Patricia Andrea Monquero

Mapas de infestação de plantas daninhas em diferentes Sistemas de colheita da cana-de-açúcar

The objective of this work was to identify the differences between the seedbank of a sugarcane field harvested mechanically and a that of a burned sugarcane field, using precision agriculture techniques. The soil sampling for seedbank determination were performed using a 2 ha regular sampling grid. The weed infestation maps were obtained by the kriging interpolation technique. The green sugarcane field presented lower weed infestation potential compared to the burnt sugarcane field, specially the monocotyledonous species. However, some dicotyledonous species can be selected, such as the Ipomoea. It was concluded that precision agriculture can be useful tool for determination of weed infestation maps and that sugarcane straw can be used as a suppression factor for various species.

Produção de palha e supressão de plantas daninhas por plantas de cobertura, no plantio direto do tomateiro

The objective of this work was to evaluate the straw yield, the weed suppression, and the effects of cover crop species on processing tomato (Lycopersicon esculentum) yield, in no tillage system. The treatments evaluated were Crotalaria juncea, Stizolobium aterrimum, Pennisetum glaucum, C. juncea + P. glaucum, C. juncea + S. aterrimum, P. glaucum + S. aterrimum, spontaneous weed cover, and bare soil. The experimental design was randomized complete blocks with four replicates. The tomato yield was not influenced by cover crops. C. juncea was more competitive than P. glaucum, when intercropped, with larger dry mass accumulation (63%). S. aterrimum had slow initial development and low competitivity with the high weed infestations. P. glaucum and C. juncea, grown alone, together, or with S. aterrimum, had dry matter yield above 20 Mg ha-1 and reduced the emergence and dry matter accumulation of weeds in the processing tomato crop.

Plantas transgênicas resistentes aos herbicidas: situação e perspectivas

RESISTANT TRANSGENIC PLANTS TO THE HERBICIDE: SITUATION AND PERSPECTIVES Genetically modified organisms (GMOs) or transgenic may be plants, animals or microorganisms that have DNA inserted into their cells from another organism. In some cases, this organism may be from a other individue of the same species, or from another species with which they would not normally cross-breed. The use of genetic modification in plant breeding aims to: increase crop yields beyond the maximum for existing varieties; reduce post-harvest losses; make crops more tolerant to environment stresses; make crops that use efficiently nitrogen and phosphorous; improve nutritional value of foods; produce plants that are resistant to certain herbicide, pests or diseases; develop alternative resources for industry such as fuels and pharmaceuticals. Many consumers are concerned that genetic modification isn’t natural and believe that conventional breeding is better than GMOs because it follows the principles of natural selection, or uses natural mutations. However, it is also possible to produce undesirable

Potencial de lixiviação de herbicidas no solo submetidos a diferentes simulações de precipitação

The objective of this work was to evaluate the influence of rainfall on leaching of herbicides recommended for sugarcane crop in Dystrophic Red Latosol. The experiment consisted in spraying trifloxysulfuron-sodium + ametryn (1463 + 37 g ha-1), imazapic (84 g ha-1), imazapyr (200 g ha-1), 1diuron + hexazinone (1170 + 330 g ha-1) and 2diuron + hexazinone (1330 + 160 g ha-1) on top of PVC columns filled with soil. After spraying, simulated rainfall of 20, 40 and 80 mm was applied on top of the columns. Cucumis sativus (cucumber) was used in bioassays to detect herbicide leaching, with evaluations accomplished 14 and 21 days after application of the treatments. After a 20 mm rainfall simulation, it was verified that the trifloxysulfuron-sodim + ametrin mixtures caused decreasing symptoms of toxicity in the 0 to 20 cm plantules, while the other herbicides had an effect up to 10 cm. The 40 mm rainfall made the mixtures1,2 diuron + hexazinone cause severe symptoms in the cucumber plants at 15 cm depth and decreasing symptoms at depths of 20 cm (formulation 2) and 25 cm (formulation 1). The herbicides trifloxysulfurom sodium + ametryn and imazapyr were detected up to 20 cm of depth. The herbicide imazapic caused toxicity up to 15 cm of depth. At 80 mm rainfall, 1diuron + hexazinone caused toxicity up to 30 cm and 2diuron + hexazinone, imazapyr, trifloxysulfuron sodium + ametryn and imazapic presented toxicity up to 25 cm of depth. It was concluded that all the herbicides evaluated tend to be leached under the influence of rainfall or artificial irrigations.

