Greasy spot of citrus, caused by Zasmidium citri-griseum (= Mycosphaerella citri), is widely distributed in the Caribbean Basin, inducing leaf spots, premature defoliation, and yield loss. Greasy spot-like symptoms were frequently observed in humid citrus-growing regions in Panama as well as in semi-arid areas in Spain, but disease aetiology was unknown. Citrus-growing areas in Panama and Spain were surveyed and isolates of Mycosphaerellaceae were obtained from citrus greasy spot lesions. A selection of isolates from Panama (n = 22) and Spain (n = 16) was assembled based on their geographical origin, citrus species, and affected tissue. The isolates were characterized based on multi-locus DNA (ITS and EF-1α) sequence analyses, morphology, growth at different temperatures, and independent pathogenicity tests on the citrus species most affected in each country. Reference isolates and sequences were also included in the analysis. Isolates from Panama were identified as Z. citri-griseum complex, and others from Spain attributed to Amycosphaerella africana. Isolates of the Z. citri-griseum complex had a significantly higher optimal growth temperature (26.8°C) than those of A. africana (19.3°C), which corresponded well with their actual biogeographical range. The isolates of the Z. citri-griseum complex from Panama induced typical greasy spot symptoms in ‘Valencia’ sweet orange plants and the inoculated fungi were reisolated. No symptoms were observed in plants of the ‘Ortanique’ tangor inoculated with A. africana. These results demonstrate the presence of citrus greasy spot, caused by Z. citri-griseum complex, in Panama whereas A. africana was associated with greasy spot-like symptoms in Spain.

The etiology and distribution of foliar fungal diseases of citrus in Panama were studied in this work. In total, 85 orchards spanning six provinces were surveyed from 2011 to 2013. Symptoms observed ranged from yellow-brown spots on the abaxial surface of the leaves, brown lesions on petals, twig dieback as well as raised pustules on leaves and fruit. Representative fungal isolates obtained from symptomatic plant tissues were identified based on morphological characteristics, sequences of the ITS, EF1-α and TUB2 loci, and pathogenicity tests. Citrus greasy spot, caused by Zasmidium citri-griseum (=Mycosphaerella citri), was identified as the most prevalent fungal disease of citrus in Panama, confirmed in 68.2% of the orchards. Postbloom fruit drop (PFD) and Key lime anthracnose, caused by Colletotrichum acutatum sensu lato, and melanose, caused by Diaporthe citri, were identified for the first time in Panama. Citrus scab, caused by Elsinoë fawcettii, was also detected. Greasy spot was found mainly in areas with a tropical monsoon climate (Am) and to a lesser extent in tropical savanna (Aw) and tropical rainforest (Af) climates. Melanose, PFD and citrus scab were detected only in areas with Am and Af climates. Information about the etiology and geographic distribution of fungal diseases in Panama will help to design effective strategies for disease management.

Citrus greasy spot, caused by Zasmidium citri-griseum ( = Mycosphaerella citri) is the most prevalent fungal disease of citrus in Panama, causing premature defoliation and yield reduction. Fungicide applications are generally needed for the control of greasy spot. In this study, the sensitivity to fenbuconazole of 34 isolates of Z. citri-griseum from Panama was determined by calculating the effective concentration needed to reduce mycelial growth by 50% (EC50). Two field trials were conducted from 2011 to 2013, to evaluate the efficacy of fenbuconazole to reduce disease severity and yield loss. The EC50 values for fenbuconazole ranged from 0.09 to 7.62 μg mL−1, with a mean EC50 value of 2.66 ± 0.36 SE μg mL−1 for mycelial growth. These data can be used for monitoring sensitivity shifts in Z. citri-griseum to fenbuconazole and reduce risk of fungicide resistance in Panama. In the field trials, sprays with fenbuconazole significantly reduced (p < 0.0001) the severity of greasy spot on leaves compared with the non-treated control. Greater disease control was obtained when three sprays of fenbuconazole were applied instead of one. Nevertheless, no significant differences (p > 0.05) were detected in yield.

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El aguacate (Persea americana Mill), por sus cualidades nutricionales, ha incrementado su uso en Panamá. Sin embargo, los árboles de aguacate se han visto afectados por la destrucción de tejidos en el haz y el envés de las hojas de las plantas dañadas. Esto se refleja en áreas cloróticas visibles en el haz, y las hojas maduras son las preferidas por el insecto para su alimentación. El propósito de la investigación fue determinar el agente causal del daño en árboles de aguacate. Se realizó un muestreo en 28 localidades en la península de Azuero, Panamá, durante el periodo de 2017 a 2019. Se cita por primera vez al insecto Pseudacysta perseae (Heidemann, 1908) (Hemiptera: Tingidae) como plaga del aguacate en Panamá y se determina su distribución en la península de Azuero.