Grant Information
| Knowledge Area | Subject of Investigation | Field of Science | Percent |
|---|---|---|---|
| 205 - Plant Management Systems | 999 - Citrus, general/other | 1020 - Physiology | 50% |
| 212 - Pathogens and Nematodes Affecting Plants | 999 - Citrus, general/other | 1160 - Pathology | 25% |
| 216 - Integrated Pest Management Systems | 999 - Citrus, general/other | 1160 - Pathology | 25% |
Citrus fruit production ranks second in Puerto Rico with 7,000 acres planted in 2012. The annual harvest of 60-70 million fruits is valued at $ 8,6 million. Citrus are produced in Puerto Rico on 2,000 farms by 700 farmers mainly in the mountainous region of the island. Citrus Greening (CG) was first detected in Puerto Rico in 2009, since then the disease has spread throughout the Commonwealth. The disease is associated with Candidatus Liberibacter asiaticus vectored by the Asian Citrus Psyllid (ACP). In Puerto Rico this devastating disease in combination with Citrus Tristeza Virus (CTV) has caused a 40% decrease in production which threatens future investment in the citrus orchards. The most severe losses due to the disease are found in the areas of San Sebastián and Lares. In well maintained orchards in the mountainous region, citrus growers still continue to produce high quality fruit. Citrus Greening and other graft transmitted diseases are present in nurseries in the Island and are the most important source of disease dissemination. The establishment of scion groves and citrus nurseries free of graft transmitted diseases is essential to produce healthy citrus plants. The Department of Agriculture in Puerto Rico will endorse only nursery production of citrus trees in protected greenhouses. Research in protected structures under Puerto Rico's climatic conditions is also needed to accelerate growth and production of citrus trees as well as to implement a certification program. In order to sustain citrus production in Puerto Rico this project will develop a program for the production of healthy citrus plants and to strengthen citrus disease detection capabilities, thus mitigating the introduction and establishment of citrus diseases in Puerto Rico. The use of clean propagative material involves strict quarantine and implementation of a certification program adjusted to the needs of the local citrus industry. The aim of this project is to establish the production of healthy budwood and nursery plants and support the certification of foundation groves and plants free of Citrus Greening (CG), Citrus Tristeza Virus (CTV), Citrus Variegated Chlorosis (CVC), Citrus Psorosis Virus (CPV) and Citrus Leprosis Virus (CLV). This project will establish the testing of mother plants, budwood and nursery plants to certify that they are free of diseases. The maintenance and distribution of true-to-type primary citrus propagative material of the commercially important cultivars will rely on the collaborating Experiment Stations and this project will support this initiative. The pathogen detection in propagative material in the foundation groves and nurseries in the Adjuntas, Corozal and Isabela Experiment Stations--the major sources of citrus plants for the nursery of the Department of Agriculture-- will contribute to the Citrus Industry in Puerto Rico. At present, there are no protocols in the island for production of citrus in screen protected greenhouses, and citrus production in nurseries requires minimum investment consisting of the use of black plastic bags and field soil as a growth media. This project will evaluate different growth media and good agronomic practices to produce citrus plants. The citrus industry has been declining by the presence of different diseases. It is important to develop new strategies for the propagation and management of nursery plants on screen protected houses that can be cost effective and reduce production time. The use certified citrus plants and the development of new propagation strategies will increase the number of nurseries with disease free plants. The knowledge obtained in this project and the importance of the use of disease free citrus plants will be taught to citrus growers and Extension professionals. The production of disease-free citrus plantings and clean stocks will sustain citrus production in Puerto Rico.
