Frente à recente detecção em território brasileiro de Monilina laxa, que assim como M. fructicola, é causadora da podridão parda do pessegueiro, e à falta de informações sobre a epidemiologia dos patógenos causadores da doença em regiões subtropicais, surgiu a necessidade deste trabalho, que teve por objetivos determinar as melhores condições de temperatura e molhamento para o desenvolvimento de M. fructicola e M. laxa in vitro e para a infecção e colonização pêssegos por conídios dos patógenos. Quatro isolados de M. fructicola e um isolado de M. laxa, provenientes de plantios do Estado de São Paulo e mantidos no laboratório de Epidemiologia da ESALQ, foram estudados. Foram avaliados os efeitos da temperatura e da duração do molhamento na germinação dos conídios in vitro e o efeito da temperatura no crescimento micelial e na esporulação dos patógenos. Ensaios para determinar a sensibilidade dos patógenos ao fungicida iminoctadina também foram conduzidos. Adicionalmente, pêssegos maduros foram adquiridos, feridos, inoculados com suspensão de conídios e incubados em diferentes temperaturas sob diferentes períodos de câmara úmida. Diariamente incidência e severidade foram avaliadas. A esporulação foi avaliada ao final de cada tratamento. A faixa ótima de temperatura para germinação de conídios de M. laxa, de 5 a 30ºC, é maior que a de M. fructicola, de 10 a 30ºC. O período de molhamento não teve influência na germinação dos conídios. A melhor faixa de temperatura para crescimento micelial tanto de M. fructicola quanto M. laxa de foi de 20 a 25ºC. A esporulação de M. laxa foi inversamente proporcional à temperatura de incubação. Não houve relação entre temperatura e produção de esporos em M. fructicola. Ambas as espécies mostraram-se sensíveis, in vitro, à molécula iminoctadina. A incidência da podridão parda foi superior a 80,9% em todos os tratamentos, para as duas espécies fúngicas. A 10ºC os períodos de incubação e de latência foram menores para M. laxa que para M. fructicola. A faixa ótima de temperatura para o desenvolvimento de lesões variou de 15 a 25ºC para os dois patógenos. A esporulação dos patógenos não mostrou relação com a temperatura nos ensaios in vivo. Diferenças nos sinais da espécie do patógeno foram observados nas lesões. / Due to the recent detection in Brazil of Monilinia laxa, that similar to M. fructicola causes the brown rot of peaches, and the lack of information about the epidemiology of the causal agents of this disease from subtropical regions, raised the need of such a study, which the aims were to determine the best temperature and wetness duration conditions to the development of M. fructicola and M. laxa in vitro and to infection and colonization of peaches by conidia from both pathogens. Four M. fructicola isolates and one M. laxa isolate, collected from infected fruit of São Paulo orchards and maintained at the Epidemiology Laboratory at ESALQ, were studied. Temperature and wetness duration effects on conidia germination in vitro and temperature effects on mycelial growth and sporulation of pathogens were evaluated. Trials to evaluate the sensitivity of isolates to the fungicide iminoctadine were also conducted. Furthermore, mature peaches were wounded on the surface, inoculated with a conidia suspension and incubated at different temperatures during different wet chamber periods. Incidence and severity of the disease were evaluated daily. Sporulation was evaluated at the end of each treatment. The favorable range of temperature to conidia germination of M. laxa, from 5 to 30ºC, was greater than M. fructicola range, from 10 to 30ºC. The wetness duration showed no influence on conidia germination. The best range of temperature for mycelial growth of both M. fructicola and M. laxa was from 20 to 25ºC. Sporulation of M. laxa showed an inverse relationship to the incubation temperature. No relationship between temperature and conidia production was found for M. fructicola. Both species were sensitive to the iminoctadine fungicide in vitro. Incidence of brown rot was greater than 80.9% in all treatments, for both species. At 10ºC incubation and latency periods were shorter for M. laxa than for M. fructicola. The best temperatures for lesion development varied between 15 and 25ºC for both pathogens. Sporulation of the two species showed no relationship to the temperature on the in vivo trials. Visual differences were observed on pathogen symptoms on fruit.

