Comunicación corta. Deterioro en las fibras de algodón causado por la enfermedad del enrollado de la hoja del algodón

The effect of cotton leaf curl disease found at Burewala (Pakistan) on the ginning out turn (GOT) and the physical and chemical characteristics of cotton fibre was evaluated by comparing healthy and cotton leaf curl disease (CLCuD)- infected plants of four cotton varieties. A highly susceptible response to CLCuD was found in all varieties tested. The disease incidence ranged from 42.6 to 81.4%. Significant differences were observed between the fibre of healthy and diseased cotton plants, of all varieties, for GOT, fibre length, fibre uniformity index, short fibre index, fibre fineness, fibre bundle strength, reflectance degree (Rd-value), yellowness (+b value) and maturity ratio. The cv. CIM-473 exhibited the highest reduction in all the quality parameters studied with the exception of Rd-value which was the lowest in cv. NIAB-999. The disease also significantly affected cellulose, protein, wax and pectin content. CLCuD adversely deteriorated the cotton fibre characteristics, however the varietal difference exists. The varieties with less deteriorated fibre by CLCuD should be an essential criterion for the selection of resistant germplasm against CLCuD.En Burewala (Paquistán) se evaluó el efecto de la enfermedad del enrollado de la hoja del algodón (CLCuD) sobre el porcentaje de hilas en las semillas (GOT) y las características físico-químicas de la fibra de algodón, comparando cuatro variedades de plantas de algodón sanas y con la enfermedad. Todas las variedades estudiadas fueron altamente susceptibles a CLCuD. La incidencia a la enfermedad varió entre el 42,6 y el 81,4%. Se observaron diferencias significativas entre las fibras de las plantas sanas y enfermas, en todas las variedades, para GOT, longitud, índice de uniformidad, índice de fibras cortas, finura, fuerza de los paquetes de fibras, reflectancia (valor Rd), amarilleamiento (valor +b) y madurez de las fibras. El cv. CIM-473 fue el que más redujo los parámetros de calidad estudiados, a excepción del valor Rd, que fue menor en el cv. NIAB-999. La enfermedad también afectó significativamente al contenido en celulosa, proteínas, ceras y pectinas. Las variedades con fibras menos deterioradas por CLCuD deben ser tenidas en cuenta en la selección de germoplasma contra el CLCuD

Preventive Control of Powdery Mildew Disease of Mango

Oidium mangiferae Berthet was found to be associated With the powdery mildew disease of mango. The air- borne conidia are released from the old tissue harboring the dormant fungal hyphae under favorable weather conditions, which produce the disease. Proper forecasting of release of airborne innoculum significantly reduced the required number of sprays needed for chemical control. Spore traps were used to monitor the concentration of airborne conidia during the months of February, March and April 1996 and l997. Daily temperature and relative humidity were noted and the spore counts from the spore traps were correlated to the meteorological data. There was a positive trend between rising temperature, lowering relative humidity and number of spores in the air alter a low temperature, high humidity and cloudy spell of weather. The maximum spore occurrences were noted around 25°C and relative humidity of 40-60%. It took 5-8 days for the emergence of disease symptoms after the first detection of airborne conidia. Ten fungicides were tested on three mango varieties (Langra, Dashehari, and Anwar Retol). The preventive sprays at the stage of first detection of air born conidia were effective in controlling the disease. Optimal timing of two sprays of fungicide were sufficient to provide preventive control (>90%). The susceptibility of inflorescence varied with its developmental stage. Proper forecasting reduced the number of sprays from 7 to 2 or 3. There was no varietal difference in incidence of the disease or response to fungicide applications. During the course of this study, we identified seedling plants which consistently showed resistance to powdery mildew

Preventive Control of Powdery Mildew Disease of Mango

Oidium mangiferae Berthet was found to be associated With the powdery mildew disease of mango. The air- borne conidia are released from the old tissue harboring the dormant fungal hyphae under favorable weather conditions, which produce the disease. Proper forecasting of release of airborne innoculum significantly reduced the required number of sprays needed for chemical control. Spore traps were used to monitor the concentration of airborne conidia during the months of February, March and April 1996 and l997. Daily temperature and relative humidity were noted and the spore counts from the spore traps were correlated to the meteorological data. There was a positive trend between rising temperature, lowering relative humidity and number of spores in the air alter a low temperature, high humidity and cloudy spell of weather. The maximum spore occurrences were noted around 25°C and relative humidity of 40-60%. It took 5-8 days for the emergence of disease symptoms after the first detection of airborne conidia. Ten fungicides were tested on three mango varieties (Langra, Dashehari, and Anwar Retol). The preventive sprays at the stage of first detection of air born conidia were effective in controlling the disease. Optimal timing of two sprays of fungicide were sufficient to provide preventive control (>90%). The susceptibility of inflorescence varied with its developmental stage. Proper forecasting reduced the number of sprays from 7 to 2 or 3. There was no varietal difference in incidence of the disease or response to fungicide applications. During the course of this study, we identified seedling plants which consistently showed resistance to powdery mildew

