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Alphabetized by first author's last name oxidasa negativa, fue oxidativa y fermentative, produjo ,ecido de: palatinosa,lactosa, celobiosa, trehalosa y a-methyl-gluc6sido. se identific6 como Er-winia carotovora subsp atroseptica.

Bark cracking of Tahiti (Persian) lime (Citrus latifolia) and its associa-tion to viroid infection in Mexico. 0. G. Alvarado-Gomez, R. F. Lee 2, R.

Rivera-Bustamante 3 , P. Rufz-Beltr~n4 , J. P. Martfnez-Soriano 3'5, and M. A. Flight behavior by Bemisia tabaci, the virus bus. David N. Byrne, RufusRocha-Pefia. 'Fac. Ciencias Biol6gicas, UANL. 2University of Florida, Lake Isaacs, and Klaas H. Veenstra. Department of Entomology, University ofAlfred, Florida USA. 3CINVESTAV-Unidad Irapuato. 4 INIFAP, Huiman- Arizona, Tucson, AZ 85721.guillo, Tabasco Mexico. 5lNIFAP, Apdo. Postal 3. General Teren, Nuevo Bemisia tabaci, sweet potato whitefly, is an important viral vector around theLe6n 67400 Mexico. world. Laboratory and field experiments have revealed a number of impor-

Tahiti (Persian) lime (ca. 18,000 ha) has become a profitable citrus crop in tant facts concerning its flight behavior. A portion of the population is capa-Mexico, because of its easy suitability for export. Severe symptoms of bark ble of sustaining flight in a vertical flight chamber for more than 1.0 hrcracking on the trunk and main branches are commonly observed in Tahiti (some for as long as 3.0 h). There appears to be only a short period of timelime groves throughout the country. These symptoms are frequently associ- when individuals will fly. Flight is most likely 6 d following ecolsion.ated to different degrees of tree deterioration and poor growth. Polyacryla- Thereafter, indirect flight muscles and mitochondria deteriorate. Using geo-mide gel electrophoresis analysis and reverse transcription-polymerase chain statistical techniques we have characterized distribution following dispersal.reaction showed the presence of the citrus cachexia viroid (a strain of the hop Most travel 2.2 km in a day's time. We are working to characterize vertical

stunt viroid) in every sample tested from three different States of the country. ditbuonnthfel.W haeeredhtsmeietooetan7mPathogenicity tests and in planta cultures on a set of herbaceous and citrus immediately upon exiting the field. We are also examining the impact ofhosts are in progress. flight on whitefly physiology to help determine range.

Identificacion de la especie del nematodo agallador de la papa Meloi-Epidemiology of whitefly-transmitted geminiviruses: Critical research dogyne sp., en navidad, N. L, Meichor Cepeda Siller y Francisco Danielneeds. P. K. Anderson. CIAT-Virology Research Laboratory, 1380 NW 78th Hemeindez Castillo. Depto. de Parasitologia, U.A.A.A.N., Buenavista, Salti-Ave., Miami, FL 33 126-1606. l1, Coahuila. CP 25315.

A conceptual framework for epidemiology, which consists of five branches Con el prop6sito de identificar la especie del genero Meloidogyne prevalenteof research, is presented. Circumstantial, etiological, mathematical, ecologi- en el Campo Experimental de la UAAAN, en Navidad, N.L., 80 muestras decal and evolutionary epidemiology are illustrated using the case of whitefly- suelo fueron colectadas, mezcladas y trasladadas a las instalaciones deltransmitted geminiviruses in Central America, Mexico and the Caribbean. ITESM, para su anelisis y preparaci6n, estas fueron puestas y distribufdas enWithin this framework, critical research needs are proposed. Finally, the una cama de crecimiento del invernadero, donde se sembraron 40 tuberculosissue of whitefly-transmitted geminiviruses as new and emerging plant dis- de papa variedad "Alpha" y transcurridos 60 dfas se retiraron al azar 20eases is raised and the ProMED-Plant electroaic conference is discussed. plantas para inspeccionar sus rafces. De los n6dulos de las raices infestadas

se aislaron hembras adultas para analizar sus caracterfsticas morfometricas,asi como las caracteristicas correspondientes a los juveniles de machos y

Erwinia carotovora subsp atroseptica asociada con la pudricion del pseu- huevos de Meloidogyne; se concluye que la especie presente en el campodotallo del banano (Musa paradisiaca) en la localidad de Sn. Rafael, Ver. experimental es M. incognita.S. Aranda, L. Fucikovsky, D. Ruiz, y J. E. Poot. Colegio de Postgraduados.Instituto de Fitosanidad. Montcillo, Edo. de M.x. C.P. 56230.

Se ha encontrado frecuentemente que en varias regiones plataneras de Ratoon stunting disease of sugarcane: Developing resistant clones. J. C.Mexico existen pudriciones blandas de pseudotallo 6 rizomas, ocasionando Comstock and J. D. Miller. USDA-ARS Sugarcane Field Sta. Star Route Boxla caida de plantas con facilidad por acci6n de vientos. Muestras 8, Canal Point, FL 33438.provenientes de la localidad de Sn. Rafael, Ver. se analizaron, observ6.ndose The purpose of this study was to evaluate the effect of parental resistance of

una udrci~ blada n e psedotlloy rzoma Seaisarontincamnte sugarcane on selecting for ratoon stunting disease (RSD) resistance in prog-bacterias de las cuales se present6 con mayor frecuencia un solo tipo de en.Sxcossahwih4prgywrevlutdTemleaetCaislamiento. En la caracterizaci6n de este, la bacteria pudri6 papa y licu6 89-2335, a clone selected from a previous study that was highly resistant togelatina, no produjo reacci6n de hipersensibilidad en tabaco, no fluoresci6 en RSD was crossed to 3 resistant females (CP 89-2365, CP 89-2375, and CPmedio B de King, mostr6 reacci6n Gram negativa, no forma endoespora, fu6 82-1592) and 3 susceptible females ('CP 72-1210', CP 89-2301, and CP 89-

2373). Resistance to RSD was determined by using a tissue blot immunoas-say to count the number of colonized vascular bundles in inoculated plants.

