Progress 09/01/05 to 08/31/08
Outputs
This was the first study of the diseases and pests in soybeans in Puerto Rico. It was the first project to implement molecular diagnostics of soybean rust and other diseases in Puerto Rico. APHIS/PPQ, the State Department of Agriculture and the seed industry in Puerto Rico were the primary end users of the developed protocols and the research outcomes of the project. The findings of this project were disseminated in workshops directed to APHIS/PPQ, State Department of Agriculture and Seed Companies. The project activities led to the detection of soybean rust in Puerto Rico from the sentinel surveillance plots. Two workshops were organized per year to train winter nursery inspectors for the detection of soybean rust and other soybean diseases. Results of the project were presented in National and International meetings. Eight abstracts were presented at the annual scientific meetings of the Puerto Rican Society of Agricultural Sciences (SOPCA) at the University of Puerto Rico. In the 2009 annual meeting, with an audience of 150 people, a graduate student working in the project received the award for the best oral presentation. Attendance to the Annual American Phytopathology Society (APS) meetings with project results resulted in a travel award in 2008. Weekly visits to the sentinel plots were important for collecting information on the presence of soybean diseases and for soybean rust surveillance in Puerto Rico. This information was shared with the Seed Industry and served as a network with Extension Specialists.
Impacts
Surveillance of Asian Soybean Rust (ASR) caused by Phakopsora pachyrhizi was conducted in 21 municipalities and in sentinel plots from 2005 to 2008 in Juana Diaz (JD), Adjuntas (Ad.) and Isabela (ISA) Experimental Stations. Lablab purpureus was the legume most commonly found infected with P. meibomiae (63 percent of positive samples). DNA extracted from leaf tissue showed amplification of a 330 bp amplicon for P. meibomiae. ASR was neither detected nor identified in sentinel plots or in 42 wild legumes surveyed in Puerto Rico. These results were confirmed by Polymerase Chain Reaction (PCR) using primers Ppa1, Ppa2, Pme1 and Pme2. The virulence of P. meibomiae on eleven of fifteen species artificially inoculated was confirmed by PCR; Phaseolus vulgaris and P. lunatus produced the shortest incubation (IP) and latent periods (LP). Phaseolus vulgaris also presented the highest number of uredinia per individual lesion. Crotalaria retusa had the longest IP, whereas Rhynchosia reticulata showed the longest LP. An immune reaction was observed in Pueraria phaseoloides, Cajanus cajan, Canavalia gladiata, Mucuna pruriens, Vigna vexillata. Crotalaria pallida, Pachyrhizus erosus, Vigna luteola, Phaseolus lunatus and Macroptilium lathyroides were found naturally infected with P. meibomiae and exhibited different types of lesions. Phakopsora pachyrhizi was never detected in any legume studied in the three years of the project. Prevalent pathogens causing diseases in soybean were Sclerotium rolfsii, Cercospora sojina, Peronospora manshurica and Xanthomonas campestris pv. glycines. Soybean stem necrosis caused by Carlavirus was identified and characterized for the first time in the southwest vegetable production area of Puerto Rico. Stunting and stem necrosis were observed at V3 as vein and petiole necrosis progressing to leaf chlorosis. Necrotic lesions developed in the stem followed by systemic necrosis leading to plant death before reaching the reproductive stage. When infection occurred in later stages of development, dark spots appeared and pods failed to fill. Viral RNA was extracted from symptomatic plants by using Reverse transcription (RT)-PCR. Electrophoresis was carried out in an agarose gel (1%). The samples amplified for the Carlavirus group. In the sentinel plots 16 species of arthropods representing 13 different genera were identified in soybean. In the Coleopteran order the American beetle, Systena basalis, was the most abundant species in Ad. The green beetle, Diabrotica graminea, in Ad. and JD. The bean beetle, Cerotoma ruficornis, was common at all locations. In the Lepidoptera order: Omiodes indicata, Spodoptera ornitogalli and Spodoptera sp., and in Ad, Spodoptera ornitogalli. Common species in the Thysanoptera order were Thrips palmi and Frankliniella schultzei. New species identified for Puerto Rico were Caliothrips phaseoli and Frankliniella gossipyana. The whitefly, Bemisia tabaci, and soybean lace bug, Nezara viridula, were the species of the Hemiptera order identified at the three locations.
Publications
- Viteri, D., Cabrera, I. and Est�vez de Jensen, C. 2009. New record of thrips species associated with soybeans in Puerto Rico. Florida Entomologist. 92(1): 181-185.
- Viteri, D., and Gordillo, L. 2009. Modeling the transmission of non persistent plant viruses for cyclic sowing-harvesting. European Journal of Plant Pathology. Volume 125, Number 3, 435-444, DOI: 10.1007/s10658-009-9493-4.
- Viteri, D., Cabrera I., and Estevez de Jensen, C. 2010. Identification and abundance of thrips species in soybean in Puerto Rico. International Journal of Tropical Insect Science.
Vol 30:57-60.
