ABSTRACT The transmission of tobamovirus by tomato and pepper seeds is an important mean of virus introduction in crops. Therefore, detecting its presence in the seed becomes essential for the preventive control of virus diseases. In this study, a method was proposed for the detection of Tobacco mosaic virus (TMV) and Tomato mosaic virus (ToMV) in tomatoes (Solanum lycopersicum) and Pepper mild mottle virus (PMMoV) in pepper (Capsicum annum) seeds. Seed lots with different levels of incidence were analyzed by biological, serological, and molecular methods. Using DAS-ELISA technique, it was possible to detect TMV up to the limit rate of 1:170 (1 contaminated seed: total seeds) and the ToMV up to 1:200 in tomato seeds; PMMoV in pepper seeds was detected up to 1:140. The IC-RT-PCR detected the TMV and ToMV up to the limit of 1:400 and PMMoV up to the limit of 1:300. The assembled lots containing only 1 contaminated seed in 1000 (1:1000) were combined into 30 sub lots for DAS-ELISA analysis and 10 sub lots for IC-RT-PCR analysis. Both techniques, DAS-ELISA and IC-RT-PCR, were efficient to detect the three viruses in all analyzed samples, but the detection of tobamoviruses with RT-PCR and biological tests was not reliable. Based on the results of this study, in which a combination of seeds in sub lots was made to reduce the number of tests performed, it is possible to make significant savings in the cost of the diagnostic methods routinely conducted in official laboratories, with high efficiency and reliability.

O objetivo deste trabalho foi avaliar a flutuação populacional do ácaro Brevipalpus phoenicis, vetor do Coffee ringspot virus (CoRSV) - agente causal da mancha-anular do cafeeiro -, bem como a sua distribuição em plantas de café e o efeito de acaricidas no seu controle em lavouras cafeeiras. O experimento foi realizado no Município de Coromandel, na região do Alto do Paranaíba, MG, durante dois anos. No segundo ano, avaliou-se o progresso da doença, e determinou-se a relação entre o crescimento populacional do ácaro e a incidência da doença. Observou-se que a mancha-anular e o ácaro ocorreram durante todo o ano, com maiores populações e incidência da doença nos meses com menores índices pluviais e temperaturas amenas. As análises de Pearson mostraram correlação negativa entre os parâmetros climáticos e a população do ácaro. Na análise da incidência da doença em diferentes épocas, verificou-se correlação positiva entre a primeira avaliação e as avaliações subsequentes. Quanto à distribuição espacial, foi observada a presença do ácaro em toda a planta; porém, as folhas são preferidas pelos adultos, enquanto os frutos são preferidos para oviposição. Os acaricidas são eficientes para manter a população do ácaro em baixos níveis, com consequente diminuição da incidência da doença.

The objective of this work was to evaluate the population fluctuation of the mite Brevipalpus phoenicis, vector of the Coffee ringspot virus (CoRSV) - the causal agent of the coffee ringspot disease -, as well as its distribution in coffee plants, and the effect of acaricides in its control in coffee crops. The experiment was carried out at the municipality of Coromandel, in the region of Alto do Paranaíba, MG, Brazil, during two years. In the second year, the progress of the disease was evaluated, and the relationship between the mite population and disease incidence was determined. Ringspot disease and mites were detected throughout the year, with larger populations and disease incidence in the months with lower rainfall and mild temperatures. Pearson analyses showed negative correlation between the climatic parameters and the mite population. In the analysis of the disease incidence in different periods, a positive correlation was found among the first and subsequent evaluations. Regarding spatial distribution, mite presence was observed in the whole plant; however, leaves are preferred by the adults, whereas the fruit are preferred for oviposition. The acaricides are effective in keeping the mite population at low levels, with consequent reduction of disease incidence.

O objetivo do trabalho foi verificar o efeito de tratamentos inseticidas, na produção e no controle da disseminação de vírus por afídeos vetores e o teor de resíduos observados nos tubérculos submetidos a esses tratamentos. Foram empregadas as cultivares, Ágata e Emeraude com Potato vírus Y. O modelo utilizado foi o de blocos inteiramente casualizados, com 12 tratamentos e 4 repetições, sendo: 1) pulverização semanal (PS), com a última aos 55 dias após o plantio (DAP); 2) PS com a última aos 69 DAP; 3) PS, com a última aos 69 DAP + aplicação de Cabrio Top; 4) pulverização a cada cinco dias, sendo a última aos 69 DAP; 5) PS sendo a última aos 80 DAP e 6) controle, sem pulverização, todos combinados com dois tratamentos de sulco (Imidacloprid e Phorate). Observou-se que a maioria dos tratamentos não impediu a disseminação dos vírus.

The objective the work was to investigate the effect of insecticide treatments on virus spread and in potato yield, as well as to evaluate the residue value of the insecticides employed in the tubers subjected to these treatments. The experiment was carried out with two cultivars in randomized blocks with 40 tubers, 4 replications and 12 treatments, as follows: 1) insecticide spraying (SI) on leaves once a week, with the last application at 55 days after planting (DAP); 2) SI on leaves once a week, with the last application at 69 DAP; 3) SI on leaves once a week, with the last application at 69 DAP + application of Cabrio Top; 4) SI on leaves every five days, with the last application at 69 DAP; 5) SI on leaves once a week, with the last application at 80 DAP; and 6) control, with no insecticides after plant emergence; and all of them combined with 2 soil treatments (Imidacloprid and Phorate). Those results show that the application of insecticides is useless when the potato seed has a high PVY incidence.