Progress 10/01/05 to 09/30/10
Outputs
OUTPUTS: Objective 1) Develop an effective spray program for the control of Sigatoka leaf spots in Puerto Rico. Black Sigatoka (BS) (Mycosphaerella fijiensis Morelet) is the most limiting disease for banana production in Puerto Rico. A spray program based on systemic and contact fungicides was studied. The fungicides were applied from ground level with a motorized backpack sprayer calibrated to deliver a total volume of 85 to 110 L/ha. Fungicides were sprayed in an oil-water emulsion, in an oil mixture, or in a water-emulsion at intervals of 14 days during rainy season and of 21 days during dry season. Five different programs with commercial fungicides and an absolute control were studied. The six programs were the following: 1) Azoxystrobin in rotation with chlorothalonil or mancozeb; 2) Propiconazole rotated with chlorothalonil or mancozeb; 3) Azoxystrobin rotated with propiconazole or chlorothalonil or mancozeb; 4) Chlorothalonil or mancozeb, 5) Orchard oil BVA #15 and 6. Absolute control (untreated plots). Results indicated that the spray program with mancozeb and chlorothalonil achieved the best values for bunch weight. A bunch weight reduction of 44.7% was observed when BS was not controlled. Objective 2: To study the epidemiology of Sigatoka leaf spots in order to understand the effects of local weather conditions on the pathogens. In order to study the effect of various climatic variables (temperature, relative humidity, rainfall, and solar radiation) on the development of black Sigatoka (severity index, youngest diseased leaf and youngest leaf spotted) we established a field experiment at the Agricultural Experimental Substation of Isabela. The results indicate that the black Sigatoka epidemic fits a logistic model with a sigmoidal shift and curvature. Among the environmental variables, temperature was the most important parameter associated with the development of black sigatoka. The severity index and temperatures maximum, average, and minimum showed Spearman coefficients of 0.67, 0.66 and 0.68, respectively. The results indicate that solar radiation contributed positively to increase the severity index, thus indicating that the higher luminic intensity, the greater is the severity index. Additionally, rainfall and relative humidity played an important role in the development of the pathogen, thus showing positive correlations with the severity index. The severity index reached values near 100% after flowering. The disease severely affected crop yield, harvesting bunches with 137.25 fruits, eight hands and 18.67 kg, for an average of 136.03 g per fruit. Taking into account only the bunch weight, we observed a yield reduction of 61%. However, if we consider the effect of the disease on fruit quality, the reduction on yield reached 100%. PARTICIPANTS: Chavarria-Carvajal, Jose (UPR) TARGET AUDIENCES: The target audiences for this project are local farmers growing bananas and plantains. Also, findings from this project should have a significant impact on future strategies for managing black Sigatoka as it continues to spread in the Caribbean. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
1. Results from this project will be helpful in developing an effective spray program for the control of BS in Puerto Rico. 2. The study of the black Sigatoka epidemic will contribute toward understanding the effects of local weather conditions on the pathogen and toward formulating strategies for the management of the disease.
Publications
- Marengo Santiago, J. I. 2010. Epidemiologia de la Sigatoka negra (Mycosphaerella fijiensis Morelet) en una plantilla de guineo en Puerto Rico. [Epidemiolofy of black Sigatoka (Mycosphaerella fijiensis Morelet) on a banana plant crop in Puerto Rico]. M.S. Thesis. Mayaguez Campus, University of Puerto Rico. 97 pp.
- Macchiavelli, R., Chavarria Carvajal, J. A., and Rodriguez Stevez, E. 2010. Ajuste de Curvas de Progreso de Enfermedad para Predecir Sigatoka Negra (Mycosphaerella fijiensis) en banano en Puerto Rico. XX Simposio de Estadistica. August 11-15, 2010, Santa Marta, Colombia.
