During the spring of 2001, approximately 10 000 yellow passion flower plants, from two orchards in the county of Livramento de Nossa Senhora, Bahia State, Brazil, exhibited intense yellow mosaic symptoms and drastic reduction of the leaf lamina and plant development. A large population of whiteflies ( Bemisia tabaci ) was also found colonizing the plants. All field samples collected tested positive for Passion fruit woodiness virus in DAS-ELISA. Five out of 20 passion flower plants inoculated with adult whiteflies collected from diseased plants in the field developed symptoms 20 -30 days after inoculation. Two of these plants gave a positive reaction in TAS-ELISA using antiserum against a begomovirus. Degenerated PCR primers amplified viral DNA fragments from the DNA-A and DNA-B components of a begomovirus infecting these plants. The fragment corresponding to the core region of the coat protein (DNA-A) was cloned and sequenced. A phylogenetic analysis placed this begomovirus isolated from passion flower in the same clade of the New World begomoviruses as several other species from Brazil. Based on the symptoms induced by this virus alone, the disease was tentatively named passion flower little leaf mosaic.
In Brazil, passion flower is grown across almost the entire country. The predominant disease of the passion flower crop is passion fruit woodiness, caused by the potyvirus cowpea aphid‐borne mosaic virus (CABMV), and transmitted by aphids in a nonpersistent manner. The disease reduces the useful life of the orchard from 36 months to approximately 18 months. Up to now, there has not been an efficient method for disease management. The aim of this work was to evaluate the efficiency of systematic roguing of diseased plants through weekly inspections, for disease management in the field. The latent and incubation periods of CABMV in passion flower vines were determined in order to optimize roguing efficiency. Passion fruit plants inoculated with CABMV started to act as sources of inoculum from 3 days after inoculation (DAI), and the symptoms were expressed, on average, at 8 DAI. Five field experiments, conducted in the states of São Paulo and Bahia, Brazil, demonstrated that systematic roguing of diseased plants was significantly efficient for managing passion fruit woodiness disease. In order to facilitate identification and subsequent removal of the infected plants, they need to be grown separately. This cultural practice can be recommended for managing passion fruit woodiness disease, provided it is applied on a regional scale by all passion fruit growers. The development of some pilot plantings for the application of roguing in a passion flower‐producing region is recommended to validate the use of this technique for managing passion fruit woodiness disease.
The Passion fruit woodiness virus (PWV) is the most important virus affecting passion fruit (Passiflora edulis f. flavicarpa Deg.) crops in Brazil. The main purpose of this work was to select mild strains of PWV and to evaluate their protective effect against a severe strain of the virus. Three mild strains were selected from outstanding plants found in orchards severely affected by the virus (F-101, F-102 and F-103) and three others were obtained from blisters formed in passion fruit vine leaves showing mosaic (F-99, F-144 and F-145). The protective effect of the mild strains was evaluated for vines under greenhouse and field conditions. Plants pre-immunized with mild strains F-101, F-102 and F-144, in a greenhouse, had partial protection against the severe strain PWV-SP. In a first field experiment, all passion fruit vines pre-immunized with the six selected mild strains showed severe symptoms of the disease, approximately four months after the challenge inoculation with the PWV-SP strain. Results from a second field experiment, with vines preimmunized with strains F-101 and F-144, followed by a quantitative evaluation of the mild strains in different leaves of the protected plants, indicated that breakdown in protection seems to be related to the low concentration and/or irregular distribution of the mild strains in leaves, which allows the existence of infection sites available for the establishment of the severe strain. Pre-immunization was not an appropriate alternative for the control of the passion fruit woodiness disease.
Fungos do gênero Trichoderma são largamente utilizados no biocontrole de fitopatógenos, além de serem capazes de estabelecer associações com plantas, aumentando seu potencial de desenvolvimento. Este trabalho avaliou o desenvolvimento e qualidade de mudas clonais de Eucalyptus camaldulensis (clone 58) inoculadas com duas espécies de Trichoderma: T. harzianum e T. virens, por diferentes métodos, a saber: tratamento das miniestacas; incorporação de grãos de arroz colonizados ao substrato; pulverização de suspensão de esporos e; adição de suspensão de esporos ao substrato + pulverização de suspensão de esporos. O uso de Trichoderma proporcionou melhor desempenho para todas as variáveis analisadas, sendo os maiores incrementos verificados no número de folhas (110%), massas secas aérea (70,4%), das raízes (54,7%) e total (64,8%) e índice de qualidade de Dickson (70,4%), em relação à testemunha, sem Trichoderma. O tratamento das minestacas com T. virens mostrou ser o tratamento mais eficiente na promoção do crescimento e qualidade das mudas. As duas espécies de Trichoderma foram detectadas nas raízes pelo teste de colonização endofítica. Seu uso mostrou ser uma alternativa promissora a ser adotada nos viveiros florestais, pois, além de atuar no biocontrole de fitopatógenos, foi capaz de promover o desenvolvimento das mudas.
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