Eficiência de herbicidas pré-emergentes após períodos de seca

This work aimed to study the effectiveness of pre-emerging herbicides after drought periods in two soil types. Two simultaneous experiments were carried out under greenhouse conditions: in the first, the herbicides (trifloxysulfuron-sodium + ametryn - 351 + 99 g ha-1) + (diuron + hexazinone - 1097 + 27,77 g ha-1), trifloxysulfuron-sodium + ametryn - 1463 + 37 g ha-1, diuron + hexazinone - 1170 + 330 g ha-1, imazapyr 200 g ha-1 and imazapic - 122,5 g ha-1 were applied in vases containing samples of Dystroferric Red Latosol (clay texture); in the second, the doses were adjusted in function of the organic matter and clay level of the soil and applied in vases with samples of Distrophic Red Latosol (medium texture). In each experiment, the species Cucumis sativus and Sorghum bicolor were used as bioindicators and 6 drought periods after herbicide applications (0, 10, 20, 40, 60 and 90 days), with four replicates. Intoxication symptoms were observed on the 7, 14 and 21 days after the bio indicators were sown. The herbicides presented greater stability, i.e. greater toxic effects on the bioindicators along the time on soil with higher clay level and organic matter; isoxaflutole and the mixtures (trifloxysulfuron-sodium + ametryn) + (diuron + hexazinone), and diuron + hexazinone showed greater residual effect in both soils affecting the bioindicators100%.

Mobilidade e persistência de herbicidas aplicados em pré-emergência em diferentes solos

The objective of this work was to verify the mobility and persistence of herbicides applied in pre-emergence on different soils and amounts of sugarcane straw. The herbicides ametryn + clomazone (1,500 + 1,000 g i.a. ha-1), isoxaflutole (187,5 g.i.a. ha-1) and diuron + hexazinone (1,170 + 330 g i.a. ha-1) were applied in soil with clayey and medium texture under the following conditions:on 10 and 15 t ha-1 of sugarcane straw followed by rain simulation ; on the ground and covered with 10 t ha-1 of sugarcane straw; on the ground without straw; and control without herbicide. At 10, 20, 40 and 60 days after herbicide application (DAA), species bioindicators such as sorghum and cucumber were sown. Percentage of phytotoxicity was observed at 21 days after emergence. The mixture ametryn + clomazone applied directly on the soil affected the bioindicator up to 40 DAA; however, after this period, the residual effect was smaller. The sugarcane straw affected the performance of this product negatively. The herbicide isoxaflutole applied directly in the soil presented residual effect up to 60 DAA, with 82.5 and 77.5% of bioindicator control, in soils with clayey and medium texture, respectively, and the presence of 10 and 15 t ha-1 of straw did not alter efficiency up to 20 DAA. The herbicide diuron + hexazinone applied on the soil without straw presented residual effect up to 60 DAA, mainly in soil with clayey texture. With 15 t ha-1 of straw, significant reduction was observed in the effectiveness of this mixture.

Lixiviação de clomazone + ametryn, diuron + hexazinone e isoxaflutole em dois tipos de solo

Objetivou-se neste trabalho avaliar a lixiviacao de herbicidas pre-emergentes recomendados para cana-de-acucar em solos com textura argilosa e media. Os ensaios consistiram na aplicacao de ametryn + clomazone (1.500 + 1.000 g ha-1), isoxaflutole (187,5 g ha-1) e diuron + hexazinone (1.170 + 330 g ha-1) no topo das colunas de solo montadas em tubos de PVC. Foram simuladas precipitacoes pluviais de 10, 20, 40 e 80 mm decorridas 24 h da aplicacao dos herbicidas. Os tubos foram desmontados para a semeadura de Sorghum bicolor e de Cucumis sativus, tres dias apos a simulacao. O herbicida ametryn + clomazone em solo com textura argilosa foi detectado aos 20 e 35 cm de profundidade, nas aplicacoes de 10 e 80 mm de agua, respectivamente. Em solo com textura media, observou-se maior efeito deste herbicida em todas as precipitacoes, em relacao ao argiloso. Com a aplicacao de 40 e 80 mm de agua, o herbicida foi detectado ate 35 cm de profundidade em solo com textura argilosa. O herbicida isoxaflutole aplicado em solo argiloso causou albinismo na parte aerea das plantas ate 15 e 25 cm de profundidade no solo com chuvas de 10 e 80 mm, respectivamente. Em solo com textura media, as maiores simulacoes de chuva possibilitaram detectar este herbicida ate 30 cm. Com a simulacao de 80 mm de chuva, o herbicida diuron + hexazinone foi encontrado aos 30 cm de profundidade em ambos os solos, provocando efeitos toxicos sobre as plantas bioindicadoras de 25 e 60% em solos argiloso e medio, respectivamente. Concluiu-se que todos os herbicidas avaliados tem tendencia a serem lixiviados por influencia das precipitacoes pluviais ou de irrigacoes artificiais, com efeitos mais pronunciados em solos com textura media e com menor teor de materia orgânica.

