APIO (ARRACACIA XANTHORRHIZA BANCROFT) CORM ROT DISEASE IN PUERTO RICO: CHARACTERIZATION AND INTEGRAL MANAGEMENT FOR ITS CONTROL

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1009013
• Project Start Date: Jan 10, 2016
• Project End Date: Jan 9, 2018
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIVERSITY OF PUERTO RICO AT MAYAGUEZ
P. O. BOX 9000
MAYAGUEZ,PR 00681

Performing Department
Agroenvironmental Sciences

Non Technical Summary
The most ancient Andean crop in America, Arracacia xanthorrhiza Bancroft, has been grown in Puerto Rico since at least 1903 and has been known as "apio", owing to the similarity of its leaves with celery. Apio is one of the most traditional food crops for the central region with a large demand. Apio, containing approximately nine percent of protein, vitamin A precursors, and having four times more calcium than potatoes, is the most wanted root crop for the food industry because of its complex of starches, oils, mineral salts and easy digestibility. The central region was able to produce enough apio to cover internal and external demands before 2004 when the incidence of the corm rot disease caused from 50 to 100% yield losses. Each season the farmers experience less production and less availability of disease-free propagation material while the import of apio keeps increasing. Currently, the farmers lack an effective control for apio's corm rot disease. The objective of this project is to provide alternatives for the control of the disease and to increase the production of apio in the central region. Our long-term goal is to provide a stable source of income for our farmers, producing enough apio to cover in-house demands and its industrialization. This project aligns with one of the goals of the Department of Agriculture: to ensure food security and to promote local crops as an alternative source of nutritional food.

Animal Health Component

50%

Research Effort Categories

Basic

20%

Applied

50%

Developmental

30%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
212	1459	1160	25%
216	1459	1160	25%
202	1459	1080	50%

Knowledge Area
212 - Pathogens and Nematodes Affecting Plants; 216 - Integrated Pest Management Systems; 202 - Plant Genetic Resources;

Subject Of Investigation
1459 - Rhizomes, tubers, bulbs, and root crops, general/other;

Field Of Science
1160 - Pathology; 1080 - Genetics;

Keywords

arracacia xanthorrhiza bancroft

apio

corm rot disease

disease-free

micropropagation

propagation material

integrated control management

Goals / Objectives
The project goals are to identify the main causal agent for the disease, to provide alternatives for the control of the disease, and to improve apio's production yield for consumption, elaboration, and propagation.Our long-term goal is to provide a stable source of income for our farmers, producing enough apio to cover in-house demands and its industrialization. This project aligns with one of the goals of the Department of Agriculture to ensure food security and to promote local crops as an alternative source of nutritional food.1. To characterize and identify the main causal agent(s) of apio corm rot disease.2. To develop an integrated control management for the corm rot disease.3. To generate certified disease-free apio propagation material for the farmers.4. To develop an educational program for the integrated control management forextension agents and apio farmers at the central region of Puerto Rico.

