In agriculture, the development of plants resistant to 2,4-D and dicamba tends to result in increased use of these herbicides in agricultural areas and consequently increases the risk in susceptible species. The aims of the present study are to assess the effects of 2,4-D and dicamba on citrus (Citrus sinensis var. Pêra Rio), lettuce (Lactuca sativa var. Stella) and tomato (Lycopersicum esculentum var. Santa Clara) and determine the best method for spray tank decontamination after applying such herbicides. All the experiments followed a completely randomized design with five replications. To study the effects of 2,4-D and dicamba on sensitive plants, experiments were performed on the following cultivated species: citrus, lettuce and tomato. Each species was subjected to 2,4-D (D, 670 g a.i. ha-1) and dicamba (D, 560 g a.i. ha-1) applied at doses of 0 D, 1 D, 0.5 D, 0.12 D, 0.03 D, 0.007 D and 0.001 D (of commercial doses (Ds)). In another experiment, the following methods were adopted to clean tanks used to spray 2,4-D and dicamba at commercial doses: wash with water (1x), water (2x), water (3x), water + 96% alcohol (1:1), water + detergent (2.5%) or no washing. The tanks were filled with water after treatment. The young tomato plants were used as bioindicators. Regarding plant sensitivity, citrus plants exhibited low potential for suffering losses due to 2,4-D and dicamba drift. The plants tolerated a dose of 0.12 D for both herbicides. Lettuce and tomato were extremely sensitive to 2,4-D and dicamba. Lettuce tolerated 2,4-D at a dose of 0.007 D but showed phytotoxicity symptoms; the tolerated dicamba dose was 0.03 D. Only the 0.03 D dose of 2,4-D was tolerated by tomato. Although the tomato plants presented phytotoxicity symptoms, the tolerated dicamba dose was 0.007 D. For the tank cleaning experiment, the spray tank cleaning by thoroughly washing in water (2x) was the most appropriate method to clean tanks used to spray 2,4-D. Washing with water (2x, at a minimum), water + alcohol (1:1) or water + detergent was equally effective to clean tanks filled with dicamba. Therefore, the study shows that the application of 2,4-D and dicamba in areas close to young Citrus sinensis plants should be avoided given that vegetable species, such as lettuce and tomato, do not tolerate the minimum drift of these herbicides. Double washing with water would be the most economical and effective method of cleaning tanks used to house these herbicides.

O objetivo deste trabalho foi avaliar o efeito do biocarvão na sensibilidade de mudas pré-brotadas (MPB) ao clomazone, imazapic e indaziflam aplicados em pré-plantioisoladamente ou em associação. Foram avaliadas duas variedades de cana-de-açúcar (RB975952 e RB 985476). O delineamento experimental foi inteiramente casualizado com 4repetições, em esquema fatorial 9 x 2, sendo nove tratamentos (imazapic 52,5 e 200 g i.a. ha-1, clomazone 1000 g i.a. ha-1, indaziflam 100 g i.a. ha-1 e associações de imazapic +clomazone (52,5 + 600; 52,5 + 1000; 200 + 600 e 200 + 1000 g i.a. ha-1 e testemunha) e apresença ou ausência do biocarvão no sulco de plantio. A RB 985476 apresentousensibilidade aos herbicidas clomazone e imazapic. A toxicidade provocada pelosherbicidas imazapic + clomazone diminiu pelo efeito do biocarvão. Para o imazapic nãohouve efeito do biocarvão na redução da fitotoxicidade. Em relação a RB 975952 foiverificada sensibilidade ao clomazone + imazapic e clomazone isolado, sendo o biocarvãoeficaz na redução da fitotoxicidade. O indaziflam foi seletivo para as duas variedades. Podese concluir que o biocarvão atuou de forma efetiva para clomazone isolado ou emassociação com o imazapic, sendo pouco efetivo para o herbicida imazapic isolado.

Microbial inoculant containing cells of Nitrospirillum amazonense is a recent technology that has been used in association with pre-sprouted seedlings to sustainably increase the productivity of sugarcane. This study aimed to assess the sensitivity of the rhizobacterium N. amazonense to the herbicides imazapic and indaziflam and the effect of this inoculation and herbicide treatments on sugarcane pre-sprouted seedlings. The In vitro sensitivity of the N. amazonense to the herbicides was assessed using the minimum inhibitory concentration technique (first assay). In this research, we evaluated imazapic (200 g a.i. ha-1) and indaziflam (100 g a.i. ha-1) at five doses: recommended dose (1×D), twice the recommended dose (2×D), one and a half of the recommended dose (1.5×D), half the recommended dose (0.5×CD), a quarter of the recommended dose (0.25×CD) and control treatment. The sensitivity of N. amazonense to imazapic and indaziflam applied at commercial doses on autoclaved soil was assessed in the second assay. The bacterial population count was performed using the most probable number technique (McCrady Table). The third assay assessed five herbicide treatments (clomazone (720 g a.i. ha−1), imazapic (200 g a.i. ha−1), tebuthiuron (800 g a.i. ha−1), indaziflam (75 g a.i. ha−1), sulfentrazone (800 g a.i. ha−1) and control without herbicide) applied in pre-planting of pre-sprouted seedlings of the variety RB 966928 in the presence and absence of the inoculant N. amazonense. The results showed that the presence of indaziflam did not interfere with the In vitro growth of the bacterium N. amazonense, regardless of the dose. Imazapic caused significant inhibition of bacterial In vitro growth from the recommended dose (200 g a.i. ha-1). The N. amazonense count in the soil of treatments that received indaziflam and imazapic application did not differ compared to the soil without herbicide. The pre-sprouted seedlings of the variety RB966928 showed high sensitivity to the herbicide imazapic, regardless of N. amazonense inoculation. Clomazone, tebuthiuron, and sulfentrazone did not interfere with the growth-promoting effect of N. amazonense. The results showed that the recommended dose of the herbicides tested does not impair the growth promoting effect of N. amazonense, and the inoculation of the pre-sprouted seedlings does not alter their sensitivity to herbicides, although the selectivity of the seedlings is differential among herbicides. Therefore, it may be concluded that the combined use of these technologies is a viable alternative to increase sugarcane productivity in a more sustainable way. © 2022 Friends Science Publishers