Cover crops used to control weeds under the no-tillage tomato production system

RESUMO - O plantio direto do tomateiro e um sistema que busca maior sustentabilidade,porem sao escassas as informacoes sobre o manejo de plantas daninhas nessa novamodalidade de cultivo. O objetivo deste trabalho foi avaliar cinco tipos de cobertura do solo(Brachiaria decumbens , B. ruziziensis, Pennisetum glaucum , comunidade infestante e tratamentosem cobertura vegetal) para plantio direto do tomateiro rasteiro, conduzido no sistemameia estaca, em complementacao ao controle quimico com herbicidas. P. glaucum foi aespecie que proporcionou maior cobertura do solo ate a colheita do tomate; todavia, a taxade decomposicao da palha foi maior que a das demais coberturas. As coberturas de solocompostas pelas gramineas forrageiras B. decumbens, B. ruziziensis e Pennisetum glaucumreduziram a densidade e a massa seca das plantas daninhas. O uso da comunidade infestantepara obtencao de palha promoveu reduzida cobertura do solo e elevada emergencia de plantasdaninhas, semelhantes as do solo sem cobertura. B. decumbens apresentou rebrota duranteo ciclo do tomateiro, o que nao ocorreu com B. ruziziensis.Palavras-chave: tomate rasteiro, supressao de plantas daninhas, plantio direto, palha.ABSTRACT - Tomato no tillage system is a more sustainable system. However, information aboutweed management in this new cultivation modality is scarce. The objective of this work was toevaluate five vegetation covers ( Brachiaria decumbens , B. ruziziensis, Pennisetum glaucum ,community weed and the treatment without vegetable covering) for no tillage system of the stakedprocessing tomato crop combined with weed chemical control. P. glaucum provided the most soilcover to the tomato crop, although straw decomposition rate was higher than those of the othercovers. The soil cover by the forage grasses B. decumbens, B. ruziziensis and Pennisetumglaucum reduced the density and dry mass of the weeds. The use of the community weeds forstraw obtaining promoted reduced covering of the soil and larger emergency of weeds, similar tothe treatment without vegetable covering. B. decumbens presented resprouting capacity duringthe cycle of the tomato that didn’t happen with B. ruziziensis.Keywords: tomato, weeds suppression, no till, straw.

Eficácia de herbicidas em diferentes quantidades de palha de cana-de-açúcar no controle de Ipomoea grandifolia

This work had as objective studies the effect of different amounts of sugarcane straw picked without burns about effectiveness of some herbicides in the I. grandifolia control. The experiment was conduced in field in the Centro de Ciencias Agrarias/UFSCar, in Araras, SP. The treatments consisted of herbicides herbicidas ametryn + trifloxysulfuron-sodium (1463 + 37 g ha-1), imazapic (84 g ha-1), imazapyr (200 g ha-1), 1diuron + hexazinone (1170 + 330 g ha-1) and 2diuron + hexazinone (1330 + 160 g ha-1) applied in pre emergence of Ipomoea grandifolia and on five growing amounts of sugarcane straw ( 0, 5, 10, 15 e 20 t ha-1). The effectiveness of control of weeds was evaluated to the 7, 14, 21 and 28 days after application of treatments (DAT).The straw reduced the population of I. grandifolia even in the treatments without herbicide use. The measure that increased the amount of straw there was reduction in the effectiveness of the herbicides and with 15 t ha-1 of straw the control was considered unsatisfactory for all of the treatments. With 20 t ha-1 the control was null for all the treatments, however, was observed that in this case, the own straw was efficient in the suppression of these weed, since the number of emerged plants was smaller, even in the treatment without herbicides.

Efeito do período de chuva no controle de Euphorbia heterophylla e Ipomoea purpurea pelos herbicidas glyphosate e sulfosate

The influence of rainfall occurrence was evaluated on the efficacy of the herbicides glyphosate and sulfosate applied in post-emergence on Euphorbia heterophylla and Ipomoea purpurea. The experiment was conducted under greenhouse conditions at the Centro de Ciencias Agrarias/UFSCar, in Araras-SP, Brazil. The treatments,plus control, consisted of two doses, in acid equivalent of sulfosate (0.66 and 1.32 kg ha-1) and glyphosate (0.72 and 1.44 kg ha-1) submitted to rainfall simulation of 20 mm for 30 minutes, 2, 4, 6, 8, and 48 h after application. The experimental design was completely randomized with four replicates. Weed control efficacy was evaluated 7, 14, and 21 d after treatments (DAT) and dry biomass was evaluated 28 DAT. E. heterophylla was not efficiently controlled by glyphosate, demanding rainfall interval longer than 24 h after application to attain a moderate control of 60% when the highest rate was applied. On the other hand, sulfosate provided control of 75% when rainfall occurred just 4 h after application. I. purpurea was not controlled by glyphosate, either Sulfosate was only effective in controlling this species at the highest application rate, without rainfall. For both species, sulfosate was less affected by rainfall occurrence.