Two hundred and twenty-five Diaporthe isolates were collected from 2005 to 2019 in almond orchards showing twig cankers and shoot blight symptoms in five different regions across Spain. Multilocus DNA sequence analysis with five loci (ITS, tub, tef-1α, cal and his), allowed the identification of four known Diaporthe species, namely: D. amygdali, D. eres, D. foeniculina and D. phaseolorum. Moreover, a novel phylogenetic species, D. mediterranea, was described. Diaporthe amygdali was the most prevalent species, due to the largest number of isolates (85.3%) obtained from all sampled regions. The second most frequent species was D. foeniculina (10.2%), followed by D. mediterranea (3.6%), D. eres and D. phaseolorum, each with only one isolate. Pathogenicity tests were performed using one-year-old almond twigs cv. Vayro and representative isolates of the different species. Except for D. foeniculina and D. phaseolorum, all Diaporthe species were able to cause lesions significantly different from those developed on the uninoculated controls. Diaporthe mediterranea caused the most severe symptoms. These results confirm D. amygdali as a key pathogen of almonds in Spain. Moreover, the new species, D. mediterranea, should also be considered as a potential important causal agent of twig cankers and shoot blight on this crop.
The process of invasion of the fruit surface by three species of armored scale insects [Lepidosaphes beckii (Newman), Parlatoria pergandii Comstock and Aonidiella aurantii (Maskell)], was studied in citrus orchards in Vale`ncia, Spain. Three periods of intense crawler migration were detected annually for L. beckii and P. pergandii. Abundance of crawlers increased throughout the year and they moved outwards in the tree canopy. The fruit was continuously invaded during the period of fruit growth, starting at a very early stage of fruit development, by crawlers of the first generation of all the three species. Differences in fruit invasion and settling behaviour were found between the three species. First-generation crawlers tended to settle under the fruit calyx in L. beckii and P. pergandii, and on the exposed fruit surface in A. aurantii. During the second generation, most A. aurantii scales originated from reproducing females already settled on the fruit, whereas in L. beckii and P. pergandii new scales came preferentially from other tree substrates or from females settled under the fruit calyx. These findings suggest changes to optimize the timing of chemical sprays for controlling the scales.
The mites Amblyseius cucumeris and A. barkeri are used in biological control commercial program against Frankliniella occidentalis. The diapause influence is essential to know the efficacy in climatic extreme conditions. The experiments were designed to verify the following: a) the effect of night temperatures on diapause induction; b) the effect of continuous darkness and low temperatures on diapause induction. In the first case A cucumeris at 12°C temperature in ecotophase diapause incidence was 100%. A. barkeri was not affected by 3 night temperatures. In the second case it could be seen that the test conditions did not induce diapause in either case.
Loquat scab caused by Fusicladium eriobotryae is the main disease affecting the loquat crop. The fungus can infect leaves and fruits, reducing the marketable quality of the latter. The efficacy of 13 fungicides against F. eriobotryae was evaluated in vitro by testing their effect on mycelial growth and conidial germination. Boscalid, chlorothalonil, didecyldimethyl ammonium chloride, and pyraclostrobin were able to reduce both conidial germination and mycelial growth of F. eriobotryae. Moreover, a growth chamber experiment was conducted to determine the pre- and post-infection activity of five selected fungicides. Difenoconazole and pyraclostrobin applications resulted in relative disease severity (RDS) values lower than 5%, even when applied 7 days before or after the inoculation. Boscalid and mancozeb applied before F. eriobotryae inoculation resulted in RDS values lower than 15%, whereas values up to 20% of RDS were obtained with copper oxychloride. Results indicate that the fungicides currently recommended in southeastern Spain against loquat scab provide adequate disease control, and new active ingredients could be added to the present management strategies. Accepted 7 May 2014. Published 27 July 2014.
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