Objetivando melhor conhecimento a respeito dos nematóides encontrados associados a fruteiras de clima subtropical e temperado, coletaram-se 149 amostras de solo da rizosfera e de raízes de amoreira-preta, caquizeiro, framboeseira, macieira, marmeleiro, nespereira, nogueira-macadâmia, oliveira, pereira, pessegueiro e umezeiro em áreas de produção do Estado de São Paulo e em uma localidade de Minas Gerais. Como resultado desse levantamento, identificaram-se 11 gêneros e as espécies relacionadas a seguir: Aorolaimus nigeriensis, Discocriconemella degrissei, Helicotylenchus dihystera, H. erythrinae, H. microcephalus, H. pseudorobustus, Helicotylenchus spp., Hemicycliophora poranga, Meloidogyne hapla, M. incognita, M. javanica, Mesocriconema onoense, M. ornata, M. sphaerocephalum, M. xenoplax, Mesocriconema spp., Pratylenchus brachyurus, P. zeae, Rotylenchulus reniformis, Scutellonema brachyurus, Tylenchulus semipenetrans, Xiphinema brevicollum, X. elongatum, X. krugi, X. setariae, X. surinamense e Xiphinema spp.. Os três gêneros mais freqüentes foram Helicotylenchus, Mesocriconema e Xiphinema, presentes em 60,4; 55,0 e 30,2 % das amostras, respectivamente; as espécies mais comuns foram H. dihystera e M. xenoplax, ocorrendo em 49 e 38,3 % das amostras. Contudo, apenas M. incognita e M. javanica estavam associados a danos em pessegueiros cujos porta-enxertos não tinham resistência genética. Em casa de vegetação, avaliaram-se as reações de genótipos das citadas fruteiras, mais goiabeira, frente aos nematóides de galhas Meloidogyne incognita raça 2 e M. javanica. As plantas, individualmente inoculadas com 5000 ovos de cada espécie de nematóide, foram conduzidas em recipientes plásticos durante 120 dias. A caracterização das reações baseou-se na capacidade reprodutiva dos parasitos, determinando-se os índices de massas de ovos e de galhas, bem como os números de nematóides por sistema radicular e por grama de raízes. Apenas a cultivar GF-677 de Prunus persica x P. dulcis comportou-se como suscetível, possibilitando desenvolvimento e multiplicação dos dois nematóides. Os demais genótipos avaliados foram hospedeiros desfavoráveis ao desenvolvimento dos nematóides, sendo considerados resistentes, embora vários deles tivessem proporcionado restritas taxas de reprodução dos parasitos. Estudou-se ainda, também sob condição de casa de vegetação, a patogenicidade de M. incognita raça 2 em caquizeiro 'Kyoto', verificando-se correlação negativa entre os níveis populacionais iniciais utilizados (0, 160, 800, 4 000, 20 000 e 100 000 ovos por parcela) e a altura e a massa seca de raízes das plantas, após seis meses da inoculação. Tendo em vista que a intensa formação de galhas radiculares observada e o efeito negativo sobre os dois parâmetros de crescimento das plantas mostraram-se associados a taxas de reprodução muito baixas do parasito, considerou-se que a reação ocorrida foi de intolerância. / In order to achieve a better knowledge on the nematodes found associated with subtropical and temperate fruits, a total amount of 149 soil and root samples were collected from within apple, blackberry, japanese apricot, loquat, macadamia, olive, peach, pear, persimmon, quince and raspberry orchards located in the states of São Paulo and Minas Gerais, Southeastern Brazil. From this survey, a number of species belonging to eleven genera were identified, namely Aorolaimus nigeriensis, Discocriconemella degrissei, Helicotylenchus dihystera, H. erythrinae, H. microcephalus, H. pseudorobustus, Helicotylenchus spp., Hemicycliophora poranga, Meloidogyne hapla, M. incognita, M. javanica, Mesocriconema onoense, M. ornata, M. sphaerocephalum, M. xenoplax, Mesocriconema spp., Pratylenchus brachyurus, P. zeae, Rotylenchulus reniformis, Scutellonema brachyurus, Tylenchulus semipenetrans, Xiphinema brevicollum, X. elongatum, X. krugi, X. setariae, X. surinamense and Xiphinema spp. The most frequent genera were Helicotylenchus, Mesocriconema and Xiphinema, which occurred in 60.4, 54.4 and 30.2 % of the samples, respectively; the two most common species found were Helicotylenchus dihystera and Mesocriconema xenoplax, detected in 49.0 and 38.8 % of the samples, respectively. However, only Meloidogyne incognita and M. javanica could be associated with peach trees that were stunted or showed general symptoms of decline; in these