The abstracts are published as submitted. They were retyped but The three crosses between resistant parents produced 48, 49 and 46% prog-not edited in the APS headquarters office. eny with high RSD resistance. The three other crosses between susceptible

Vol. 86, No. 11 (Supplement), 1996 3113

female parents and the same resistant male parent resulted in lower percent- als were retained and 10% in the other two selections, based on yield andage (13, 22 and 35%) of resistant progeny. The cross involving the most agronomic characteristics. The 14 most promising lines were selected in thesusceptible female parent produced the fewest resistant progeny. 1995 Winter-Spring experiments, some of them, yielding up to three times as

much as the local landraces and showing reduced rate of increase of CMVincidence. These 14 lines and some others are now the parents in the crosses

Properties of tomato yellow mosaic geminivirus in Venezuela. Rafaela C. for the fourth breeding cycle.de Uzcitegui. Lab. de Biotecnologfa y Virologia Vegetal. CMBC. Institutode Investigaciones Cientfficas. Apdo. 21827. Caracas 1020-A Venezuela.The ToYMV is the principal tomato (Lycopersicon esculentum Mill) viral Biocontrol of charcoal rot and rhizoctoniasis on common bean by an-

disease in Venezuela. It is transmitted by Bemisia tabaci (Genn). For many tagonistic strains of B.aillus cereus and Burkholdedia cepacia. J.me

years this whitefly has only transmitted the ToYMV without colonizing L. Galu6, R. Echavez-Badel, E. C. Schr6der, and M. Alameda. Departm

esculentum. Currently this has changed and the life cycle of B. tabaci can be Crop Protection and Agronomy & Soils, University of Puerto Rico, May-

developed on the plant. The ToYMV was isolated from field samples and aguez, Puerto Rico 00681-5000.

transmitted by insect and mechanical inoculation to several Solanaceae. Strains of Bacillus cereus (UPRM 10042) and Burkholderia cepacia (UPRAfter mechanical inoculation on Nicotiana benthamiana Domin and L. es- 5C) reduced charcoal rot (Macrophomina phaseolina) and rhizoctoniasisculentum, clear symptoms were observed and used for viral multiplication. (Rhizoctonia solani) on common bean (Phaseolus vulgaris). Bean seedsVirus isolation and purification showed 28-30 nm geminate particles, dipped into the bacterial suspensions and planted in the field were protectedA260/280:1.43.ssDNA, Mw 28000. Antisera to ToYMV was obtained and against these pathogens. Incidence of charcoal rot was significantly (P=0.05)serological assays were performed on different kinds of weeds that showed less than the untreated controls. The biofungicide effect of B. cereus and B.symptoms, where Abutilon umbelletum (L.) Malvaceae, appears like the first cepacia was similar to that of seed treated with Captan and Benlate. Biocon-natural host. The ToYMV caused losses: 63% Nema 1401, 61% Nema 512, trol mechanisms of these rhizobacteria have not been identified conclusively.43% Nema 1400 and 44% Pacesseller. The plants were affected by the virus It appears that antibiosis may play an important role. Further studies onand by the feeding habits of the whitefly, showing a different rate of infec- mechanisms of action are contemplated.tion according to the plants age and the geographical area.

Identificacion de aislamientos de Rhizoctonia binucleadas afectandoMolecular approaches to the differentiation of strains of citrus tristeza papa en Coahuila y Nuevo Leon. F. D. Hernandez C. *, Z. Alonso C.*; F.virus. V. J. Febres, B. Cevik, H. R. Pappu, S. S. Pappu, R. F. Lee, and C. L. Lara V.*; G.A. Frfas T.*; y M. Cepeda S*. Depto. de Parasitologia, Univer-Niblett. Plant Pathology Department, University of Florida, Gainesville, FL sidad Aut6noma Agraria "Antonio Narro", Buenavista, Saltillo, Coahuila.**32611-0680, USA, and 'Citrus Research and Education Center, Lake Alfred, Farmacia Agroquimica de Mexico, Ramos Arizpe, Coahuila.FL 33850 USA. Aislamientos de papa realizados en la regi6n de Coahuila y Nuevo Le6nCitrus tristeza virus (CTV) will become increasingly important with the indicaron la presencia de cepas binuceladas de Rhizoctonia. Se seleccionaronrecent establishment of Toxoptera citricida, its most efficient aphid vector, in cuatro cepas y se identificaron como R. cerealis considerando el ndmero dethe Caribbean islands and Central and North America. Effective disease niicleos, diaimetro de la hifa, color de micelio, tipo de crecimiento, presenciadiagnosis requires the differentiation of the many biologically and serologi- y diaimetro de esclerocios. Las cuatro cepas de R. cerealis se inocularon encally diverse strains of CTV. The monoclonal antibody 13 (MCA13) (Permar macetas con suelo esteril y papa veriedad Alpha y Gigant mostrando que estaet al. Phytopathology 80:224-228) reacts predominantly with severe strains. especie es patogdnica en papa. Este es el primer reporte en Mdxico de laCharacterization of the MCA13 epitope enabled the development of bi-di- patogenicidad de R. cerealis en papa.rectional polymerase chain reaction (PCR), which detects co-infecting mildand severe strains. Coupling PCR with single stranded conformation poly-morphism or the hybridization with probes specific to portions of the capsid Efectividad biologica de fungicidas para el contol de Rhizoctonia solaniprotein gene (CPG) identifies known or unique strains of CTV. Their identity en papa, en San Rafael, Galeana, N. L. Francisco Daniel Hernndezcan then be confirmed by sequencing of their CPGs. Castillo, Melchor Cepeda Siller y Gustavo Martin G6mez. Depto. de Parasi-

tologifa, UAAAN, Buenavista, Saltillo, Coahuila. CP 25315.

Los nematodos entomopatogenos, una alternativa para el control de Con el objetivo de evaluar el comportamiento de fungicidas para elcHelicoverpa zea en maiz Dulce. W. Figueroa, S. Torres, J. Romdn, S. de Rhizoctonia solani, se estableci6 durante el ciclo Primavera-Otofio deSotomayor. Estaci6n Experimental Agrcola, Apartado 21360, Rio Piedras, 1995, un diseflo estadifstico de bloques al azar con 4 repeticiones y 6 tra-PRtomao. Etamien tos. (Farbendazol 10k, Farbendazol 12kg, Farbendazol 15kg,

P.C.N.B. 12 It + Benlate 1.0kg, Monceren 5kg y Testigo), aplicados a laUna de las plagas mi6s severas en la producci6n de mafz dulce es Heli- siembra, con un gasto equivalente a 600 It de agua; los pardimetros evaluadoscoverpa zea. Para su control se ha sugerido el uso de nemdtodos entomo- fueron: Incidencia de la enfermedad a los 55 dias de la emergencia de laspat6genos. Para evaluar esta alternativa se realizaron dos pruebas de campo plantas, incidencia y severidad de la enfermedad en tubdrculo y rendimientocon los gdneros, Steinernema puertoricensis, S. riobravis, S. cubana y Het- y calidad de la cosecha. Los resultados indican que Farbendazol (a diferenteserorhabditis spp. en dos aplicaciones dirigidas a la mazorca (al momento de dosis), Monceren y PCNB + Benlate controlan la enfermedad satisfactoria-la florecida y 30 d!as despu-s). Se us6 un testigo con qufmicos y uno abso- mente en estado de plntula. El Farbendazol en sus diferentes dosis y laluto. En la primera prueba se observ6 una mortalidad del insecto de 62.53 y mezcla de PCNB + Benlate disminuyen la incidencia y severidad del72.36% cuando se aplic6 Heterorhabditis spp y S. riobravis respectivamente. pat6geno en tubdrculo en menor proporci6n que el Monceren.El testigo con insecticida tuvo un 29% de mortalidad y el control absoluto un17.24%. En la segunda prueba se midi6 el indice de penetraci6n del insecto yse observ6 menor penetraci6n en los tratamientos con nemdtodos. Los Efectividad biologica de fungicidas para el control de Alternaria solaninemditodos entomopat6genos demuestran ser una altemativa biol6gica poten- en papa en Rancho Nuevo, Arteaga, Coahuila. Francisco Danielcial para el control de insectos y la reducci6n del uso de insecticidas. Herndndez Castillo, Melchor Cepeda Siller y Juan Herndndez E. Depto. e

Parasitologia, UAAAN, Buenavista, Saltillo, Coahuila. CP 25315.