Preventive Control of Powdery Mildew Disease of Mango

Oidium mangiferae Berthet was found to be associated With the powdery mildew disease of mango. The air- borne conidia are released from the old tissue harboring the dormant fungal hyphae under favorable weather conditions, which produce the disease. Proper forecasting of release of airborne innoculum significantly reduced the required number of sprays needed for chemical control. Spore traps were used to monitor the concentration of airborne conidia during the months of February, March and April 1996 and l997. Daily temperature and relative humidity were noted and the spore counts from the spore traps were correlated to the meteorological data. There was a positive trend between rising temperature, lowering relative humidity and number of spores in the air alter a low temperature, high humidity and cloudy spell of weather. The maximum spore occurrences were noted around 25°C and relative humidity of 40-60%. It took 5-8 days for the emergence of disease symptoms after the first detection of airborne conidia. Ten fungicides were tested on three mango varieties (Langra, Dashehari, and Anwar Retol). The preventive sprays at the stage of first detection of air born conidia were effective in controlling the disease. Optimal timing of two sprays of fungicide were sufficient to provide preventive control (>90%). The susceptibility of inflorescence varied with its developmental stage. Proper forecasting reduced the number of sprays from 7 to 2 or 3. There was no varietal difference in incidence of the disease or response to fungicide applications. During the course of this study, we identified seedling plants which consistently showed resistance to powdery mildew

Generating information for rural development : some suggested courses of action for ISD; final draft

"Report of the Rural Development Committee

Preventive Control of Powdery Mildew Disease of Mango

Oidium mangiferae Berthet was found to be associated With the powdery mildew disease of mango. The air- borne conidia are released from the old tissue harboring the dormant fungal hyphae under favorable weather conditions, which produce the disease. Proper forecasting of release of airborne innoculum significantly reduced the required number of sprays needed for chemical control. Spore traps were used to monitor the concentration of airborne conidia during the months of February, March and April 1996 and l997. Daily temperature and relative humidity were noted and the spore counts from the spore traps were correlated to the meteorological data. There was a positive trend between rising temperature, lowering relative humidity and number of spores in the air alter a low temperature, high humidity and cloudy spell of weather. The maximum spore occurrences were noted around 25°C and relative humidity of 40-60%. It took 5-8 days for the emergence of disease symptoms after the first detection of airborne conidia. Ten fungicides were tested on three mango varieties (Langra, Dashehari, and Anwar Retol). The preventive sprays at the stage of first detection of air born conidia were effective in controlling the disease. Optimal timing of two sprays of fungicide were sufficient to provide preventive control (>90%). The susceptibility of inflorescence varied with its developmental stage. Proper forecasting reduced the number of sprays from 7 to 2 or 3. There was no varietal difference in incidence of the disease or response to fungicide applications. During the course of this study, we identified seedling plants which consistently showed resistance to powdery mildew

Isolation and Characterization of Fusarium moniliforme var. subglutinans from Malformed Mango

Mango malformation occurs in most mango growing regions of the world. Floral and vegetative malformation have been reported. There is general agreement that the fungal pathogen Fusarium moniliforme var. subglutinans or Fusarium subglutinans is the causal agent. Healthy and malformed samples of both floral and vegetative tissues were collected from different varieties of mango grown in several locations to verify the association of F.moniliforme with mango malformation disease in Pakistan. The fungus was isolated and cultured. Frequency of fungal association with the disease ranged between 90- 94%, There was less recovery of fungus from asymptomatic tissue (12- 15%). There was no difference among the commercial mango varieties in the level of susceptibility to this disease. However, seedling germplasm and land races showing resistance to mango malformation were identified. The in vitro growth characters of the fungus were determined on different culture media, at varying temperatures, light and pH conditions. Mycelial growth on potato dextrose agar was better than nine other media tested. At pH 7.00, the ideal temperature for growth was between 25-30° C. Normally, the malformation is not controlled by fungicide application. The in vitro sensitivity of fungus to six fungicides at three concentrations was determined to seek potential means of chemical control

