ITEMS FROM MEXICO

 

INIFAP, CAMPO EXPERIMENTAL VALLE DEL YAQUI

Apdo. Postal 515, km 12 Norman E. Borlaug, entre 800 y 900, Valle del Yaqui, Cd. Obregón, Sonora, México CP 85000,

INIFAP, CAMPO EXPERIMENTAL CENTRO-ALTOS DE JALISCO

km 8 Carr. Tepatitlan-Lagos de Moreno, Tepatitlán, Jalisco, México CP 47600.

AND CIMMYT - INTERNATIONAL MAIZE AND WHEAT IMPROVEMENT CENTRE

Evaluation of high quality elite genotypes of bread wheat for resistance to Karnal bunt. [p.81-83]

Guillermo Fuentes-Dávila and Javier Ireta-Moreno.

Introduction. Karnal bunt occurs naturally on bread wheat (Mitra 1931), durum wheat, and triticale (Agarwal et al. 1977). Infected grains are in general partially affected, but sometimes completely infected grains can also be found (Bedi et al. 1949; Chona 1961; Mitra 1935). The susceptibility of bread wheat to Karnal bunt has been well documented (Fuentes-Dávila et al. 1992, 1993) reaching infection levels greater than 50 % under artificial inoculations; therefore, it is important to continue evaluating new advanced lines and cultivars, as a measure to avoid economic problems, which could derive from the release of susceptible cultivar for commercial use.

Materials and methods. Seventy, high-quality, elite bread wheat genotypes were evaluated for resistance to Karnal bunt during the agricultural season autumn-winter 2001-02 in the Yaqui valley, Sonora, Mexico. Planting dates were 8 and 20 November, 2001, using approximately 10 g of seed on 1-m beds with two rows. A mist-irrigation system was used 3 to 5 times a day during 15 each time, to provide high relative humidity in the experimental area. Inoculations were made by injecting 1 ml of an allantoid sporidial suspension (10,000/ml) during the boot stage on 10 heads/genotype. Harvest was done manually, and the counting of healthy and infected grains was done by visual inspection. Genotypes evaluated were various advanced wheat lines generated by the CIMMYT-INIFAP collaborative breeding program.

Results and discussion. The range of infection for the first planting date was 0 to 65.48 %, with and average of 27.27 %; within this group, only two lines showed infection levels below 5 % (Figure 1). The range of infection for the second planting date was 1.59 to 75.79 %, with and average of 34.10 %; three lines showed infection levels below 5 %. Only four sister lines showed consistently infection levels below 6.91 % (SKAUZ/2*STAR, 3KBY; 4KBY; 5KBY; 8KBY) (Table 1) (lines that show less than 5 % infection are considered as resistant (Fuentes-Dávila and Rajaram 1994). The susceptible check WL-711 had an infection level of 86.09 %. In general, the group of lines evaluated showed a high level of infection, reaching 75.79 % (BOW//BUC/BUL/3/WEAVER/4/STAR, Table 2). These results indicate the predominant susceptible reaction in this particular group of bread wheats, and the difficulty to generate wheats that combine quality, yield, resistance to leaf rust and to Karnal bunt. Although bread wheat cultivars Arivechi M92 (Camacho-Casas et al. 1992) and INIFAP M97 and TOBARITO M97 (Camacho-Casas et al. 1998) partly were released because they are resistant to Karnal bunt, they are not being cultivated commercially, because they do not comply with the quality requirements by the milling industry. Joint efforts between INIFAP and CIMMYT continue to assure acceptable resistance levels to Karnal bunt in the new and promising lines of bread wheat so that a commercial and viable crop can be produced for the farmers in northwest Mexico, and that also complies with the industry's quality standards.

References.

• Agarwal VK, Verma HS, and Khetarpal RK. 1977. Occurrence of partial bunt on triticale. Plant Prot Bull 25:210-211.
  Bedi SKS, Sikka MR, and Mundkur BB. 1949. Transmission of wheat bunt due to Neovossia indica (Mitra) Mundkur. Ind Phytopathol 2:20-26.
• Camacho-Casas MA, Félix-Valencia P, Huerta-Espino J, Salazar-Gómez JM, and Salazar-Huerta FJ. 1993. Baviácora M92 y Arivechi M92: nuevas variedades de trigo harinero. Folleto Técnico Número 20. Secretaría de Agricultura y Recursos Hidráulicos. Instituto Nacional de Investigaciones Agropecuarias. Centro de Investigación Regional del Noroeste, Campo Experimental Valle del Yaqui. Ciudad Obregón, Sonora, México. 24 p (In Spanish).
• Camacho-Casas MA, Félix-Valencia P, Huerta-Espino J, and Martínez-Santana JJ. 1998. INIFAP M97 y TOBARITO M97: variedades de trigo harinero para el noroeste de México. Folleto Técnico Número 33. Instituto Nacional de Investigaciones Agropecuarias. Centro de Investigación Regional del Noroeste, Campo Experimental Valle del Yaqui. Ciudad Obregón, Sonora, México. 20 p (In Spanish).
• Chona BL, Munjal RL, and Adlakha KL. 1961. A method for screening wheat plants for resistance to Neovossia indica. Ind Phytopathol 14:99-101.
• Fuentes-Davila G and Rajaram S. 1994. Sources of resistance to Tilletia indica in wheat. Crop Prot 13(1):20-24.
• Fuentes-Davila G, Rajaram S, Pfeiffer WH, and Abdalla O. 1992. Results of artificial inoculation of the 4th Karnal Bunt Screening Nursery (KBSN). Ann Wheat Newslet 38:157-162.
• Fuentes-Davila G, Rajaram S, Pfeiffer WH, Abdalla O, Van-Ginkel M, Mujeeb-Kazi A, and Rodríguez-Ramos R. 1993. Resultados de inoculaciones artificiales del 5o. vivero de selección para resistencia a Tilletia indica Mitra. Revista Mexicana de Micología 9:57-65. In Spanish.
• Mitra M. 1931. A new bunt of wheat in India. Ann Appl Biol 18:178-179.
• Mitra M. 1935. Stinking smut (bunt) of wheat with a special reference to Tilletia indica Mitra. Ind J Agric Sci 5:1-24.