Horizontal resistance in beans to local pathosystems in the Mixteca re- En el ciclo de primavera-verano de 1995 con el objetivo de estudiar la efec-gion, Puebla, Mexico. R. Garcia-E., R.A. Robinson, P. Ramfrez-V., F. tividad biol6gica de fungicidas para el control de Alternaria solani en elCastillo-G., F. Romero-R., K. Gardezi-A. Colegio de Postgraduados IFIT, cultivo de la papa, se estableci6 un disefio estadistico de bloques al azar conMontecillos, Texcoco, Mexico, 56230. 6 tratamientos y 4 repeticiores. Los fungicidas y dosis usadas fueron:

Cuprotalonil 2kg/ha, Cuprotalonil 3kg/ha, Cuprotalonil 4kg/ha, Daconil WRecurrent mass selection has been used in an interdisciplinary bean breeding 75 1 .0kg/ha, Cupertr6n 31lt/ha y el testigo; la primera aplicaci6n se realiz6 alproject started in 1989, intended to accumulate resistance to all races of the aparecer los primeros sfntomas de la enfermedad en el follaje, posteriormentetwo locally most important disease problems in the Mixteca Region: Coin- se hicieron otras 6 aplicaciones con intervalos que variaron erttre 7 y 8 dias;mon Blight and Common Mosaic Virus. So far three breeding cycles have los pardimetros evaluados fueron: incidencia de la enfermedad en hojas,been completed. Every one of them included strong artificial selection pres- severidad de la enfermedad en hojas y rendimiento a la cosecha. Se deter-sure, through the individual inoculation of every single plant (to avoid es- min6 que los fungicidas Cuprotalonil (en las diferentes dosis utilizadas),capes) of a designated pathotype of each of the two pathogens (selected Daconil y Cupertr6n controlan satisfactoriamente la enfermedad. El fungi-isolates for their ability to induced disease to every one of the seven original cida Cuprotalonil en las dosis 3 y 4kg/ha fue el mejor, pues se obtuvo controlparents of the whole program). In the first selection only 1% of the individu- de la enfermedad.

Si114 PHYTOPATHOLOGY

Comparisons of fungicides for control of cucurbit powdery mildew. G. J. Recently ingredients from the tropical tree Azadirachta indica have beenHolmes, M. Vilchez, and A. 0. Paulus. University of California Cooperative used as biological insecticides to control efficiently whitefly eggs, instarExtension Service, 1050 E. Holton Rd., Holtville, CA 92250; Plant Pathol- stages and adults. Neem oil at 1O0g/I with an ultra-low volume sprayer at 10-ogy Department, University of California, Riverside, CA 92521, USA. 20 1/ha reduced oviposition and adult populations 90% on cucumber and

Powdery mildew of cucurbits caused by Sphaerotheca fuliginea reduces squash. On okra 0.25% acqeous Neem seed kernel extract controlled

vigor of plants and can cause early cessation of harvest. Powdery mildew whiteflies. On zucchini drastic reduction was obtained by high volume

trials were conducted in 1991, 1995 and 1996 at two University of California weekly sprays of 5-10% extracts or by ultra low volume Neem oil spray at

Research and Extension Centers (Irvine and El Centro). Susceptible zucchini 10-20 1/ha. Neem extracts do not harm spiders, coccinellids and other preda-

squash (var. Ambassador), casaba melon (var. Golden Beauty), and canta- tors of whiteflies and they are not toxic to warmblooded animals. Neem

loupe (var. Topmark) were used. Fungicides were applied at 7-to-14-day products mixed with pyrethroids in integrated pest management have the

intervals using a 7.5 L CO2, pressurized Hudson sprayer at 31 psi. Disease potential to protect the environment.

severity was high in all trials and fungicide efficacy varied significantly.Most treatments reduced disease severity. Sulfur gave excellent control inone test, moderate in others. Tebuconazole, thiophanate-methyl/iprodione Monosporascus root rot/vine decline of watermelon in Mexico. R. D.and myclobutanil were the most effective treatments. Triadimefon, beno- Martyn, J. S. Batten, Y.-J. Park, and M. E. Miller. Department of Plant Pa-myl/triadimefon, chlorothalonil and fenarimol gave moderate control. Potas- thology and Microbiology, Texas A&M University, College Station (77843)sium silicate and potassium carbonate provided little disease control. and Weslaco (78596) TX.

Monosporascus root rot/vine decline, caused by the soilborne fungus Mono-sporascus cannonballus, is emerging as a serious disease of melon (Cucumis

Transmission of geminivirus by the whitefly, Bemisia tabaci (Genn.). melo) and watermelon (Citrullus lanatus) worldwide. In April 1996, a surveyWayne B. Hunter and J. E. Polston. Univ. of Florida, GCREC, 5007 60th St. of several commercial melon and watermelon fields near the city of Teco-E., Bradenton, FL 34203. man, Colima confirmed infection of 'TriX-313' and 'Sangria' watermelon by

The movement of two different geminiviruses through the whitefly, Bemisia M. cannonballus in one field. Perithecia were observed on the roots andtabaci, biotype-B were examined. Both tomato mottle geminivirus and cab- several isolates of M. cannonballus were recovered from samples broughtbage leaf curl geminivirus were detected in the filter chamber and midgut of back to Texas A&M University. Isolates were confirmed as M. cannonballuswhiteflies by fluorescent and confocal laser microscopy. Tomato mottle by PCR amplification of the ITS region of the rDNA with Monosporascus-geminivirus was also detected in the primary salivary glands. These are the specific primers and by the formation of perithecia and ascospores in culture.sites within the whitefly through which these geminiviruses must pass before Pathogenicity of each isolate was confirmed in greenhouse tests. Althoughviral transmission can occur. Results suggest these geminiviruses are circu- other melon and watermelon fields showed various vine decline symptoms,lative but nonpropagative. Once ingested the geminivirus appears to be ab- M. cannonballus was not confirmed from these other fields. This report ex-sorbed to the membranes of the filter chamber and midgut where they pass tends the known geographic range of this fungus in the Western hemisphereinto the hemocoel. The geminivirus then contacts and passes through the to now include Mexico.membrane of the salivary glands where the virus can move into the salivaryducts and is eventually salivated out during feeding. Feeding and geminivi-rus acquisition are discussed. Suppression of Rhizoctonia solani and Fusarium spp. in Brassica oleracea

