Resistance and differential susceptibility of Bidens pilosa and B. subalternans biotypes to ALS-inhibiting herbicides (original) (raw)
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Científica, 2016
This work aimed at determining possible resistance of three biotypes of Cyperus iria to inhibiting herbicides of acetolactate synthase enzyme (ALS). An experiment at greenhouse was conducted out where suspected resistance biotypes were multiplied through seeds in pots filled with soil. The treatments were arranged in a trifactorial (AxBxC) design, where factor A consisted of three biotypes of Cyperus iria, from three locations of the state of Rio Grande do Sul (named Santa Maria 1, São Borja 3 and Cachoeira do Sul 7). Factor B corresponds to three herbicides (pyrazosulfuron-ethyl, ethoxysulfuron and bentazon). Factor C refers to herbicide doses (zero, 50% of registered dose; registered dose, two, four and eight times registered dose of herbicides). For resistance measurement, it was used resistance factor calculation (RF) and for dose-response curves through regression analysis, RF on dry mass (DM) of plants. It was observed that São Borja 3 and Cachoeira do Sul 7 biotypes have a low resistance factor (1 < RF < 10) to pyrazosulfuron-ethyl and ethoxysulfuron herbicides. These showed lower susceptibility to ethoxysulfuron (RF = 5.49-6.76) than pyrazosulfuron-ethyl (RF = 2.21-2.47). The clear distinction in the susceptibility of biotypes, include responses of chemical control to field due to the long period of use of ethoxysulfuron herbicide. It is concluded that this factor characterizes low-level resistance, being a cross-resistance type, thus demonstrating the ineffectiveness of ALS-inhibiting herbicides to control this species.
Weed Research, 2007
Two Alisma plantago-aquatica biotypes resistant to bensulfuron-methyl were detected in rice paddy fields in Portugal’s Mondego (biotype T) and Tagus and Sorraia (biotype Q) River valleys. The fields had been treated with bensulfuron-methyl-based herbicide mixtures for 4–6 years. In order to characterize the resistant (R) biotypes, dose–response experiments, absorption and translocation assays, metabolism studies and acetolactate synthase (ALS) activity assays were performed. There were marked differences between R and susceptible (S) biotypes, with a resistance index (ED50R/S) of 500 and 6.25 for biotypes Q and T respectively. Cross-resistance to azimsulfuron, cinosulfuron and ethoxysulfuron, but not to metsulfuron-methyl, imazethapyr, bentazone, propanil and MCPA was demonstrated. No differences in the absorption and translocation of 14C-bensulfuron-methyl were found between the biotypes studied. Maximum absorption attained 1.12, 2.02 and 2.56 nmol g−1 dry weight after 96 h incubation with herbicide, for S, Q and T biotypes respectively. Most of the radioactivity taken up by the roots was translocated to shoots. Bensulfuron-methyl metabolism in shoots was similar in all biotypes. The R biotypes displayed a higher level of ALS activity than the S biotype, both in the presence and absence of herbicide and the resistance indices (IC50R/S) were 20 197 and 10 for biotypes Q and T respectively. These data confirm for the first time that resistance to bensulfuron-methyl in A. plantago-aquatica is target-site-based. In practice, to control target site R biotypes, it would be preferable to use mixtures of ALS inhibitors with herbicides with other modes of action.
2010
*Boursier FRIA RÉSUMÉ L'hérédité de la résistance par mutation de cible chez le vulpin des champs a été évaluée en observant le pourcentage d'individus résistants engendrés par croisements. Après germination, les plantes ont été génotypées comme homo-ou hétérozygotes pour la mutation W574 du gène de l'ALS conférant la résistance. Les individus sont ensuite transplantés en parterre extérieur et croisés entre eux et avec des individus issus d'une population sensible connue. Pour éviter un apport de pollen extérieur, les plantes sont ensachées dans un tissu pollen-proof lors de la floraison. Le taux d'autogamie facultative a également été testée, en isolant les épis un par un. Les semences issues des croisements sont ensuite récoltées et testées en serres. Leur ADN a également été analysé.
