From brian at gweep.ca Wed Apr 7 11:28:29 2004 From: brian at gweep.ca (Brian Edmonds) Date: Sat Jan 15 17:14:02 2005 Subject: PRO/PL> Bacterial stem rot, pepper - Italy (Sardinia) Message-ID: <373c7fpuiw.fsf@lios.aq2.gweep.ca> BACTERIAL STEM ROT, PEPPER - ITALY (SARDINIA) ************************************************* A ProMED-mail post ProMED-mail is a program of the International Society for Infectious Diseases Date: 1 Apr 2004 From: ProMED-mail Source: Journal of Phytopathology Vol. 152 (1) [edited] Bacterial Stem Rot in Greenhouse Pepper (_Capsicum annuum_ L.) in Sardinia (Italy): Occurrence of _Erwinia carotovora_ subsp. carotovora_ M. Fiori and A. Schiaffino Dipartimento di Protezione delle Piante, Universita degli studi di Sassari, Via E. De Nicola, 07100 Sassari, Italy. An unusual bacterial disease was observed in pepper plants during research carried out in greenhouses in central-north Sardinia. The characteristics were the presence of lesions and exudates on stems, pit soft rot, and a brownish-black color in the petioles and leaf veins. Only 2 of 21 isolates were pathogens. 1 was obtained from exudate present on the stem and the other from pith. Experimental infections revealed that the bacterial isolates were particularly aggressive in the stems and fruit of pepper and tomato. Biochemical, physiological and serological tests, in conjunction with fatty acid profile analysis, confirmed that they were _Erwinia carotovora_ subsp. _carotovora_ (Jones) Bergey et al. The product of 434-bp polymerase chain reaction (PCR) enabled a preliminary identification of isolates to be made. Restriction fragment length polymorphism (RFLP) analysis of amplification products showed that isolates DPP 23ef and DPP 24m, strain type CFBP 2046 and DPP 281, isolated from pepper fruit, belonged to RFLP group 12, whereas DPP 29, also isolated from pepper fruit, was included in RFLP group 1. ------------------------------ ProMED-mail [Taxonomic studies indicate that Ecc can be transferred to the new genus _Pectobacterium_ (_P. carotovorum_ subsp. _carotovorum_, Pcc). Thus Ecc and Pcc are synonyms. Ecc is ubiquitous, causing disease in glasshouse crops and appears to be present at low frequency in various regions of Italy. 2 pepper isolates of Ecc characterized in this report were pathogenic in tomato, thus possibly putting that crop at risk. Diagnosis of the disease requires careful analysis, because the tomato pith pathogen, _Pseudomonas corrugata_ can be confused with Ecc. Ecc survives readily in field residues. Disease management depends upon use of hypochlorite-treatment of seeds, avoidance of wounding, and early detection of the pathogen. Should an outbreak occur in glasshouse production units, all plants should be destroyed, and the crop should be treated with fixed copper sprays. At the close of production, all plant residues should be removed and subjected to solarization for at least 45 days during summer. - Mod.DH] .......................................dh/msp/pg/dk *##########################################################* ProMED-mail makes every effort to verify the reports that are posted, but the accuracy and completeness of the information, and of any statements or opinions based thereon, are not guaranteed. The reader assumes all risks in using information posted or archived by ProMED-mail. ISID and its associated service providers shall not be held responsible for errors or omissions or held liable for any damages incurred as a result of use or reliance upon posted or archived material. ************************************************************ Visit ProMED-mail's web site at . Send all items for posting to: promed@promedmail.org (NOT to an individual moderator). If you do not give your full name and affiliation, it may not be posted. Send commands to subscribe/unsubscribe, get archives, help, etc. to: majordomo@promedmail.org. For assistance from a human being send mail to: owner-promed@promedmail.org. ############################################################ ############################################################ From brian at gweep.ca Wed Apr 7 11:28:50 2004 From: brian at gweep.ca (Brian Edmonds) Date: Sat Jan 15 17:14:02 2005 Subject: PRO/PL> Sweet potato viruses - Spain Message-ID: <37ptajofxu.fsf@lios.aq2.gweep.ca> SWEET POTATO VIRUSES - SPAIN ********************************* A ProMED-mail post ProMED-mail is a program of the International Society for Infectious Diseases Date: 1 Apr 2004 From: ProMED-mail Source: American Phytopathological Society, Plant Disease Notes [edited] 1st Report of Sweet potato chlorotic stunt virus and Sweet potato feathery mottle virus Infecting Sweet Potato in Spain. R. A. Valverde, Department of Plant Pathology and Crop Physiology, Louisiana State University, Baton Rouge, 70803; G. Lozano and J. Navas-Castillo, Estacion Experimental "La Mayora", CSIC, 29750 Algarrobo-Costa, Malaga, Spain; and A. Ramos and F. Valdes, Departamento de Biologia Vegetal, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain. Plant Dis. 88:428, 2004; published on-line as D-2004-0203-02N, 2004. Accepted for publication 9 Jan 2004. Sweet potato chlorotic stunt virus (SPCSV), family Closteroviridae and Sweet potato feathery mottle virus (SPFMV), family Potyviridae) are whitefly- and aphid-transmitted, respectively, which in double infections cause sweet potato virus disease (SPVD), a serious sweet potato (_Ipomoea batatas_ Lam.) disease in Africa (2). During the past decade, sweet potato plants showing symptoms similar to SPVD have been observed in most areas of Spain. Nevertheless, not much information is available about the identity of the viruses infecting this crop in Spain. During the summer of 2002, sweet potato plants with foliar mosaic, stunting, leaf malformation, chlorosis, and ringspot symptoms were observed in several farms in Malaga (southern Spain) and Tenerife and Lanzarote (Canary Islands, Spain). Vine cuttings were collected from 21 symptomatic plants in Malaga and from 8 plants on Lanzarote and 6 on Tenerife. Scions were grafted to the indicator hosts, Brazilian morning glory (_I. setosa_) and _I. nil_ cv. Scarlett O'Hara. 3 weeks after graft inoculations, all plants showed various degrees of mosaic, chlorosis, leaf malformation, and stunting. 