Production of allantoid secondary esporidia of Tilletia indica in vitro by teliospores isolated from bread and durum wheat infected under natural conditions. [p.83-85]

Irazema Fuentes-Bueno and Guillermo Fuentes-Dávila.

Introduction. Karnal bunt is a floral-infecting organism (Mundkur 1943) that partially infects seed of bread wheat (Mitra 1931), durum wheat, and triticale (Agarwal et al. 1977). Tilletia indica is a fungus that upon teliospore germination, produces a promycelium or promycelia, and primary sporidia at the apex; primary sporidia germinate directly or indirectly; in the latter case, giving rise to allantoid secondary sporidia on sterigmata from which they are forcibly discharged. These in turn, germinate directly or by repetition (Krishna and Singh 1983; Fuentes-Davila and Duran 1986). Chona et al. (1961) evaluated several inoculation methods in the field, indicating that injection during the boot stage of wheat using sporidial suspensions produced the highest levels of infection. Singh and Krishna (1982) evaluated the injection technique at several phenologic stages of the wheat plant from panicle initiation to milky stage using sporidial suspensions, and reported that the most susceptible stage for inoculation was when awns were just emerging (stage 49, Zadoks et al. 1974) (84 % infected grain as compared to boot with 75 %, heading with 4 %, and 6 % at flowering). Field inoculations have required the use of more specific propagules of the fungus, as it has been with the allantoid secondary sporidia, in order to obtain consistent high levels of infection (Singh et al. 1988; Fuentes-Dávila et al. 1993). In this report, we present results of production of allantoid secondary sporidia in vitro, derived from teliospores obtained from grain of durum wheat and bread wheat infected under natural conditions.

Materials and methods. Infected grains from cultivars Baviacora M92 and Altar C84 were obtained from commercial fields in the Yaqui Valley, Sonora, Mexico, during the crop cycle autumn-winter 2002-03.

Teliospore isolation and germination. Teliospores were scraped off infected grains with a dissecting needle and kept in a water-Tween 20 solution for 24 h, then the suspension was filtered through a 60 µm nylon sieve and centrifuged at 3,000 rpm. After discarding the supernatant, sodium hypochlorite 0.5 % a.i. was used to disinfect teliospores for 2 min while centrifuging again. Teliospores were then rinsed twice with sterile distilled water while centrifuging. Teliospores were resuspended in sterile distilled water in the centrifuge tube and 1 ml of the teliospore suspension was spread on Petri plates with 2 % water-agar (AA), which were incubated at 20C in darkness. After 6 to 9 days, teliospore germination was evaluated using a compound microscope at 10X.

Inoculum multiplication. Pieces of AA with germinated teliospore were removed and placed upside down on the lid of Petri plates containing potato-dextrose-agar (PDA). After 10 to 14 days, 2 to 3 ml of sterile distilled water were added to the plates and the colonies were scraped gently using a sterile spatula. Hyphae and sporidia were inoculated onto other plates with PDA using a sterile syringe, and the plates were incubated at 20C in darkness for about 9 days.

Production of allantoid secondary sporidia. After incubation, pieces of PDA with the different fungal propagules were transferred and placed upside down on the lids of sterile glass Petri plates, in order to induce production of allantoid secondary sporidia (Dhaliwal and Singh 1989; Fuentes-Dávila et al. 1993). Three ml of sterile distilled water were added to the bottom of the plates. Plates with fungal propagules derived from teliospores produced on Altar C84 and Baviacora M92 were kept separately and incubated under two regimes: a) within an incubator at 20 C in darkness and b) at room temperature (range 23-28 C, mean 26.4 C) with a 14 h photoperiod. There were four plates (replicates) per fungal culture-cultivar, and the evaluation was carried out six times (groups). Water from the plates was collected every two days in order to do sporidia counts; water collection and sporidia counts were repeated five times. Sporidia were counted using a hemocytometer.