L. var. acephala by bed solarization and metam sodium in Bermuda. R.J. McGoverni and F. Harper2 . 'Univ. FL-IFAS, Gulf Coast REC, Bradenton,

Fungicides tested for control of lettuce downy mildew (Bremia lactucae). FL 34203 and 2Dept. Agric., Fisheries & Parks, Hamilton, Bermuda.F. F. Laemmlen, A. 0. Paulus, and M. Vilchez. Cooperative Extension, SantaMaria 90345 and Plant Pathology Department, University of California, A field (sandy loam) in Devonshire, Bermuda was used to evaluate the ef-Riverside, CA 92521, USA. fectiveness of soil solarization and metam sodium (MS) in reducing soil-

borne disease in field-produced kale (Brassica oleracea L. var. acephala)Fungicide trials were established in Lompoc, CA on variety Pybas 251 and in transplants during the summer, 1995. Soil treatments were clear, low densitySanta Maria, CA, on variety Top Gun during spring of 1996. Ten fungicides polyethylene mulch (PE, 25 pim), white PE (25 pm) plus MS (702 l/ha), andalone and in combination were applied 4 times at 14 day intervals in the clear PE plus MS. Treatments and an untreated control (bare soil) were repli-Lompoc trial. Fluazinam provided excellent control with the granular appli- cated three times using 1.2 x 10.4 m beds arranged in a randomized completecation but caused stunting and yellowing. All other fungicides were ineffec- block design. Mulches were applied and MS incorporated through rotovationtive for control and included CGA 245 (12.5 gr ai/Ha), metalaxyl M/maneb, 20 cm deep on 29 Jun. Mulches were removed on 26 Aug. and kale 'Dwarfmancozeb, fosetyl-al and Curzate M8/maneb. Eight fungicides alone and in Blue Curled Vates' was seeded on 15 Sept. Biomass data was obtained fromcombination were applied 4 times at 10-day intervals in the Santa Maria trial. 10 transplants on Oct. 16. Infection rate was evaluated on the same date byThe most effective fungicid for control were i) dimethomorph/maneb, ii) plating the crown and roots of five randomly selected transplants from eachmaneb first spray followed by propamocarb for the last three sprays, and iii) block on acidified potato dextrose agar after surface disinfestation in 10%CGA 245, at the rate of 25 gr. al/Ha. Curzate M8/mancozeb, maneb, and NaOC1. Average maximum soil temperatures (2:00 PM) under clear PE at 5,metalaxyl M/mancozeb-first and third spray and mancozeb-2nd and 4th 15 and 30 cm were 48.2, 36.9, and 33.6°C, respectively, and were highersprays did not provide effective commercial control of downy mildew. than corresponding temperatures in bare soil or under white PE. Infection

rate by Rhizoctonia solani and Fusarium spp. was significantly decreased byA single chain Fv antibody against citrus tristeza closterovirus expressed all treatments and the fresh weight of both roots and shoots were signifi-in Nicotiana benthamiana. K. L. Manjunath', R. Chandrika', D. Shalitin2, cantly increased by treatment with clear PE plus MS in comparison to theM. Bar-Joseph2 , C. A. Powell3 , C. LNiet 4, n .F e' CEUi untreated control.versity of Florida, Lake Alfred, FL 33850, USA, 2 Volcani Center, Bet Da-gan, Israel, 3IRREC, Univ. of Florida, Fort Pierce, FL, 4plant Path. Dept., Pyiceia n clgclcaatrzto fltueclrssvrsUF, Gainesville, FL 32611, USA. Pyiceia n clgclcaatrzto fltueclrssvrs

J. M. McLain and R. Creamer. Department of Plant Pathology, University ofCitrus tristeza closterovirus (CTV) is a major limiting factor in citrus pro- California, Riverside, CA 92521.duction. Studies were initiated to produce antibodies against the virus in vivofor plant immunotherapy. A monoclonal antibody, 25/2 against CTV was Lettuce chlorosis virus (LCV), is efficiently transmitted by the silverleafselected, single chain Fv antibody gene was constructed and cloned into a whitefly Bemisia argentifolii, and has been observed causing chlorosis onplant expression vector, pGA482. This construct was used to transform lettuce in the Imperial Valley of California since 1993. The virus is charac-Nicotiana benthamiana plants by Agrobacterium mediated transformation. terized by long flexuous rod particles 950-1550 nm in length, a ssRNATransgenic gene was detected by polymerase chain reaction and nucleic acid genome of app. 15 kb, and single capsid protein of app. 28 kD. LCV is se-hybridizations. The expressed transgenic protein showed binding properties rologically distinct from other clostero- and clostero-like viruses such assimilar to its parent antibody in immunoprecipitation studies. BYV, LIYV, and TICV. The virus host range includes melon, tobacco, Da-

tura, and Chenopodium. LCV has been detected naturally infecting severalcommon weeds that are also good hosts for the vector. All lettuce varieties

Control of whitefly vectors and pests with Neem tree natural products. tested are susceptible to LCV-infection, and the disease is usually foundKarl Maramorosch, Entomology Department, Rutgers University, New randomiy distributed through a field. Imidacloprid insecticide treatmentsBrunswick, NJ 08903, USA. reduce, but do not block virus infection.

The alarming increase in whitefly infestations and whitefly-borne viruses hasbeen paralleled by resistance of Bemisia tabaci to chemical insecticides.