- Rodrigues, J.C.V., Viteri, D., Est�vez de Jensen, C. and Kitajima, E.W. 2008. Occurrence of a whitefly transmitted Carlavirus in soybean in Puerto Rico. Phytopathology, Vol 98, Number 6, S-134.
- Vega, B., and Estevez de Jensen, C. 2008. Description of the infection of Phakopsora meibomiae in legume hosts. Phytopathology, Vol 98, Number 6, S-163.
- Vega, B., and Estevez de Jensen, C. 2008. Occurrence of American Soybean Rust Phakopsora meibomiae in legumes in Puerto Rico. Phytopathology, Vol 98, Number 6, S-162.
- Viteri, D., Gordillo, L., Estevez de Jensen, C. 2008. A mathematical model for Carlavirus disease incidence on experimental soybean plots in Puerto Rico. Phytopathology, Vol 98, Number 6, S-164.
- Vega, B. and Est�vez de Jensen, C. 2010. Virulence of Phakospsora meibomiae in wild and cultivated legumes in Puerto Rico. J. Agric. Univ. P.R. 94(3-4): 211-224.
- Estevez de Jensen, C., Wisler, G., Harmon, C., Vega, B., Viteri, D. and Hernandez, J., 2009. Monitoring Phakopsora Rust in Puerto Rico. J. Agric. Univ. P.R. 93(1-2): 125-137.
- Vega, B., Beaver, J., Est�vez de Jensen, C. and Steadman, J.R. 2009. First report of bean rust (Uromyces appendiculatus) race 19:63 in Puerto Rico. Plant Health Progress. doi:10.1094/PHP-2009-0325-01-BR.
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Progress 09/01/06 to 08/31/07
Outputs
Insects: The most commonly found population species was Coleoptera and produced significant defoliation in the experimental fields. Cerotoma ruficornis, Diabrotica graminea, and Systena basalis were identified in soybean and dry bean. Spodoptera ornithogalli was only identified in soybeans. In 2006 and 2007, three insect scouting methods were evaluated with visual being the most efficient. Omiodes indicata was the most abundant arthropod identified by the visual technique in soybeans. Cerotoma ruficornis, Omiodes indicata, Diabrotica graminea were identified in Juana Diaz. In Isabela, Cerotoma ruficornis showed the highest population in soybean and dry bean while Omiodes indicata, Spodoptera ornithogalli, Urbanus proteus and Nezara viridula had low populations. Diseases: In Isabela and Juana Diaz in 2006 and 2007 a viral disease was present. Symptoms during V6 include blackening of the central veins of the leaves, progressing to stem necrosis during R1 -R2 growth
stages. At R3 and R6, pods developed dark spots and grain failed to fill. Pods remained small and grain shaped was distorted, wrinkled and seeds stayed green. During R7 infected plants dried and died. Incidence in Juana Diaz was 15 percent and in Isabela was 20 percent. Samples from Juana Diaz were tested positive for Carlavirus with PCR. Other major diseases observed in soybeans in Juana Diaz were Phomopsis spp. producing leaf spots, a low incidence of Sclerotium rolsfii causing stem base rot at V1-V2 growth stage, and frogeye leaf spot caused by Cercospora sojina. These diseases started in March with a low incidence and severity (DS 3 percent) and progressed to April (DS 10 percent) and May (DS 40 percent). These diseases were prevalent in all locations. Downy mildew caused by Peronospora manshurica was observed in Isabela during the months of January and May which are characterized by mild temperatures (72 F) and high precipitation (13.3 inches). Phyllosticta spp. was isolated from
leaf spots on soybean for the first time. Bacterial pustule, caused by Xanthomonas axonopodis pv. glycines, was observed in Isabela during the months of June and July, associated with heavy rainfall (June, 12 inches). Disease severities averaged from 20 percent to 30 percent at R7 growth stage. Soybean Rust During 2006 to 2007, no soybean rust was observed in sentinel plots planted in Juana Diaz or Isabela. A survey was conducted in 2006-07 in different municipalities in Puerto Rico to collect wild and crop host plants for soybean rust. Lablab purpureus was collected from all the municipalities, and DNA from leaf tissue infected with rust amplified for P meibomiae. None of the DNA samples were positive for P. pachyrhizi. Pachyrhizus erosus and Cannavalia ensiformi collected in Isabela were also infected with P. meibomiae . At Yahuecas, Vigna spp. was found to be infected with P. meibomiae. Pathogenicity tests conducted with soybeans, Lablab and Cannavalia resulted in infection by P.
meibomiae. So far Asian soybean rust on Lablab purpureus or any leguminous species has not been observed or identified in Puerto Rico.
Impacts
A plant disease and insect reference collection was organized in order to develop a comprehensive guide to pest and diseases of soybean and dry bean within various areas in Puerto Rico. This reference collection will support the DDIS database. Comprehensive information on the insect population dynamics in soybeans and dry beans was completed for three geographic regions in Puerto Rico. Two invited presentations on the results of the surveillance of soybean rust in Puerto Rico funded by this project were given at: The Second Soybean Rust Symposium in Missouri, November 2006 and American Phytopathological Society Annual Meeting, Caribbean Division, Cancun, Mexico, May 2007.