Results and discussion. Sporidia counts from teliospores obtained from Altar C84 and incubated at 20 C in darkness had a minimum of 615 allantoid secondary sporidia and a maximum of 2,064 with an average of 1,541.16 (Figure 2). The range of sporidia from cultures incubated at room temperature was 98-2,665 with an average of 2,148.16. Sporidia counts from teliospores obtained from Baviacora M92 and incubated at 20 C in darkness had a minimum of 57 allantoid secondary sporidia and a maximum of 2,187 with an average of 642 (Figure 3). The range of sporidia from cultures incubated at room temperature was 182-1,297 with an average of 693.66. Production of sporidia at room temperature which fluctuated from 23 to 28 C and with a 14 h photoperiod, was greater than at 20 C in darkness in all groups from teliospores obtained from cv. Altar C84 and in four from Baviacora M92; in the first cv. the minimum and maximum difference in sporidia production was 37 and 1,433, respectively, with and average of 607, whereas in the latter, it was 57 and 800, respectively, with an average of 436. In Baviacora M92, the minimum and maximum difference in sporidia production in the two groups with greater production at 20 C in darkness was 376 and 1,058, respectively, with an average of 717. Overall production of allantoid secondary sporidia was greater by teliospores obtained from Altar C84 than from Baviacora M92. This preliminary evaluation of sporidia production in vitro, indicates that although optimum temperature for teliospore germination is 15-25 C, diminishing considerably below 5 and over 30 C (Mitra 1935; Krishna and Singh 1982; Zhang et al. 1984; Smilanick et al. 1985), optimum temperature for sporidia production is between 24 and 26C (Smilanick et al. 1989). More experimentation is needed to determine: a) the effect of light on sporidia production, as Krishna and Singh (1982) and Zhang et al. (1984) have reported that light has a stimulatory germination effect on teliospores; and b) if the difference in sporidia production can be attributed to physiologic forms of T. indica.

References.

• Agarwal VK, Verma HS, and Khetarpal RK. 1977. Occurrence of partial bunt on triticale. Plant Protection Bull 25:210-211.
  Chona BL, Munjal RL, and Adlakha KL. 1961. A method for screening wheat plants for resistance to Neovossia indica. Ind Phytopath 14:99-101.
• Dhaliwal HS and Singh DV. 1989. Production and inter-relationship of two types of secondary sporidia of Neovossia indica. Curr Sci 58(11):614-618.
• Fuentes-Davila G and Duran R. 1986. Tilletia indica: cytology and teliospore formation in vitro and in inmature kernels. Can J Bot 64:1712-1719.
• Fuentes-Davila G, Rajaram S, Pfeiffer WH, Abdalla O, Van-Ginkel M, Mujeeb-Kazi A, and Rodríguez-Ramos R. 1993. Resultados de inoculaciones artificiales del 5o. vivero de selección para resistencia a Tilletia indica Mitra. Revista Mexicana de Micología 9:57-65 (In Spanish).
• Krishna A and Singh RA. 1982. Effect of physical factors and chemicals on the teliospore germination of Neovossia indica. Ind Phytopath 35:448-455.
• Krishna A and Singh RA. 1983. Citology of teliospore germination and development in Neovossia indica the incitant of Karnal bunt of wheat. Ind Phytopath 36(1):115-123.
• Mitra M. 1931. A new bunt of wheat in India. Ann Appl Biol 18:178-179.
• Mitra M. 1935. Stinking smut (bunt) of wheat with a special reference to Tilletia indica Mitra. Ind J Agric Sci 5:1-24.
• Mundkur BB. 1943. Karnal bunt, an air-borne disease. Curr Sci 12(8):230-231.
• Singh DV, Dhaliwal HS, and Metzger RJ. 1988. Inoculum and time for screening against Karnal bunt disease of wheat. Ind Phytopath 41:632-633.
• Singh RA and Krishna A. 1982. Susceptible stage for inoculation and effect of karnal bunt on viability of wheat seed. Ind Phytopath 35(1):54-56.
• Smilanick JL, Hoffmann JA, and Royer MH. 1985. Effect of temperature, pH, light, and desiccation on teliospore germination of Tilletia indica. Phytopath 75:1428-1431.
• Smilanick JL, Prescott JM, Hoffmann JA, Secrest LR, and Weise K. 1989. Environmental effects on survival and growth of secondary sporidia and teliospores of Tilletia indica. Crop Protect 8:86-90.
• Zadoks JC, Cheng TT, and Konzak CF. 1974. A decimal code for the growth stages of cereals. Weed Res 14:415-421.
• Zhang Z, Lange L, and Mathur SB. 1984. Teliospore survival and plant quarantine significance of Tilletia indica (causal agent of Karnal bunt) particularly in relation to China. Eur Plant Protect Bull 14:119-128.

Evaluation of elite durum wheat genotypes for resistance to Karnal bunt under artificial field inoculation in the Yaqui valley, Sonora, Mexico, during the crop cycle 2004-05. [p.85-87]

Guillermo Fuentes-Dávila and Karim Ammar.

Introduction. Karnal bunt occurs naturally on bread wheat (Mitra 1931), durum wheat, and triticale (Agarwal et al. 1977). Affected kernels are usually partially infected and completely infected ones are rare (Mitra 1935; Bedi et al. 1949; Chona et al. 1961). Durum wheat cultivars and advanced lines with resistance to Karnal bunt under artificial inoculations have been reported by Bedi et al. (1949) and Fuentes-Davila et al. (1992, 1993). Currently, durum wheat is the most important crop for the autumn-winter crop cycle in the southern part of Sonora state, Mexico; therefore, new elite lines and cultivars from the INIFAP-CIMMYT collaborative program should be evaluated for resistance to T. indica, in order to avoid possible economic problems for farmers by the release of a susceptible cultivar.