Objective 1. Will be carried out for the foundation groves in the Agricultural Experiment Stations (AES) at Isabela and Adjuntas. Mother trees kept in insect-proof screenhouses will be tested twice a year for Candidatus Liberibacter asiaticus (CLA) using Conventional Polymerase Chain Reaction (PCR) with specific primers OI1 and OI2. Serological methods will be used for detection of Citrus Tristeza Virus (CTV) (TAS-ELISA), Citrus Variegated Chlorosis (DAS-ELISA) and Citrus Canker (PCR); these will be carried out once a year. Mother trees will also be examined for Citrus Psorosis Virus (CPsV) and Citrus Leprosis Virus (CLV) using biological indexing and confirmation by PCR. The mother trees to be certified at the AES collection comprises the orange varieties: Hamlin, Rose Red Rhode, Valencia, Valent, Washington Navel, Pera, Marrs Early, Valencia Cambert, Lane Late (Nevo) and Trovita. For mandarine: Encore, Murcott (honey tangerine) Clementina Fina, Clementina Marisol, Nova and Dancy. For Tangelo, two varieties Orlando and Seminol, and for Lime: Mexican Lime, Giant Key Lime, Lima Tahiti (Persa), Variegated Pink Lemon and Seedless Mexican. The Limes are: Limon "Improved Mayer", C-35, C32, "Swingle", "Carrizo" and Fly Dragon. In grapefruit, two cultivars Star Ruby and Rio Red. In addition, two ornamentals: Kumquat and Calamondin. Scion trees infected with a pathogen will be removed from the foundation groves. Propagation material from each source tree will be maintained in nursery rows and they will be registered. The expected outputs will be the number of mother plants analyzed, registered propagative material, and analyses conducted in the different citrus species. Knowledge about the absence of pathogens in mother plants for budwood production and nursery plants will create confidence for the citrus growers to continue investing in citrus production in Puerto Rico.Objective 2. At the Isabela, Adjuntas and Corozal Experiment Stations, increased trees will be maintained in a screened greenhouse. The analysis of graft transmissible diseases in seedlings and increased trees will be carried out once a year from the nurseries of the AES for CLA, CTV and CVC. The nursery of the State Department of Agriculture will also be included. In the commercial nurseries, Enseñad where 10% of the plants will be sampled from each of the different citrus species and will be sampled evenly distributed in the blocks. The expected outputs will be the number of citrus plants analyzed and the budwoods distributed.Objective 3. With the purpose of accelerating root mass growth, Carrizo (C. sinensis x P. trifoliate) and Swingle citrumelo (C. paradise Macf. X P. trifoliate) rootstocks will be evaluated. First, seeds germinated in Promix will be transplanted in different combinations of: sand, compost, rice hulls, peat moss, bagasse, composted poultry manure, coco peat, coffee parchment skin or "pergamino". Each component and the mixes will be analyzed for physical and chemical properties. The best media combination based on substrate aeration, total porosity, water holding capacity and chemical properties (pH and EC) will be selected. These combinations will be compared with the standard used in Puerto Rico of Promix® and sand (2:1) as a control. Rootstocks liners will be planted in 4"x 4"x12"pots. Each media/rootstock combination will be fertilized with either slow release fertilizer or fertigation and treatments will be arranged in four blocks in a randomized complete block design. Cost of all the materials and production methods will be recorded to evaluate the profitability of the methods.
Target Audience
Citrus growers and the general public. The Citrus Grower's Association. The Puerto Rico Dept. of Agriculture citrus program. Researchers and Extension Specialists that attend meetings. Undergraduate and graduate students. Pontifical Catholic University of Puerto Rico, Biotechnology Program-CEIBA.
Changes / Problems
Hurricane Maria had a major impact in the project nurseries and growers orchards. The Enseñat nursery did not continue operations, due the high costs for restoration after Hurricane Maria. In replacement the PRDAG supported private growers (Rubén RamÃrez, "Hacienda RamÃrez", Raúl Toledo Vélez. "La Hacienda Citrus Inc." and José L. Torres, "Hacienda Los Eucaliptos" to continue with the production of citrus plants under screen-protected structures.
Training & Professional Development
Graduate students Diana Intriago Mendoza and Sandra Arce completed their Msc. degree program with project funds. Lab Technician Olga Gonzalez was trained in qPCR for detection and quantification of HLB. Melisa Feng, undergraduate student was trained in the DNAble HLB detection test. Citrus Growers received information about the best agronomic practices to produce healthy citrus plants in nurseries.
Dissemination Streams
Graduate student Diana Intriago Mendoza presented her oral exam and research findings. Sandra Arce, graduate student presented her oral exam and research results in two forums attended by citrus growers and students. Participation in the Annual Fruits Commodity Group Meeting, 2018. Meetings held with the Extension Service Specialists and personnel of the PRDAG. Dissemination of protocol about sample collection for Huanglongbing detection, directed to citrus growers and the general public Three meetings with citrus growers and personnel of the "Fruits Program" of the Puerto Rico Department of Agriculture were conducted in September 21, October 18 and November, 2018. During the meetings the steps towards the prevention of the psyllid and HLB in citrus nurseries were included in the presentations. Dissemination of results of the project in a citrus workshop conducted in the experiment Station of Isabela directed to 44 growers and Extension educators.
