Josimar Batista Ferreira

Intensidade da ferrugem asiàtica (Phakopsora pachyrhizi H. Sydow & P. Sydow) da soja [Glycine max (L.) Merr.] nas cultivares Conquista, Savana e Suprema sob diferentes temperaturas e periodos de molhamento foliar

The asian rust (Phakopsora pachyrhizi Sydow) which has been reported in areas of tropical and subtropical climates around the world, causes significant soybean [Glycine max (L.) Merr.] yield reduction. The disease progress is influenced by biotic factors as interaction pathogen-host and abiotic factors of the environment. The objective of this work was to study the effects of temperature and leaf wetness period in the asian rust progress in the cultivars Conquista, Savana and Suprema. The experiment was conducted at the Department of Plant Pathology at Federal University of Lavras, in growth chamber at temperatures of 15, 20, 25 and 30 °C and leaf wetness periods of 0,6, 12, 18 and 24 hours. The plants were inoculated by spraying a suspension of inoculum of P. pachyrhizi at concentration of 104 urediniospores.mL-1. Severity and incidence data were integrated by the area under disease progress curve for severity (AUDPCS) and incidence (AUDPCI). Non-linear regression models were adjusted for the disease severity (AUDPCS) and incidence (AUDPCI). Volume under the response surface of temperature and leaf wetness was calculated for incidence (VURSI) and severity (VURSS) to detect differences between cultivars. Higher soybean rust intensity occurred with leaf wetness above 15 hours and temperatures close to 20 oC, for the three tested cultivars. Temperatures above 30 oC and below 15 oC reduced the disease progress. Disease intensity was reduced in leaf wetness below 6 hours. All cultivars were susceptible, but higher VURSI and VURSS occurred in Conquista cultivar, followed by Savana and Suprema cultivars. Disease intensity was not statistically different between Savana and Suprema cultivars. Temperature and leaf wetness were different among cultivars for AUDPCI.

ESTUDOS HISTOPATOLÓGICOS DA INTERAÇÃO COLLETOTRICHUM GLOEOSPORIOIDES - CAFEEIRO

In studies involving the interaction Colletotrichum gloeosporioides - coffee trees (Coffea arabica L.) there is little information regarding the pre-penetration, penetration and colonization pathways of this pathogen. The objectives of this work were: 1. to study through scanning electron microscopy (SEM) the pre-penetration and penetration events of C. gloeosporioides in hypocotyls of coffee plantlets; 2. to observe the colonization of Colletotrichum spp. in branches and fruits of coffee trees with blister spot symptoms. The study took place in three trials. In the first trial, it was observed and reported the pre-penetration events of C. gloeosporioides inoculated on hypocotyls of coffee cv. Acaia Cerrado with and without wounds. The second trial was performed to investigate the colonization of diseased coffee branches that presented drastic wilt and local necrosis was observed. Finally the third trial investigated the colonization of this pathogen in diseased coffee fruits. When C. gloeosporioides was inoculated, germination could be observed in wounded hypocotyls 6 hours after inoculation. Better adhesion of conidia was evident at surface depressions of hypocotyls and germination started by emission of one or two terminal germ tubes. Round or sub-round shaped apressoria appeared 12 hours after inoculation. Up to 72 hours, acervula formation was not observed on inoculated tissues. The wilted branches presented colonization in the phloem and cortical tissues. In fruits at different stages of maturation, it was observed colonization in tissues near the epidermis and collapse of the stomata in the affected area.In studies involving the interaction Colletotrichum gloeosporioides - coffee trees (Coffea arabica L.) there is little information regarding the pre-penetration, penetration and colonization pathways of this pathogen. The objectives of this work were: 1. to study through scanning electron microscopy (SEM) the pre-penetration and penetration events of C. gloeosporioides in hypocotyls of coffee plantlets; 2. to observe the colonization of Colletotrichum spp. in branches and fruits of coffee trees with blister spot symptoms. The study took place in three trials. In the first trial, it was observed and reported the pre-penetration events of C. gloeosporioides inoculated on hypocotyls of coffee cv. Acaia Cerrado with and without wounds. The second trial was performed to investigate the colonization of diseased coffee branches that presented drastic wilt and local necrosis was observed. Finally the third trial investigated the colonization of this pathogen in diseased coffee fruits. When C. gloeosporioides was inoculated, germination could be observed in wounded hypocotyls 6 hours after inoculation. Better adhesion of conidia was evident at surface depressions of hypocotyls and germination started by emission of one or two terminal germ tubes. Round or sub-round shaped apressoria appeared 12 hours after inoculation. Up to 72 hours, acervula formation was not observed on inoculated tissues. The wilted branches presented colonization in the phloem and cortical tissues. In fruits at different stages of maturation, it was observed colonization in tissues near the epidermis and collapse of the stomata in the affected area.

