Revista Mexicana de Fitopatología ISSN: 0185-3309 [email protected] Sociedad Mexicana de Fitopatología, A.C. México Ávila Quezada, Graciela Dolores; Téliz Ortiz, Daniel; Mora Aguilera, Gustavo; Vaquera Huerta, Humberto; Tijerina Chávez, Leonardo Spatial and Temporal Dynamic of Scab (Sphaceloma perseae Jenk.) on Avocado (Persea americana Mill) Revista Mexicana de Fitopatología, vol. 21, núm. 2, julio-diciembre, 2003, pp. 152-160 Sociedad Mexicana de Fitopatología, A.C. Texcoco, México Available in: http://www.redalyc.org/articulo.oa?id=61221209 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative 152 / Volumen 21, Número 2, 2003 Spatial and Temporal Dynamic of Scab (Sphaceloma perseae Jenk.) on Avocado (Persea americana Mill.) Graciela Dolores Ávila-Quezada, Daniel Téliz-Ortiz, Gustavo Mora-Aguilera, Colegio de Postgraduados (CP), Instituto de Fitosanidad, km 36.5 Carr. México-Texcoco, Montecillo, Edo. de México 56230; Humberto Vaquera-Huerta, CP, Instituto de Socioeconomía, Estadística e Informática; and Leonardo Tijerina-Chávez, CP, Instituto de Recursos Naturales. Correspondence to: [email protected]; [email protected]; (current address of first author: CIAD, A.C., Av. 4 Sur 3820, Fracc. Vencedores del Desierto, Delicias, Chihuahua, México 33089). (Received: October 7, 2002 Accepted: November 19, 2002) Ávila-Quezada, G.D., Téliz-Ortiz, D., Mora-Aguilera, G., en 60 frutos por árbol. Quince frutos se seleccionaron y Vaquera-Huerta, H., and Tijerina-Chávez, L. 2003. Spatial etiquetaron en cada punto cardinal en la parte baja (1-3 m.) and temporal dynamic of scab (Sphaceloma perseae Jenk.) de cada árbol. Los datos se analizaron mediante índices de on avocado (Persea americana Mill.). Revista Mexicana de dispersión, autocorrelación espacial, y mapas geotopográficos Fitopatología 21:152-160. y de isolíneas. Se encontró agregación de árboles enfermos Abstract. Spatial and temporal dynamics of scab was studied en todas las fechas de muestreo. Al inicio de la epidemia se in a Hass avocado orchard in Michoacan, Mexico in 2000. detectaron patrones de proximidad espacial con correlación Monthly severity assessments were made in 60 trees in 60 significativa. El análisis de autocorrelación espacial mostró fruits per tree, by a logarithmic diagrammatic scale. Fifteen cuadrantes con correlación significativa en el segundo mes fruits were selected and labeled in each cardinal position in de evaluación, no se presentó autocorrelación significativa the lower part (1-3 m.) of each tree. Data were analyzed by en los siguientes meses. La enfermedad progresó en frutos indexes of dispersion, spatial lag autocorrelation, and inmaduros, conforme el fruto fue madurando, se observó una geotopographics and isopaths maps. Aggregation of diseased asíntota en la curva del progreso de la enfermedad. La trees was found for all evaluation dates. Spatial proximity enfermedad se manifestó en marzo, 30 días después de que patterns with significant correlation were detected at the la velocidad del viento incrementó, cuando la temperatura beginning of the epidemic. Spatial lags autocorrelation media mensual estuvo entre 13.7°C (feb) y 14.3°C (mar), y analysis showed quadrats with significant correlation in the la humedad relativa media mensual entre 60% (feb) y 45% second month of the evaluation, there were no significant (mar). La severidad final fue baja 0.82%, con una tasa de autocorrelations in the following months. The disease infección aparente de b-1 = 0.013. La incidencia de la progressed in immature fruits, as the fruit was ripening, an enfermedad estuvo directamente relacionada con la incidencia asymptote in the disease progress curve was observed. The del daño por trips. La incidencia de la roña alcanzó el 97% y disease appeared in March, 30 days after the wind speed la incidencia de daño por trips 90%. Ambas epidemia fueron increased, when the monthly average temperature was estadísticamente similares de acuerdo con el traslape de los between 13.7°C (Feb.) and 14.3°C (Nov.), and the relative intervalos de confianza (95%) de los parámetros c y b. humidity monthly average between 60% (Feb.) and 45% (Mar.). Final severity was low 0.82%, with apparent infection Palabras clave adicionales: Patrón espacial, epidemiología, rate b-1 = 0.013. Disease incidence was directly related with daño por trips, Sphaceloma perseae. thrips damage incidence. Scab incidence reached 97% and thrips damage incidence 90%. Both epidemics were Avocado scab injures the pericarp of young fruits of statistically similar according to the splice of the confidence susceptible avocado (Persea americana Mill.) varieties intervals (95%) of the c and b