Weeds harbor Fusarium species that cause malformation disease of economically important trees in western Mexico

Mango malformation disease (MMD) caused by Fusarium spp. is an important limiting factor in most production areas worldwide. Fusarium mexicanum and F. pseudocircinatum have been reported as causing MMD in Mexico. These two pathogens also cause a similar disease in Swietenia macrophylla (big-leaf mahogany malformation disease or BLMMD) in central western Mexico, while F. pseudocircinatum was recently reported as causing malformation disease in Tabebuia rosea (rosy trumpet) in the same region. These studies suggest that additional plant species, including weeds, might be hosts of these pathogens. The role that weed hosts might have in the disease cycle is unknown. The objectives of this work were to recover Fusarium isolates from understory vegetation in mango orchards with MMD, identify the Fusarium isolates using DNA sequence data, and determine if F. mexicanum is capable of inducing disease in the weedy legume Senna uniflora (oneleaf senna). Additional objectives in this work were to compare Fusarium isolates recovered from weeds and mango trees in the same orchards, by characterizing their phylogenetic relationships, assessing in vitro production of mycotoxins, and identifying their mating type idiomorph. A total of 59 Fusarium isolates from five species complexes were recovered from apical and lateral buds from four weed species. Two of the species within the F. fujikuroi species complex are known to cause MMD in Mexico. Trichothecene production was detected in five isolates, including F. sulawense and F. irregulare in the F. incarnatum-equiseti species complex and F. boothii in the F. sambucinum species complex. Both mating types were present among mango and weed isolates. This is the first report of herbaceous hosts harboring Fusarium species that cause mango malformation in Mexico. The information provided should prove valuable for further study of the epidemiological role of weeds in MMD, and help manage the disease.

Sistemas silvopastoriles: mitigación de gases de efecto invernadero, bosque seco tropical - Colombia

Introducción. Los sistemas silvopastoriles (SSP) juegan un papel destacado en la captura de carbono en el suelo y mitigación de gases de efecto invernadero. Objetivo. Cuantificar los servicios ecosistémicos ofrecidos por cuatro SSP en comparación con una pradera con gramíneas, en el valle medio del río Sinú, en Colombia. Materiales y métodos. Se midieron los flujos de metano y óxido nitroso mediante el uso de cámaras cerradas, durante un periodo de ocho semanas consecutivas (septiembre a noviembre, 2013). También se midió el carbono orgánico en el suelo a dos profundidades (0-5 y 5–15 cm), por el método de combustión y se determinaron variables fisicoquímicas del suelo. El diseño correspondió a bloques completos al azar con cinco tratamientos y tres repeticiones. Los tratamientos correspondieron a cuatro sistemas silvopastoriles conformados por diferentes componentes arbóreos: Tectona grandis (SSP1), Tabebuia rosea (SSP2), Pachira quinata (SSP3) y Acacia mangium (SSP4), en comparación a una pradera con solo gramínea (Megathyrsus maximus cv. Mombasa). Resultados. Los mayores contenidos de materia orgánica, fósforo y calcio se registraron dentro de los SSP. El carbono orgánico en el suelo (COS) fue mayor dentro de los SSP (39,43±15,34 t C ha-1) en comparación con la pradera (33,43±17,63 t C ha-1). Los SSP se comportaron la mayor parte del tiempo como sumideros de metano, al inmovilizar en promedio -460±0,42 µg CH4 m-2 h-1. Las menores tasas de emisión de óxido nitroso se evidenciaron dentro de los sistemas SSP1 y SSP2 (460±0,60 y 620±1,19 µg N2O m-2 h-1, respectivamente). Conclusión. La implementación de SSP contribuye en la disminución de procesos degradativos (físicos y químicos) del suelo, al aumento de las reservas de carbono del suelo y, por consiguiente, son una estrategia de mitigación de gases de efecto invernadero en los sistemas ganaderos.

Evaluación de plantaciones de Tabebuia rosea (Bertol.) DC. y Swietenia macrophylla King en el Centro-Occidente de México

El éxito en el establecimiento y desarrollo de las plantaciones forestales depende de que las especies sean las adecuadas para las condiciones edafoclimáticas de los sitios de plantación. El objetivo de este estudio fue evaluar la supervivencia y crecimiento de plantaciones de 12 años con Tabebuia rosea (rosa morada) y Swietenia macrophylla (caoba), en cuatro localidades de Jalisco, Colima y Nayarit. Se determinó la diferencia estadística entre localidades con análisis de varianza y prueba de comparación de medias de Tukey, para las variables supervivencia, diámetro normal, altura, volumen y sus incrementos medios anuales. Los resultados indican que la supervivencia de T. rosea varió de 35 a 82 % y en S. macrophylla entre 79 y 83 %. Hubo diferencias significativas (p < 0.05) entre localidades en las variables de crecimiento. T. rosea destacó por su diámetro normal, altura y volumen en la localidad IV (Costa de Jalisco), mientras que S. macrophylla tuvo un mejor desarrollo en diámetro normal y volumen en la localidad II (El Verdineño); posiblemente, por el efecto del tipo de suelo en estos sitios. Los resultados sugieren que lugares bajo condiciones edafoclimáticas similares a esas localidades son aptos para el establecimiento de plantaciones forestales con ambas especies tropicales en el Centro-Occidente de México.

Cydianerus latruncularius (Coleoptera: Curculionidae) damaging trumpet trees leaves (Handroanthus spp., Bignoniaceae) in Brasília, Brazil

Cydianerus latruncularius Perty (Coleoptera: Curculionidae) were observed associated with trumpet trees (Handroanthus spp.) in Brasília, Brazil, in 2019. To contribute with information about their habits and damage, 15 trees (Handroanthus impetiginosus = 7, H. roseoalbus = 4, and Tabebuia rosea = 4) were evaluated and 31 individuals of C. latruncularius were captured, often found within or close to leaf rolls caused by the psyllid Trioza tabebuiae Burckhardt & Santana (Hemiptera: Triozidae). The damage caused by C. latruncularius consists of irregular injuries at the leaves’ edges. This is the first report of this beetle occurring on trumpet trees.

