O objetivo deste estudo foi avaliar o ataque do cupim rizófago (Procornitermes triacifer) sobre a cultivar de arroz Aimoré, em sistema de plantio direto. Foram instalados três experimentos em blocos ...ao acaso com três repetições. A parcela consistiu de quatro fileiras de plantas, de 5,0 m, espaçadas de 0,4 m. Os tratamentos foram: três sulcadores e três compactadores de sulco, no primeiro experimento; três sulcadores e dois limitadores de profundidade, no segundo experimento; e, no terceiro experimento, cinco sulcadores, testados sobre resíduos culturais de soja, andropogon e braquiária. Os sulcadores foram testados com ou sem facão subsolador. Os dois primeiros experimentos foram repetidos três anos (2002/2003 a 2004/2005), sendo a semeadura do primeiro ano realizada com a aplicação do inseticida thiamethoxam 10 G (20 kg ha-1) em mistura com o adubo, aplicados na base do sulco de plantio. O terceiro experimento foi realizado em um só ano (2003/2004). O dano de cupim foi quantificado separadamente nas fileiras externas das parcelas e naquelas situadas nos níveis mais alto e mais baixo do terreno. O inseticida testado e os sulcadores de disco duplo usados em associação com o facão subsolador foram restritivos ao ataque de cupins, enquanto os resíduos culturais de soja foram favoráveis ao ataque do inseto.
PALAVRAS-CHAVE: Inseticida; fitófago subterrâneo.
The objective of this study was to evaluate the damage of the root feeder termite (Procornitermes triacifer) on upland rice cultivar Aimoré under no-tillage system. Three experiments in randomized complete block design with three replications were carried out. The plot was made up by four 15 m plant rows spaced by 0.4 m. Treatments were: three furrow openers and three seed firming devices in the first experiment; three furrow openers and two seed depth controllers in the second experiment; and, in the third experiment, five furrow openers tested on soybean, Andropogon, and Brachiaria residues. The furrow openers were tested with or without subsoiler. The two first experiments were repeated for three years, 2002/2003 through 2004/2005. In the first year, it was used the insecticide thiamethoxam 10 G (20 kg ha-1) mixed to starter fertilizer. The third experiment was conducted only in 2003/2004. Termite damage was quantified separately in the external rows and also in the rows located at higher and lower areas. The insecticide and the double disk furrow openers combined with the subsoiler were restrictive to the insect attack, while higher level area rows and soybean crop residue were favorable to attack.
KEY-WORDS: Insecticide; underground phitophagus; seed drills; mulch.
During 1994 to 1996, studies were conducted in western Nebraska, to develop a pest management program for Mexican bean beetle (Epilachna varivestis Mulsant) in dry bean (Phaseolus vulgaris L.) based ...on egg mass sampling. A sampling survey to describe the spatial and probability distributions of egg masses produced a data set of 12,290 egg mass samples from four fields over two years. Semivariograms showed no sign of aggregation, even though the presence of macroscale trends indicated that Mexican bean beetle egg densities may be greater in areas of the field near edges adjacent to beetle overwintering sites. Egg masses had a negative binomial distribution. Life tables were developed by following known Mexican bean beetle cohorts (egg masses) in three fields in each of two years. High mortality occurred in the egg and first two larval stages. Egg mortality was related to drought-stressed bean plants, because stressed plants turn over their leaves and expose eggs to sunlight. The cumulative mortality ranged from 92.07% to 95.82%, in 1995 and from 60.89% to 75.6% in 1996. No parasitized larvae were observed in the study fields or those held for parasitism tests. Yield-loss relationships for Mexican bean beetle on dry bean were determined in a third study. Results from a series of experiments were combined with data from the other two studies to develop economic injury levels (EILs) and economic thresholds (ETs) and a sequential sampling program for Mexican bean beetle. The EILs calculated in larvae/row-m were converted to egg masses/row-m and adjusted to reflect the average survivorship to the adult stage. Because sampling is based on egg masses, growers can make management decisions and take management actions before significant injury will occur. An interactive spreadsheet was developed to calculate Mexican bean beetle EILs, ETs, and sequential sampling plans. The spreadsheet allows users to input economic and other data specific to their situation. The pest management tools presented in this work should provide a useful model for management programs for other insects pests in other systems.
The rice (Oryza sativa L.) plants are able to generate fertile tillers after harvest. This sprouting, called ratoons, allows a second harvest, which may become a feasible alternative to increase ...yields in different ecosystems, mainly in low lands, due to its adaptability. As soil tillage and seeding are not required, the ratoon cultivation demands 60% less water and 50% less labor than the main crop. Additionally, it increases the rice production per cultivation area and time as the season is shorter than of the main crop. The success of the ratoon crop is determined by management practices adopted for the main crop, such as seeding date, height of cutting the plants, fertilizer management, seeding and harvesting procedures as well as practices that promote a fast and uniform sprouting, like nitrogen fertilizers, irrigation water management and crop protection. Ratoons represent an alternative to increase production without additional land area and with lower production costs, reducing seasonality of machinery use, increasing yields of tropical low lands with environmental and product quality, improving farmers livelihoods. The regional impacts of ratooning in the lowlands of Rio Formoso microregion of Tocantins State were evaluated in the economic, social and environmental dimensions, considering a period of five years. The economic assessment was based on the economic surplus method, using official production data from 2003 to 2007 and the production costs for irrigated rice in Tocantins State. Ratooning was estimated to be adopted in 20% of cultivated area, generating an economic surplus varying from 2 million reais in season 2002/2003 to 0.3 million reais in season 2006/2007, representing an additional production of 13 thousand tons of paddy in 2003 and 1.2 thousand tons in 2007. The social and environmental assessments were based on the Ambitec-Social and Ambitec-Agro, developed by Embrapa Environment. Rice ratooning in the study area obtained social impact index of 0.43 and an environmental impact index of 0.03.