Next Reporting Steps
Nothing Reported
Target Audience
Citrus growers and the general public who plant "tested" citrus plants from nurseries of the Experimental Stations of UPRM and the Puerto Rico Dept. of Agriculture citrus program. Researchers who test citrus budwood prior to the establishement of citrus experiments. Publications and presentations at scientific meetings to diseminate results of the project. Undergraduate and graduate students who receive training in the HLB testing.
Changes / Problems
The Enseñat nursery will not continue operations temporary, due the high costs for restoration after Hurricane Maria. In replacement the PRDAG will support private growers (Rubén RamÃrez, "Hacienda RamÃrez", Raúl Toledo Vélez. "La Hacienda Citrus Inc." and José L. Torres, "Hacienda Los Eucaliptos" to continue with the production of citrus plants under screen-protected structures.
Training & Professional Development
Graduate student Diana Intriago Mendoza has completed her research: 1. Quantification of the titer of Candidatus Liberibacter asiaticus of RICO varieties. 2. Evaluation of Huanglongbing in eight mandarin genotypes (Citrus reticulata Blanco) grafted onto three rootstocks. The PI prepared an abstract for the 6th International Huanglongbing Conference in Riverside, CA to present project results and discussed findings with the participants. The PI participated in an online Tier 2 annual meeting (June 5th) of the Citrus Clean Plant Network and presented progress in the testing of citrus plants.
Dissemination Streams
The Pamphlet of "how to collect samples for Huanglonbing detection" provides a set of recommendations for the accurate diagnostics as well as for the proper collection of leaf samples for HLB identification. Three meetings with citrus growers and personel of the "Fruits Program" of the Puerto Rico Department of Agriculture were conducted in September 21, October 18 and November, 2018. During the meetings the steps towards the prevention of the psyllid and HLB in citrus nurseries were included in the presentations.
Next Reporting Steps
1. To conduct the monthly meetings with citrus growers moving towards the continuation of the testing of citrus plants in commercial nurseries. 2. Prepare a manuscript with the findings of the tolerance/resitance of the citrus RICO cultivars. 3. To submitt a manuscript for publication entitled: Evaluation of Huanglongbing in eight mandarin genotypes (Citrus reticulata Blanco) grafted onto three rootstocks. 4. To prepare a pamphlet in how to manage ACP and HLB in citrus plant after leaving the nursery. <br><br>
<br>What was accomplished under these goals? Objective 1. In Adjuntas and Corozal Substations, mother plants were re-tested for HLB. The Citrus spp. collection in Corozal composed of 77 varieties were tested for CLAs' and all were negative. These varieties were under screen during the storm and the damage was minimal allowing the protection of the plants. Selected cultivars from this collection was used to start a new collection of Citrus spp. that is already in Isabela in a screen-proof nursery. The testing of this material was completed for CLAs. From Isabela a total of 47 composite samples of diferent genotypes were tested free of HLB. In Adjuntas leaf samples of 375 mother plants were collected. Citrus cultivars tested were: Cara-Cara, Vengasay Lemon/HRS898, Marrs Early, Rio Red, Clementina, Encore, Cidra Etrog/Swingle, Pink Variegate Lemon, Thaiti, Nagami Kumquat, Swingle, Mexican Lime, Rhode Red Valencia, Volckameriana, Improved Meyer, Cleopatra, C-32/HRS897, Washington Navel, Minneaola tangelo, Sedlees Lisbon, Fly Dragon, Torvita, Giant Key Lime, Lane Late, Hamlin, Smooth Flat Seville, Pera, Honey, Valencia Campbell, C-35/HRS897, C-32/HRS897 and Orlando Tangelo. Objective 2. The testing of citrus diseases in budwood and trees of commercial nurseries was not continued, the nurseries are being re-built. At the present the only commercial citrus varieties grown under protected structures are at the Adjuntas and Isabela Experiment Stations of the University of Puerto Rico. Objective 3. In Corozal an evaluation of citrus rootstocks and substrates concluded. Results determined the effect of different substrated mixes and fertilizer (18-6-2) treatments 5.6 g and 8.5 g on the rootstocks Carrizo citrange and Swingle citrumelo. The substrate that contained 33% rice husks was not efficient in the growth of the rootstocks. Carrizo presented better growth on a coffee compost mixture of Promix + sand + coffee compost (1:1:1). Swingle outperformed on rice husk consisting of Promix + sand + rice husk (1:1:1). Rhode Red Valencia"grafted on Carrizo with the coffee substrate increased dry weight. Montlhy meetings with citrus nursery growers were accomplished and the steps towards the prevention of the psyllid and HLB in citrus nurseries were included in two presentations. Two peer reviewed publications resulted from the project. <br><br><b>Publications</b><br>
Target Audience
Citrus growers, Researchers, Extension Agents, Department of Agriculture personnel, undergraduate and graduate students and homeowners.