Malformation Disease in Tabebuia rosea (Rosy Trumpet) Caused by Fusarium pseudocircinatum in Mexico

Tabebuia rosea (rosy trumpet) is an economically important Neotropical tree in Mexico that is highly valued for the quality of its wood, which is used for furniture, crafts, and packing, and for its use as an ornamental and shade tree in parks and gardens. During surveys conducted in the lower Balsas River Basin region in the states of Guerrero and Michoacán, symptoms of floral malformation were detected in T. rosea trees. The main objectives of this study were to describe this new disease, to determine its causal agent, and to identify it using DNA sequence data. A second set of objectives was to analyze the phylogenetic relationship of the causal agent to Fusarium associated with Swietenia macrophylla trees with malformation surveyed in the same region, and to compare mycotoxin production and the mating type idiomorphs of fusaria recovered from T. rosea and S. macrophylla. Tabebuia rosea showed malformed inflorescences with multiple, tightly curled shoots, and shortened internodes. A total of 31 Fusarium isolates recovered from symptomatic T. rosea (N = 20) and S. macrophylla (N = 11) trees were identified by molecular analysis as F. pseudocircinatum. Pathogenicity tests showed that isolates of F. pseudocircinatum recovered from T. rosea, induced malformation in inoculated T. rosea seedlings. Eighteen F. pseudocircinatum isolates were tested for their ability to produce mycotoxins and other secondary metabolites. Moniliformin, fusaric acid, bikaverin, beauvericin, aurofusarin and 8-O-methylbostrycoidin were produced by at least 1 strain of the 18 isolates tested. A multiplex PCR assay for mating type idiomorph revealed that 22 F. pseudocircinatum isolates were MAT1-1 and 9 were MAT1-2. Here we report a new disease of T. rosea in Mexico caused by F. pseudocircinatum.

Ecuaciones alométricas, biomasa y carbono en plantaciones forestales tropicales en la costa de Jalisco

La estimación de la biomasa aérea es una herramienta clave para determinar el potencial de almacenamiento de carbono de un taxón. En el occidente de México, se han establecido plantaciones forestales con especies tropicales, pero se desconoce el contenido y distribución de biomasa aérea seca, así como el almacenamiento de carbono. En este estudio se estimaron estos en plantaciones de 12 años de edad con los taxa nativos: Enterolobium cyclocarpum y Tabebuia rosea, e introducidas: Gmelina arborea y Tectona grandis, ubicadas en la Costa de Jalisco. Además, se ajustaron modelos lineales, potenciales y polinomiales de la relación de la biomasa aérea seca con respecto al diámetro normal. En las cuatro especies, la mayor proporción de la biomasa aérea seca (58-67 %) se obtuvo en el fuste. El diámetro normal resultó ser un buen predictor de la biomasa aérea seca total de las especies estudiadas, de las cuales dos se ajustaron a modelos potenciales y dos a modelos polinomiales, con los cuales es posible estimar dicho atributo de forma rápida, sencilla y a menor costo en comparación al método destructivo. T. grandis, G. arborea y E. cyclocarpum presentaron tanto el contenido de biomasa más alto (161 kg ha-1, 134 kg ha-1 y 130 kg ha-1), como el mayor potencial de almacenamiento de carbono: 144.6 Mg ha-1, 120.8 Mg ha-1 y 117.5 Mg ha-1, respectivamente. Las plantaciones forestales con estas especies pueden contribuir a la captura de carbono y mitigación del calentamiento global a largo plazo.

Tabebuia rosea (pink poui).

T. rosea is a medium to large tree attaining a height of 28-37 m with a d.b.h. of 50-100 cm. It is widespread from Mexico to Peru, Venezuela and Ecuador. T. rosea is a very important species in these regions, its timber is valuable and of good quality, it is excellent to work and has an attractive finish. It shows good performance in forestry plantations and enrichment planting trials, and also has high potential to be used in afforestation projects. This species is also used in agroforestry (e.g. alley cropping), as a live fence, as a shade tree and as an ornamental. It is the national tree of El Salvador.

Photosynthetic plasticity of a tropical tree species, Tabebuia rosea, in response to elevated temperature and [CO2]

Atmospheric and climate change will expose tropical forests to conditions they have not experienced in millions of years. To better understand the consequences of this change we studied photosynthetic acclimation of the neotropical tree species Tabebuia rosea to combined 4°C warming and twice-ambient (800 ppm) CO. We measured temperature responses of the maximum rates of ribulose 1,5-bisphosphate carboxylation (V), photosynthetic electron transport (J), net photosynthesis (P), and stomatal conductance (gs), and fitted the data using a probabilistic Bayesian approach. To evaluate short-term acclimation plants were then switched between treatment and control conditions and re-measured after 1–2 weeks. Consistent with acclimation, the optimum temperatures (T) for V, J and P were 1–5°C higher in treatment than in control plants, while photosynthetic capacity (V, J, and P at T) was 8–25% lower. Likewise, moving control plants to treatment conditions moderately increased temperature optima and decreased photosynthetic capacity. Stomatal density and sensitivity to leaf-to-air vapor pressure deficit were not affected by growth conditions, and treatment plants did not exhibit stronger stomatal limitations. Collectively, these results illustrate the strong photosynthetic plasticity of this tropical tree species as even fully-developed leaves of saplings transferred to extreme conditions partially acclimated.