Materials and methods. Fourteen elite, durum wheat advanced genotypes and the cultivar Samayoa C2004 (pedigree: SOMAT_4/INTER_8; selection history: CDSS95B00181S-0M-1Y-0B-1Y-0B-0Y-0B-14EY-0Y) were evaluated for reaction to Karnal bunt during the crop cycle 2004-05. Planting dates were 10 and 28 November, 2004, using approximately 10 g of seed for a bed with two 1-m rows. A mist-irrigation system was used 3-5 times/day during 15 min each time to provide a humid environment in the experimental area. Inoculation was done by injection during the boot stage applying 1 ml of an allantoid sporidial suspension (10,000/ml) to ten spikes for each genotype. Harvest was done manually, and the evaluation and counting of healthy and infected kernels was by visual inspection.

Results and discussion. The range of infection for the first planting date was 0-10.85, with a mean of 1.83; five lines did not have any infected grain (Figure 4). The range of infection for the second planting date was 0-13.66 with a mean of 3.30; four lines did not show any infected grains. The difference between the mean percent infection of the first and second planting dates and the mean of the three highest levels of infection of the susceptible check WL711 (79.22 %) was 77.39 and 75.92, respectively. Genotypes 1 and 6 did not show any infection in both planting dates (Table 3). Lines with less than 5 % infection are considered resistant (Fuentes-Dávila and Rajaram, 1994). Six lines had infection levels in category 0.1-2.5 %, two in 2.6-5.0 %, two in 5.1-10.0 %, and three in category 10.1-30.0 % (Figure 5). The cultivar Samayoa C84 had a range of infection of 3.71-13.31 with a mean of 8.51% (Figure 4, genotype No. 8). Although, results indicate that the high level of resistance to KB in durum wheat has been maintained in the new elite germ plasm coming out of the CIMMYT program, some genotypes are moderately susceptible, like cultivar Samayoa C84. Collaborative efforts between INIFAP and CIMMYT are continuing to ensure adequate levels of KB resistance in new promising material of durum wheat, in order to provide a commercially viable crop for the growers in the state of Sonora and maximize their access to export markets.

References.

• Agarwal VK, Verma HS, and Khetarpal RK. 1977. Occurrence of partial bunt on triticale. Plant Protection Bull 25:210-211.
• Bedi SKS, Sikka MR, and Mundkur BB. 1949. Transmission of wheat bunt due to Neovossia indica (Mitra) Mundkur. Ind Phytopath 2:20-26.
• Chona BL, Munjal RL, and Adlakha KL. 1961. A method for screening wheat plants for resistance to Neovossia indica. Ind Phytopath 14:99-101.
• Fuentes-Davila G and Rajaram S. 1994. Sources of resistance to Tilletia indica in wheat. Crop Protect 13(1):20-24.
• Fuentes-Davila G, Rajaram S, Pfeiffer WH, and Abdalla O. 1992. Results of artificial inoculation of the 4th Karnal Bunt Screening Nursery (KBSN). Ann Wheat Newslet 38:157-162.
• Fuentes-Dávila G, Rajaram S, Pfeiffer WH, Abdalla O, Van-Ginkel M, Mujeeb-Kazi A, and Rodríguez R. 1993. Resultados de inoculaciones artificiales del 5 vivero de selección para resistencia a Tilletia indica Mitra. Revista Mexicana de Micología 9:57-65 (In Spanish).
• Mitra M. 1931. A new bunt of wheat in India. Ann Appl Biol 18:178-179.
• Mitra M. 1935. Stinking smut (bunt) of wheat with a special reference to Tilletia indica Mitra. Ind J Agric Sci 5:1-24.

Effect of Prothioconazole on seed germination from treated plots of the bread wheat cultivar Bacanora T88 after foliar application. [p.87-89]

Irazema Fuentes-Bueno and Guillermo Fuentes-Dávila.

Introduction. Karnal bunt or partial bunt of wheat which is caused by the fungus T. indica and is an important disease of wheat seed and grain in the southern part of Sonora state, Mexico (Fuentes-Dávila 1997). Wheat is the most important crop in that region during the crop cycle autumn-winter, occupying approximately 200,000 ha with an average yield of 5 t/ha. Karnal bunt causes economic losses due to the effect on quality of seed, grain, and flour (Peña et al. 1992); quarantine regulations also have negative economic effects on farmers, seed producers, and the industry (Brennan et al. 1990). Because no commercial wheat cultivars are immune to the disease, the application of fungicides is an important component of the integrated control management. Based on the life cycle of the pathogen, application of fungicides during heading-flowering-anthesis provides good control of the disease that under certain conditions also is feasible economically (Salazar-Huerta et al. 1997). Fungicides reported to significantly control the disease include benomyl (Benlate), carbendazim (Bavistin), mancozeb (Dithane-M45), and fentin hydroxide (Duter) (Singh and Prasad 1980); triadimenol (Baytan) and triadimefon (Bayleton) (Singh and Singh 1985); propiconazole (Tilt), etaconazole (Vangard), mancozeb (Manzate), and copper hydroxide (Kocide) (Smilanick et al. 1987); propiconazole (Figueroa and Valdés 1991; Salazar-Huerta et al. 1997); propiconazole and epoxyconazole (Opus) (Figueroa-López and Alvarez-Zamorano 2000); and tebuconazole (Folicur) and propiconazole (Fuentes-Dávila et al. 2005).

