Controle químico da lagarta-enroladeira (Bonagota cranaodes Meyrick) na cultura da macieira

Apple leafroller, Bonagota cranaodes Meyrick (Lepidoptera: Tortricidae), is one of the major apple pests in Southern Brazil. Laboratory and field experiments were conducted with chlorpyriphos-ethyl (Lorsban 480 CE - 72 g of a.i./100 L), methidathion (Supracid 400 - 60 g of a.i./100 L), phosmet (Imidan 50 PM - 100 g of a.i./100 L), trichlorphon (Dipterex 500 - 150 g of a.i./100 L), tebufenozide (Mimic 240 SC - 21.6 g of a.i./100 L), fenitrothion (Sumithion 500 CE - 75 g of a.i./100 L) and carbaryl (Sevin 850 PM - 153 g of a.i./100 L) to control the pest in apple orchards. In laboratory, all insecticides caused 100% of mortality on first-instars larvae while fourth and fifth instar larvae were satisfactorily controlled only using chlorpyriphos-ethyl, tebufenozide and trichlorphon. Chlorpyriphos-ethyl application after peaks of B. cranaodes males capture in pheromone traps resulted in less than 1% of fruit damage at harvest, while tebufenozide resulted in 4.6% compared to 9.8% in a non-treated area.A lagarta-enroladeira, Bonagota cranaodes Meyrick (Lepidoptera: Tortricidae), é considerada uma das principais pragas da macieira no Brasil. Com o objetivo de selecionar inseticidas visando ao controle do inseto, experimentos de laboratório e campo foram conduzidos com clorpirifós-etil (Lorsban 480 CE - 72 g de i.a./100 L), metidatiom (Supracid 400 - 60 g de i.a/100 L), fosmet (Imidan 50 PM - 100 g de i.a./100 L), triclorfom (Dipterex 500 - 150 g de i.a./100 L), tebufenozide (Mimic 240 SC - 21,6 g de i.a./100 L), fenitrotiom (Sumithion 500 CE - 75 g de i.a./100 L) e carbaril (Sevin 850 PM - 153 g de i.a./100 L). Todos os inseticidas provocaram 100% de mortalidade de lagartas recém-eclodidas em laboratório, porém, o controle de lagartas de 4o e 5o ínstar, após seu estabelecimento nas plantas de macieira, somente foi satisfatório com clorpirifós-etil, tebufenozide e triclorfom. A pulverização de clorpirifós-etil, após picos de captura dos machos de B. cranaodes com armadilhas de feromônio sexual resultaram em menos de 1% de frutos danificados na colheita em comparação com 4,6% com tebufenozide, e 9,8% na testemunha

Nematicides: history, mode, and mechanism action

Nematodes are non-segmented invertebrate animals, which are one of the major phytosanitary problems worldwide, especially in tropical and subtropical regions, attacking the root system of plants they removing photo-assimilates and reducing the absorption capacity of water and nutrients of plant. In order to avoid economic losses by reducing productivity and quality, synthetic compounds have been developed to control nematodes. The use of these synthetic compounds, known as chemical control, has high economic importance, being the current tool most used by farmers for control of these individuals. Moreover, only in Brazil, the trade of these products reaches hundreds of millions of dollars per year. This review aims to address the fundamental aspects of nematode biology and the chemical control of the major genus (Meloidogyne, Heterodera, and Globodera). It covers the historical evolution of the chemical control agents since its beginning in the nineteenth century until today, their mode of action (fumigants and non-fumigants), mechanisms of action (inhibition of the acetylcholinesterase enzyme, opening of the chloride channel, inhibition of electron transport in the electron transport chain, enzymatic inactivation, as a Dauer phase-inducing agent or agent that ensures the organism remains irreversibly in the Dauer phase), the products available for each crop, including their commercial names and forms of application

Correlação entre resistência à brusone em cultivares de trigo e taxa de esporulação de conídios de Pyricularia oryzae Triticum

The use of resistant wheat cultivars is a fundamental strategy to minimize the damages caused by blast, a disease caused by the fungus Pyricularia oryzae Triticum (PoT). The objective of this study was to evaluate (a) the reaction to blast of Brazilian wheat cultivars and (b) to determine whether there is correlation between severity of symptoms on wheat spikes and “sporulation rate of PoT conidia per gram of wheat spike rachis” (Rscon). Plants of 16 wheat cultivars were grown in greenhouse until flowering (Zadoks stage 65), when their spikes were inoculated with a suspension formed by mixing the conidia of three PoT isolates. The evaluated variables were blast severity on spikes at 5, 7 and 11 days after inoculation (dai) and Rscon. Rachis were evaluated individually to determine the Rscon. Correlation analyzes were carried out between blast severity means on spikes of cultivars at 5, 7 and 11 dai and the log of Rscon. The cultivars ORS Feroz, ORS Destak, CD 116, ORS 1403, ORS 1401, TBIO Aton and TBIO Mestre stood out for being classified in the statistical groups with the highest resistance to blast for the four variables considered in the study. The correlation between blast severity on spikes at 5, 7 and 11 dai and Rscon was not significant.A utilização de cultivares de trigo resistentes é estratégia fundamental para minimizar danos causados pela brusone, doença causada pelo fungo Pyricularia oryzae Triticum (PoT). O objetivo do estudo foi avaliar (a) a reação à brusone de cultivares brasileiras de trigo e (b) verificar a correlação entre a severidade dos sintomas na espiga e a “taxa de esporulação de conídios de PoT em ráquis de espigas de trigo” (Txcon). Plantas de 16 cultivares de trigo foram conduzidas em casa-de-vegetação até o florescimento (estádio 65 da escala de Zadoks), quando as espigas das mesmas foram submetidas à inoculação com uma suspensão formada pela mistura de conídios de três isolados de PoT. As variáveis avaliadas foram a severidade de brusone nas espigas aos cinco, sete e 11 dias após a inoculação (dai) e a Txcon. A Txcon foi determinada de forma individualizada para os ráquis. Foram realizadas análises de correlação entre as médias de severidade de brusone nas espigas das cultivares aos cinco, sete e 11 dai e o log das Txcon. As cultivares ORS Feroz, ORS Destak, CD 116, ORS 1403, ORS 1401, TBIO Aton e TBIO Mestre se destacaram por terem sido classificadas nos grupos estatísticos de maior resistência à brusone para as quatro variáveis consideradas no estudo. Verificou-se a existência de correlação entre a severidade de brusone nas espigas aos 5, 7 e 11 dai e Txcon