- Chavarria Carvajal, J. A., Macchiavelli, R., and Marengo, J.I. 2010. Epidemiologia de la Sigatoka negra (Mycosphaerella fijiensis Morelet) en guineo en Puerto Rico. [Epidemiology of black Sigatoka (Mycosphaerella fijiensis Morelet) on bananas in Puerto Rico]. Annual Meeting SOPCA. November 12, 2010, San Juan, Puerto Rico.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: Experiments to study the incidence and severity of Black Sigatoka (BS) were recently completed after four years in the field at Corozal and Isabela. These experiments were conducted with banana (Musa acuminata, AAA cv Grand Naine). In both experiments BS remained untreated with fungicides, in order to get the maximum expression of the pathogen. Disease progress was monitored weekly taking into consideration different parameters, such as the Severity Index (SI), the youngest diseased leaf (YDL) and the youngest leaf spotted (YLS). Also, plant parameters such as bunch weight were recorded for a plant crop and two ratoon crops, to determine the damage caused by BS. The effects of BS on agronomic parameters, such as number of functional leaves at flowering and harvesting, plant height, plant diameter and crop yield, were also recorded in each trial. At this moment data recorded are under statistical analysis. The experiment to evaluate the efficacy of contact and systemic fungicides for the control of BS on banana (Musa acuminata, AAA cv Grand Naine) is in progress at Isabela, Puerto Rico. At this moment the plant crop and the first ratoon crop have been harvested. The experiment consisted of six treatments and four replicates arranged in a RBD. The treatments under study are 1) Rotation of Abound with Manzate 75, Dithane M-45 or Bravo 720; 2) Rotation of Tilt with Manzate 75, Dithane M-45 or Bravo 720; 3) Rotation of Abound or Tilt with Manzate 75, Dithane M-45 or Bravo 720; 4) Rotation of Manzate 75, Dithane M-45 or Bravo 720; 5) Control with Orchard Oil BVA #15; 6) Absolute control. The fungicides were applied at intervals of 14 days during the rainy season and high incidence of BS. The sprays were extended to 21 days during the dry season and low incidence of BS. Fungicide was applied at ground level with a motorized backpack sprayer calibrated to deliver a volume of 48 to 60 L/ha. We expect to harvest the second ratoon crop around August 2010 to proceed to analyze final data and publish the results from this experiment. PARTICIPANTS: Dr. Jose A. Chavarria Carvajal, Plant Pathologist at AES-University of Puerto Rico Puerto Rico, is the PD for this project. Dr. Chavarria is responsible for studies on incidence and severity of BS and for the fungicide trials conducted during this project. Juan Ortiz, Economist at Corozal Station, is responsible for economic analysis of data generated by this project. TARGET AUDIENCES: The target audiences for research being conducted under this proposal are local, regional and international Musa spp. farmers who will benefit from the knowledge being gained by the project. Although no formal field days have been held, collaborators, fellow researchers at the Agricultural Experiment Station, University of Puerto Rico as well as extension personnel involved with Musa spp., at University of Puerto Rico have visited the experimental sites. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Studies on incidence and severity of Black Sigatoka (BS) showed that the youngest diseased leaf (YDL) and the youngest leaf spotted (YLS) decrease with crop age, thus demonstrating the importance of appling control measures to slow disease progress and avoiding the loss of photosynthetic area on the banana plant. Severity Index (SI) increases with time, becoming more limiting after flowering and reaching maximum values at the end of each cropping cycle. The incidence and severity of BS are closely related to rainfall patterns and temperature predominant in the areas of study. Field data suggest that BS will be more expensive and difficult to manage in the mountainous region (Corozal) than in the coastal region (Isabela). Results from the fungicide trial indicated that eight spray cycles were completed in treatments 1, 2, and 3. Meanwhile nine cycles were completed in treatments 4 and 5. No chemical was applied to treatment 6 (Absolute Control). Bunch weight recorded on the banana plant crop was as follows: treatment 1) 23.14 kg; 2) 25.77 kg; 3) 23.79 kg; 4) 28.32 kg; 5) 21.80 kg; and 6) 16.53 kg. Results indicated that without a proper control of BS, bunch weight is reduced by 34.6% in comparison with that in plants treated with fungicides. However, fruit quality dropped drastically thus causing crop losses of 80-100%. The use of orchard oil alone was not effective in reducing BS damage when compared with contact and systemic fungicides. The estimated cost of chemical control of BS (per plant and hectare) varied from $ 0.00 (untreated plots) to $1,508.00 per hectare (rotation of Abound and Tilt with contact fungicides). We expect to continue the evaluation of the fungicide experiment until the harvest of the second ratoon crop around August 2010.