Prothioconazole (Proline 250 EW or 480 SC) is a fungicide that belongs to the group that inhibits sterol biosynthesis, which is an effective tool for control of plant diseases (Kuck 2004). This product has been evaluated for Karnal bunt control in the collaborative INIFAP-CIMMYT Karnal bunt research program in the Yaqui Valley, Sonora, Mexico. A component of this project was to determine the effect of Prothioconazole on seed germination from treated plots of bread wheat after foliar application.

Materials and methods. The experiment was carried out in the Yaqui Valley, during the crop cycle autumn-winter 2004-05. Treatments (Table 4) were applied on bread wheat cultivar Bacanora T88, under a randomized complete block design with four replications (experimental unit was four beds with two rows each 3 x 0.80 m). Bacanora T88 is a susceptible cultivar to Karnal bunt. Inoculation was done by injection of 1 ml of a sporidial suspension of 10,000/ml during the boot stage (stage 49, Zadoks et al. 1974), on 20 spikes/replication. Fungicides were applied with a motorized Robin RS450 sprayer with four nozzles. During applications (2) (10 and 20 days after inoculation), 4 x 4-m plastic pieces were used to avoid carry over of product to other plots. After collection of inoculated spikes and spikes from the experimental plots for yield assessment, seed from the latter was used to evaluate germination twelve months after fungicide application. The seed was kept at room temperature during that period of time. For germination tests, five rows with five seeds (25) were placed on wet paper towel within plastic bags, and incubated at room temperature (23-28C) with a 14-h photoperiod. Four replications were made per treatment. After 5 days, seed germination was evaluated by visual inspection, considering the initial growth of coleoptile and seminal roots as germinated. Abnormal seed germination was also registered as a possible indicator of negative effects of the fungicide on seed.

Results and discussion. The range of the average seed germination was 79.75-84.75 % with a mean of 83.15 % (Figure 6). The untreated check had an average of 84.5 %, and the difference between the check and the various treatments was 0.25, 0.25 (Prothioconazole 250 EW, 125 g a.i./ha), 1.5, 4.75, 2, 0.25 (Prothioconazole 480 SC, 150 g a.i./ha), and 2.75 for treatments 1-7, respectively. The range of the average abnormal seed germination was 8.75-16.25 % with a mean of 11.50 % (Figure 7). The untreated check had an average of 14 %, and the difference between the check and the various treatments was 3, 5.25, 2.25, 3.25, 2.5, 3.75, and 4.50 for treatments 1-7, respectively. Treatment 3 (Prothioconazole 250 EW, 150 g a.i./ha), which had the highest rate of the product in the EW formulation, showed the highest percentage of abnormal seed germination. This preliminary report indicates that Prothioconazole might have a negative effect on seed germination at high rates when applied as foliar spray and even after a long period of time after application and that plots for wheat seed production treated with other fungicides as foliar sprays should be evaluated for seed germination.

References.

• Brennan JP, Warham EJ, Hernandez J, Byerlee D, and Coronel F. 1990. Economic Losses from Karnal bunt of wheat in Mexico. CIMMYT Economic Working Paper 90/02.
• Figueroa-López P and Álvarez-Zamorano R. 2000. Opus (epoxiconazole): una nueva opción para controlar al Carbón Parcial del trigo (Tilletia indica Mitra) en aplicación foliar. In: XIIth Biennial Workshop on the Smut Fungi (Fuentes-Dávila G Ed). Sociedad Mexicana de Fitopatología, A.C., pp. 31-34 (In Spanish).
• Figueroa LP and Valdés AJC. 1991. Evaluación de fungicidas sistemáticos para el control del Carbón Parcial (Tilletia indica (Mit.) en trigo en el Valle del Yaqui. In: Memorias XVIII Congreso Nacional de la Sociedad Mexicana de Fitopatología, 24-26 July, 1991, Puebla, Puebla, México. Abstract. p. 209 (In Spanish).
• Fuentes-Dávila G. 1997. Carbón Parcial del trigo: situación actual y perspectivas. In: Primer Simposio Internacional del Trigo. Cd. Obregón, Sonora, México, pp. 105-118 (In Spanish).
• Fuentes-Dávila G, Tapia-Ramos E, Toledo-Martínez JA, and Figueroa-López P. 2005. Evaluación de efectividad biológica de folicur 250 EW (Tebuconazol) para el control del carbón parcial (Tilletia indica) del trigo en el valle del Yaqui, Sonora, México. In: Memorias del XXXII Congreso Nacional de Fitopatología/VII Congreso Internacional de Fitopatología, 26-29 September, 2005, Chihuahua, Chihuahua, México. Abstract L-1 (In Spanish).
• Kuck K-H and Mehl A. 2004. Prothioconazole: Sensitivity profile and anti-resistance strategy. Pflanzenschutz-Nachrichten Bayer 2:225-236.
• Peña RJ, Amaya A, and Del Toro E. 1992. Efecto del almacenamiento y del lavado de grano en las características de calidad de muestras de trigo (variedad Seri M82) con diferentes niveles de carbón parcial (Tilletia indica). In: Estado actual de la investigación sobre el carbón parcial en México (Fuentes-Dávila G and Hettel GP Eds). Reporte Especial de Trigo No. 7, México, D.F.: CIMMYT. Pp. 24-32 (In Spanish).
• Salazar-Huerta FJ, Figueroa-Lopez P, Smilanick JL, and Fuentes-Davila G. 1997. Evaluation of foliar fungicides for control of Karnal bunt of wheat during 1986-1989 in northwestern Mexico. Revista Mexicana de Fitopatología 15:73-80.
• Singh A and Prasad R. 1980. Control of Karnal bunt of wheat by a spray of fungicides. Ind J Mycol Plant Path 10:2 (Abstract).
• Singh SL and Singh PP. 1985. Effect of some fungicide applications against Karnal bunt (Neovossia indica) of wheat. Ind Phytopath 38:593 (Abstract).
• Smilanick JL, Hoffman JA, Cashion NL, and Prescott JM. 1987. Evaluation of seed and foliar fungicides for control of Karnal bunt of wheat. Plant Dis 71:94-96.
• Zadoks, J.C., Cheng, T.T., and Konzak, C.F. 1974. A decimal code for the growth stages of cereals. Weed Research 14:415-421.