cases, the rootstocks did not have genetic resistance to root-knot nematodes. The host suitability of several genotypes of the mentioned fruit species, plus guava, were evaluated in relation to Meloidogyne incognita race 2 and M. javanica under greenhouse conditions. The plants were individually inoculated with 5,000 nematode eggs and kept to grow in plastic bags for four months. Nematode reproductive rate was determined with basis on gall index, egg mass index and numbers of nematodes per root system and per gram of roots. Only the cultivar GF-677 of Prunus persica x P. dulcis was susceptible to both nematode species. All other genotypes were poor/resistant hosts, even that some allowed the parasites to reproduce at low rates. The pathogenicity of Meloidogyne incognita race 2 to persimmon cv. Kyoto was also studied under greenhouse conditions. After six months of the inoculation with increasing nematode population levels - 0; 160; 800; 4,000; 20,000; and 100,000 eggs/plant - a negative correlation with plant height and top dry weight values was obtained. As an intense root galling was associated with low nematode reproductive rates and some depressive effects on the plant growth, the reaction was rated as being of intolerance.

No description available.

Resumo: Dos vírus que infectam o maracujazeiro no Brasil, atualmente o Cowpea aphid borne mosaic virus (CABMV), é considerado fator limitante à cultura. Dependendo da velocidade de disseminação e idade com que as plantas são infectadas no campo, a cultura torna-se comercialmente improdutiva. O presente estudo teve como objetivo, avaliar a diversidade e a dinâmica populacional dos afídeos na região da Alta Paulista, SP e a possibilidade de transmissão do vírus pela semente. Assim, quatro locais (Leste e Oeste da cidade de Marília e Municípios de Ocauçú e Guaimbê) foram monitorados durante 24 meses com armadilhas amarelas de água do tipo Moericke. Constatou-se nas quatro regiões a predominância do gênero Aphis. Outras espécies coletadas foram Myzus persicae, Geopenphigus flocculosus, Brevicoryne brassicae, Rhopalosiphum spp, Dysaphis spp e Lipaphis erysimi. A flutuação populacional de formas aladas do gênero Aphis, caracterizou-se por apresentar maiores revoadas em maio, junho, agosto e setembro. As espécies de Aphis (A. fabae, A. gossypii, A. spiraecola) devem ser os principais vetores do CABMV na região. Plantios novos, ao lado de plantações infectadas, tornam-se infectadas em três meses. Nos testes de transmissão através de sementes, do total de 13056 semeadas oriundas de plantas doentes, germinaram 10592, e em avaliações visuais dois meses após a germinação, não foram observadas plantas sintomáticas, indicando a não transmissão pela semente. / Abstract: From the viruses were described infecting passionfruit plants in Brasil, and the Cowpea aphid borne mosaic virus (CABMV), is considered the most hazardous. Depending on the spread velocity of aphids and the age that the plants are infected, the crops doesn’t produce commercial fruits. The present study was designed to evaluate the diversity and dynamic population of aphids in the Alta Paulista, SP region and aspects of seed transmission. For this, four regions (East and West of Marília city, Guaimbê and Ocauçú) were monitored for 24 months using yellow water Moerick trap. The predominance of the genus Aphis was observed in the four evaluated areas. Other species founded in the area were: Myzus persicae, Geopenphigus flocculosus, Brevicoryne brassicae, Rhopalosiphum spp, Dysaphis spp and Lipaphis erysimi. The population curve of alate Aphis spp showed the highest frequency of flights during May, June, August and September. The Aphis spp (A. fabae, A. gossypii, A. spiraecola) probably is the most important vector of the CABMV in the region. New crops near old infected plants, were infected in three months. To evaluate properties of seed transmission, from 13056 collected from infected plants, 10592 were germinated and evaluated during two months for the presence of visual symptoms. No plants with simptoms were observed indicating no seed transmission. / Orientador: Marcelo Agenor Pavan / Coorientador: Valdir Atsushi Yuki / Banca: Renate Krause Sakate / Banca: Aloisio Costa Sampaio / Banca: Alexandre Levi R. Chaves / Banca: Hugo Kuniyuki / Doutor

