Programa de Pós-Graduação em Agronomia
http://repositorio.ufsm.br/handle/1/2317
2024-03-28T21:51:56ZIntegração de bioinseticidas com inseticidas químicos no controle de mosca-branca (Bemisia tabaci) na cultura da soja
http://repositorio.ufsm.br/handle/1/31631
Integração de bioinseticidas com inseticidas químicos no controle de mosca-branca (Bemisia tabaci) na cultura da soja
Parisi, Pedro Bolzan
Arnemann, Jonas André
One of the significant challenges in soybean production is pest control, with the whitefly
(Bemisia tabaci) being particularly noteworthy. Categorized as a pest with high phytosanitary
risk, the whitefly is considered one of the primary threats to soybeans. Managing the whitefly
poses a considerable challenge, primarily due to its relatively short life cycle, high reproductive
rate, and its nature as a polyphagous pest. These characteristics make it willing to evolve
resistance to chemical insecticides commonly used for its control. In this context, biological
control has emerged as a crucial agent for innovation and sustainability on whithefly
management. Thus, our goal was to assess the effects of bio insecticides (entomopathogenic
fungi and plant extracts) applied alone and in combination with chemical insecticides to manage
whitefly on soybean. Two experiments were conducted, with 14 treatments tested under field
and laboratory conditions. In the field, treatments involved two sprays, with a 10-day interval.
Treatments effectiveness was evaluated on nine dates through evaluating the adults and nymphs
of whitefly. In the lab, treatments were tested by immersing leaves in the insecticide solution,
and effectiveness was assessed on seven dates. Randomized block and completely randomized
designs were employed for field and lab experiments, respectively. Both followed a two-factor
model, and the interaction between the analyzed factors (insecticide treatments x evaluation
times) was significant for both experiments. In the field trials, all treatments exhibited positive
effect in the control of whiteflies, with particular emphasis on the mixed group (bioinsecticide
+ chemical insecticide), showing significant mortality on both stages of B. tabaci on all
evaluation dates. Notably, the strain ESALQ 1296 of Isaria fumosorosea, combined with the
dinotefuran + piriproxyfen, achieved an average efficiency of 91.9% in the adults control of B.
tabaci. However, on B. tabaci nymphs control, the strain ESALQ PL63 of Beauveria bassiana
mixed with dinotefuran + Pyriproxyfen reached the highest control efficiency (78.1%). Among
entomopathogenic fungi, the strain PL 63 of Beauveria bassiana exhibited the highest average
efficiency (83.6%) in the adult control, while the strain ESALQ 1296 of Isaria fumosorosea
showed the highest control on nymphs (67.6%) of B. tabaci. Between the plant extracts, the
extract from the fruit of Trichilia claussenii showed the highest control averages (88.6% and
69.2% for adults and nymphs of B. tabaci, respectively), statistically standing out positively
and distinguishing itself from the others. In lab trials, all treatments achieved 100% control of
B. tabaci after 7 days. The observed high efficiencies demonstrate biological insecticides are
crucial positive allies in the whitefly control in soybeans, reducing costs, mitigating insect
resistance selection, and minimizing environmental impacts.
Universidade Federal de Santa Maria
Dissertação
2024-02-20T00:00:00ZManejo na entressafra do arroz com herbicidas pré-emergentes para controle de arroz-daninho e redução do banco de sementes
http://repositorio.ufsm.br/handle/1/31608
Manejo na entressafra do arroz com herbicidas pré-emergentes para controle de arroz-daninho e redução do banco de sementes
Lucas, Tilio Adan
Ulguim, André da Rosa
Weedy rice (Oryza sativa L.) is the most important weed in irrigated rice crop, being one of
the main factors limiting cereal productivity in Rio Grande do Sul (RS), Brazil. One of the
main management methods for this weed is the Clearfield® cultivation system, which allows
for both pre- and post-emergence management of the crop, due to the tolerance of cultivars
to herbicides from the imidazolinone chemical group. However, there are currently weedy
rice biotypes resistant to these herbicides, necessitating the adoption of other management
practices to adhere to the principles of integrated weed management. An alternative is
autumnal management using pre-emergent herbicides to reduce the seed bank in the soil.
However, as it is of the same species as cultivated rice, it is important to evaluate the impacts
of using these herbicides on crop development. Thus, the objective of this study was to
determine the effect of pre-emergent herbicide use in autumnal management on the control
and reduction of the weedy rice seed bank. Field experiments were conducted in a
randomized complete block design with four replications in a commercial rice production
area during the 2021/22 and 2022/23 growing seasons in Dom Pedrito, RS, Brazil. The
scheme used was factorial, with factor A consisting of different herbicide application times,
referred to as June, July, and August, corresponding to 100, 78, and 47 days, and 42, 26, and
10 days before rice sowing for the agricultural years 2021/22 and 2022/23, respectively.
