-The presence of weeds and nematodes can affect of sugarcane yield. This research evaluated whether weeds that are very frequent in mechanized harvested sugarcane can be hosts for root-knot nematodes: Meloidogyne incognita or Meloidogyne javanica. Regarding nematode hospitability, ten weed species as well as a control sample (tomato) were evaluated; they were inoculated with M. incognita and M. javanica. The plants were inoculated with 2,000 eggs and second-stage juveniles (J 2 ), and there were three plants per experimental unit (6,000 eggs and J 2 per pot -repeatition); 60 days after inoculation (DAI), the plants were removed and evaluated according to reproduction factor (RF), nematode final population (FP) and reproducibility index (RI). Regarding weed hospitability, it was found that Luffa aegyptiaca acted as a host for both nematodes, with RF > 1, which was higher than the control sample. Digitaria horizontalis was classified as a host for M. incognita and as a non-host for M. javanica. Mucuna aterrima and Crotalaria spectabilis presented the lowest RF and FP. Ricinus communis and Ipomoea triloba presented galls when inoculated with M. incognita, but were not considered host, since they presented RF < 1. None of the weed species was considered immune, i.e., with RF = 0. The lowest RF values of M. incognita (race 3) were related to Crotalaria spectabilis and Euphorbia heterophylla plants. This demonstrates the ability of crotalarias in decreasing nematode population in the field and justifies its use in several areas before planting main crops. Keywords

The herbicides saflufenacil and indaziflam have recently been registered in Brazil for weed control in sugarcane crops; however, little information exists regarding their residual effects or influences on soil microorganisms. Therefore, the present study aimed: (a) to determine the effects of saflufenacil and indaziflam on soil microorganisms and (b) to evaluate the residual and dose effects of these herbicides on soybean, sunflower, sunn hemp and peanut crops. The herbicides indaziflam (100 g a.i. ha

The plants commonly known as morning glory belong to the genera Ipomoea and Merremia and are among the most important weeds in Brazil. Greenhouse studies were conducted in 2016/2017 to compare the susceptibility of different morning glory species-Ipomoea quamoclit, I. nil, I. hederifolia, I. triloba, Merremia aegyptia, and M. cissoides to soil-applied herbicides and to evaluate the effectiveness of these herbicides after periods of drought. In the first experiment, to evaluate the efficacy of each herbicide at pre-emergence stage, a fully randomized 6 (doses) x 6 (species) factorial experimental design with six replicates was used. The herbicides tebuthiuron (3,200; 1,600; 800; 400; 200 and 0.0 g a.i ha-1), amicarbazone (2,100; 1,050; 750; 375; 187 and 0.0 g a.i ha-1), sulfentrazone (1,200; 600; 300; 150 75 and 0.0 g a.i ha-1), mesotrione (240; 120; 60; 30; 15 and 0.0 g a.i ha-1), saflufenacil (200; 100; 50; 25; 12 and 0.0 g a.i ha-1), and imazapic (360; 180; 90; 45; 22 and 0.0 g a.i ha-1) were applied. Ipomoea hederifolia, I. nil, and I. quamoclit were most susceptible to saflufenacil; I. triloba and M. cissoides were most susceptible to tebuthiuron; and M. aegyptia was most susceptible to amicarbazone. Therefore, the best herbicide treatment depends on the species of morning glory. In the second experiment, to determine the effectiveness of herbicides after periods of drought, the treatments were arranged, for each herbicide, in a fully randomized 6 x 5 factorial design with four replicates, six species of morning glory, and five sowing times after periods of drought (0, 15, 30, 45, and 60 days after application (DAA) of the herbicides) relative to the application of the amicarbazone (1,050 g a.i ha-1), imazapic (180 g a.i ha-1), mesotrione (120 g a.i ha-1), saflufenacil (100 g a.i ha-1), sulfentrazone (600 g a.i ha-1), and tebuthiuron (1,600 g a.i ha-1). Herbicide effectiveness after periods of drought began to decrease after 15 days for saflufenacil; 30 days for imazapic, mesotrione, and tebuthiuron; 45 days for amicarbazone; and 60 days for sulfentrazone. Preemergence application of amicarbazone and sulfentrazone exhibited consistent efficacy during the drought periods, satisfactorily controlling the species of morning glory.

Influence of the sowing depth and amount of sugarcane straw on the emergence of Chloris polydactyla and Eleusine indica and their control by herbicides applied pre-emergence Influência da profundidade de semeadura e da quantidade de palha de cana-de-açúcar na emergência de Chloris polydactyla e Eleusine indica e controle por herbicidas aplicados em pré-emergência AbstractThe objective of this study was to evaluate the effect of the sowing depth and amount of sugarcane straw on the soil on the emergence of Chloris polydactyla ('capim-branco') and Eleusine indica (Indian goosegrass) and to determine the efficacy of herbicides applied pre-emergence in the control of these species under different straw amount and rainfall regime conditions. The experiments were conducted in a completely randomized design with four replications. In the first experiment, the effects of six sowing depths (0.5, 1, 2, 4, 8, and 10 cm) and six sugarcane straw amounts (0, 1, 2, 4, 8 and 10 t ha -1 ) were assessed on the emergence of Indian goosegrass and 'capim-branco' in a 6 x 6 factorial arrangement. In the second experiment, the efficacy in the control of these species was evaluated for one control without herbicide and five treatments (indaziflam, metribuzin, tebuthiuron, indaziflam + metribuzin, and indaziflam + tebuthiuron) applied pre-emergence over four straw amounts (0, 1, 2, and 4 t ha -1 ) in a 6 x 4 factorial arrangement. This experiment was evaluated under two rainfall regimes in separate experiments (simulation of 20 mm of rainfall 1 or 10 days after herbicide application). The 'capim-branco' showed a marked reduction in emergence beginning at 2 t ha -1 of straw and a 2 cm sowing depth. For the Indian goosegrass, the decline in emergence mainly occurred beginning at 4 t ha -1 of straw and a 4 cm sowing depth. Only some of the Indian goosegrass plants emerged at the greater sowing depths (8 and 10 cm) and straw amounts (8 and 10 t ha -1 ), whereas no emergence of the 'capimbranco' was observed under these conditions. The treatments with sowing at a 1 cm depth and with 0, 1, 2, and 4 t ha -1 of straw provided the highest emergence percentage for the species. Application of the herbicide indaziflam alone was the only ineffective treatment for the control of the weeds regardless of the amount of straw and the water regime used. We concluded that the increase in the sowing depth and the amount of straw significantly reduced the emergence of the species and that the presence of straw and the dry period interfered with the herbicide efficacy. Key words: Indian goosegrass. 'Capim-branco'. Sugarcane. Straw. ResumoObjetivou-se com esse trabalho avaliar o efeito da profundidade de semeadura e da quantidade de palha de cana-de-açúcar sobre o solo na emergência de Chloris polydactyla (capim-branco) e Eleusine indica (capim pé-de-galinha), assim como determinar a eficácia de herbicidas aplicados em pré-emergência no controle dessas espécies, sob diferentes quantidades de palha e regimes de precipitação pluvial. Os experimentos foram real...

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