Evaluation of elite triticale (X Triticosecale) genotypes for resistance to Karnal bunt under artificial field inoculation in the Yaqui valley, Sonora, Mexico, during the 2004-05 crop cycle. [p.89-91]

Guillermo Fuentes-Dávila and Karim Ammar.

Introduction. The Karnal bunt fungus T. indica occurs naturally on bread wheat (Mitra 1931), durum wheat, and triticale (X Triticosecale; Agarwal et al. 1977). Affected kernels are usually partially infected and completely infected ones are rare (Mitra 1935; Bedi et al. 1949; Chona et al. 1961). Since the early 1980s, resistance and inmunity in triticale cultivars and experimental advanced lines under artificial inoculations were reported (Meeta et al. 1980; Fuentes-Davila et al. 1992). Advanced lines were selected primarily for their resistance to a new race of yellow rust that appeared in Central Mexico and to which most CIMMYT triticales are susceptible (Hede et al. 2002). Sources of resistance to this race also include progenies from crosses with either bread or durum wheat. The objective of this work was to evaluate twenty elite triticale genotypes for resistance to Karnal bunt.

Materials and methods. Twenty elite, advanced triticale genotypes were evaluated for Karnal bunt resistance during the 2004-05 crop cycle. Planting dates were 10, 18, and 26 November, 2004 using approximately 10 g of seed for a bed with two 1-m rows. A mist-irrigation system was used 3-5 times/day during 15 min each time to provide a humid environment in the experimental area. Inoculation was by injection during the boot stage applying 1 ml of an allantoid sporidial suspension (10,000/ml) to 10 heads/genotype. Harvest was done manually, and the evaluation and counting of healthy and infected kernels was by visual inspection. Tested genotypes included the long term yield check POLLMER TCL 2003, recently released as feed grain cultivar in the state of Sonora, and two new candidates for commercial release in the same state. These three genotypes are susceptible to yellow rust in central Mexico. The remaining 17 genotypes are new advanced lines selected for their resistance to yellow rust in the central Mexican highlands and internationally, representing the genotypic variability available in the current feed and forage triticale germ plasm of the CIMMYT program.

Results and discussion. The range of infection for the first planting date was 0-0.56, with a mean of 0.046. Eighteen lines did not have any infected kernels (Figure 8). No infected grains were obtained in the second date. For the third planting date the range of infection was 0-0.21 with a mean of 0.017. Eighteen lines did not show any infected grain. The difference between the mean percent infection of the first, second, and third planting dates and the mean of the three highest levels of infection of the susceptible check WL711 (79.22 %) was 79.17, 79.22, and 79.20 %, respectively. Only the lines SUSI_2/5/Tapir/Yougi_1//2*MUSX/3/Erizo_7/4/ Faras_1/6/Varsa_2/7/754.3/ IBEX//BUF_2 (CTSS98Y00367S-0M-4Y-0M-0Y-9B-2Y-0B), 804/BAT/3/MUSX/ LYNX//STIER_12-3/4/Varsa_3-1/5/Fahad_8-1*2//HARE_263/ Civet (CTSS98Y00236S-0M-1Y-0M-0Y-8B-1Y-0B), BAT*2/BCN//CAAL/3/Erizo _7/Bagal_2//Faras_1 (CTSS99Y00246S-1Y-0M-0Y-5B-1Y-0B), and T1505_WG//Erizo_10/BULL_1-1/3/Erizo_10/BULL_1-1/4/COPI_1/5/ARDI_1/TOPO1419//Erizo_9/3/SUSI_2 (CTSS00Y00759T-0TOPB-8Y-7M-1Y-3M-3Y-3M-6Y) fell within the 0-2.5 % infection category. Lines with less than 5 % infection are considered resistant (Fuentes-Dávila and Rajaram 1994). Sixteen lines did not have any infected kernels in the three evaluations (Table 5). Genotypes 10, 11, and 12 did not have any infected kernels in previous evaluations (Fuentes-Dávila and Ammar 2005). These results indicate that the high level of resistance to KB in triticale has been maintained in the new elite germ plasm coming out of the CIMMYT program. Collaborative efforts between INIFAP and CIMMYT to ensure adequate levels of KB resistance in new promising material is being continued in order to provide a sound, safe, and commercially viable feed grain option for the growers in the State of Sonora.

