Sweet Orange Fruit Age and Inoculum Concentration Affect the Expression of Citrus Black Spot Symptoms.

Citrus black spot (CBS), caused by , affects different citrus species worldwide. CBS is mainly expressed as false melanose and hard spot symptoms. There is no consensus in the literature about the period when fruit are susceptible to infection and the length of the CBS incubation period.

First Report of Powdery Mildew on Flamboyant Tree Caused by Erysiphe quercicola in Brazil.

Flamboyant (Delonix regia) is an ornamental tree that is native to Madagascar and frequently used in gardens and parks worldwide. Powdery mildew was observed on flamboyant plants in the cities of Piracicaba and São Carlos (State of São Paulo, Brazil) during the springs of 2010 and 2011. All sampled plants (~15 plants) were affected by the disease.

Liberibacters Associated with Citrus Huanglongbing in Brazil: 'Candidatus Liberibacter asiaticus' Is Heat Tolerant, 'Ca. L. americanus' Is Heat Sensitive.

In São Paulo State, Brazil, 'Candidatus Liberibacter americanus' and 'Candidatus Liberibacter asiaticus' are associated with huanglongbing (HLB). Affected municipalities occur mainly in the central and southern regions, where the annual number of hours above 30°C is two to five times lower than that in the extreme northern and western regions. The influence of temperature on sweet orange trees infected with 'Ca.

Graft Transmission and Cultivar Reaction of Citrus to 'Candidatus Liberibacter americanus'.

Little is known about 'Candidatus Liberibacter americanus', a causal agent of huanglongbing or greening disease in Brazil, or its interaction with citrus trees. Greenhouse experiments were conducted with the objective of determining conditions favorable for transmission from field affected trees to young potted plants, to evaluate the reaction of multiple citrus species to the disease, and to determine the efficiency of pathogen propagation from individual buds. Single buds or bark pieces of various sizes or bark plus wood (budstick) that were removed from symptomatic or asymptomatic branches were used as sources of inoculum.