parameters. affecting their commercial value. This disease has been reported to be caused by the fungus Sphaceloma perseae Additional keywords: Spatial pattern, epidemiology, damage Jenk. (Jenkins, 1934a, 1934b; Morales, 2000), and its by thrips, Sphaceloma perseae. association with the damage by thrips, is probable (Marroquín-Pimentel, 2000). Scab appears on the first stages Resumen. La dinámica espacial y temporal de la roña se of fruit development (Vidales, 1996; Marroquín-Pimentel, estudió en un huerto de aguacate Hass en Michoacán, México 1999), causing crop losses up to 53% (Vidales, 1996). The en el 2000. Con una escala logarítmica diagramática se disease is widely spread in many countries, and its constant realizaron evaluaciones mensuales de severidad en 60 árboles presence and chemical control increase production costs Revista Mexicana de FITOPATOLOGIA/ 153 (Marroquín-Pimentel, 2000). Disease control in Michoacan, Table 1. Phenological stages of avocado (Persea americana) the number one avocado producing state in Mexico (Téliz, fruit cv. Hass based on fruit size and corresponding heat units, 2000), is carried out by continuous fungicide sprays in an orchard in Zirosto, Los Reyes, Michoacan, Mexico, in (Marroquín-Pimentel, 1999) without previous knowledge of 2000. the disease epidemiology. Some epidemiological studies in Phenological Size (mm) Size (mm) Approx. heat Michoacan have described the temporary progress of this stage wide long unitsy disease as graphical explorations and prediction models 1 3-7 4-10 316 (Vidales, 1996; Marroquín-Pimentel, 1999; Morales, 2000); 2 8-19 11-23 609 however, studies on disease spatial distribution, which are 3 20-29 24-39 870 important for management, have not been conducted. Spatial 4 30-49 40-66 1134 pattern analysis has been proposed to understand the dynamics 5 50-70 WGz 67-82 1418 of diseases (Madden, 1989), to develop more precise 6 > 70 DGz > 82 1648 sampling plans (Madden et al., 1996), for better evaluation ySince fruit set; 10ºC as base temperature. of harvest losses related to incidence and severity (Hughes, zWG = whitish green; DG = dark green. 1988), and to design and analyze experiments in more efficient ways (Hughes and Madden, 1995). There are several methods that examine the space relations of diseased plants; among trees), and disease severity (average percent of symptomatic all, indices of dispersion are solid for their strength and fruits in each tree). Severity was assessed on 60 fruits, 15 per biological basis (Campbell and Madden, 1990), but these each of the four cardinal points in the lower part of each tree methods have the disadvantage of providing little spatial (1-3 m height). Severity was measured by a logarithmic information, because they neither indicate the location of the diagrammatic scale of eight classes (Ávila-Quezada et al., sampling sites nor its relation with neighboring sites (Larkin 2001). Both fruit sides were assessed, from fruit set to et al., 1995). However, the spatial autocorrelation analysis physiological maturity. allows the determination of the intensity and direction of Damage by thrips assessment. Incidence of damage by aggregates of diseased plants, or the direction of pathogen thrips was assessed on the same fruits evaluated for scab and propagules between rows and throughout rows (Gottwald et on the same dates. al., 1989b). Isopath contour maps or lines of equal values of Temporal analysis. The monthly average of scab and damage disease severity, is another method that describes the spatial by thrips incidence and scab severity was adjusted by the Weibull model (Y = 1-exp[-(t/b)c]), where t = time, b = change of the disease over time (Minogue and Fry, 1983a, estimator of the rate parameter in the inverse form and, c = 1983b; Van der Bosch et al., 1988a, 1988b). In this study the form of the curve. This model was chose to obtain the average spatial and temporal progress of avocado scab in a commercial monthly rates of disease intensity (b-1). grove was characterized in Michoacan, Mexico, with the Spatial pattern analysis. The spatial pattern of the disease purpose of obtaining information as a support to propose was examined with Morisita´s index of dispersion (Ig) and sampling plans and efficient methods for prevention and Lloyd´s index of patchiness (LIP), as well as geotopographics controling the disease. and isopath contour maps of diseased tress and spatial lag autocorrelation analysis. In this analysis, each tree was MATERIALS AND METHODS consider as a spatial unit, and severity the analyzed variable Orchard description. An orchard with mild scab infection (Gottwald et al., 1992a). Proximity