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Spectroscopy has become one of the most used non-invasive methods to detect plant diseases before symptoms are visible. In this study it was possible to characterize the spectral variation in leaves of Solanum lycopersicum L. infected with Fusarium oxysporum during the incubation period. It was also possible to identify the relevant specific wavelengths in the range of 380–1000 nm that can be used as spectral signatures for the detection and discrimination of vascular wilt in S. lycopersicum. It was observed that inoculated tomato plants increased their reflectance in the visible range (Vis) and decreased slowly in the near infrared range (NIR) measured during incubation, showing marked differences with plants subjected to water stress in the Vis/NIR. Additionally, three ranges were found in the spectrum related to infection by F. oxysporum (510–520 nm, 650–670 nm, 700–750 nm). Linear discriminant models on spectral reflectance data were able to differentiate between tomato varieties inoculated with F. oxysporum from healthy ones with accuracies higher than 70% 9 days after inoculation. The results showed the potential of reflectance spectroscopy to discriminate plants inoculated with F. oxysporum from healthy ones as well as those subjected to water stress in the incubation period of the disease.

Bacterial wilt is one of the most important vascular diseases that generate high worldwide losses. The main strategy to control it involves early detection of infected plants that mitigate its spread in the field. This research characterized the spectral response of healthy plants, infected with Ralstonia solanacearum E.F. Smith race 2 and subjected to water stress, in two banana cultivars by spectroscopy reflectance. The spectral data were used to detect vascular wilt during the incubation period of the disease in Gros Michel and Cavendish banana cultivars. The reflectance data were collected from the leaves using a portable spectrometer. Both varieties of healthy plants showed a typical low reflectance in the visible range, with a peak of green of around 12% in Williams and 5% in Gros Michel. In the measured infrared range, the two varieties presented values between 60 and 70% in the latest days post-infection measurements, decreasing to ~ 50% after 12 dpi. The results obtained indicate that plants infected with R. solanacearum have no initial increase in reflectance in the visible (Vis) range, whereas decrease rapidly after 6 dpi in the 700–1000 nm range. This methodology identifies three wavelengths (710, 770, and 965 nm) that allow differentiation between ill and healthy plants after 6 days post-inoculation, with a percentage of correct classification that ranges from 96 to 100%. The spectral response characterization in healthy plants and those subjected to various types of stress is a fundamental input for the development of early disease detection systems based on spectroscopy techniques.

There is evidence that all plants coexist with endophytes, indicating a fundamental role that is unknown. The objective was to evaluate the biotechnological potential of endophytes from Passiflora edulis f. edulis in two aspects: as a plant growth promoter and as a control for the pathogen Fusarium oxysporum. An in vitro phase was used in which the antifungal activity in a dual culture was studied, where the UNE075 and UNE004 fungi inhibited the radial growth of the pathogen by up to 67.63% and 63.89%, respectively. Additionally, higher inhibition percentages were seen with UNE075 (33.78%) and UNE098 (32.32%) because of the action of volatile organic compounds on F. oxysporum. Likewise, the production of indoleacetic acid (IAA) as a growth-promoting compound was quantified, with notable results with UNE017 (11.99 [micro]g/mL) and UNE022 (7.59 [micro]g/mL). The capacity of the fungi to solubilize phosphorus was determined. UNE098 generated the greatest solubilization by reducing the pH culture medium. In the in vivo phase in the greenhouse, the effect of inoculation with endophytes on the growth of P. edulis f. edulis plants was evaluated. Biomass accumulation and leaf area were determined, where UNE067 stood out because of its effect on fresh weight, total dry weight. In general, the evaluated endophytes have biotechnological potential for use in organic crop management programs and for biological control.

Fusarium wilt is the greatest threat to Musaceae production worldwide; remote sensing techniques based on reflectance spectroscopy are proposed for its detection. The spectral response of leaves of healthy plants and plants infected with Fusarium oxysporum f. sp. cubense Race1 (Foc R1) from two banana cultivars during the incubation period of the disease were characterized. Spectra of 400-1000 nm were measured in healthy and Foc R1-infected plants on Gros Michel (GM: susceptible) and Williams (W: resistant) bananas with an Ocean Optics HR2000+ portable spectrometer. Similar general patterns were obtained in the spectra for both cultivars for the Vis, around 25% in the green region, but, as the foliar development progressed, reflectance decreased throughout the entire spectral range, close to 12.5% (green region of Vis range) on leaf 4 of both. Four wavelengths were discriminant for the healthy plants in the cultivars. Additionally, reflectance increased in the infected plants in the incubation period throughout the range, decreasing rapidly once the first visible symptoms appeared. The results suggested that an increase in reflectance at discriminating wavelengths can be used to diagnose diseased plants in the asymptomatic period, and a rapid decrease in this suggests the onset of the symptomatic phase.