Vol. 86, No. 11 (Supplement), 1996 $115

Drip irrigation applications of ICIA 5504 reduces symptom expression of El objetivo del proyecto fue el de generar un programa de control integradomonosporascus root rot/vine decline on cantaloupe (Cucumis melo L.). del pat6geno. Se tiene seleccionado germoplasma tolerante al tiz6n tardio;M. E. Miller, and R. D. Martyn. Texas A&M University, Weslaco 78596 and conforme se increment6 la densidad de plantas el daflo por tiz6n tardio esCollege Station 77843. mayor; se han detectado como sobresalientes aquellos productos cuyo ingre-

ICIA 5504, Folcur, RH-3866, and EXPI0625A at 420, 560, 350 and 395 diente activo es el Mancozeb. Se identificaron mediante plantas diferencia-

glha, respectively, were applied to cantaloupe cvs. 'Magnum 45' and les, gran variabilidad de razas del hongo; el inicio del dafto se present6 eng/ha repecivey, wre ppled o catalupecvs 'Manum45'and variedades susceptibles entre los 14 y 18 valores acumulados de intensidad

'Explorer' either as foliar applications or through drip irrigation lines to de acuerdo al sistema de pron6stico Wallin's.

control Monosporascus cannonballus, the causal agent of Monosporascus

root rot/vine decline. Fungicide, application method, and variety had a sig-nificant effect (p=0.05) on root disease severity ratings, isolation frequency Evaluation of Mexican inbred lines of sorghum for resistance to Macro-of M. cannonballus, visual vine ratings and total fruit yield. Plots treatedwith ICIA 5504 and plots receiving fungicides through drip irrigation lines Pecina Quintero and G. J. Vandemark. CINVESTAV, Unidad Irruhstr.had significantly lower root disease severity ratings, visual vine ratings and Pe Qta n G n C Irapuato,isolation frequency and higher yields than plots receiving other fungicide Apdo. Postal 629, Irapuato, Gto. M6xico.treatments. There was also a significant interaction between fungicide and M. phaseolina is the causal agent of charcoal stem rot of sorghum. Disease isapplication method on these variables. 'Explorer' had lower root disease greatest when infection is associated with high temperatures and post anthe-severity ratings and higher total fruit yield than 'Magnum 45'. sis drought stress. We conducted greenhouse tests to evaluate the resistance

of eight Mexican lines of sorghum against M. phaseolina. Two lines from theU.S.A., BTx-623 (Sus) and SCO-599-1 1E (Res), were included as controls

Pathogenicity genes of Phytophthora capsici expressed during its interac- for experimental conditions. The eight Mexican and 2 U.S.A. lines weretion with pepper (Capsicum annuum). C. I. Muiioz and A. M. Bailey. CIN- grown in complete blocks of 5 plants per block with 3 repetitions. IrrigationVESTAV-IPN U. Irapuato. A. P. 629. Irapuato, Guanajuato; C.P. 36500. was suspended when a block reached the 50% flowering stage. Plants wereMexico. Fax: (462) 45849. E. mail: abailey@irapuato.ira.cinvestav.mx inoculated 20 days after the mean bloom date of a block by inserting a tooth-

Phytophthora capsici causes blight of peppers, a serious disease in Mexico. pick covered with sclerotia through the stem approximately 2-3 cm above-

To find out the pathogenicity genes involved in P. capsici-pepper interaction ground. Plants were evaluated for disease symptoms 22 days after inocula-

we are analyzing differential gene expression of induced mycelia with pepper tion by splitting the stem lengthwise and measuring the size of the resulting

plants. After different times, mycelia is collected and the total RNA extracted lesion. The incidence of disease was 100% in this investigation. Lines BTx-

for further RT-PCR reactions (differential display technique). This method 623 and SCO-599-1 1E had the highest and lowest mean lesion length, re-

involves the reverse transcription of the mRNAs with oligo dT primers fol- spectively. The Mexican lines Var-B and LRB-210 were not significantly

lowed by a PCR amplification in the presence of a decamer arbitrary in se- different than the most resistant line, and line LRB-1 19B was not signifi-

quence. mRNA differential display technique has been used to identify and cantly different than the most susceptible line. Currently we are conducting a

clone differentially expressed genes in cell differentiation and development, greenhouse diallele analysis of 10 lines and 45 F1 families for resistance to

The use of y-ATP in this technique has the advantage of making it highly M. phaseolina.sensitive, besides it prevents amplification of rRNA, a frequent problem with35S isotope. Our system is working out, and we have identified several differ-ential cDNAs respective to different times in the interaction of P. capsici Ecological behaviour of the sclerotia of Scierotium cepivorum Berk. L.with its host. Our aim is the transformation of P. capsici wild type strain with Ptrez y V. Olalde. Centro de Investigaci6n y Estudios Avanzados del Insti-disrupted differentially expressed genes to find out their role in infection. tuto Politecnico Nacional, CINVESTAV-IPN, Unidad Irapuato. A.P. 629. J.R. S6.nchez. Instituto de Ciencias Agricolas de la Universidad de Guanajuato,

ICAUG. A.P. 311. Irapuato, Gto., M6xico. A. R. Entwistle. HRI. Warwick,Gene to gene relationship bean-common blight, a non genetic demonstra- CV35 9EF, UK.tion. sR. Navarrete M., 1R. Garcia E., and 2j. A. Acosta G. 1 SFIT, Colegio de . cepivorum sclerotia germinate only in response to root exudates or extractsPostgraduados, 2INIFAP-CEVAMEX, C.P. 56230. of plants in the genus Allium. S. cepivorum isolates appear to vary in their

To determine the relationship bean-X. campestris pv. phaseoli (Xcp) the responsiveness to stimulants. Some respond rapidly and the final germinationPerson-Habgood (P/H) differential interaction test was used, this is a non percentage is high; other isolates fail to respond or respond less readily. Thegenetic test based on the matricial arrangement of the data. Leaves of 20 main objective of this study was to observe rates of germination, viabilitybean genotypes (P. vulgaris L.), bred and landraces, were inoculated with 7 and dormancy in the sclerotia of S. cepivorum Berk. Sclerotia were collectedisolates of Xcp from the Mexican Plateau. 12 days after the inoculation sus- in March 1994 from infection sites within a field located in the Bajio regionceptible or resistant reaction was scored. The results showed a pathogenic of Mexico. The samples were derived from several infection sites, each in-variability of Xcp isolates, since caused different reactions on different fection site comprised two depth sites (0-10 cm. and 11-20 cm.). Sclerotiagenotypes. A gene to gene relationship was found using data from 6 geno- were removed from infested soil and Petri dishes were filled with moist soiltypes and 5 isolates, thus the P/H interaction test was fitted. With this pre- and covered with nylon gauze. Firm sclerotia were transferred to the gauzeliminary set of data it was possible to designate four races of Xcp with the and the lid replaced. The dishes were transferred to plastic boxes containinggenotypes 92 VEF-254-MES, Guanajuato 132, Negro Puebla and Hidalgo DADS, incubated at 19±2'C, and germination was recorded after 5, 10 and90. This is the first designation of races using P. vulgaris genotypes. 15 days. Sclerotia of S. cepivorum are characterized by their longevity and a

requirement for a host stimulant for germination. However, the high rates ofloss of field-produced sclerotia after 8 months burial in soil, together with the

Increasing IgG yields with the standard protein A affinity chromatogra- novel patterns of germination of surviving sclerotia, suggest that other typesphy. F. Ochoa, K. L. Manjunath, and R. F. Lee. University of Florida. Citrus of behaviour may occur.Research and Education Center. Lake Alfred, FL 33850.

