“Weeds do not sow themselves from the sky. If there is a certain weed seed bank in the field, it will be there after a year as well. In general, weed seeds maintain their germination ability from 5 to 30 years. However, by using special metazachlor mixtures adapted for winter rapeseed, the amount of weeds can be significantly reduced,” says Linas Agro pesticide product expert Petras Kiseliovas.
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The field has memory
According to P. Kiseliovas, one of the most important things for a farmer planning weed control in winter rapeseed crops is to know the history of their field well. Even if a particular weed has not been seen in a specific field for some time, it does not necessarily mean it has disappeared from the field. Seeds in the soil can “wait” for favorable germination conditions, and when the soil is disturbed and they receive light, the problem may reappear.
“If the weed is present in the field this year, it means we can have it next year as well. The simplest way for a farmer to prepare is to know their fields, know what weeds were present last year, which ones are present this year, and which were last seen in that field when growing winter rapeseed. Then, solutions can be immediately chosen that would help effectively control the specific field situation,” explains P. Kiseliovas.
According to him, there is no universal combination for all fields – one active ingredient may control some weed species well but be weaker against others. Therefore, knowing your field allows you to purposefully select the most effective weed control measures.
Weed control is not a one-season job
Even effective weed control in one season does not completely solve the problem – this process should be carried out every season, notes P. Kiseliovas.
“The main weed control measures in winter rapeseed crops should be attempted in autumn, leaving only corrections for spring for what could not be done before winter. Of course, suitable weather conditions may not always be available in autumn, so decisions need to be adapted to the situation,” advises the specialist.
He points out that in cases of winter rapeseed weed control, metazachlor-based products are the most widely used among farmers.
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“Metazachlor has its spectrum of action: it works very well against some weeds, but weaker against others. Accordingly, we can add another active ingredient to this active substance and thus address specific winter rapeseed crop problems. However, mixtures with metazachlor require moist soil – then they work best. If it is dry, the effect will be weaker. Again, everything depends on the specific situation,” explains P. Kiseliovas.
However, choosing an additional active ingredient may change the entire planned spraying scenario. For example, according to P. Kiseliovas, the possibilities of using mixtures containing metazachlor are quite broad – if chosen properly, they can be used after sowing, during germination, or after rapeseed emergence. But choosing specific product combinations, for example with clomazone, significantly narrows the usage time.
“It is important to emphasize that a mixture with clomazone can only be used up to rapeseed emergence, no later than 3 days after sowing. If delayed, we can harm the rapeseed itself: they will experience stress, turn pale, grow poorly, or even die completely,” says the Linas Agro specialist.
Finally, weed control in winter rapeseed is important not only for the result of one crop species. The more weeds are controlled before they mature and spread seeds, the lower the likelihood that their reserves in the soil will increase, and the problem will spread further in the same or other farm fields in the coming seasons.
About AB Linas Agro
AB Linas Agro is one of the largest agribusiness companies, managing 9 companies in Lithuania, Latvia, Estonia, and ensuring the entire chain of operations – from seed sales to grain purchasing. The company belongs to AB Akola group.
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