References.

• Agarwal VK, Verma HS, and Khetarpal RK. 1977. Occurrence of partial bunt on triticale. Plant Prot Bull 25:210-211.
  Bedi SKS, Sikka MR, and Mundkur BB. 1949. Transmission of wheat bunt due to Neovossia indica (Mitra) Mundkur. Ind Phytopath 2:20-26.
• Chona BL, Munjal RL, and Adlakha KL. 1961. A method for screening wheat plants for resistance to Neovossia indica. Ind Phytopath 14:99-101.
• Fuentes-Dávila G and Ammar K. 2005. Evaluation of elite triticale (X Triticosecale) genotypes for resistance to Karnal bunt (Tilletia indica Mitra) under artificial field inoculation in the Yaqui valley, Sonora, Mexico, during the crop cycle 2003-2004. Ann Wheat Newslet 51:83-85.
• Fuentes-Davila G and Rajaram S. 1994. Sources of resistance to Tilletia indica in wheat. Crop Protect 13(1):20-24.
• Fuentes-Davila G, Rajaram S, Pfeiffer WH, and Abdalla O. 1992. Results of artificial inoculation of the 4th Karnal Bunt Screening Nursery (KBSN). Ann Wheat Newslet 38:157-162.
• Hede AR, Skovmand B, Singh R, Payne T, Huerta J, Ammar K, and Rajaram S. 2002. The importance of germplasm diversity for triticale breeding. In: Proc 5th Internat Triticale Symp, Radzików, Poland, 30 June-5 July, 2002. Pp. 67-76.
• Meeta M, Dhiman JS, Bedi PS, and Kang MS. 1980. Incidence and pattern of "Karnal" Bunt symptoms on some triticale varieties under adaptive research trial in the Punjab. Ind J Mycol Plant Path 10:Lxxxiv.
• Mitra M. 1931. A new bunt of wheat in India. Ann Appl Biol 18:178-179.
• Mitra M. 1935. Stinking smut (bunt) of wheat with a special reference to Tilletia indica Mitra. Ind J Agric Sci 5:1-24.

Evaluation of elite bread wheat lines and synthetic hexaploid wheat derivatives (T. turgidum subsp. turgidum/Aegilops tauschii//T. aestivum subsp. aestivum) for resistance to Karnal bunt. [p.90-92]

Guillermo Fuentes-Dávila and Ravi P. Singh.

Introduction. Tilletia indica is the causal agent of Karnal bunt of wheat (Mitra 1931). Control of this pathogen is difficult because teliospores are resistant to physical and chemical factors (Krishna and Singh 1982; Zhang et al. 1984; Smilanick et al. 1988). Chemical control can be accomplished by applying fungicides during flowering (Fuentes-Dávila et al. 2005). However, this measure is not feasible when quarantine does not allow tolerance levels for seed production. The susceptibility of bread wheat has been documented (Fuentes-Dávila et al. 1992, 1993) reaching infection levels above 50 % under artificial inoculation. However, bread wheats that have consistently shown low infection levels are known to occur (Fuentes-Dávila and Rajaram 1994). Resistance sources are also known in durum wheat and triticale germ plasm under natural and artificially inoculated conditions (Bedi et al. 1949; Fuentes-Davila et al. 1992). Villareal et al. (1994) reported that 49 % of the synthetic hexaploids (SH) evaluated during three crop cycles under artificial inoculation, were immune to the disease. Villareal et al. (1996) registered four SHs as immune sources. The resistant reaction appears to be conferred by the genetic base of Ae. tauschii and T. turgidum subsp. turdigum. The objective of this work was to evaluate elite bread wheat lines, synthetic hexaploid wheat derivatives, commercial cultivars, and candidates for release for resistance to Karnal bunt under artificial inoculation.

Materials and methods. One hundred and two elite bread wheat lines and synthetic hexaploid wheat derivatives, four commercial cultivars, and two candidates for release were evaluated for resistance to Karnal bunt during the 2004-05 autumn-winter crop cycle in the Yaqui valley, Sonora, Mexico. Planting dates were 10 and 28 November, 2004, using approximately 10 g of seed on 1-m beds with two rows. A mist-irrigation system was used 3 to 5 times each day for 15 min each time to provide high relative humidity in the experimental area. Inoculations were carried out by injecting 1 ml of an allantoid sporidial suspension (10,000/mL) during the boot stage on 10 heads/line. Only lines, cultivars, and candidates for release that had 5 % infection or less were evaluated on the second planting date. Harvest was done manually, and the counting of healthy and infected grains was by visual inspection to calculate the percentage of infection (infected grains).