La evidencia muestra que todas las plantas conviven con endófitos, lo cual indica que desempeñan un papel fundamental aún por dilucidar. El objetivo de este trabajo fue evaluar el potencial biotecnológico de endófitos provenientes de Passiflora edulis f. edulis, en dos aspectos:  como acción promotora de crecimiento vegetal y como controladores del patógeno Fusarium oxysporum. Se empleó una fase in vitro en la que se estudió la actividad antifúngica en cultivo dual, encontrándose que los hongos UNE075 y UNE004 lograron inhibir el crecimiento radial del patógeno hasta en un 67,63 % y 63,89 %, respectivamente. Adicionalmente, por acción de compuestos orgánicos volátiles sobre F. oxysporum, se observaron que los mayores porcentajes de inhibición fueron dados por los hongos UNE075 (33,78 %) y UNE098 (32,32 %). Asimismo, se cuantificó la producción de Acido indolacético (AIA) como compuesto promotor del crecimiento, destacándose UNE017 (11,99 µg/mL) y UNE022 (7,59 µg/mL). Por otra parte, se determinó la capacidad de los hongos para solubilizar el fósforo. UNE098 fue la cepa que generó mayor solubilización mediante la reducción del pH en el medio de cultivo.  En la fase in vivo en invernadero se evaluó el efecto de la inoculación con endófitos sobre el crecimiento de plantas de gulupa, se determinó la acumulación de biomasa, sobresaliendo UNE067 por su efecto sobre el peso fresco, el peso seco total y el área foliar. En general, se observó que los endófitos evaluados tienen potencial biotecnológico para uso en programas de manejo del cultivo orgánico y para control biológico.

Se reporta por primera vez la presencia de Anagyrus kamali Moursi y Gyranusoidea indica Shafee, Alam y Agarwal (Hymenoptera: Encyrtidae), parasitoides de la cochinilla rosada del hibisco (CRH), Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae) en la Isla de San Andrés, Colombia. Se proveen notas breves para diferenciar las dos especies de parasitoides.   

RESUMEN Mycosphaerella fijiensis M. Morelet, es uno de los agentes causales del “complejo Sigatoka”, el cual, es la enfermedad más destructiva en los cultivos de banano y plátano. En el presente trabajo, se modeló espacialmente mediante técnicas geoestatísticas, la hoja más joven manchada (HMJM), como variable biológica indicadora del estado de severidad de la enfermedad en la plantación, con el objetivo de determinar su estructura y categoría de dependencia espacial. La HMJM se evaluó en las semanas 43, 45, 46 y 47 de 2005, em 71 plantas de banano cv. Gran Enano con emisión reciente de su inflorescencia, ubicadas en las intersecciones de una malla irregular, con una distancia mínima entre pares de plantas de 21 m y una distancia máxima de 1077 m, en una finca bananera situada en el municipio de Carepa (Antioquia), zona de vida bosque húmedo tropical (bh-T). La variable presentó un comportamiento anisotrópico para las semanas 45, 46 y 47; éste, se describió a partir de un modelo gaussiano en cada una de las semanas, con un rango de dependencia espacial decreciente de 673.25, 345.53 y 296.36 m, respectivamente, el cual diverge de los modelos reportados en otras investigaciones en patosistemas similares. Los modelos que se ajustaron para las semanas 45 y 47, evidenciaron fuerte dependencia espacial; el modelo de la semana 46, moderada dependencia espacial y el modelo de la semana 43, nula dependencia espacial. RESUMO Mycosphaerella fijiensis M. Moleret é um dos agentes causadores do “complexo Sigatoka”, o qual é a doença mais destrutiva na cultura da banana e do plátano. No presente trabalho, foi modelada espacialmente, mediante técnicas geoestadisticas, a folha mais jovem manchada (FMJM) como a variável biológica indicadora da severidade da doença na cultura, com o objetivo de determinar a sua estrutura e categoria de dependência espacial. A FMJM foi avaliada nas semanas 43, 45, 46 e 47 de 2005, sobre 71 plantas de bananeira cultivar Gran Enano com emissão recente da inflorescência. Demarcou-se, no campo, uma malha irregular, com uma distância mínima entre pares de plantas de 21 m e uma distância máxima de 1077 m, numa fazenda, localizada no Município de Carepa (Antioquia), região de floresta úmida tropical (fu-T). A variável apresentou um comportamento anisotrópico para as semanas 45, 46 e 47, foi descrito a partir de um modelo Gaussiano em cada uma das semanas, com uma gama de dependência espacial decrescente de 673.25, 345.53 y 296.36 m, respectivamente, o que diverge dos modelos reportados em outras pesquisas, em patossistemas similares. Os modelos que se ajustaram para as semanas 45 e 47, mostraram forte dependência espacial; o modelo da semana 46, moderada dependência espacial e o modelo da semana 43, sem dependência espacial.

Se reporta por primera vez la presencia de Anagyrus kamali Moursi y Gyranusoidea indica Shafee, Alam y Agarwal (Hymenoptera: Encyrtidae), parasitoides de la cochinilla rosada del hibisco (CRH), Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae) en la Isla de San Andrés, Colombia. Se proveen notas breves para diferenciar las dos especies de parasitoides.  First report of Anagyrus kamali Moursi and Gyranusoidea indica Shafee, Alam and Agarwal (Hymenoptera: Encyrtidae), parasitoids of the pink hibiscus mealybug Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae), on San Andres Island, Colombia Here we report for the first time the presence of Anagyrus kamali Moursi and Gyranusoidea indica Shafee, Alam and Agarwal (Hymenoptera: Encyrtidae), parasitoids of the pink hibiscus mealybug (PHM), Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae), on San Andres Island, Colombia. Brief notes are provided to allow differentiation of the two parasitoid species. 

Se reporta por primera vez la presencia de Anagyrus kamali Moursi y Gyranusoidea indica Shafee, Alam y Agarwal (Hymenoptera: Encyrtidae), parasitoides de la cochinilla rosada del hibisco (CRH), Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae) en la Isla de San Andrés, Colombia. Se proveen notas breves para diferenciar las dos especies de parasitoides.