Thesis (M.A. Agricultural Management (Plant Production)) -- University of Limpopo, 2015 / Tomato (Solanum lycopersicum L.) production had been ranked as the most important commodity in terms of job and wealth creation within the auspices of the National Development Plan (NDP) framework in Limpopo Province. However, soil-borne diseases including plant-parasitic nematodes preclude the successful monoculturing of this commodity and therefore inducing instability in job creation. Generally, after growing a tomato crop for one season in commercial tomato-production systems, the land is being fallowed for 3-5 years under natural grasses. Attempts are being initiated to ensure that during the 3-5 years the land be occupied by an economic alternative crop in order to level off job instability as broadly articulated in the NDP framework. The production of sweet stem sorghum (Sorghum bicolor L.) for ethanol production during the 3-5 years fallowing period could potentially be attractive to commercial tomato-producing famers. Preliminary agronomic evaluations demonstrated that sweet stem sorghum var. ndendane-X1 had attributes to fulfil the identified need. However, the degree of nematode resistance of the variety to Meloidogyne incognita race 2 and M. javanica, which are dominant in Limpopo Province, along with the compatibility of var. ndendane-X1 to phytonematicides used in tomato production had not been documented. The objectives of the study were, therefore, to determine whether sweet stem sorghum var. ndendane-X1: (1) had any degree of nematode resistance to M. incognita race 2 under both greenhouse and microplot conditions, (2) had any degree of nematode resistance to M. javanica under greenhouse conditions, and (3) would be compatible with phytonematicides used in suppression of population densities of xiv Meloidogyne species in tomato production under field conditions. In the greenhouse trials, seeds were sown in 20-cm-diameter plastic pots and each seedling inoculated with 0, 600, 1 000, 1 400, 1 800 and 2 200 eggs and second-stage juveniles (J2s) of M. incognita race 2 or M. javanica. Treatments were arranged in a randomised complete block design (RCBD), with 10 replicates (n = 60). In the microplot trial, seeds were sown in 30-cm-diameter plastic pots and buried 75% deep in a 0.30-m intra-row and 0.25-m inter-row spacing. Treatments, namely, 0, 200, 600, 1 000, 1 400, 1 800 and 2 200 J2s of M. incognita race 2 were arranged in RCBD, with 14 replications (n = 98). In a Meloidogyne-infested field trial, seeds were sown at 0.2-m inter-row and 0.3-m intra-row spacing, with treatments 0, 2, 4, 6, 8 and 10 g nemafric-BG phytonematicide/plant, arranged in RCBD, with 13 replications (n = 78). The degree of nematode resistance was measured using host-status and host-sensitivity, which provide information on reproduction of the target nematode and plant damage due to nematode infection, respectively. Nematode reproduction was measured through the reproductive factor (RF), which is a proportion of final nematode population density (Pf) to initial nematode population density (Pi), summarised as RF = Pf/Pi. In all nematode resistance trials, RF was equivalent to zero, which implied that var. ndendane-X1 was a non-host to both M. incognita race 2 and M. javanica. Additionally, in both greenhouse and microplot trials, sweet stem sorghum var. ndendane-X1 did not suffer any significant damage due to infection by Meloidogyne species. Using nematode-plant relation concepts, sweet stem sorghum var. ndendane-X1 was resistant to M. incognita race 2 and M. javanica under greenhouse and microplot conditions. Under field conditions, nemafric-BG phytonematicide reduced eggs and J2s of Meloidogyne species in root and soil samples xv by 76-85% and 24-65%, respectively, without nematode effect on plant growth, suggesting that nemafric-BG could be integrated with nematode resistance in var. ndendane-X1 to manage nematode population densities. In conclusion, pilot projects where sweet stem sorghum var. ndendane-X1 could be used during the 3-5 years fallowing period in a tomato-sweet stem sorghum crop rotation system should be established to assess: (i) the economics of the proposed cropping system, (ii) the effect of the cropping system on soil-borne diseases, including plant-parasitic nematodes, and (iii) the effect of the cropping system on soil health.