Changes / Problems
The webinar series planned were not accomplished, due to internet limitations. Plans are to publish two brochures with Citrus Diseases and management directed to Citrus growers and the general public.
Training & Professional Development
Graduate student Diana Intriago Mendoza was trained in "cloning" for rDNA sequences of Candidatus Liberibacter asiaticus and in the Optimization of the Real Time PCR protocols. The training was in the University of Puerto Rico Biology Department. Diana Intriago Mendoza a Master's student presented her Thesis research progress at the Caribbean Food Crop Society Annual Meeting held in San Juan in July 2017. The PI participated in the 5th International Huanglongbing Conference in Orlando, US and presented project results and discussed findings with the participants. The PI participated in the Clean Plant Diagnostic Network meeting in Orlando and presented the accomplishments of the project. The Co-PI attended the Caribbean Food Crops Society Meeting in San Juan, PR, July 2017, and presented project research results.
Dissemination Streams
Field day directed to school and undergraduate students In Corozal Station. Meetings with attendance of Researchers, Citrus Growers and Extension Service in Isabela Station disseminating project results and agronomic practices for HLB management. Citrus producers received information about the best agronomic practices important to produce healthy Citrus plants in nurseries. An informative meeting about the progress of the project for a multidisciplinary group or researcher working in Citrus, this meeting was held on January in Corozal Station. During the Citrus Clean Plant Network meeting in Orlando, Fl., a presentation in the progress of the certification program of Citrus plants grown in nurseries in Puerto Rico.
Next Reporting Steps
Training activities: The graduate student Diana Intriago Mendoza will be trained in the use of Electron Microscopy to document colonization of Candidatus in Citrus. This activity will be carried out at the University of Puerto Rico Biology Department. The PI will attend the International Plant Pathology Conference in Boston, August 2018. The graduate student will attend the International Mycology Conference in San Juan, July 2018. The PI, Co-PI and graduate student will attend the Annual SOPCA Scientific Society meeting in Puerto Rico, 2018 <br><br>
<br>What was accomplished under these goals? Project objectives aimed to establish a certification and clean stock program for citrus propagative material of commercial varieties in collaboration with the Citrus Clean Plant Network (CCPN) were accomplished. Objective 1. Currently, the Substation Adjuntas maintains the foundation of 20 commercial varieties, under screen protected structures which provides Citrus growers and the Puerto Rico Department of Agriculture (PRDA) with tested Citrus spp. plants for multiplication and sale. The Isabela Station provides with buds of commercial varieties. These commercial varieties are the foundation for new Citrus plants to be distributed by the PRDA to Citrus growers. At the experiment stations in two protective screen houses approximately, 20,000 pathogen-tested Citrus spp. plants were produced in 2017. Cultivars included rootstock/scion: Swingle/Encore, Swingle/Road Red Valencia, Swingle/Cara Cara. Other cultivars included: Mexican Swingle, Mexican 812, Mexican 897, Valencia Campbell Swingle, Valencia Campbell 812, Valencia Campbell 897, Cleopatra Fina 812, Nebo, Trovita, Marrs' Early, Chironja and Pera. The tests for Candidatus Liberibacter asiacticus (CLAs) were conducted using conventional Polymerase Chain Reaction (PCR) and the DNAble Molecular Detection Kit for HLB Liberibacter asiaticus (EnviroLogix) for the commercial nurseries. The tests for Citrus Tristeza Virus (CTV) and Citrus Variegated Chlorosis (CTV) were carried out with serological assays (AGDIA). The increased capacity to produce Citrus spp. planting material through the establishment of diseased-tested