Cross-Resistance of Rice Flatsedge to Als-Inhibiting Herbicides
Planta Daninha, 2017
Cyperus iria (CYPIR) is one of the main weeds in irrigated rice crops. The intense chemical control with acetolactate synthase (ALS) inhibiting herbicides favors the selection of cross-resistance. This study aimed to evaluate the crossresistance of CYPIR to ALS-inhibiting herbicides in irrigated rice in Rio Grande do Sul. Two experiments arranged in a factorial scheme, in a completely randomized design, with four replications were conducted. Experiment I consisted of resistant (CYPIR-R) and susceptible (CYPIR-S) biotypes and ALS-inhibiting herbicide doses: imazethapyr (106 g a.i. ha-1); pyrazosulfuron-ethyl (20 g a.i. ha-1); penoxsulam (36 g a.i. ha-1) and, as an alternative herbicide, bentazone (960 g a.i. ha-1); corresponding to 0; 1/16; 1/8; 1/4; 1/2; 1; 2; 4; 8 and 16x (x = maximum registered dose). Experiment II followed the same procedures, with doses of 0; 1/64; 1/32; 1/16; 1/8; 1/4; 1/2; 1 and 2x for CYPIR-S and 0; 1/2; 1; 2; 4; 8; 16; 32; 64 and 128x for CYPIR-R; including ...
Sensibilidade de biótipos de azevém a glyphosate, iodossulfurom-metílico e clethodim
Revista Brasileira de Herbicidas, 2015
Ryegrass (Lolium multiflorum) is an annual grass, traditionally used as forage that has become weed in crops in the south of Brazil. It has been observed that there are ryegrass biotypes resistant to glyphosate that survive the application of herbicides that inhibit ALS and ACCase. Therefore, the objective was to evaluate the sensitivity of different ryegrass biotypes to glyphosate, iodosulfuron-methyl and clethodim herbicides. The experiment was carried out in a greenhouse, in randomized blocks, in a triple factorial arrangement with three repetitions. Four ryegrass biotypes were used, where: biotype 1 (B1), susceptible to glyphosate; biotype 2 (B2), resistant to glyphosate; biotype 3 (B3) and biotype 4 (B4), biotypes suspected to be resistant to iodosulfuron-methyl. The doses were standardized in 0; 0.25; 0.5; 1; 2; 4 and 8 times the commercial doses of glyphosate (1080 g ha-1 a.i.) and clethodim (96 g ha-1 a.i.). The variables evaluated were control, in a percentage scale, and dry shoot biomass (DSB) of the plants at 28 days after the application of treatments (DAT). With that data, we calculated the parameters of the equation, from which the necessary dose was determined to reduce the DSB in 50% comparing to the non-treated plants (GR50) and the resistance factor (F). Biotypes B2, B3 and B4 obtained Resistance factors (F) above 10 comparing to glyphosate and iodosulfuron-methyl herbicides, B3 being the highlighted biotype because, besides being resistant to those two herbicides, also showed an F value close to the clethodim threshold, which can characterize a low resistance level to this herbicide. All biotypes, except the control one, were resistant to the iodosulfuron-methyl and glyphosate herbicides, which characterizes multiple resistance to those herbicides. The clethodim herbicide can be an alternative for the control of biotypes resistant to glyphosate and iodosulfuron-methyl; however, attention should be paid to the chemical handling of these populations, because we identified biotypes with low resistance level to this herbicide.