Publications
- No publications reported this period
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Four field experiments are in progress to determine the incidence and severity of black Sigatoka (BS) on Musa spp. in Puerto Rico. Two field experiments are located at the Isabela Substation, where incidence and severity have been recorded in bananas (Musa acuminata, AAA cv. Grand Naine). A second experiment is in progress at this site to evaluate systemic and contact fungicides for the control of BS, using a backpack sprayer from the ground. In December 2008, the second ratoon was started on the first experiment; meanwhile, the fungicide experiment started the first ratoon. A second set of experiments were in progress at the Corozal Substation. The first one was to evaluate incidence and severity of BS on bananas and the second experiment had as its objective to evaluate the curve of progress of BS on plantains (Musa acuminata x M. balbisiana, AAB). In December 2008 the first ratoon in bananas was completed at Corozal; meanwhile, the plant crop in plantains was completed. We expect to continue banana experiments up to a second ratoon to finish the data collection on this project. PARTICIPANTS: Dr. J. Chavarria. Project Leader. Department of Crop Protection, Mayaguez Campus, University of Puerto Rico. Mr. J. Ortiz. Department of Economics, Mayaguez Campus, University of Puerto Rico. TARGET AUDIENCES: Research on this project will provide Puerto Rican farmers with information and new strategies for the chemical control of BS. Data on incidence and severity of BS will provide valuable information based on local weather conditions about the progress of BS at two different ecological areas in Puerto Rico. Experiments with chemical products will provide information for increasing the efficiency in controlling the pathogen and for delaying the development of fungicide resistance. This project will contribute to increase the knowledge necessary for improving disease management and for reducing environmental contamination produced by the continuous use of chemicals, while maintaining agricultural productivity and profitability at an economical level. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Incidence and severity of BS has varied from low to severe at Isabela and Corozal substations during 2008. At Isabela, incidence and severity was low (Disease Index: 5.70%) from January to May 2008. This period corresponded with the lower values for precipitation and relative humidity. During June, July 2008 incidence increased to a moderate value (DI: 10.86%). August to December were the months with highest incidence and severity, DI: 75%. At Corozal, from January to March 2008 there was a high DI: 85%. From April to August 2008 the incidence was moderate (DI: 53%), but increased again from September to December (DI: 72%). The experiment to evaluate the efficacy of contact and systemic fungicides consisted of six treatments and four replicates arranged in a RBD. The treatments under study are 1) Rotation of Abound plus Manzate 75, Dithane M-45, or Bravo 720, applied at intervals of 14 to 21 days; 2) Rotation of Tilt plus Manzate 75, Dithane M-45 or Bravo 720; 3) Rotation of Abound + Tilt + Manzate 75, Dithane M-45 or Bravo 720; 4) Rotation of Manzate 75, Dithane M-45, or Bravo 720; 5) Orchard Oil BVA #15; 6) Absolute control. The fungicides were applied at intervals of 14 days during rainy season and high incidence of BS. The spraying was extended to 21 days during the dry season and low incidence of BS. At the end of the banana plant crop a total of eight spray cycles had been used for treatments 1, 2 and 3. Meanwhile, nine cycles had been used for treatments 4 and 5. No control was applied on treatment 6 (Absolute Control). Bunch weight for each treatment was as follows: Treatment 1) 23.14 kg; 2) 25.77 kg; 3) 23.79; 4) 28.32 kg; 5) 21.80 and 6) 16.53 kg. Results indicate that without a proper control of BS crop yield may be reduced by 34.6% in comparison with yield when fungicides were used in treatments 1 through 4. Treatment 4 attained the best value for bunch weight, with 28.32 kg. The use of orchard oil alone was not very effective increasing bunch weight when compared with the use of fungicide treatments. We expect to continue the evaluation of the fungicide experiment until the harvest of the second ratoon crop.