citrus material is contributing to the planting of healthy Citrus in Puerto Rico. Objective 2. The testing of citrus diseases in budwood and trees of commercial orchards and nurseries. Commercial citrus varieties grown under protected structures at Adjuntas and Isabela Experiment Stations were inspected for graft-transmissible diseases in Las Marias, Santa Isabel, Utuado and Castaner. Citrus plants were tested for CLas, CVC, and CTV. This determination helped the growers to select disease free for multiplication in nurseries in "La Balear" (Hamlin, Chironga, Navel and Valencia). At " Finca Utuado" (Swingle/Thaiti, 798/Thaiti, 792/Encore, 794/Encore, 756/Thaiti and Rod Red Valencia) were tested free of CLAs, CTC and CVC. At a nursery in Santa Isabel, Thaiti budwood was tested. Objective 3. Evaluation of Citrus growth in different containers size to assess the current nursery practices and improve the recommendations. The experiment was conducted at the Agricultural Experiment Station citrus screened nursery in Corozal, Puerto Rico. Three citrus rootstocks were evaluated: Carrizo citrange (Citrus sinensis [L.] Osbeck x Poncirus trifoliata), Swingle citrumelo (Citrus paradise Macf. x Poncirus trifoliata) and HRS 812 (Citrus reticulate x Poncirus trifoliata [L.] Raf.). After three months of growth the seedlings were transplanted to five different containers. Half of the treatments were also fertilized with 6.19 grams of Triple superphosphate (0-45-0) on the hole before planting. Height and diameter of the trunk were measured every two weeks for eight months after planting. Plants grown in the larger container were significantly greater in height and diameter (measured with a caliper) than the others. The addition of fertilizer also increased height and diameter significantly. HRS 812 grew taller but had the smallest diameter. Swingle had the largest diameter. These results demonstrate that plant growth can be reduced by the reduction of container volume. Plants grown in a larger container with healthier and more robust root systems may be needed to survive the transplanting stress and exposure to citrus greening in the field. A field study to automate the process of evaluation of Citrus trees employing a color camera onboard a unmanned aerial vehicle (UAV) to acquire images of a citrus orchard located at the Substation Fortuna, Puerto Rico was concluded. The images were taken from the UAV at an altitude of 100 feet. Plant height, canopy coverage area and stem diameter were manually recorded for comparison with the parameters determined from the UAV images. The observed plant parameters correlated well with the determined plant parameters from the color UAV images. The average errors in measurements were 22.4%, 14.5% and 47.5% for the plant diameter, plant height and plant canopy volume. Huanglongbing severity was evaluated to identify the effect of nutrient management on the disease. Evaluation of Citrus growth in different pot sizes and liners in progress. <br><br><b>Publications</b><br>
Target Audience
Citrus growers, Agricultural Agents, Department of Agriculture personnel, undergraduate and graduate students and homeowners.
Changes / Problems
The webinar series have not been released due to problems with internet conection speed.
Training & Professional Development
A Master student and the Co-PI participated in the Citrus Expo in Florida, August 2016. They attended oral presentations and learned about HLB management, visited the nursery production facilities, and learned about new products for citrus production. The graduate student Diana Intriago Mendoza received a training in Candidatus Liberibacter asiaticus detection using PRC and Real time PCR.
Dissemination Streams
Results have been shared by several field days with school students, undergraduate university students, and Extension Service urban gardening short courses. Participants have learned about HLB, the importance of citrus production in Puerto Rico, and about the current stage of the research program.
