Conditions affecting germination and growth of Fusarium mangiferae, causal agent of mango malformation disease, were studied in vitro. Both conidial germination and colony growth required temperatures >5 degrees C and reached a peak at 28 and 25 degrees C, respectively. A minimum 2-h wetness period was required for conidial germination, reaching a peak after 8 h of wetness. High incidence of fungal colonization in buds, predominantly the apical buds, was detected compared with inoculated leaves. The pathogen was detected in the roots of inoculated soil 19 weeks postinoculation but not in aboveground parts of the plants, and symptoms of the disease were not observed, either. Dry, malformed inflorescence debris serving as a source of inoculum caused significantly higher colonization (52 and 20%) of inoculated buds, compared with that (0%) of the untreated controls. Incidence of sampled leaf disks bearing propagules of F. mangiferae from an infected orchard peaked in June and July and decreased during the following months, whereas airborne infections on 1-month-old branches was the highest in May and June, corresponding with inoculum availability released from infected inflorescences. Colonization pattern, determined in naturally infected vegetative and woody branches, was significantly higher in node sections than in the internode sections. This study sheds light on infection dynamics, colonization patters, and the disease cycle of F. mangiferae in mango.

Holland, R. M., Christiano, R. S. C, Gamliel-Atinsky, E., and Scherni. H. 2014. Distribution of Xylella fastidiosa in blueberry stem and root sections in relation to disease severity in the field. Plant

Inoculum availability and conidial dispersal patterns of Fusarium mangiferae, causal agent of mango malformation disease, were studied during 2006 and 2007 in an experimental orchard. The spatial pattern of primary infections in a heavily infected commercial mango orchard corresponded with a typical dispersal pattern caused by airborne propagules. Malformed inflorescences were first observed in mid-March, gradually increased, reaching a peak in May, and declined to negligible levels in August. The sporulation capacity of the malformed inflorescences was evaluated during three consecutive months. Significantly higher numbers of conidia per gram of malformed inflorescence were detected in May and June than in April. Annual conidial dissemination patterns were evaluated by active and passive trapping of conidia. A peak in trapped airborne conidia was detected in May and June for both years. The daily pattern of conidial dispersal was not associated with a specifically discernable time of day, and an exponential correlation was determined between mean relative humidity (RH) and mean number of trapped conidia. Higher numbers of conidia were trapped when RH values were low (<55%). This is the first detailed report on airborne dispersal of F. mangiferae, serving as the primary means of inoculum spread.

A considerable number of plant feeding mites representing different families such as Acaridae, Siteroptidae, Tydeidae, and Tarsonemidae interact with plant pathogenic fungi. While species within the Eriophyoidea appear to be the most common phytophagous mites vectoring virus diseases, little is known of their role in fungal pathogen epidemiology. In the present article, we present two studies on eriophyoid-fungal relationships. The first focusing on the association between Aceria mangiferae and the fungal pathogen Fusarium mangiferae in mango is presented as a case study. The second, as the research is still in a preliminary phase, reports on quantitative and descriptive associations between the cereal rust mite Abacarus hystrix and rusts caused by Puccinia spp. Mango bud tissue colonized with F. mangiferae, and wheat and quackgrass leaves colonized with Puccinia spp., supported significantly higher populations of eriophyoid mites. Both mite species were observed bearing the spores of the respective pathogens on their body integument. Aceria mangiferae vectored the pathogen's spores into the bud, the sole port of entry for the fungal pathogen and the frequency and severity of fungal infection increased in the presence of A. mangiferae. While it appears that eriophyoids are playing a role in fungal epidemiology, clearly further research is needed to enhance our understanding of direct and indirect (plant mediated) interactions between plant pathogens and eriophyoid mites in different plant-pathogen systems.