Project Methods
To characterize and identifythe main causal agent(s) of apio corm rot disease.Apio farmer fields will be selected to collect samples of soil and tissue (corm, and roots) from symptomatic and asymptomatic plants to test nematode presence and identification. Nematode populations, plant-parasitic nematodes and free-living nematodes, will be assessed for four apio farms. Nematode populations will be extracted, using the Baermann's funnel method as described by Chavarría-Carvajal (1988). Populations will be expressed as a number of nematodes/100 cm3 of soil and number of nematodes/100 g of fresh tissue. To identify plant pathogenic bacteria, oomycete and fungi, soil and plant tissue (properly disinfected) samples will be processed to perform serial dilutions on nutrient broth media, 10-4 for bacteria and 10-3 for fungi, and transfer 100ul from the dilution into nutritive agar plates. Agar plates will contain specific selective media for bacteria and fungi, and for obligate biotrophic fungi and oomycetes plant tissue will be used as bait. Since bacteria and fungi occur in various forms, they are often expressed as colony forming unit per weight of tissue or volume of soil (CFU/g or CFU/cm3).To develop an integrated control management for the corm rot disease. After identification of the best candidate(s) causal agent(s), an experiment will be carefully selected and established at a farmer's field. The location will be selected from areas that have been previously planted with apio and in which the disease was present.The field experiment to evaluate the effectiveness of different treatments for the control of apio corm rot disease will consist of eight treatments arranged in a randomized complete block design(RCBD) with four replicates. Treatments will include 1. Solarization. 2. The combination of biological and chemical products. 3. Incorporation of cured compost from chicken manure and solarization. 4. Pre-treatment of the propagation material before planting. 5. Ground cover crops as pest and pathogen antagonists and as green manure, before planting. 6. Intercropping with a short cycle crop. 7. Integrated control management combining treatments; and 8. Absolute control (untreated plots). The effectiveness of each treatment will be established based on pathogen populations, disease incidence, considering the treatment effects on agronomic traits, such as harvesting and corm weight. To evaluate if there is a significant difference between treatments a statistical analysis will be run using Info Stat software.To generate certified disease-free apio propagation material for the farmers.The development for conventional plant tissue culture follows different stages. a.) Establishment, the plant tissue will be isolated from local varieties, from intact and healthier plants under sterile conditions the plant tissue will go through several reduction and disinfection steps until it is transferred on enriching media with nutrients to stimulate the growth. b.) Multiplication, the plant tissue is transferred from establishment to a media with different hormone types to stimulate the plantlets to produce new shoots for multiplication. It will go through repeated cycles of multiplication, thus, a single explant sample may be increased from one to four (1:4), or less, in four weeks. c.) Pre-transplant, this stage involves stimulation of the plantlets/shoots formed to produce roots and hardening under sterile environmental conditions. Apio rooting has been reported as a major challenge. d.) Hardening, this stage needs of a conditioned greenhouse that can provide the proper conditions for the plantlets adjustment, and allow the gradual exposition of them to the environmental conditions. After this stage, the plantlets will be ready for distribution to the farmers and be able to grown in the field.To develop an educational program for the integrated control management for the extension agents and apio farmers at the central region of Puerto Rico. We will elaborate brochures with information about the apio cultivation, the corm rot disease and instructions for the control of the disease. In collaboration with the agricultural extension agents from the central region, we will schedule training meetings for extension agents, and agricultural field days with the apio farmers to encourage them back to produce enough apio to cover domestic demands, export, and for commercialization of elaborated products. The strategy and outcomes from this project could be extended to other commodity crops.