Results and discussion. The range of infection for the first planting date was 0-45.48 %, with a mean of 10.04 %. Four lines did not have infected grain (Figure 9). Twenty-two lines were within the category of 0.1-2.5 % infection, 11 in 2.6-5.0 %, 21 in 5.1-10.0 %, 41 in 10.1-30 %, and 3 had more than 30 % infection. The susceptible check had 79.22 % infection. Thirty-seven lines with 5 % infection or less were evaluated in the second planting date. The range of infection was 0-41.73 % with a mean of 7.73. Five lines did not have infected grain, 7 were within the 0.1-2.5 % infection category, 8 were 2.6-5.0 %, 5 were 5.1-10.0 %, 11 were 10.1-30 %, and one had more than 30 % infected grain (Figure 10). Fifty-four percent of the lines originally classified as resistant were resistant in the second planting date (Fuentes-Dávila and Rajaram 1994), which emphasizes the importance of several planting dates in order to avoid escapes (Fuentes-Davila 1997). Only the line, CROC_1/Ae. tauschii (205)//KAUZ/3/Attila (CMSS93Y01031S-13Y-5KBY-010M-010Y-8M-0KBY-0M), did not have infected grain on both dates (Table 6). Seven lines (five are sister lines of CROC_1/Ae. tauschii (205)//KAUZ/3/Attila) had 0.1-2.5% infection levels and eleven 2.6-5.0 % (seven of these lines have Ae. tauschii in the pedigree). Cultivars Tacupeto F2003, Tarachi F2000, and Wheatear, a candidate for release, had 26.45, 18.37, and 19.86 % infection, respectively, in the first planting date and were not further evaluated. Only the cultivar Kronstad F2003 showed levels of infection below 5 % on both dates with a mean of 2.68 %, whereas Rayon F89 and Berkut, another candidate for release, had 8.94 and 28.51 % infection, respectively, on the second planting date. Our results show that synthetic-derived bread wheats provide a new level of resistance, almost immunity to Karnal bunt.

References.

• Bedi SKS, Sikka MR, and Mundkur BB. 1949. Transmission of wheat bunt due to Neovossia indica (Mitra) Mundkur. Ind Phytopath 2:20-26.
• Fuentes-Dávila G. 1997. Carbón Parcial del trigo: situación actual y perspectivas. In: Primer Simposio Internacional del Trigo. Cd. Obregón, Sonora, México. Pp. 105-118 (In Spanish).
• Fuentes-Davila G and Rajaram S. 1994. Sources of resistance to Tilletia indica in wheat. Crop Protect 13(1):20-24.
• Fuentes-Davila G, Rajaram S, Pfeiffer WH, and Abdalla O. 1992. Results of artificial inoculation of the 4th Karnal Bunt Screening Nursery (KBSN). Ann Wheat Newslet 38:157-162.
• Fuentes-Davila G, Rajaram S, Pfeiffer WH, Abdalla O, Van-Ginkel M, Mujeeb-Kazi A, and Rodríguez-Ramos R. 1993. Resultados de inoculaciones artificiales del 5o. vivero de selección para resistencia a Tilletia indica Mitra. Revista Mexicana de Micología 9:57-65 (In Spanish).
• Fuentes-Dávila G, Tapia-Ramos E, Toledo-Martínez JA, and Figueroa-López P. 2005. Evaluación de efectividad biológica de folicur 250 EW (Tebuconazol) para el control del carbón parcial (Tilletia indica) del trigo (Triticum aestivum), en el valle del Yaqui, Sonora, México, durante el ciclo de cultivo 2003-2004. In: Abstr XIII Cong Latinoamericano de Fitopatología, III Taller de la Asociación Argentina de Fitopatólogos. 19-22 April, 2005, Villa Carlos Paz, Córdoba, Argentina. HC-29, p 271 (Abstract).
• Krishna A and Singh RA. 1982. Effect of physical factors and chemicals on the teliospore germination of Neovossia indica. Ind Phytopath 35:448-455.
• Mitra M. 1931. A new bunt of wheat in India. Ann Appl Biol 18:178-179.
• Smilanick JL, Hoffmann JA, Secrest LR, and Wiese K. 1988. Evaluation of chemical and physical treatments to prevent germination of Tilletia indica teliospores. Plant Dis 72:46-51.
• Villareal RL, Mujeeb-Kazi A, Fuentes-Davila G, Rajaram S, and Del Toro E. 1994. Resistance to Karnal bunt (Tilletia indica Mitra) in synthetic hexaploid wheats derived from Triticum turgidum X T. tauschii. Plant Breed 112:63-69.
• Villareal RL, Mujeeb-Kazi A, Fuentes-Davila G, and Rajaram S. 1996. Registration of four synthetic hexaploid wheat germplasm lines derived from Triticum turgidum X T. tauschii crosses and resistant to karnal bunt. Crop Sci 36:218.
• Zhang Z, Lange L, and Mathur SB. 1984. Teliospore survival and plant quarantine significance of Tilletia indica (causal agent of Karnal bunt) particularly in relation to China. Eur Plant Protect Bull 14:119-128.