Next Reporting Steps
Results from objective two about different pot sizes on citrus tree liners. Continuing with objective three (study staking and grafting techniques to accelerate growth of citrus trees) with a new master student. The graduate student Diana Intriago Mendoza will receive a training in "cloning" for rDNA sequences of Candidatus Liberibacter asiaticus in the UPR Biology Department. <br><br>
<br>What was accomplished under these goals? Project objectives were aimed to establish a certification and clean stock program for citrus propagative material of commercial varieties. The University of Puerto Rico (UPR) at the Substations of Isabela and Adjuntas maintain a foundation of 20 commercial varieties, a collection of 33 accessions of Citrus spp. under screen protected structures. These commercial varieties and the collection were tested, with the support of HATCH and the Citrus Clean Plant Network, for Candidatus Liberibacter asiaticus (CLAs), Citrus Tristeza Virus (CTV) and Citrus Variegated Chlorosis (CVC). At the experiment stations in two protective screen houses approximately, 6,000 pathogen-tested Citrus spp. plants were produced in 2016. Cultivars included rootstock/scion: Swingle/Encore, Swingle/Road Red Valencia, Swingle/Cara Cara. Other cultivars included:, Nebo, Trovita, Marrs' Early, Chironja and Pera. The tests for Citrus Greening were conducted using conventional Polymerase Chain Reaction (PCR) with the primer set OI1/OI2c. The DNAble Molecular Detection Kit for HLB Liberibacter asiaticus (EnviroLogix)TM was used for the commercial nurseries. The tests for Citrus Tristeza Virus and Citrus Variegated Chlorosis were carried out with serological assays (AGDIA). The increased capacity to produce Citrus spp. planting material through the establishment of diseased-tested citrus material is contributing to the planting of healthy Citrus in Puerto Rico. 2. The testing of citrus diseases in budwood and trees of commercial orchards and nurseries was conducted in the Finca Ensenat of the Puerto Rico Department of Agriculture for 7,000 Citrus spp. rootstocks. A total of 3,000 plants were tested for release to growers in May 2016. Three growers nurseries were tested during 2016. "La Balear" (Hamlin, Chironga, Navel and Valencia) and " Finca Utuado" (Swingle/Thaiti, 798/Thaiti, 792/Encore, 794/Encore, 756/Thaiti and Rod Red Valencia) were tested free of CLAs, CTC and CVC. At a nursery in Santa Isabel, 1,000 Thaiti budwoods were tested. 3. Another goal of the project was to evaluate the growth in different pot sizes using different substrates. The media mix with 33% coffee compost was recommended versus the control media composed of sand and peat moss for the production of citrus tree liners under protected structures. The rice hulls on the media caused a detrimental effect on the citrus plant growth. Coco-peat in the media and compost had similar results, with the control media based on sand and peat-moss. Evaluation of the use of different pot sizes is still in progress. Data has been collected and the final harvest was scheduled for January 2017. <br><br><b>Publications</b><br>
Target Audience
Citrus Growers Extension Specialists Agricultural Agents Orange juice marketers Homeowners
Changes / Problems
Nothing Reported
Training & Professional Development
Two graduate students were mentored during their first year of their Master degree program.
Dissemination Streams
In collaboration with the Puerto Rico IPM program the results of this project were disseminated to Citrus Growers, Extension Specialists and Researchers. The project PI presented talks about Systemic Citrus Diseases and the importance of the use of Healthy Citrus Plants. The project CoPI participated with a presentation of the Status of the Citrus Program in PR. The PI and Co-PI participated in Professional Annual Meetings, presenting results of this project and establishing networks with other researchers and projects involved in citrus research.
Next Reporting Steps
Objective 1. Continue with the annual inspections and analyses in the Adjuntas and Isabela nurseries and orchards. Support conservation and evaluation of the Citrus Germplasm Collection in Rio Piedras and Adjuntas. Objective 2. Start the inspections and disease certification of the Department of Agriculture "Ensenat" and growers nurseries in Coamo, San Sebastian, Utuado and Las Marias. Objective 3. Disseminate results of the findings and prepare publication. Objective 4. Continue with the evaluation of the different containers and the selected substrates. Objective 5. Prepare the Webinar "Diseases in Citrus". <br><br>
