeds. There are no adverse crop effects, according to the company, and UK trials this spring showed a powerful performance in wet conditions. This pre-em mix might even remove the need for a post-em spray. Registration is under way and if successful, the product could be launched in 2001.

Not to be outdone, Monsantos new sterile brome molecule sulfosulfuron (sold as Monitor in Eire) doubles as a post-em couch and cleaver herbicide in potatoes – but not in the UK. Its had a first commercial season in Poland, where its sold as Apyros. There are no residues in the tubers; following crop restriction applies on sugar beet in the next year. As yet there are no plans to launch sulfosulfuron as a potato herbicide in the UK.

However, sulfosulfuron is being groomed for its major role in the cereal sector as the first sterile brome spring treatment. Its not perfect, in that instead of killing sterile brome it turns it into a "bonsai" brome, freezing its growth. This is fine for the crop, because weed competition is removed and so yield potential is restored, but it does raise the question of weed seed set.

Monsanto results show that seed set can be reduced by up to 90%. Might future work on timing and spray sequences tighten this figure up? Certainly European trials experience does point to some impressive yield performance following treatment, in crops with a bad brome problem. Distributors are questioning whether this product might be a useful headland/patch spray. It could be integrated with pre-harvest Roundup (glyphosate) as a programmed approach.

As a sulfonyl urea, there are other questions to be addressed. What restrictions might be possible on the following crop? How might it fit in with other sulfonyl urea herbicides on the same crop, given the limits on total sulfonyl urea sprays?

Price of Monitor in Eire works out at about £13/ha (£5.26/acre), where it is used with Frigate as an adjuvant. It is hoped that sulfosulfuron will be registered in time for a UK launch in spring 2000.

Another sulfonyl urea, iodosulfuron-methyl, is on the way from Aventis CropScience. This is a true low dose, Ally-type spring cereal broadleaved weed herbicide, but with the benefit of useful cleaver control and good activity against ryegrass and annual meadow grass. Restrictions on following crops are likely to be similar to Ally. Registration permitting, it should be commercialised for spring 2001 and is likely to be sold both as a straight and as a co-formulation with Eagle (amidosulfuron), to widen the weed control spectrum.

Not quite a sulfonyl urea, but a close relation is spring cereal herbicide BAY MKH6561 from Bayer – a user-friendly, shortened chemical name has yet to be established. Suffice to say this molecule is active at fairly low doses and has some systemic activity so controls couch, wild oats, bromes and blackgrass. It will eliminate target site resistant blackgrass, but enhanced metabolism resistant plants may not succumb. Watch out for this product sold as a straight in 2002.

Clobbering annual meadow grass and blackgrass in rape, beet, potatoes or pulses may eventually be possible with new grass weed killer tepraloxydim from BASF, which has come through the trialling system as BAS 620H. Its a Laser type product, but will be pre-formulated with an adjuvant. Although its a "dim" molecule, tepraloxydim has better activity against target site resistant blackgrass than might have been thought. The company is hoping for registration in spring 2001.

Finally, adjuvants from toothpaste? One company hoping to catch Monsantos eye was Hampshire Chemical, which has developed N-acyl sarcosinate as a useful adjuvant for glyphosate which is, according to its research, much safer than commercial proprietary adjuvants used with Roundup (glyphosate). Its been used for many years in toothpaste and household products.

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