Progress 01/10/16 to 01/09/18

Outputs
Target Audience:The target audience for this project are Extension Service Agents from Barranquitas, Orocovis, and Jayuya, as well as farmers of these municipalities and graduate students of the Agroenvironmental Sciences department at UPR-Mayaguez campus. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?I was invited to present at the 62nd Tropical Horticulture Meeting on September 7, 2016. "Adoption and Adaptation of an Andean Crop in Puerto Rico: Arracacia xanthorrhiza". It is published in the summaries of the meeting. Prepared a field day and a presentation on tissue culture at the EEA of Corozal for the 62nd Tropical Horticulture Meeting on September 9, 2016. Prepare a training on the results obtained in the first experiment for the control of apio corm rot aimed for agricultural agents and farmers interested in apio cultivation on February 7, 2017. At the EEA of Corozal. Participation at the American Phytopathology Society - Caribbean Division, from February 26 to March 1, 2017. As a poster presentation we showed the work in apio tissue culture and the student, Mayra Cathme, as an oral presentation talk about the first report of nematodes associated with apio corm rot. Both presentations were published in Phytopathology. How have the results been disseminated to communities of interest?Personal interactions with the farmers as well through theextension agents. Anew municipalityhave been included, Jayuya, as an opportunity to increase the disease-free propagation material and the apio production. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? 1. To characterize and identify the main causal agent(s) of apio corm rot disease. The results of this project, identified phytoparasitic nematodes associated with the cultivation of apio being Rotylenchulus reniformis the most frequent with a population density of 388 nematodes per cc. While other plant pathogenic candidates as bacteria and fungi presented a low population density, not significant for pathogenicity. From bacteria, Erwinia carotovora, Clavibacter michiganensis and Pseudomonas spp. were presented in the soil samples. And from fungi, was found Fusarium solani, Fusarium oxysporum, Rhizoctonia spp. y Rhizopus spp.. Based on these results we started the control experiment, and the treatments were oriented to decrease and control plant parasitic nematodes under the hypothesis that these were the main causal agent. 2. To develop an integrated control management for the corm rot disease. The best treatments to control the disease were: i) Use of compost with chicken manure & solarization; ii) Use as cover crops Crotalaria juncea and Tagetes patula and iii) The Integrated management practice. These three treatments showed the greatest reduction of populations of phytoparasitic nematodes, increase of populations of free-living nematodes (beneficial), increase the organic matter content in the soil, as well as the beneficial fungi populations, reduction in the severity and incidence of the corm rot disease and increase in crop yield. For the objective 2, during June and August 2015, we began to prepare the soil and some treatments at the experimental field in Barranquitas. The experiment was planted on September 8 of 2015, and we sent the last soil samples for analysis before harvesting on June 2016. A second experiment was started on September 26, 2017, at the same experimental plot in Barranquitas to test the use of an alternative crop for rotation and different composts to improve the soil and confirm the best strategy for the control of the apio corm rot disease. 3. To generate certified disease-free apio propagation material (seed) for the farmers. The standardization of the tissue culture protocol for apio was established and we obtain a total of 180 plantlets, but the greenhouse for the hardening phase didn't have the right environmental conditions or a controlled system that allow us to regulate this. As a result, the survival rate for the plantlets was 20% and these plantlets were utilized for a germination rate experiment to compare it with the seed from Jayuya and Barranquitas. The best germination rate was obtained from the tissue culture seed with a 99%, followed from the Jayuya seed with a 98%, and the lowest germination was from Barranquitas seed with a 45%. The laboratory infrastructure at the EEA of Corozal was lost after hurricane Maria last September, therefore we need to recover it to be able to produce and deliver certified disease-free apio seed for the farmers. 4. To develop an educational program for the integrated control management for extension agents and apio farmers at the central region of Puerto Rico. Outreach: We had a field day with the extension agents and farmers interested in apio production at the Agricultural Experiment Station of Corozal, on February 7 2017, to present the results of this project and our recommendations.

Publications

• Type: Journal Articles Status: Published Year Published: 2017 Citation: Martha C. Giraldo, Solving the Problem of Apio (Arracacia xanthorrhiza ) Corm Rot Disease. Biology, Earth and Environment Nov 29, 2017. https://doi.org/10.26320/SCIENTIA56
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: M Cathme, MC Giraldo, JA Chavarria-Carvajal, A Gonzalez Velez, Plant-parasitic nematode associated to corm rot disease of apio (Arracacia xanthorrhiza Bancroft) in Puerto Rico, Phytopathology, 2017, 107, 10.
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: MC Giraldo, L Sanchez, Establishment of disease free propagation material for Apio (Arracacia xanthorrhiza Bancroft) by tissue culture in Puerto Rico, Phytopathology, 2017, 107, 21.

