Research brings recommendations for voluntary soybean control in a corn consortium with sunn hemp

The control of voluntary soybeans in a corn consortium with sunn hemp, causing less damage to the sunn hemp, is a challenge for producers. Research carried out by Embrapa Agrossilvipastoril sought to provide a technical recommendation for the dose and application times of atrazine for the control of voluntary soybeans that is selective for Crotalaria ochroleuca and Crotalaria spectabilis.

In the 12 treatments conducted, in which the doses, times of application and combinations varied, only in the treatment using 500g/ha of atrazine in pre-emergence, plus 500g/ha of the same product after 21 days of emergence, was there efficiency in controlling voluntary soybeans without causing damage to Crotalaria ochroleuca. Crotalaria spectabilis was susceptible to all treatments tested.

“Atrazine is a low-cost herbicide, with several product options using this active ingredient. It is very effective in controlling voluntary soybeans, but, at the doses recommended for single corn, it also controls sunn hemp. So we tested reduced doses of atrazine, modalities and times of application to see what would work in the consortium”, explains Embrapa Agrossilvipastoril researcher, Fernanda Ikeda.

In the research, doses of 250g/ha and 500g/ha of atrazine were evaluated applied at different times, such as pre-emergence, 14,21, 28 and 500 days after emergence, and also combinations of the mixture of paraquat + diuron (250+250) in pre-emergence with atrazine (500 and XNUMX) in post-emergence and only paraquat with diuron in pre-emergence.

The research was carried out before the ban on the use of paraquat in Brazil, which began in 2021. In any case, although it is selective for the species of sunn hemp evaluated, the product, at the dose used, did not control voluntary soy.

According to researcher Fernanda Ikeda, an alternative for controlling voluntary soybeans without causing harm to sunn hemp is to sow only corn, wait for the guax plants to emerge, apply the herbicide and only then sow the sunn hemp.

“This strategy would have no effect on the two species of sunn hemp and could also contribute to the residual control of some broad-leaved and some narrow-leaved weed species,” says the researcher.

This research was carried out in a greenhouse. Based on the results, new experiments have been carried out in the field. The objective is to find alternatives that can be used to control voluntary soybeans, thinking about the production system, in this case, the intercropping of corn with sunn hemp.

The results of the tests can be seen in detail in the Research and Development Bulletin nº6, “Selectivity of atrazine and [paraquat + diuron] in Crotalaria spp. and voluntary soy control” available for free access in the library on the Embrapa Agrossilvopastoril portal. To download the publication, click here.

Direct link to the publication: https://www.embrapa.br/busca-de-publicacoes/-/publicacao/1138172/seletividade-de-atrazine-e-paraquat--diuron-em-crotalaria-spp-e-controle-de-soja-voluntaria.