Publications
- Cabrera, I., Estevez de Jensen, C. Velez, A., and Morales, R. 2007. Insectos prevalentes y su incidencia en Soya (Glycine max) y Habichuelas (Phaseolus vulgaris) en tres diferentes localidades, Juana Diaz, Isabela, y Adjuntas. Memorias Sociedad Protorriquena de Ciencias Agricolas (SOPCA) p. 24. 10 de Noviembre de 2007. Guayanilla, Puerto Rico.
- Cabrera, I., Segarra, A., Estevez de Jensen, C. 2006. Reporte de nuevos hospederos de Spissistilus festinus Say (Homoptera: Membracidae) para Puerto Rico. The Journal of Agriculture of the University of Puerto Rico. Vol. 91. No 1-2 (53-55).
- Viteri, D., Cabrera, I., Hodges, A., Estevez de Jensen, C., Vega, B. 2007. Field Evaluation of Trapping Methods for insects on Soybean (Glycine max L.) and Dry Bean (Phaseolus vulgaris L.) in Puerto Rico. Proceedings Canadian Entomological Society Annual Meeting. Saskatoon, Canada.
- Estevez de Jensen, C., Harmon, C, L,, Vega B., and Viteri D., 2007. Surveillance of Soybean Rust in Puerto Rico. Proceedings American Phytopathological Society Annual Meeting, Caribbean Division, Cancun, Mexico.
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Progress 09/01/05 to 09/01/06
Outputs
Three field trials were planted at Juana Diaz (Soybean and Dry Beans), Isabela (Soybean, Dry Bean and Pigeon Pea) and Adjuntas for surveillance of diseases and insects. Each trial was sowed in a sequence of three planting dates approximately every 45 days. A total of seven evaluations were conducted in each location to monitor diseases and pests. Isolations of samples with fungal and bacterial diseases in culture media were performed. Digital images were obtained from the different diseases observed and 32 samples have been sent to the Distance Diagnostic Information System. In Juana Diaz in dry beans at Vegetative 3 growth stage the fungi identified were Sclerotium rolsfii, species of Pythium and Rhizoctonia solani producing stem rot and damping-off. During Vegetative 5-7 growth stage species of Alternaria and the presence of viral diseases were the most common. During Reproductive 1-4 growth stages viral diseases were prevalent. In Juana Diaz in soybean during
Vegetative 1-2 growth stage, stem rot caused by Sclerotium rolsfii was the only disease observed. During Vegetative 3-5 growth stage different foliar diseases were observed and the fungi identified were species of Cercospora, Alternaria and Curvularia. In soybeans viral diseases have been more important, starting symptoms during Vegetative 6, and progressing to stem necrosis during Reproductive 1-2 growth stages. At Reproductive 3 and 6 pods developed dark spots and grain fail to fill. During Reproductive 7 the soybean plant dried and died. In soybeans in Juana Diaz, species of Phomopsis were isolated from leave spots. Pathogenicity tests are pending. At Isabela in dry beans Sclerotium rolsfii was the causal agent for 1 percent of the plants to die at Vegetative 3 growth stage. The incident of foliar diseases was low. Bacterial diseases were severe during Reproductive 1-4. In Soybean during Vegetative 1-2 growth, Sclerotium rolsfii caused stem base rot. During Reproductive 3 growth
stage infection by species of Peronospora was detected in soybeans. In pigeon pea stem rot caused by Sclerotium rolsfii was identified. In Adjuntas Vegetative 3-5 growth stage the incidence of foliar diseases was low. The following insects were identified in soybeans and dry beans at Isabela and Juana Diaz: Urbanus proteus (Lepidoptera), Diabrotica graminea (Coleoptera), Anticarsia gemmatalis (Lepidoptera) and Cerotoma ruficornis (Coleoptera). Two new plant hosts for Membracidae (Hemiptera) for Puerto Rico, Spissistilus festinus Say was detected at Juana Diaz and also later collected from the Lajas experiment station. This species is known to be an important pest of alfalfa and legumes in the southern U.S., and it could eventually be a significant pest for Puerto Rican agriculture.
Impacts
1. Digital images collected from soybean and dry bean diseases and insects provide a valuable pictorial reference for pests of concern. This information will be available for developing field guides, or extension publications that can assist scouts in monitoring for important pests of soybean in Puerto Rico. 2. Even though some diseases have been detected, the overall low incidence of disease reports is interesting. Comprehensive information on the diseases present, including their incidence and severity, has been collected. If the low incidence for disease reports continues in the next field season, growers may be able to reduce fungicide or other control measures relating to these diseases. 3. Several insect pests and data on the season occurrence of these pests in soybeans and dry beans have been reported. Additionally, two new hosts for Puerto Rico, for S. festines, has been detected
Publications
- Irma Cabrera Asencio , Alejandro Segarra , Elva C. Estevez. 2006. Reporte de nuevos hospederos de Spissistilus festinus Say (Homoptera: Membracidae) para Puerto Rico. Nota de Investigacion. The Journal of Agriculture of the University of Puerto Rico. Submitted.
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