Estudos histoplásticos da interação Colletotrichum gloeosporioides: cafeeiro

In studies involving the interaction Colletotrichum gloeosporioides - coffee trees (Coffea arabica L.) there is little information regarding the pre-penetration, penetration and colonization pathways of this pathogen. The objectives of this work were: 1. to study through scanning electron microscopy (SEM) the pre-penetration and penetration events of C. gloeosporioides in hypocotyls of coffee plantlets; 2. to observe the colonization of Colletotrichum spp. in branches and fruits of coffee trees with blister spot symptoms. The study took place in three trials. In the first trial, it was observed and reported the pre-penetration events of C. gloeosporioides inoculated on hypocotyls of coffee cv. Acaia Cerrado with and without wounds. The second trial was performed to investigate the colonization of diseased coffee branches that presented drastic wilt and local necrosis was observed. Finally the third trial investigated the colonization of this pathogen in diseased coffee fruits. When C. gloeosporioides was inoculated, germination could be observed in wounded hypocotyls 6 hours after inoculation. Better adhesion of conidia was evident at surface depressions of hypocotyls and germination started by emission of one or two terminal germ tubes. Round or sub-round shaped apressoria appeared 12 hours after inoculation. Up to 72 hours, acervula formation was not observed on inoculated tissues. The wilted branches presented colonization in the phloem and cortical tissues. In fruits at different stages of maturation, it was observed colonization in tissues near the epidermis and collapse of the stomata in the affected area.In studies involving the interaction Colletotrichum gloeosporioides - coffee trees (Coffea arabica L.) there is little information regarding the pre-penetration, penetration and colonization pathways of this pathogen. The objectives of this work were: 1. to study through scanning electron microscopy (SEM) the pre-penetration and penetration events of C. gloeosporioides in hypocotyls of coffee plantlets; 2. to observe the colonization of Colletotrichum spp. in branches and fruits of coffee trees with blister spot symptoms. The study took place in three trials. In the first trial, it was observed and reported the pre-penetration events of C. gloeosporioides inoculated on hypocotyls of coffee cv. Acaia Cerrado with and without wounds. The second trial was performed to investigate the colonization of diseased coffee branches that presented drastic wilt and local necrosis was observed. Finally the third trial investigated the colonization of this pathogen in diseased coffee fruits. When C. gloeosporioides was inoculated, germination could be observed in wounded hypocotyls 6 hours after inoculation. Better adhesion of conidia was evident at surface depressions of hypocotyls and germination started by emission of one or two terminal germ tubes. Round or sub-round shaped apressoria appeared 12 hours after inoculation. Up to 72 hours, acervula formation was not observed on inoculated tissues. The wilted branches presented colonization in the phloem and cortical tissues. In fruits at different stages of maturation, it was observed colonization in tissues near the epidermis and collapse of the stomata in the affected area.

Incidência de Colletotrichum spp. em frutos de Coffea arabica L. em diferentes estádios fisiológicos e tecidos do fruto maduro

Especies de Colletotrichum estao presentes em todos os orgaos do cafeeiro. A importância desses fungos para a cultura do cafeeiro ainda e muito discutida, pois tratam-se de populacoes de especies de Colletotrichum ocasionando diversos sintomas ou colonizando as plantas de forma endofitica. O estudo foi realizado com o objetivo de verificar a presenca de Colletotrichum spp. em diferentes estadios de desenvolvimento do fruto de cafeeiro e nos tecidos do exocarpo+mesocarpo, endocarpo e endosperma de frutos maduros. Este trabalho foi realizado no Laboratorio de Diagnose e Controle de Enfermidades de Plantas da Universidade Federal de Lavras-(UFLA). Os frutos foram coletados na area experimental do Setor de Cafeicultura da UFLA com cafeeiros das cultivares Catuai Vermelho, Catuai Amarelo, Icatu, Topazio, Katipo, Rubi, Acaia Cerrado e Mundo Novo. Nos estadios de formacao do fruto, verificaram-se altos valores de incidencia, com media de 86,6%. Em relacao as cultivares, as maiores incidencias foram em Topazio e Rubi, ambas com 94,4% e as menores incidencias nas cultivares Icatu e Mundo Novo, com 72,8% e 78,4%, respectivamente. A incidencia de Colletotrichum spp. variou tanto entre cultivares como entre os tecidos do fruto. No exocarpo+mesocarpo, as cultivares Topazio, Rubi e Acaia Cerrado tiveram porcentagens de colonizacoes de 84,72%, 79,16% e 77,77%, respectivamente, enquanto a cultivar Icatu teve 48,6%. No endocarpo, a maxima colonizacao foi de 9,72% na cultivar Rubi e a menor colonizacao na cultivar Acaia Cerrado, com 1,39%. No endosperma, a cultivar Rubi teve novamente o maior indice de colonizacao (8,33%) e as cultivares Mundo Novo e Katipo ambas com 1,39% de colonizacao. Verificou-se a presenca de Colletotrichum spp. nas sementes de todas as cultivares estudadas.

Histopathological studies of the interaction Colletotrichum gloeosporioides - coffee tree.