Isolation and Characterization of Fusarium moniliforme var. subglutinans from Malformed Mango

Mango malformation occurs in most mango growing regions of the world. Floral and vegetative malformation have been reported. There is general agreement that the fungal pathogen Fusarium moniliforme var. subglutinans or Fusarium subglutinans is the causal agent. Healthy and malformed samples of both floral and vegetative tissues were collected from different varieties of mango grown in several locations to verify the association of F.moniliforme with mango malformation disease in Pakistan. The fungus was isolated and cultured. Frequency of fungal association with the disease ranged between 90- 94%, There was less recovery of fungus from asymptomatic tissue (12- 15%). There was no difference among the commercial mango varieties in the level of susceptibility to this disease. However, seedling germplasm and land races showing resistance to mango malformation were identified. The in vitro growth characters of the fungus were determined on different culture media, at varying temperatures, light and pH conditions. Mycelial growth on potato dextrose agar was better than nine other media tested. At pH 7.00, the ideal temperature for growth was between 25-30° C. Normally, the malformation is not controlled by fungicide application. The in vitro sensitivity of fungus to six fungicides at three concentrations was determined to seek potential means of chemical control

Short communication. Partial resistance of a cotton mutant to Cotton leaf curl Burewala virus

Cotton leaf curl disease (CLCuD), caused by Cotton leaf curl Burewala virus (CLCuBV), is a major constraint for a successful production of cotton in Pakistan. All the available cotton cultivars are susceptible to this virus. Breeding for resistance to CLCuBV is the best tactic to reduce economic losses caused by this virus. In the absence of a resistant source the present investigations were carried out to find out CLCuBV-resistant genotypes by mutagenization. NIAB-111 (female parent) was crossed separately with two male parents, NIAB-999 and CIM-499. The resulting F1 seeds were gamma irradiated. Resistance to CLCuBV was evaluated by visual symptom scoring in the field conditions and in nethouse/greenhouse using whitefly and graft inoculations. Out of 20 mutants tested in M5 generation, one, mutant M-112-59/22 showed partial resistance to CLCuBV, as concluded from its low severity index (SI) of 2.3 and percent disease index (PDI) of 20. M-112-59/22 consistently expressed resistance to CLCuBV in the normal cotton growing season, while it showed a more moderate resistance response when sown late in the field, or under greenhouse conditions following inoculation by whiteflies (SI = 3.3) or graft inoculation (SI= 3.4). The yield per plant of M-112-59/22 was higher than its parents with desirable fiber characteristics even under conducive disease development conditions. These results show that mutant M-112-59/22 is a CLCuBV partially resistant source when yield, fiber quality and response to virus infection are collectively taken into consideration.La enfermedad de la hoja rizada del algodón (CLCuD), causada por el virus Burewala de la hoja rizada del algodón (CLCuBV), es un obstáculo importante para la producción de algodón en Paquistán, ya que todos los cultivares de esta planta son susceptibles a este virus. La mejor táctica para reducir las pérdidas económicas causadas por este virus es la mejora genética para resistencia a CLCuBV. Este trabajo se llevó a cabo para buscar genotipos resistentes a CLCuBV por mutagenización. NIAB-111 (progenitor femenino) se cruzó por separado con dos progenitores masculinos, NIAB- 999 y CIM-499. Las semillas F1 resultantes fueron tratadas con radiación gamma y se evaluó la resistencia a CLCuBV por visualización de los síntomas en campo y mediante inoculaciones con mosca blanca y por injerto en invernadero. Se analizaron 20 mutantes en la generación M5 y uno de ellos, M-112-59/22, mostró resistencia parcial a CLCuBV, como se deduce de su bajo índice de severidad (SI = 2,3) y bajo porcentaje de incidencia de enfermedad (PDI = 20). M- 112-59/22 expresó consistentemente resistencia a CLCuBV durante la temporada normal del algodón, mientras que mostró una resistencia más moderada cuando se sembró tardíamente o en condiciones de invernadero tras inoculaciones mediante moscas blancas (SI = 3,3) o injertos (SI = 3,4). El rendimiento por planta de M-112-59/22 fue mayor que los parentales, con características de fibra adecuadas, incluso en condiciones propicias al desarrollo de la enfermedad. Estos resultados mostraron que M-112-59/22 es una fuente parcialmente resistente al CLCuBV cuando se tiene en cuenta en conjunto el rendimiento, la calidad de la fibra y la respuesta a la infección por el virus