Antagonism between fungicide-insecticide treatments and dietholate in irrigated rice seeds

Abstract: The plant safener dietholate can be used for seed treatments (ST) to improve the selectivity of clomazone in rice cultures, thus allowing the application of higher dosages of this herbicide. The objective of this research was to evaluate the interaction between seed fungicide-insecticide treatments with and the plant safener dietholate in irrigated rice. Three experiments were carried out, and the first of them was conducted in a laboratory, following a completely randomized experimental design with four replications. Different ST and treatment-to-sowing intervals were evaluated. The second and third experiments were performed in field conditions, in a completely randomized block design with four replications. In experiment two, seeds were treated with different fungicides, in association or not with dietholate; while in experiment three, the effect of the ST with fungicides and dietholate with clomazone application were assessed. The results evidenced that the association between carboxin + thiram + dietholate reduced seed germination, vigor, and the dry mass of shoot of rice plants. The longer it takes between ST and sowing, the more rice seed germination is negatively affected. The association between fungicides and dietholate may have been antagonistic, and thus interfered with the culture growth potential.