Sometimes IgG purification for immunodiagnosis uses can be critical espe-cially when the antiserum used is against a less immunogenic pathogen In vitro sensitivity of Scierotium cepivorum Berk. to selected fungicides.and/or the availability of a specific antiserum is restricted. High yields and L. Pe~rez and V. Olalde. Centro de Investigaci6n y Estudios Avanzados delpure IgG are important needs to be addressed. While several methods for IgG Instituto Politecnico Nacional, CINVESTAV-IPN, Unidad Irapuato. A.P.purification are currently used in most laboratories, affinity chromatography 629. C. Castafleda and J. R. Sainchez. Instituto de Ciencias Agricolas de lawith protein A provided the best results in terms of yields and purity what- Universidad de Guanajuato. ICA-UG. A.P. 311. Irapuato, Gto., M6xico.ever the IgG subclass. We found increased yields of IgG by monitoring the White rot caused by Scierotium cepivorum Berk., is a serious disease ofelution procedure. In our study we demonstrate that it is possible to increase Allium species. Since the early 1980's, the dicarboximide fungicidesthe IgG yields significantly following our method rather than following the (iprodione, vinclozolin and more recently, procymidone) have providedpublished protein A procedures. good control of the pathogen. However, these fungicides are known to

have a propensity for selecting for tolerant strains, as has been observedResultdos de investigacion en el control de tizon tardio (Phytophthora in the case of other pathogens. In this paper fungicide sensitivity of

infetan) d lapapaen oahilay Nuvo eon V.M. PrgaT. . Hres isolates from 15 fields are described in order to compare the variabilityinfstns d l paa n oauia NuvoLen.V.M.Para .,A.Flre of the fungus within a large growing region. 15 isolates of S. cepivorum

0., G. Frias T. C.E. SAL-CIRNE-INIFAP. A.P. #5 C.P. 25250. Arteaga, were collected from a number of garlic fields in the Bajio region.Coah., M6xico. Isolates were made from fields with a known history of dicarboximide

En el sur de Coahuila y Nuevo Le6n se cultivan alrededor de 4500 hectireas usage. All isolates were screened for resistance to tebuconazole, thia-de papa y se utilizan en m~is del 90% variedades susceptibles al tiz6n tardfo, bendezole, 2tiocianometiltiobenzotiasol, procymidone and iprodione at

Si116 PHYTOPATHOLOGY

concentrations of 1.25, 4.0, 4.0, 3.33 and 3.33 i.a.g/l, respectively. Seven Citrus tristeza closterovirus-infected citrus protoplasts used as inoculumisolates exhibited mycelial growth with procymidone, three isolates to infect citrus trees. M. Price, J. Grosser, K. S. Derrick, and R. F. Lee.with iprodione and two with 2tiocianometiltiobenzotiasol. Sensitivity Citrus Research and Education Center, 700 Experiment Station Road, Uni-was consistently exhibited to tebuconazole and thiabendazole. The re- versity of Florida, Lake Alfred, FL 33850.suits indicate a pattern of variability among Sclerotium cepivorum isolates in Infectivity studies of citrus tristeza virus (CTV) and its RNA genome havethe Bajfo region. been difficult due to inherent problems associated with long, fragile particles

having woody hosts. We report the development of an in vitro Citrus sinensiscv. Hamlin protoplast system using CTV genomic RNA as inoculum for

Obtention of virus free (potyvirus) garlic plants. L. PUrez, R. Ramfrez y J. transmission to citrus trees. CTV genomic RNA from purified virions wasG. Salinas. Instituto de Ciencias Agrfcolas de la Universidad de Guanajuato. inoculated into Hamlin protoplasts using polyethylene glycol. After 24 h, theA.P. 311. Irapuato, Gto., Mexico. infected protoplasts were slash-inoculated into Macrophylla (C. macro-

Garlic production in Mdxico has been reduced due to virus infestation. The phylla) and Mexican Lime (C. aurantifolia) receptor trees. After 6 weeks,main objective of this study was to obtain virus free garlic seeds, in the most plant extracts were assayed for CTV capsid protein, positive- and negative-important garlic types growing on Bajfo region. Garlic bulbs were submitted strand CTV genomic RNAs, and virus particles. Eighty percent of the treesto thermotherapy: one week 32°C, two weeks 36°C and three weeks 380 C. inoculated with infected protoplasts tested positive for CTV. This is the firstAfter thermotherapy treatment seeds were planted "in vitro" on MS report of infecting citrus plants using infectious CTV genomic RNA as themedium with 2 mg/i of BAP and 0.1 mg of ANA during 30 days. Growing inoculum.buds were transferred to MS medium with active charcoal during 60 dayswhere they developed small bulbs. These bulbs were grown on greenhouseconditions. Small pieces of buds were submitted to serological test ELISA Distribution of geminiviruses in Mexico: The case of PVH and TPV. R.for potyvirus group using Agdia, Inc. antiserum and its control. The best Rivera-Bustamante, J. A. Garz6n-Tiznado, J. Brown, and I. Torres-Pacheco.treatment was on Taiwan cultivar with thermotherapy and meristematic Plant samples from important horticultural areas in Mexico were collecteddissection with 82.5% of plants with negative lecture, in opposition to during several seasons and analyzed for the presence of geminiviruses. TheTaiwan treated with rivavirin which only showed 32.5% of plants with analysis confirmed the presence of geminiviruses in all horticultural areas ofnegative lecture, over commercial control employed showed 100% of plants Mexico in pepper, tomato, tomatillo (Physalis ixocarpa), cucurbits, andwith positive lecture. tobacco. We also analyzed the distribution of well characterized geminivi-

ruses: pepper huasteco virus (PHV), pepper jalapefio virus (PJV) and chinodel tomate virus (CdTV). PHV is widely distributed in Mexico as it was

Performance of tolerant garlic lines (Sir-Sal) to Allium white rot found in both coastal areas as well as in central Mexico in pepper and tomato(Sclerotium cepivorum Berk.). L. PJrez, J. Salinas, J. R. Sdnchez. Instituto samples. Pepper jalapefio virus (PJV) and chino del tomate virus (CdTV)de Ciencias Agricolas de la Universidad de Guanajuato. ICA-UG A.P. 311. showed a more restricted distribution although in all cases, the viruses appearIrapuato, Gto., Mdxico. E. Redondo. ISETA-Roque, Gto., M6xico. to have become more widely distributed over time. Partial DNA sequences of

The main objective of this study was to know adaptation response and yield PJV (PJV A) and CdTV (CdTV B) were also obtained. Comparative se-

potential of 75 tolerant garlic lines to S. cepivorum in Bajio area at Central quence analysis showed that PJV and the previously described Texas pepper

region of M6xico, during two years 1994-95. Trails were conducted on sites geminivirus (TPV) are strains of the same virus. Similarly, CdTV showed a

with high initial inoculum density (25 sclerotia per 50 g. of soil). Garlic lines very high level of sequence identity with the recently described tomato leaf

were annually evaluated using a randomized block design with three replica- crumple virus (TLCrV) also suggesting that they both are strains of the same

tions. The highest percentages of alive plants on the 75 evaluated lines were virus.

