Lilian Gomes de Moraes Dan

Seletividade de clomazone isolado ou em mistura para a cultura do algodoeiro

Clomazone is one of the most important herbicides applied in pre-emergence in cotton, even though not much is known about its selectivity to this crop. This work was carried out to evaluate the selectivity of clomazone applied alone or in tank mixtures with other herbicides applied in pre-emergence in cotton. The experiment was designed as a randomized block, with four replicates, using two-fold checks. Thirteen treatments were evaluated, constituted by different combinations of clomazone with S-metolachlor, diuron, prometryne, alachlor, oxyfluorfen, and trifluralin. After herbicide application, visual crop injury was evaluated, as well as stand, plant height, number of bolls per plant and cotton+seed yield. Clomazone alone applied at 1.00 and 1.25 kg ha-1 or associated to S-metolachlor (0.76 kg ha-1), diuron (1.50 kg ha-1), prometryne (1.50 kg ha-1), alachlor (1.44 kg ha-1), and trifluralin (1.80 kg ha-1) was selective to cotton cv. Nu-Opal. However, its association with oxyfluorfen (1.25 + 0.19 kg ha-1), with trifluralin + diuron (1.25 + 1.80 + 1.50 kg ha-1), and with trifluralin + prometryne (1.25 + 1.80 + 1.50 kg ha-1) resulted in reduced cotton yield.

Influência do estádio de desenvolvimento de Cenchrus echinatus na supressão imposta por atrazine

Cenchrus echinatus is an important weed in areas cultivated with corn, sorghum and pearl millet in Brazil. Although atrazine is one of the most used herbicides in such crops, not much has been done to determine weed susceptibility as a function of its growth stage at post-emergence applications. This work aimed to evaluate the suppression imposed by the herbicide atrazine applied at post-emergence, during three developmental stages of this weed. The assay was carried out under greenhouse conditions, in pots of 10 dm-3, in a factorial scheme 5 x 3 composed by five rates of atrazine (0; 0.5; 1.5; 2.5 and 4.0 kg ha-1 ), combined with three stages of C. echinatus development during herbicide spraying at post-emergence (first pair of leaves; second pair of leaves and two tillers). Applications performed at later stages of weed development were inefficient to provide control, despite significant reductions of dry biomass, plant height and production of reproductive structures. Aiming at weed control, the best results were found for rates ³ 3.5 kg ha-1 in plants at the stage of first pair of leaves.

Supressão imposta pelo mesotrione a Brachiaria brizantha em sistema de integração lavoura-pecuária

Mesotrione is an important herbicide applied to corn, but little is known about the susceptibility of species, such as Brachiaria brizantha to this herbicide. The objective of this study was to evaluate the suppression imposed by mesotrione in Brachiaria brizantha, intercropped with maize. The trial was conducted in a randomized block design with four replications, corresponding to seven doses of mesotrione (0; 12; 24; 48; 96; 144 and 192 g ha-1), a control (corn without interference) and a treatment with beard grass grown as a single. Both crops were sown on the same day. The herbicide was applied at 20 days after emergence of the species. Mesotrione showed the greatest potential for plant toxicity in B. brizantha plants, when applied at a dose of 192 g ha-1. However, grass forage showed satisfactory tolerance to the herbicide, indicating potential use in crop-livestock systems. The inter-specific competition led to reductions in corn yield, and the best dose-response relationship to benefit both cultures was obtained by using 96 g ha-1 of mesotrione.

Insecticide Treatment and Physiological Quality of Seeds

The use of high-quality seeds enhances the probability of success of a crop. Another important factor is the use of techniques which target the improvement of seed field performance. Applications (seed dressing) of fungicides, inoculants, insecticides and micronutrients on seeds are practices most used by farmers for several years. These products have provided more favorable conditions to crop’s growth as well as its development. Chemical treatment on seeds have been one of the most common techniques in use on current farming due to its low-cost technology, low-environmental impact, and, in general, a significant effect on yield (Zambolim, 2005). High quality seed is one of the essential prerequisites to achieve higher crop productivity. Seed physiological quality is influenced by genetic traits inherited from their parent trees, as well as germination and vigor, which are affected by environmental conditions, harvesting methods, drying process, processing, storage and packing (Zambolim, 2005). Nevertheless, storage of insecticide treated seeds may cause significant reduction on both germination and vigor as demonstrated by a number of authors (Bittencourt et al., 2000); (Gotardo et al., 2001). This fact might be related to deterioration caused by the use of insecticides, which induce the formation of free radicals and subsequent oxidative stress (Braguini, 2005). Chemical treatment on seeds has become an important procedure on agricultural production by a number of reasons. Firstly, by using this kind of treatment, many pest insects attacking not only seeds but also in some cases the aerial part of plants can be efficiently controlled. Secondly, these products can be handled in either protected or controlled environment regardless of climatic conditions, therefore, reducing additional and unwanted machinery movement in the land for cultivation. These arguments are added to the fact that, in that referred kind of treatment; small quantities of products are used per area unit, which implies lower risks of environmental contamination. In addition, chemical treatment is a procedure of simple implementation and low cost (Goulart, 1999; Machado, 2000).

Tolerância do cultivar de milheto ADR-300 ao herbicida atrazine

The aim of this study was evaluate the selectivity of the herbicide atrazine to the culture of pearl millet (Pennisetum glaucum). The test was implemented in units of 10 dm -3 o f soil under conditions of a greenhouse in a completely randomized design in factorial scheme 5 x 3 with four replicates, corresponding to five dose of atrazine: 0; 0.5; 1.5; 2.5 and (4.0 kg i.a. ha -1 ), applied in three stages of growth of pearl millet (two, four and eight expanded leave), cultivar ADR-300. We evaluated the levels of phytotoxicity at 7; 14 and 21 days after application, plant height, dry mass and mass of spike. The major symptoms of phytotoxicity, reducing the number of tillers and dry biomass were obtained from applications made in the early stages of culture and intensified with increasing dose of atrazine. With respect to the mass of spike, doses below 1.5 kg ha -1 of atrazine showed greater flexibility in the application stage and can be used

Potential Use of Tembotrione (HPPD-Inhibitor Herbicides) in Grain Sorghum

Hugo De Almeida Dan1, Alberto Leao De Lemos Barroso2, Rubem Silverio De Oliveira Junior 1, Lilian Gomes De Moraes Dan1, Sergio De Oliveira Procopio3, Jamil Constantin1 and Guilherme Braga Pereira Braz1 1Center for Advanced Studies in Weed Research, Agronomy Department, State University of Maringa, Parana, 2University of Rio Verde, Goias, 3Brazilian Agricultural Research Corporation, Londrina, PR, Brazil