Progress 01/10/16 to 09/30/16

Outputs
Target Audience:The target audience for this project are Extension Service Agents from Barranquitas, Orocovis, and Jayuya, as well as farmers of these municipalities and graduate students of the Agroenvironmental Sciences department at UPR-Mayaguez campus. Changes/Problems:From January 10th, 2017 the technician, Luis Sanchez, will not longer be able to work in this project. He worked since the beginning of the project in the establishment of the in vitro collection of apio, but since the collection needs to be renewed, we will begin the search for a new technician that can continue his job. What opportunities for training and professional development has the project provided?This project has provided the opportunity for the professional development oftwo graduate students by allowing them to complete their Master degree at the Crop Protection program. The students are Mayra Cathme, from Ecuador, who will defend her thesis this semester, and Paulina Andrea Cevallos, who just started in the Master program. How have the results been disseminated to communities of interest?Farmers and extension agents for the main apio producing municipalities of Barranquitas and Orocovis have been reached. A new region have been included, Jayuya, as an opportunity to increase the disease-free propagation material and the apio production. What do you plan to do during the next reporting period to accomplish the goals?1. To characterize and identify the main causal agent(s) of apio corm rot disease. For objective 1: we will analyze the results of the first field experiment to be able to conclude which is the most probable causal agent for the corm rot disease found at Barranquitas and Orocovis, and to perform the pathogenicity assays needed to test and prove the initial hypothesis. 2. To develop an integrated control management for the corm rot disease. For objective 2: We expect to have the results and conclusions from the first experiment by the first semester of 2017 and be able to generate a workshop on February 2017, oriented to farmers and extension agents, to present recommendations for apio production in the mountain region. For the second experiment, we will use disease-free propagation material of apio obtained from tissue culture and from farmers from Jayuya, where the disease has not been reported. The planting date will be during the first semester of 2017. 3. To generate certified disease-free apio propagation material for the farmers. For objective 3, we need to renew the current apio in-vitro collection and improve the steps and protocol for hardening the plantlets at the greenhouse before planting them in the field. 4. To develop an educational program for the integrated control management for extension agents and apio farmers at the central region of Puerto Rico. Nothing to report for the objective 4.

Impacts
What was accomplished under these goals? 1. To characterize and identify the main causal agent(s) of apio corm rot disease. For the objective 1, we evaluated the population of plant pathogenic candidates present in the soil before beginning the treatments and we found a population density of 388 nematodes per cc of the plant phytoparasitic nematode, Rotylenchulus reniformis. Other plant pathogenic candidates, as bacteria and fungi, presented a low population density, not significant for pathogenicity. From bacteria, only Erwinia spp. was commonly present in the soil samples. And from fungi, Fusarium spp and Verticillium spp. were found. Based on these results we started the control experiment, and the treatments were oriented to decrease and control plant parasitic nematodes under the hypothesis that these were the main causal agent. 2. To develop an integrated control management for the corm rot disease. For the objective 2, during June and August 2015, we began to prepare the soil and some treatments at the experimental field in Barranquitas. The experiment was planted on September 8 of 2015, and we sent the last soil samples for analysis before harvesting on June 2016. A second experiment was started on September 26, 2017, at the same experimental plot in Barranquitas to test the use of an alternative crop for rotation and different composts to improve the soil and test the best strategy for the control of the apio corm rot disease. 3. To generate certified disease-free apio propagation material for the farmers. For the objective 3, we have the standardization of the tissue culture protocol for establishment and multiplication of yellow and white apio. 4. To develop an educational program for the integrated control management for extension agents and apio farmers at the central region of Puerto Rico. Nothing to report for the objective 4.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Cathme M., Martha C. Giraldo,, Jos� A. Chavarr�a-Carvajal and Agenol Gonz�lez-V�lez."IDENTIFICACI�N DEL AGENTE CAUSAL Y M�TODOS DE CONTROL PARA LA PUDRICI�N DEL CORMO EN APIO (Arracacia xanthorrhiza Bancroft) EN PUERTO RICO". One oral presentation at the 2016 Proceedings of the annual scientific meeting of the Puerto Rican Society of Agricultural Sciences, Puerto Rico. [e-mail]
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Giraldo Martha C. and Luis A. Sanchez."IDENTIFICACI�N DEL AGENTE CAUSAL Y M�TODOS DE CONTROL PARA LA PUDRICI�N DEL CORMO EN APIO (Arracacia xanthorrhiza Bancroft) EN PUERTO RICO". One poster presentation at the 2016 Proceedings of the annual scientific meeting of the Puerto Rican Society of Agricultural Sciences, Puerto Rico.