- What are the active substances for geranium in rapeseed?
- Do all combinations cope with this weed at a similar level?
The geranium is more common than before
The lesser cranesbill is a weed that has become quite a big problem in rapeseed and corn plantations in recent years. This weed can grow up to 50 cm. The highest intensity of emergence is associated with April and May, i.e. the time of corn sowing, but the second stage in which emergence is quite large is September and October). It is therefore a weed that will very quickly start competing with winter rapeseed. It produces a tap root that reaches about 30 cm into the soil profile.
While a dozen or so years ago, the cranesbill was not a major problem, it is now increasingly necessary to include it in protection programs on our farms. Sometimes, we only observe particularly high densities on "crosslands", although plantations where the weed occurs with great intensity throughout the field are no longer an exception.
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What about geraniums in rapeseed?
Pethoxamid copes very well with the small cranesbill in winter rape. High effectiveness has been confirmed at an active substance dose of 1200 g/ha (2 l/ha in the case of "600 EC" products). In practice, for example, with clomazone, a lower dose is often applied (1.75 l/ha – 1050 g pethoxamid). In many cases, the treatment will still be effective, despite a slightly lower dose, because the cranesbill is also limited by clomazone to some extent. However, the application of clomazone alone does not guarantee the elimination of the cranesbill from the plantation. Similarly, the joint application of clomazone with metazachlor. It will limit the development of this weed, but it will not be fully effective. If we have a cranesbill problem on the plantation, we implement pethoxamid for protection in the pre-emergence treatment. To extend protection, we can, for example, administer clomazone with pethoxmid and a small admixture of metazachlor.
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What is the cost of pre-emergence herbicide protection in rapeseed?
Satisfactory results can also be obtained by combining quinmerac with metazachlor. Whereby metzachlor should be applied practically in maximum doses, and quinmerac in the range of 170 – 250 g of active substance per hectare.
In the case of the need for corrective treatments, picloram and clopyralid are often implemented (also in the basic foliar treatment). However, these substances cope quite averagely with the geranium, i.e. they are able to weaken it, although they do not guarantee its elimination. The geranium petiole is also sensitive to the foliar application of halauxifen-methyl.