Factor B consisted of the herbicides s-metolachlor (1440 g a.i. ha-1
), sulfentrazone + diuron
(210 and 420 g a.i. ha-1
), piroxasulfone (170 g a.i. ha-1
), and flumioxazin (50 g a.i. ha-1
), in
addition to the control (no application). The evaluated variables were control (%), number
of plants (m2
) at crop pre-harvest, number of full, viable, and non-viable wild rice seeds m-2
in the soil, as well as crop injury (%) and grain yield (kg ha-1
). The herbicides showed control
values below 25%, and low reduction of the seed bank in the soil, being considered
ineffective in this application modality. The herbicides s-metolachlor, sulfentrazone +
diuron, and flumioxazin exhibited the highest injury values; however, they did not
significantly affect crop productivity. Thus, when applied before rice sowing, the herbicides
s-metolachlor, sulfentrazone + diuron, pyroxasulfone, and flumioxazin do not provide
satisfactory control and do not significantly reduce the wild rice seed bank.
Universidade Federal de Santa Maria
Dissertação
2023-12-15T00:00:00ZSuscetibilidade de Euschistus heros e Diceraeus furcatus (Hemiptera: Pentatomidae) a inseticidas no Rio Grande do Sul
http://repositorio.ufsm.br/handle/1/31554
Suscetibilidade de Euschistus heros e Diceraeus furcatus (Hemiptera: Pentatomidae) a inseticidas no Rio Grande do Sul
Moreira, Rafaella Pretto
Bernardi, Oderlei
The Neotropical brown stink bug, Euschistus heros (Fabricius, 1798), and the green belly stink
bug, Diceraeus furcatus (Fabricius, 1775) (Hemiptera: Pentatomidae), are key sucking pests of
soybean and maize in Brazil and other South American countries. The management of both
species is usually carried out through chemical control. Thus, a 2-year study was carried out to
assess the susceptibility to insecticides in populations of E. heros and D. furcatus collected in
soybean in southern Brazil. Adult stink bugs collected throughout the 2021/2022 and 2022/2023
seasons were exposed to the field label doses of selected insecticides commonly applied for
their control in dip-test bioassays using fresh green bean pods (Phaseolus vulgaris L.).
Populations of both species exhibited high mortality and relatively low geographic and
interspecific variation in susceptibility to the field label doses of acephate, ethiprol, acetamiprid
+ bifenthrin and imidacloprid + bifenthrin. Diceraeus furcatus was also susceptible to
dinotefuran + lambda-cyhalothrin. In contrast, populations of both species had relatively low
mortality and a wide geographic variation in susceptibility to the field label doses of lambdacyhalothrin,
acetamiprid, thiamethoxam + lambda-cyhalothrin and sulfoxaflor + lambdacyhalothrin.
In summary, our study documents the existence of significant variation in
susceptibility of E. heros and D. furcatus to field doses of selected insecticides commonly
applied for their control, both among geographical areas and among species in southern Brazil.
It is expected that the results presented will contribute to more effective control and resistance
management of stink bugs in soybean and maize in southern Brazil and neighboring countries.
Universidade Federal de Santa Maria
Dissertação
2024-02-16T00:00:00ZRequerimentos ambientais para germinação de sementes de Amaranthus hybridus L. resistente e suscetível a herbicidas
http://repositorio.ufsm.br/handle/1/31488
Requerimentos ambientais para germinação de sementes de Amaranthus hybridus L. resistente e suscetível a herbicidas
Tronquini, Sérgio Mateus
Ulguim, André da Rosa
Amaranthus hybridus L. is part of the Amaranthaceae family and in recent years the number of cases of herbicide resistance in Brazilian crops has increased. The main purpose of this research is to characterize the germination and emergence of A. hybridus L. biotypes (resistant and susceptible to herbicides) in response to environmental requirements. The project was separated in to two studies, the first was to characterize the environmental factors that interfere with the germination of the species and the second was the influence of different amounts of straw on germination and emergence, as well as the application of pre-emergent herbicides to control the species. For the first study, seven studies were carried out in a completely randomized experimental design with four replications, including the initial characterization of the populations, the influence of photoperiod, the influence of air temperature, the influence of osmotic potential and light quality on the germination of the species. For the second study, three experiments were conducted in a completely randomized design with four replications: the influence of burial depth; the influence of the amount of straw on the emergence of the biotypes; and the influence of the amount of straw on the pre-emergence chemical control of the species. No differences in response were identified between the biotypes tested. A. hybridus L. showed neutral photoblastic seed characteristics, with light being an additive factor, with a temperature range for germination between 20 and 35°C, with the optimum being close to 30°C. Due to the size of the seeds, emergence is affected under water stress of less than -2.0 Bar and soil depth of more than 2.0 cm. The straw influences on emergence in quantities higher than 4 t.ha-1, reduces the population and in interaction with herbicides can be used as a weed-management method. The environmental conditions favorable to the germination of this species are observed in the same months as the soybean crop cycle in the state of Rio Grande do Sul, Brazil, and this is the time to intensify monitoring and management.
Universidade Federal de Santa Maria
Dissertação
2023-11-08T00:00:00Z