observed in Pocitas 500-13, Pocitas 750-4, Pocitas 750-5 and Cristal LPM.These lines showed the highest yield also, with 5683 kg/ha, 4650 kg/ha, Agroecology of a whitefly-transmitted geminivirus in an arid and i4977 kg/ha and 4367 kg/ha, respectively. In relation to number of cloves per Atroranow inregion in nn Mexic V.lated serrano pepper, growing region in northeastern Mexico. Vbulb Pocitas lines had up to 35 cloves, whereas Cristal LPM showed a mean Snchezl, G. Frias1 , L. Aguirre1, L. Bravol, E. Cortdzl, J. Quezadal, R.number of 13 cloves. Ruiz1 , M. Herndndezl, U. Rangel1 , J. Garz6n 2, R. Rivera2, R. Gilbertson 3,

and M. Rojas3. 1UAAAN Buenavista, Saltillo, Coahuila. 2CINVESTAV-Irapuato, Guanajuato. 3University of California, Davis, California.

Tomato geminiviruses in the Caribbean: Their identification and man-

agement. J. E. Polston, University of Florida, Bradenton, FL. Field, greenhouse and laboratory experiments on a whitefly-transmittedserrano pepper disease known regionally as Chino, were conducted in 1990-

Geminiviruses have become major pathogens of tomato (Lycopersicon escu- 1995 to generate basic information for developing management strategies tolentum Mill.) in several countries in the Caribbean. These epidemics usually reduce crop losses. Rain was presumably identified as an important factor forappear three to five years following the introduction of their vector, Bemisia whitefly population outbreaks. Nicotiana glauca, a well adapted perennialtabaci, biotype B, which feeds and readily reproduces on tomato. Some of weed in arid agroecosystems, was a host for both, the geminivirus identifiedthese epidemics appear to be due to extensions of the geographic range of as Jalapeflo Pepper Virus, and its whitefly vector (Bemisia tabaci). Infectedknown viruses, others appear to be due to new viruses. Mixed infections Nicotiana glauca were found to be an important source of inoculum forof multiple geminiviruses are common. Tomato geminiviruses are readily Chino's disease epidemics. In the greenhouse, time from inoculation todetected using PCR with an array of primers, squash or dot blot symptoms development was 10-12 days on seedlings and 10-27 days onhybridization with a variety of labeled probes, and by ELISA using adult plants. Field observations indicate that this incubation period could becommercially available broad-spectrum monoclonal antisera. Management as long as 30-45 days. First whitefly arrivals were responsible for chinoof these viruses has proven nearly impossible when tomato are produced epidemics. Critical infection periods during the development of the plantyear-round. Currently, the best control is achieved through the use of were identified and methods to keep plants disease free during this periodinsecticides based on scouting, sanitation, tolerant cultivars and crop-free were evaluated.periods.

Citrus tristeza virus in south east Texas. M. Skarial, J. V. da Gra~a2, N.Alternate hosts of citrus tristeza closterovirus. M. Price, K. S. Derrick, and Solfs-Gracia1, and R. Parker3 . 1Texas A&M University-Kingsville CitrusR. F. Lee. Citrus Research and Education Center, 700 Experiment Station Center, Weslaco, TX 78596, 2University of Natal, Pietermaritzburg, SouthRoad, University of Florida, Lake Alfred, FL 33850. Africa, 3Texas Agricultural Extension Service, Orange, TX 77631.

A major obstacle in studying citrus tristeza virus (CTV) replication is its Commercial citrus in Texas is located in the Lower Rio Grande Valleywoody citrus hosts. After CTV inoculation by grafting, budding, or slashing, (LRGV) where sweet oranges and grapefruit are grown on sour orange root-it is difficult to do meaningful time-course studies since it takes 4-6 weeks stock. Certain strains of citrus tristeza virus (CTV) cause serious economicpost inoculation to detect virus. A single experiment can take 3-6 months. damage. Past surveys for CTV in the LRGV, based on enzyme linked im-We report CTV transmission to tomato and datura varieties. Seven days munosorbent assay (ELISA), detected a low incidence of CTV in some door-post inoculation, CTV capsid protein was detected in these plants by yard trees, commercial orchards, and nurseries. Field symptoms of the dis-Western blots. Chlorosis, stunting, leaf curling, and localized necrosis ease have not been evident so far. Cold tolerant citrus cultivars are grown onwere observed in CTV-infected tomato (L. esculentum) plants. In CTV- trifoliate rootstocks in the southeast and the coastal bend areas of Texas, asinfected Datura (D. stramonium) plants, chlorosis was the major symptom dooryard trees. Some of these trees originated outside Texas where tristezaobserved. virus has been reported. Between December 1994 and May 1995, citrus leaf

Vol. 86, No. 11 (Supplement), 1996 3117

samples were collected from Hardin, Jefferson, Orange, and Newton counties Biological and chemical control of Rhizoctonia solani on potato in Gua-to evaluate the incidence and severity of CTV in dooryard citrus. Leaf sam- najuato Mexico. G. Virgen - Calleros1 , V. Olalde - Portugal and R. Rocha-ples were collected and tested by ELISA. A total of 134 samples was R.2. 'CINVESTAV-IPN U. Irapuato. Apdo. Postal 629 Irapuato, Gto. Mex-collected from eight locations. Twenty-one trees from three locations showed ico. 2INIFAP-CAE-BAJIO, Celaya, Gto. Mexico.a positive CTV reaction. The CTV positive samples were from Armstrong A field trial was conducted to evaluate the efficacy of several controearly satsuma, Owari satsuma, Nippon orangequat, Meyer lemon, Neapolitan Aiel agas Ronductd t eate the as ofsseveralcntltangerine, Hamlin sweet orange, navel orange, and sour orange cultivars. ures against R. solani AG-3. Treatments were as follows: 1)fluazinam, 250gCTV infected trees in these counties could be an inoculum source for the a.i/3 ton of tuberseed and a furrow drench of 1750g a.i/ha, 2) pencycuron,brown citrus aphid, the insect vector for CTV. Effective quarantine regula- formaldehyde dip of tuberseed for 2 mi and a furrow drenchoof i/h, g ao 1 .ition and surveys to detect and destroy severe CTV strains are necessary to of ICIA5504, 4) 2x10 12 spores of Bacillus subtilis (B.s)/ton of tuberseed andprotect commercial citrus in the LRGV. a furrow drench of 5x101 spores/ha, 5) a 1.8% of formaldehyde dip of tuber-

seed for 2 min and a furrow drench of 5000g of SoilGard (Gliocadium virensAscospore release of Mycosphaerella caryigena and downy spot disease G1-21)/ha and 6) untreated control Stems were evaluated 20 and 45 days afteroccurrence on pecan groves in central Nuevo Leon, Mexico. Nora Solfs- planting for damage due to R. solani on a scale 0-4. No significant differ-Gracia, Mario A. Rocha-Pefia y David Cort6s-Ortega. INIFAP, Apdo. Postal ences were observed between treatments for disease incidence and severity at3. General Terdn, Nuevo Le6n 67400 M6xico. 20 days. After 45 days, ICIA5504 was the most effective (0.25), while theuntreated control exhibited the most severe disease (1.06). Sclerotia were