Publications
- No publications reported this period
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: The overall goal of this research is to develop strategies for the chemical control of Black Sigatoka (BS) (Mycosphaerella fijiensis) and to understand the factors affecting the epidemiology of BS in Puerto Rico. The objectives of this project are 1) to develop an effective spray program for the control of Sigatoka leaf spots in Puerto Rico and 2) to study the epidemiology of Sigatoka leaf spots in order to understand the effects of local weather conditions on the pathogens. Three field experiments were established at Isabela (August 2006) and Corozal (February 2007 and October 2007) Puerto Rico Agricultural Experiment Stations, Mayaguez Campus, University of Puerto Rico. The first two experiments at both localities were planted with banana (Musa acuminata, AAA cv. Grand Naine) spaced at 2.4 m between rows and 2.1 m between plants for a population density of 1,983 plants per hectare. The third experiment was established October 2007, with plantain as the main crop. In all
experiments Sigatoka remained untreated in order to guarantee maximum disease expression. The influence of weather conditions (i.e., rainfall, temperature, relative humidity and solar radiation) were recorded on a daily basis to establish the effects of weather variables on disease incidence and severity. An RCB design was used in both experiments, with four replicates. Each experimental plot consisted of six rows of seven plants each. Six plants (two rows of three plants each) were studied. In each trial the disease progress curve was recorded every week.
PARTICIPANTS: Jose A. Chavarria -Project Leader Juan Ortiz
TARGET AUDIENCES: The main target audiences for this project are banana and plantain farmers in Puerto Rico. Sigatoka leaf spots represent the most serious threat for banana and plantain production in Puerto Rico, because local production relies on germplasm that is highly susceptible. It is estimated that the Puerto Rican farmers are no yet prepare for a proper management and control of Sigatoka leaf spots, and a Sigatoka epidemic will cause severe destruction and crop losses in the main banana and plantain industries, specially those located in the mountainous region. The overall goal of this project is to study alternatives for the proper control of Sigatoka leaf spots, to reduce their negative impact on the production of bananas and plantains. Further research on fungicides will not only identify effective products, but also, may provide the Puerto Rican farmers (main target audiences) with new products with different modes of action that can be used in a management spray program
aimed to increase the efficiency in the control of the pathogen and to delay the development of fungicide resistance.
PROJECT MODIFICATIONS: The original objectives of this project were to: 1) Study the sensitivity in vitro of Yellow Sigatoka and Black Sigatoka isolates to commercial fungicides; 2) Develop an effective spray program for the control of Sigatoka leaf spots in Puerto Rico, and 3) Study the epidemiology of Sigatoka leaf spots to understand the effects of local weather conditions on the pathogens. The project was reorganized during October 2007 and the firsts objective was eliminated. From that date the project will concentrate efforts on two main objectives: 1). Develop an effective spray program for the control of Sigatoka leaf spots in Puerto Rico, and 2) Study the epidemiology of Sigatoka leaf spots to understand the effects of local weather conditions on the pathogens.
Impacts
a. Isabela Trial: The severity index caused by black Sigatoka (BS) on banana was recorded weekly for 42 weeks. The index increased with plant age, showing maximum values between flowering and harvesting times (94%). The youngest diseased leaf (YDL) had a mean value of 3.4 at the beginning of disease appearance in the field, but at the end of the plant crop decreased strongly upward to reach the first leaf. The youngest leaf spotted (YLS) decreased with plant age reaching the second leaf at the end of the experiment. Rainfall was more plentiful during weeks 19 through 31 after planting, thus increasing the severity index. A decrease or increase of relative humidity tended to decrease or increase the severity index after a 2-3 week period. However, after the 32nd week the inocolum pressure was so high that disease kept progressing with plant age. BS had a severe effect on crop yield. Bunches from plants affected by BS weighted an average of 16.1 kg. Studies conducted by
Chavarria-Carvajal (1998) indicated that a plant crop with Yellow Sigatoka is capable of producing a bunch weight of 24.24 kg. However, in the present study the average bunch weight obtained from untreated BS plots was only 16.1 kg; that amount is a 33.7% reduction in yield. However, disease severity reached such magnitude under field conditions where most bunches ripened early, thus causing a physiological abortion from the banana plant. Under these circumstances, real yield losses may rank between 80% and 100%. b. Corozal Trial: At the beginning of the experiment BS was not observed in the experimental area. Yellow Sigatoka was the predominant pathogen. First symptoms of YS appeared during the second week of June 2007, that is, four months after planting. BS infection was observed for the first time in this experiment during late September 2007, but probably reached the experimental plants in late July or early August 2007. At the moment of this report, BS is the dominant pathogen
in the youngest banana leaves; meanwhile, YS remains present in older banana leaves. Disease severity increased with plant age, reaching a high value in late August 2007. The youngest diseased leaf and the youngest leaf spotted both descended rapidly after the middle of July, probably because of the arrival of BS in the area. A high rainfall period during the second week of June 2007 coincided with the appearance of the first symptoms of BS in the plot. Subsequently the severity index constantly increased, reaching a value close to 65%. Data on relative humidity and disease index are not conclusive during the period reported. However, data on temperature maintain a close pattern with the disease index, showing once again the importance of this variable on disease development .
