Weed Control J 2021; 20: e202100739

Research Article

Selectivity of herbicides with residual activity in onion grown in direct seeding

DOI: 10.7824/wcj.2021;20:00739

Abstract

Background

The direct seeding system can be an alternative to reduce costs and labor in onion production, as it does not require the steps of production and transplantation of seedlings. However, this system results in early weed interference, lengthening the critical period of interference prevention.

Objective

To evaluate the selectivity of herbicide applications with residual activity on onions.

Methods

Three studies were carried out in a greenhouse. The first was carried out in a 5 x 4 factorial scheme, evaluating the herbicides flumioxazin, oxadiazon, oxyfluorfen, pendimethalin and diuron at 0, 30, 60 and 100% of the herbicide reference dose. In the second study, two herbicides, pendimethalin and diuron, were applied at three stages of onion development: total pre-emergence with application after sowing, application at the end of germination, 15 days after sowing and application in the onion establishment, at 21 days after sowing. A third experiment was carried out comparing the selectivity of S-metolachlor to onion.

Results

The herbicide application in the onion establishment phase was more selective. The herbicides oxadiazon, oxyfluorfen and flumioxazin showed no potential use in the initial application due to their high phytotoxicity.

Conclusion

The application of pendimethalin and S-metolachlor at the end of onion establishment was selective and another alternative to weed control in the no-tillage onion production system.