Downy spot by Mycosphaerella caryigena (anomorph = Cercosporella observed in 1.12% of tubers with the ICIA treatment, and 4.21 and 7.86%caryigena) is a common foliar disease on pecan groves in central Nuevo respectively for the pencycuron and control treatments. B.s was intermedi-Leon, Mexico. In extreme situations, severe defoliation may affect nut yields ated in its efficacy as compared to other treatments, while SoilGard was notin several subsequent crops. Fungicide spray programs rarely are successful significantly more effective than the untreated control. Grant by CONACYTbecause of an apparent erratic infection period from one year to another. Two (Miguel Hgo).different pecan groves were studied for ascospore release and disease occur-rence over a period of three subsequent years. Mature ascospores of M.caryigena were consistently present in dead leaves on the ground in April Tinangaja viroid incidence in coconut palms on Guam. George C. Wall',and May every year. Ascospores in the air were coincident with the first Melany P. Puglisi1, Richard A. J. Hodgson 2, and John W. Randles2.spring rains, were intermittent throughout the spring and summer and de- 'CALS/AES University of Guam. 2Department of Crop Protection, Waitecreased in late summer. Downy spot symptoms appeared within a period of 6 Campus, University of Adelaide.to 8 weeks after detection of ascospores in the air. Disease severity was dif- Tinangaja disease of coconut palms, first reported in 1917, causes early se-ferent in every grove and in different years. nescence in affected trees on Guam. It is caused by the Coconut Tinangaja

viroid (CTiVd), closely related to the coconut cadang-cadang viroidMechanisms of Mucuna dee(ingiana against plant-parasitic nematodes. (CCCVd), a commercially devastating viroid afflicting the coconut industryR. Vargas and A. Pantoja. University of Puerto Rico, Department of Crop in the Philippines. CCCVd has wiped out over 50,000 coconut trees in theProtection, Mayag.ez, P.R. 00681. past 50 years. Hybridization experiments have demonstrated a 64% similarity

in the RNA of the two viroids. The symptoms of Tinangaja and cadang-

Greenhouse experiments using Mucuna root exudates, collected in the in-i- cadang include a reduced crown, tapered trunk, deformed nuts and earlygation water of a hydroponic system, showed the strong effect of plant me- senescence. In CCCVd-infected trees, nuts become smaller and are scarred.tabolites on nematodes. This effect may be explained in two distinct mecha- With CTiVd infection, nuts are small, elongated, deformed, scarred along thenisms of resistance. Root exudates contain several compounds (phytoalexins) middle, and produce no kernel. Older trees are more susceptible to bothwhich were highly toxic to the root-knot nematode (Meloidogyne incognita). viroids; once a tree is infected, it will only live for 5-10 years. Younger treesThese phytoalexins had been isolated and characterized from the organic die much faster. The distribution of Tinangaja in certain parts of Guam hasfraction of these extracts and determined as pterocarpanes, isoflavanes, and been mapped in transects from September 1995 to April 1996, recording theisoflavonones. Other studies suggest that Mucuna-rhizosphere has a distinct frequency of symptoms. RNA electrophoresis and northern transfer to mem-microflora with high population of beneficial microorganisms. In a biocon- branes were run to confirm the presence of CTiVd. In undisturbed areas,trol screening, the most abundant species of rhizobacteria and fungi showed approximately 20% of the trees show symptoms, while in developed areasantagonism against nematodes. One or both of these mechanisms of Mucuna incidence levels reach 60%. The vector for CTiVd is unknown. High ici-may be involved with the nematode suppression in the field. dence in populated areas suggests mechanical transmission by humans.

Phytophthora resistant capsicums. Benigno Villal6n. Texas Agricultural Tomato chlorosis virus (ToCV) is a new closterovirus distinct from otherExperiment Station. 2415 East Highway 83, Weslaco, TX 78596. whitefly-transmitted closteroviruses. G. C. Wisler, R. H. Li, H.-Y. Liu, J.Phytophthora root rot is a very serious disease of chile. The Texas Agricul- E. Duffus, G. W. Simone, R. C. Hochmuth, and J. R. Knight.tural Experiment Station at Weslaco has placed emphasis in obtaining ge- A new closterovirus was identified in greenhouse grown tomato plants innetic resistance to chile wilt since 1988. Genetic resistance to this fungus via North Central Florida. The virus causes interveinal yellowing and necrosis intraditional plant breeding has been found in several hundred capsicum infected plants and reduces yield due to loss of photosynthetic area. Thisgenotypes. Phytophthora capsici has been routinely cultured and propagated problem had been previously called "yellow leaf disorder" and was attributedand used for inoculation of pepper breeding lines. Thousands of advanced to either pesticide phytotoxicity, physiological/nutritional disorders, or anmultiple virus and insect resistant pepper breeding lines have been screened unknown virus. This new virus, ToCV, is transmitted by four whiteflies,for resistance by inoculating seedlings with an initial zoospore concentration including the greenhouse (Trialeurodes vaporariorum), banded wing (T.of 5,000 zoospores/ml. Forty to 50 day old seedlings were inoculated at abutilone), sweet potato (Bemisia tabaci), and silverleaf (B. argentifolii)weekly intervals with increasing zoospore concentrations of up to 100,000. whitefly. ToCV is similar to the previously described tomato infectiousPlants that survived inoculations from 50,000 to 100,000 were transplanted chlorosis virus (TICV) with respect to symptomatology and dsRNA patternsto another greenhouse for selling crossing and seed increase purposes. There in agarose gels, suggesting a bicomponent genome for ToCV like TICV.are several lines surviving high inoculum concentration in bells, jalapefios, ToCV is distinct from TICV and other whitefly-transmitted closteroviruseslong green/red chiles, paprikas, yellow wax types, cayennes, serranos, etc. based on limited serological cross-reactivity, and lack of reactions in mo-Limited amounts of seed will be available for experimental purposes under a lecular hybridization studies. Whereas TICV has been found in California,memorandum of understanding. Italy, and North Carolina, ToCV has yet only been detected in Florida.

S118 PHYTOPATHOLOGY