Publications
- No publications reported this period
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Progress 01/01/06 to 12/31/06
Outputs
This project was approved by USDA and the Puerto Rico Agricultural Experiment Station (PR-AES) in November 2005. Funds were finally released by the PR-AES in April 2006. During 2006, two field experiments were established at the Isabela and Corozal Substations. The main objective of both experiments is to determine the Disease Indexes (DI) caused by black Sigatoka (Mycosphaerella fijiensis) at Isabela and by yellow Sigatoka (M. musicola) at Corozal. In the Corozal region M. fijiensis has not yet been reported. The determination of the disease index (curve of disease progress) at both experimental sites will serve to establish the basis for developing an effective control for both pathogens. During the year 2007, a new experiment will be established for the chemical control of black Sigatoka to evaluate some of the most effective fungicides used against black Sigatoka in producing areas worldwide. Objectives 2 and 3 of the original project are in progress. Preliminary
results indicate that DI caused by M. fijiensis on bananas (Musa acuminata, AAA cv. 'Grand Naine') varied from 20.1 to 39.8% at Isabela. These parameters are considered intermediate to low in comparison with DI observed in Central America. This data indicates that local conditions at Isabela are less favorable for disease development in comparison with those of Central America regions.
Impacts
Sigatoka leaf spots represent the most serious threat for banana and plantain production in Puerto Rico, because local production relies on germplasm that is highly susceptible. It is estimated that Puerto Rican farmers are not yet prepared for proper management and control of Sigatoka leaf spots and that an epidemic will cause severe destruction and crop losses in the main banana and plantain industries, especially in the mountainous region. The main impact of this project is to provide local farmers with the technology needed to reduce the negative impact of Sigatoka leaf spots in the production of bananas and plantains. Research on this project will not only identify effective fungicides, but also may provide the Puerto Rican farmers with new products with different modes of action that can be used in a management spray program. Impact will be an increase in the efficiency in the control of the pathogen, and a delay in the development of fungicide resistance. Also,
this project will study the influence of weather on the spread, penetration, incubation, infection, and reproduction of the pathogen. This knowledge will be necessary for improving disease management and for reducing environmental contamination produced by the continuous use of chemicals, while maintaining agricultural productivity and profitability.
Publications
- No publications reported this period
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Progress 01/01/05 to 12/31/05
Outputs
This project was approved by the USDA and the Puerto Rico Agricultural Experiment Station in November 2005. Because the project is just starting we do not have any results.
Impacts
Sigatoka leaf spots represent the most serious threat for banana and plantain production in Puerto Rico because local production relies on germplasm that is highly susceptible. It is estimated that Puerto Rican farmers are not yet prepared for proper management and control of Sigatoka leaf spots. A Sigatoka epidemic would cause severe destruction and crop losses in the main banana and plantain industries especially those located in the mountainous region. This project is to provide local farmers with the technology needed to reduce the negative impact of Sigatoka leaf spots on the production of bananas and plantains. Research on this project will not only identify effective fungicides but may also provide Puerto Rican farmers with new products with different modes of action that can be used in a management spray program intended to increase the efficiency in the control of the pathogen and to delay the development of fungicide resistance. Also, this project will study
the influence of weather on the spread, penetration, incubation, infection, and reproduction of the pathogen. This knowledge will be necessary to improve disease management and to reduce environmental contamination produced by the continuous use of chemicals, while maintaining agricultural productivity and profitability.
Publications
- No publications reported this period
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