In studies involving the interaction Colletotrichum gloeosporioides - coffee trees (Coffea arabica L.) there is little information regarding the pre-penetration, penetration and colonization pathways of this pathogen. The objectives of this work were: 1. to study through scanning electron microscopy (SEM) the pre-penetration and penetration events of C. gloeosporioides in hypocotyls of coffee plantlets; 2. to observe the colonization of Colletotrichum spp. in branches and fruits of coffee trees with blister spot symptoms. The study took place in three trials. In the first trial, it was observed and reported the pre-penetration events of C. gloeosporioides inoculated on hypocotyls of coffee cv. Acaia Cerrado with and without wounds. The second trial was performed to investigate the colonization of diseased coffee branches that presented drastic wilt and local necrosis was observed. Finally the third trial investigated the colonization of this pathogen in diseased coffee fruits. When C. gloeosporioides was inoculated, germination could be observed in wounded hypocotyls 6 hours after inoculation. Better adhesion of conidia was evident at surface depressions of hypocotyls and germination started by emission of one or two terminal germ tubes. Round or sub-round shaped apressoria appeared 12 hours after inoculation. Up to 72 hours, acervula formation was not observed on inoculated tissues. The wilted branches presented colonization in the phloem and cortical tissues. In fruits at different stages of maturation, it was observed colonization in tissues near the epidermis and collapse of the stomata in the affected area.In studies involving the interaction Colletotrichum gloeosporioides - coffee trees (Coffea arabica L.) there is little information regarding the pre-penetration, penetration and colonization pathways of this pathogen. The objectives of this work were: 1. to study through scanning electron microscopy (SEM) the pre-penetration and penetration events of C. gloeosporioides in hypocotyls of coffee plantlets; 2. to observe the colonization of Colletotrichum spp. in branches and fruits of coffee trees with blister spot symptoms. The study took place in three trials. In the first trial, it was observed and reported the pre-penetration events of C. gloeosporioides inoculated on hypocotyls of coffee cv. Acaia Cerrado with and without wounds. The second trial was performed to investigate the colonization of diseased coffee branches that presented drastic wilt and local necrosis was observed. Finally the third trial investigated the colonization of this pathogen in diseased coffee fruits. When C. gloeosporioides was inoculated, germination could be observed in wounded hypocotyls 6 hours after inoculation. Better adhesion of conidia was evident at surface depressions of hypocotyls and germination started by emission of one or two terminal germ tubes. Round or sub-round shaped apressoria appeared 12 hours after inoculation. Up to 72 hours, acervula formation was not observed on inoculated tissues. The wilted branches presented colonization in the phloem and cortical tissues. In fruits at different stages of maturation, it was observed colonization in tissues near the epidermis and collapse of the stomata in the affected area.

Intensity of Powdery Mildew in Soybean Under Changes of Temperature and Leaf Wetness

Soybean Glycine max L. Merr. is cultivated in several tropical and subtropical regions of the world. United States (USA) and Brazil are the worlds largest producers and exporters of oilseed (Agrianual, 2008; Miyasaka & Medina, 1981). Despite the high production and export of Brazilian soybeans, many factors have affected the quality or quantity of production of that crop, causing reduction in financial returns per unit area, such as disease epidemics. Among the diseases, powdery mildew, whose etiologic agent is Microsphaera diffusa Cke. & Pk., suddenly began to cause significant damage in soybean, despite having a broad host range and have been reported in Brazil, Canada, Republic of China, India, Puerto Rico, South Africa, United States (Sinclair, 1999), Germany, Argentina and Bolivia (Sartorato & Yorinori, 2001) . According to Yorinori & Hiromoto (1998), crops widely affected by the disease, had estimated reductions between 30 and 40% of yield, in the same order of magnitude as those reported abroad by Dunleavy (1978) and Philips (1984). The susceptibility of cultivars and the influence of climate favored epidemics with high rates of disease progress, in successive years in Brazil. Considering the lack of resistance of most of the cultivars, chemical control is required, especially in the south and the high plains of the savannah biome (Sartorato & Yorinori, 2001). In 1996/97, epidemics of powdery mildew in soybean in a great extent of Brazil, from the Central West region to the Rio Grande do Sul state, resulted in average losses of 15 and 20% in susceptible cultivars, with extremes ranging from 50 to 60% (Yorinori & Hiromoto, 1998 ; Seganfredo & Silva, 1999). M. diffusa is distinguished from M. polygoni by presenting cleistothecium with appendages forked at its end (Sartorato & Yorinori, 2001; Grau, 1975). The fungus is an obligate parasite that develops throughout the soybean shoot, including leaves, stems, petioles and pods. Symptoms can range from chlorosis, green islands, rusty spots, defoliation or severe combination of these symptoms, depending on the reaction of cultivars. Chlorotic spots and necrosis on the leaf veins indicate a hypersensitivity reaction. However, the most obvious is the very structure and powdery white fungus on the surface of infected parts (Yorinori, 1982; Yorinori, 1986, Tanaka et al., 1993; Yorinori et al., 1993; Sinclair, 1999; Sartorato &