El objetivo fue identificar selectividad de herbicidas postemergentes en el pasto insurgente (Brachiaria brizantha Richard Stapf) y huaxín [Leucaena leucocephala (Lam.) de Wit] para establecer asociaciones. El estudio se efectuó en Mocochá, Yuc., en 2004 y 2005. En junio de ambos años, semillas de insurgente (INS) y de huaxín (HUA) fueron sembrados a chorrillo en un arreglo de dos hileras de INS por una de HUA. Se evaluaron bentazon, imazethapyr y metribuzin en tres distintas dosis aplicadas en una sola ocasión y en dos y tres secuencias, en dosis única. En ambos años, metribuzin resultó fitotóxico en INS (10 a 95 %) y HUA (55 a 100 %); en contraste, bentazon e imazethapyr fueron tolerados por estas especies. En 2004, bentazon y metribuzin destacaron por su buen control de malezas (82 %); en 2005 se observó un control similar (P>0.05) entre los tres herbicidas, siendo este moderado (65 %). En este estudio se cuantificó que por cada 1,000 kg (MS/ha) de malezas acumulado, el rendimiento de forraje de la asociación disminuyó 190 kg (MS/ha). Bentazon en dosis de 0.8 kg i.a./ha asperjado en tres ocasiones durante el periodo de crecimiento vigoroso de las malezas, destacó por registrar una producción de forraje similar (P>0.05) a la alcanzada en las áreas libres de malezas (deshierbe). En regiones tropicales, bentazon podría ser una opción útil para el control de malezas dentro de una asociación insurgente-huaxín. ABSTRACT A study was carried out at Mocochá, Yucatán, México with the objective of determining whether the application of bentazon, imazethapyr or metribuzin would improve postemergence (POST) weed control without damaging a huaxin (leucaena, guaje, leadtree, wild tamarind) {Leucaena leucocephala (Lam.) de Wit} and insurgente grass (Brachiaria brizantha Richard Stapf) association. In both June 2004 and 2005, insurgente grass (INS) and huaxin (HUA) were seeded in an arrangement of two by one rows, respectively. Herbicide treatments were a single application of bentazon, imazethapyr or metribuzin at three different rates each, and the same herbicides at a single rate but applied sequentially two and three times during the growing season. Metribuzin damaged INS (10 to 95 %) and HUA (55 to 100 %) in both years. Overall, both forage species were tolerant to bentazon and imazethapyr. In 2004, both bentazon and metribuzin showed a greater weed control (82 %) than imazethapyr (70 %); in 2005, weed control was similar for all three herbicides (P>0.05), which averaged a moderate 65 %. This study shows that an increase in 1,000 kg DM ha -1 of weed biomass, decreases forage yield for this association by 190 kg DM ha -1 . Forage yields with bentazon applied three times at a 0.8 kg a.i. ha -1 rate were similar to those in the weed-free control. In tropical areas, bentazon should be an interesting option for weed control in insurgente-huaxin associations.
Pesticide Biochemistry and Physiology, 2002
A Rotala indica accession from Chonnam province, Korea was tested for resistance to sulfonylurea (SU) herbicide, imazosulfuron. The accession was confirmed to be resistant (R) and was cross-resistant to other SU herbicides, bensulfuron-methyl, cyclosulfamuron, and pyrazosulfuron-ethyl, but not to imidazolinone herbicides, imazapyr, and imazaquin. Multiple resistance was tested using eight herbicides with target sites other than acetolactate synthase (ALS). The R biotype was susceptible to other herbicides with different modes of action, such as fentrazamide and mefenacet. Herbicide mixtures, butachlor + pyrazolate and MCPB + molinate + simetryne can also control R biotype of R. indica. Although mixtures of SU herbicides with other modes of action can control the R biotype, use of these mixtures should be avoided. In vivo ALS activity of the R biotype was 35-, 26-, 278-, and 7-fold more resistant to bensulfuron-methyl, cyclosulfamuron, imazosulfuron, and pyrazosulfuron-ethyl, respectively, than the S biotype. The resistance mechanism of R. indica to imazosulfuron was mainly due to an alteration in the target enzyme, ALS. Since the level of resistance to other SU herbicides in the enzyme assay was much lower than that in the wholeplant assay, other mechanisms of resistance, such as herbicide metabolism, or reduced absorption and translocation may be involved. There was no indication of fitness difference between the R and S biotypes.