Read herbicide labels closely and think hard about cereal weed treatments ahead of winter oilseed rape.
The reminder, from several sources, comes after a stubble turnip grower claimed on-line to be “increasingly convinced” that using sulfonylurea (SU) herbicides on barley before brassicas such as oilseed rape was “disastrous”.
Individual labels and mixture restrictions must be heeded, urges Hutchinsons’ Dick Neale.
“PSD and therefore growers tend to lump SUs all into the same box.”
But in practice each active ingredient degrades differently.
“The key issue with the likes of Ally is to read between the lines on the label.”
Oilseed rape is supported as a following crop with no cultivation restrictions.
But only cereals should be sown within 16 months of using the herbicide on set-aside or linseed.
SU herbicides often contain two active ingredients, and autumn and spring treatment sequences can complicate the picture, he adds.
“Growers must be aware of the restrictions that apply and not get complacent regarding the cultivations required.”
AICC member Andrew Cotton says:
“This is a complex and thorny area, particularly with the autocast system which has revolutionised rape growing on heavy Oxford and London clays.”
Charles Malone, Suffolk AICC, says low rainfall after SUs may lead to trouble especially if the next crop is sown early.
“I will deep cultivate if it turns out to be a very dry summer.”
Sulfonylureas differ, so check the specific label, says DuPont’s Neil Morey.
The firm’s wide range of label recommendations is backed by 15 years’ experience, he notes.
Ally Max (metfulfuron-methyl + tribenuron-methyl), for example, accommodates autocasting.
Growers must remember the importance of timing and stewardship when using Atlantis (iodosulfuron-methyl-sodium + mesosulfuron-methyl), says Bayer’s Gordon Anderson-Taylor.
Oilseed rape may be established by min-till to at least 6cm after autumn wheat treatment, he notes.
But if other ALS products were applied in sequence with it, ploughing is required.
“In all cases where Atlantis is used in spring, drilling of rape must be preceded by ploughing.”