As plantas de arroz (Oryza sativa L.) possuem a capacidade de gerar perfilhos férteis após o corte dos colmos na colheita. Esta brotação, denominada soca, possibilita o segundo cultivo de arroz, o qual pode constituir-se numa alternativa prática para aumentar a produtividade de grãos em muitos agroecossistemas, principalmente em várzeas, visto que esta é a espécie mais adaptada. Sem a necessidade de preparo do solo nem de semeadura, o seu cultivo usa 60% menos água e 50% menos mão-de-obra que a cultura principal. Além disso, é uma prática que aumenta a produção de arroz por unidade de área e de tempo por apresentar menor duração de crescimento que um novo cultivo. O sucesso do aproveitamento da soca é determinado pelas práticas empregadas na cultura principal, tais como: época de plantio, altura do corte das plantas, manejo de fertilizantes, sistema de plantio e colheita, bem como pelas práticas que promovem uma rápida e uniforme brotação como fertilização nitrogenada, manejo de água e tratos fitossanitários. Ênfase deve ser dada na sua importância como uma alternativa para aumentar a produção sem acrescer a área de cultivo e com menor custo de produção, possibilitando reduzir a sazonalidade do uso de máquinas e implementos, aumentar a produtividade das várzeas tropicais com qualidade ambiental e de produção, além de incrementar a renda líquida dos produtores. Os impactos regionais da adoção dessa tecnologia, implantada em várzeas tropicais da microrregião do Rio Formoso, no Estado do Tocantins, foram avaliados nas dimensões econômica, social e ambiental, no período de cinco anos. Para avaliação econômica foi utilizada a metodologia do excedente econômico, utilizando-se dados conjunturais oficiais do período de 2003 a 2007 e do custo de produção do arroz irrigado no Estado do Tocantins. Para o período analisado, a soca foi adotada em 20% da área total cultivada com arroz irrigado e foi estimado um benefício econômico que variou de dois milhões de reais, na safra 2002/2003, para trezentos mil reais, na safra 2006/2007, correspondentes a um adicional de aproximadamente 13 mil toneladas de arroz em casca, em 2003, e 1,2 mil toneladas de arroz em casca, em 2007. Para avaliação social e ambiental utilizou-se o Sistema Ambitec Social e Ambiental, respectivamente, desenvolvido pela Embrapa Meio Ambiente, com obtenção do índice de impacto de 0,43 para a dimensão social e de 0,03 para a dimensão ambiental
The objective of this study was to evaluate the damage of the root feeder termite (Procornitermes triacifer) on upland rice cultivar Aimoré under no-tillage system. Three experiments in randomized ...complete block design with three replications were carried out. The plot was made up by four 15 m plant rows spaced by 0.4 m. Treatments were: three furrow openers and three seed firming devices in the first experiment; three furrow openers and two seed depth controllers in the second experiment; and, in the third experiment, five furrow openers tested on soybean, Andropogon, and Brachiaria residues. The furrow openers were tested with or without subsoiler. The two first experiments were repeated for three years, 2002/2003 through 2004/2005. In the first year, it was used the insecticide thiamethoxam 10 G (20 kg ha-1) mixed to starter fertilizer. The third experiment was conducted only in 2003/2004. Termite damage was quantified separately in the external rows and also in the rows located at higher and lower areas. The insecticide and the double disk furrow openers combined with the subsoiler were restrictive to the insect attack, while higher level area rows and soybean crop residue were favorable to attack. KEY-WORDS: Insecticide; underground phitophagus; seed drills; mulch.
The impact of the Diatraea saccharalis natural infestation on yield of 24 genotypes of upland rice was studied in an experiment carried out in field conditions. The attack of D. saccharalis on stems ...and its effect on spikelet weight was determined using a yield loss index and by regression analysis. The index used quantifies the spikelet mass loss per bored stem in relation to spikelet mass no bored stem. The estimates obtained with these two methods were different. Less than 10% of genotypes showed a linear relationship between the infestation and stem borer damage. Estimated yield losses based on the index seemed more appropriate to the conditions of the experiment. Infestations by D. saccharalis did not visibly affect the weight of spikelets of five genotypes, caused a small reduction in two genotypes, and caused economic losses in the most of them (17 genotypes). The CNAs9023 genotype was the least infested and presented the highest weight of spikelets, and showed more resistance than CNAs9028, which was more infested and produced less. KEY-WORDS: Upland rice; stem borer; sampling; genotype evaluation.
The rice stalk stink bug,
Tibraca limbativentris
Stål, is an important rice pest in Brazil, causing significant damage to rice plants and consequently yield losses, with a high invasive potential in ...Mexico and USA. The male-produced sex pheromone of this species was recently identified as a 7:3 mixture of (3
S
,6
S
,7
R
)-1,10-bisaboladien-3-ol (
1
) and (3
R
,6
S
,7
R
)-1,10-bisaboladien-3-ol (
5
) (a.k.a. zingiberenols). The aim of this study was to evaluate field responses of
T. limbativentris
females to the racemic mixture and stereoisomers of 1,10-bisaboladien-3-ol, including the male-produced sex pheromone. The results obtained in two rice-producing areas of Brazil (Rio Grande do Sul and Santa Catarina) showed that traps baited with the main component
1
alone, the racemic mixture, and a mixture of
1
and
5
were attractive to females of
T. limbativentris
. The minor component
5
was unable to attract females when used alone. The results indicate that the sex pheromone of
T. limbativentris
and racemic mixture of 1,10-bisaboladien-3-ol were equally attractive to co-specific females in rice fields, and they could be a tool to incorporate in rice stalk stink bug management programs.
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