<br>What was accomplished under these goals? 1. To establish a certification and clean stock program for citrus propagative material of commercial varieties. Twenty seven varieties from the Isabela nursery were inspected and declared free of diseases: Carrizo/HRS 850, Swingle/Tahiti, Swingle/Mandarina Nova, Limón de Cabra, Mandarina Nova, HRS 812/Tahiti, Campbell/Valencia, Carrizo/Mexican Lime, Campbell Mucela, Campbel/Valencia, Campbell Swingle, Campbell/Meyer, Improved Meyer, Carrizo/Murcot, Clementina Fina, Carrizo/Clementina, Marizon/Swingle, Flying Dragon, Thornless Mexican Lime, Pink Lemon, Lane Late, Washington Navel, Clementine Algerica, Rhode Red, Mineola, Marr's Early/HRS 812, HRS-957, Hamlin, Encore, Orlando and Cara Cara . All were negative for C. L. asiaticus (CLA), CitrusTristeza Virus (CTV) and the Citrus Variegated Chlorosis. At the Adjuntas nursery, 2% of the 3,000 citrus plants were tested for CG, CVC and CVT and were declared disease free. Also mother plants were analyzed and found healthy. cultivars included: rootstock/scion: Swingle/Encore, Swingle/Road Red Valencia, Swingle/Cara Cara. In addition analyses were carried out in varieties Trovita, Marrs' Early, Chironja and Pera. At Corozal, improved cultivars Urayer, C35, Valencia Campbell, Dancy Frost Nucellas, C-32, Swingle, Hamlin and Limón TahitÃwere tested for CG, CVC and CVT . At the Isabela nursery 5% of the 3,000 citrus plants were analyzed for the same diseases and all were declared disease free and sold to citrus growers. 2. To develop a strategic plan for analysis of citrus diseases in budwood and nursery trees for commercial growers and nurseries aimed to produce disease free citrusplants. La "Balear" nursery and orchard were visited and analyses for CLA, CVC and CTV were carried out in rootstocks and mother plants. This determination helped thegrower to select disease-free Hamlin, Chironja, Navel and Valencia cultivars for multiplication. 3. Evaluate different container types, sizes and combinations of media and fertilizer to improve root mass of citrus rootstocks to accelerate growth of citrus rootstock calipers and graft the cultivars sooner than traditional production. In this study the effect of different substrate compositions were studied in the growth of citrus rootstocks, Carrizo Citrange and Swingle Citrumelo. The treatments included were: (1) a control that included a commercial substrate + sand (1:1), and the treatments (2) commercial substrate + sand + coconut (1:1:1), (3) commercial substrate+ sand +coffee compost (1:1:1) and (4) commercial substrate + sand and rice. The treatments were compared with 5.6 g and 8.5 g of 18-6-12 (NPK) in Carrizo Citrange and Swingle Citrumelo. Citrus plants from the Carrizo Citrange and Swingle Citrumelo that included the coffee compost, increased their caliper diameter when compared with the control. <br><br><b>Publications</b><br>
Target Audience
Puerto Rico Citrus Growers Association Extension Specialists Puerto Rico Department of Agriculture Researchers
Changes / Problems
Nothing Reported
Training & Professional Development
During this reporting period the project PI attended the Fruit Commodity Group Annual meeting and presented a talk about the Citrus Certification Program. The project PI contacted the National Clean Plant Network and presented a justification to include Puerto Rico in the Citrus Network.
Dissemination Streams
The results of the analysis conducted in the Germplasm Bank of the Isabela Experiment Station and the parent citrus trees of the Adjuntas Experiment Station were presented at the Annual Fruit Commodity Group on December.
Next Reporting Steps
For objective 1, in the next reporting period plans are to complete the analysis of the Parent trees for severe strains of Citrus Tristeza Virus and to begin the disease testing of the "Ensenad" citrus nursery of the Department of Agriculture in Las Marias. Also to support citrus growers that produce their own rootstocks with the testing of parent trees and nursery plants. For objective 3, a graduate student was hired to start the evaluation of different container types, sizes and combinations of media and fertilizer. For objective 4, the study of staking and grafting techniques to speed up scion growth on citrus rootstocks will be carried out in Corozal Experiment Station. For Objective 4. For the next reporting period the plan is to prepare the Webinar in Citrus Greening and to complete the "Conjunto Tecnologico de Citricos" in collaboration with the Commodity Group Leader. The Co-PI of the project will participate in the International Citrus Greening Conference in Orlando, Florida. <br><br>
<br>What was accomplished under these goals? • Two visits to the Citrus orchard of Parent trees of the Adjuntas Experiment Station were conducted. • Observations of the parent material, phytosanitary status and vigor were carried out and 45 citrus samples were collected for testing. • The parent trees were free of symptoms of graft-transmissible pathogens based on the initial visual inspection; gummosis, citrus blight, citrus canker, citrus greening, decline, leprosis and evidence of unacceptable bud mutation. • The laboratory analysis was carried out at the Plant Disease Clinic (Juana Diaz Experiment Station) for Citrus Greening (Polymerase Chain Reaction or PCR), Citrus Tristeza Virus (DAS-ELISA) and Citrus Variegated Chlorosis (DAS-ELISA). Parent trees that were positive for Citrus Greening and Citrus Tristeza Virus (CTV) were eliminated and healthy trees were covered by insect- proof screen. Parent trees of exceptional characteristics will be separated to conduct shoot-tip grafting or other acceptable techniques to eliminate graft-transmissible pathogens. • The Citrus Germplasm Bank of the Isabela Experiment Station was tested twice for citrus greening (PCR and Real time PCR), Citrus Tristeza Virus (DAS-ELISA) and Citrus Variegated Chlorosis (DAS-ELISA, results were negative for all three diseases. <br><br><b>Publications</b><br>