Thesis (M.S. in plant pathology)--Washington State University, December 2007. / Includes bibliographical references.

Revised 02/2015; Originally published: 2000. / The most important disease of woody dicotyledonous plants in Arizona is Phymatotrichopsis root rot (Cotton or Texas root rot) caused by a unique and widely distributed soil-borne fungus, Phymatotrichopsis omnivora. The fungus is indigenous to the alkaline, low-organic matter soils of the southwestern United States and central and northern Mexico.

Resistance (R) genes, a key factor in determining the resistance of plants, have been shown often to be highly allelic entities existing in duplicated regions of the genome. This characteristic suggests that R-gene acquisition may have arisen through frequent genetic rearrangements as a result of transient, reduced genome stability. Tabacco plants transgenic for a recombination construct exhibited reduced genome stability upon infection with a virulent pathogen (tobacco mosaic virus). The reduced genome stability manifested as an increase in recombination events in the transgene. Such increases were observed following a virulent pathogen attack. This increase in recombination was shown to be systemic and was observed prior to systemic viral movement suggesting the presence of a systemic recombination signal. Further molecular analyses revealed that specific R-gene loci experience a large frequency of rearrangements following a virulent pathogen encounter. The possible targeting of instability to R-gene regions may be controlled through epigenetic processes, in particular, DNA methylation. / xiii, 119 leaves ; 29 cm.

Commercial production of native tree and shrub species from seed can be unpredictable. Rosa corymbifera 'Laxa' is one such species of commercial importance as a rootstock, and is characteristic of the Rosaceae family. During the investigation, a standard commercial pretreatment was used to determine the unpredictable nature of this species with regard to germination. It was found that germination varied from as low as 2% in one year to a high of 63% in a subsequent year. The average germination was 26% over this period. This presents a very real dilemma to the grower with respect to meeting demand from highly unpredictable species. This dilemma is inherent in native tree production from seed. Germination became high and predictable with the addition of a compost maker, Garotta. During the same five year period the lowest germination achieved was 75% and the highest 99%. The average germination was 89%. Germination was vastly increased in percentage terms as well as becoming reliable from year to year. The benefits to the grower in using this technique are potentially great in terms of time and resources. Not only is this pretreatment highly predictable, it is safe and easy to apply, unlike alternatives such as the use of concentrated sulphuric acid to burn off the seed coat. During the pretreatment of Rosa corymbifera'Laxa' the influence of microorganisms was assessed. Microbes were found within the pretreatment and their presence was established as being required to overcome the dormancy of the seeds. Low microbial numbers and activity were found in the commercial pretreatment, resulting in low germination. High microbial numbers and activity were found in the Garotta pretreatment, resulting in high and predictable germination. Total absence of microbes was found to result in zero germination.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 4 uppsatser.