4 field collections (2 from Malaga, one from Tenerife, and one from Lanzarote) with severe symptoms on _I. setosa_ were selected for whitefly (_Bemisia tabaci_ biotype Q) transmission experiments. Acquisition and transmission periods were 48 h. _I. setosa_ was the acquisition host, and _I. nil_ was the transmission host. For each isolate, groups of 10 whiteflies per _I. nil_ plant were used. All _I. nil_ plants used as transmission hosts with the 4 field collections showed chlorosis and leaf malformation. Reverse-transcription polymerase chain reaction (RT-PCR) was performed on _I. setosa_ (grafted with the 4 selected field collections) and _I. nil_ plants (from the whitefly transmission experiments) with primers for the HSP70h gene of SPCSV. A 450-bp DNA fragment was obtained with all _I. setosa_ and _I. nil_ samples. Sequencing of the 450-bp DNA from 2 samples from Malaga yielded a nucleotide sequence with 98 to 99 percent similarity to the HSP70h gene of West African SPCSV isolates. Foliar samples from _I. setosa_, originally grafted with the 21 vine cuttings, were used for nitrocellulose membrane enzyme-linked immunosorbent assay (NCM-ELISA) testing with antiserum specific to SPFMV-RC (provided by J. Moyer, North Carolina State University, Raleigh). Positive control was sap extract from _I. setosa_ that was infected with the common strain of SPFMV. Procedures for NCM-ELISA-ELISA were as described (4). NCM-ELISA testing suggested that SPFMV was present in all samples. RT-PCR was conducted with degenerate primers POT1/POT2 (1). The nucleotide sequence that was amplified by these 2 primers spans part of the Nlb protein and part of the coat protein gene of potyviruses. All samples yielded the expected 1.3-kb DNA. Sequencing of the RT-PCR products of 2 isolates from Malaga and sequence comparisons yielded nucleotide sequences with 97 percent similarity to 2 East African isolates (Nam 1 and Nam 3) of SPFMV (3). These results confirm the presence of SPCSV and SPFMV in sweet potato in Spain. References: (1) D. Colinet and J. Kummert. J. Virol. Methods 45:149, 1993. (2) R. W. Gibson et al. Plant Pathol. 47:95, 1998. (3) J. F. Kreuze et al. Arch. Virol. 145:567, 2000. (4) E. R. Souto et al. Plant Dis. 87:1226, 2003. ------------------------------ ProMED-mail [SPVD is considered the most damaging virus disease of sweet potato in Africa and may be the most serious disease in the crop worldwide. SPFMV is ubiquitous, whereas SPCSV has been reported only from Africa (Nigeria, Uganda, Kenya, Zaire), Asia (Taiwan, China, Indonesia, Philippines), America (USA, Brazil, Argentina, Peru) and Israel. The fact that both viruses are present in Spain indicates that SPVD can be expected to spread in the country. Virus research at the International Potato Center in Peru is focused on SPVD because of its debilitating effect on resource-poor farms, especially in sub-Saharan Africa. Unfortunately, SPFMV-resistant cultivars originating from CIP were found to be susceptible to SPVD. Identification of genes for resistance to both SPCSV and SPFMV is a high priority. In China, using healthy planting materials resulted in yields that were 2-3 times greater than SPVD-infected plants. Similar results were obtained in African trials. Additional references: - Mod.DH] [see also: 2001 ---- Cucurbit yellow stunting dis. crinivirus - Portugal 20010529.1040] .......................................dh/pg/dk *##########################################################* ProMED-mail makes every effort to verify the reports that are posted, but the accuracy and completeness of the information, and of any statements or opinions based thereon, are not guaranteed. The reader assumes all risks in using information posted or archived by ProMED-mail. ISID and its associated service providers shall not be held responsible for errors or omissions or held liable for any damages incurred as a result of use or reliance upon posted or archived material. ************************************************************ Visit ProMED-mail's web site at . Send all items for posting to: promed@promedmail.org (NOT to an individual moderator). If you do not give your full name and affiliation, it may not be posted. Send commands to subscribe/unsubscribe, get archives, help, etc. to: majordomo@promedmail.org. For assistance from a human being send mail to: owner-promed@promedmail.org. ############################################################ ############################################################ From brian at gweep.ca Wed Apr 7 11:28:36 2004 From: brian at gweep.ca (Brian Edmonds) Date: Sat Jan 15 17:14:03 2005 Subject: PRO/PL> Chickpea chlorotic dwarf virus - Syria Message-ID: <37y8p7ofy9.fsf@lios.aq2.gweep.ca> CHICKPEA CHLOROTIC DWARF VIRUS - SYRIA ******************************************** A ProMED-mail post ProMED-mail is a program of the International Society for Infectious Diseases Date: 1 Apr 2004 From: ProMED-mail Source: American Phytopathological Society, Plant Disease Notes [edited] 1st Report of Chickpea Chlorotic Dwarf Virus Infecting Spring Chickpea in Syria. ------------------------------------------------- S. G. Kumari, K. M. Makkouk, N. Attar, and W. Ghulam, Virology Laboratory, ICARDA, P.O. Box 5466, Aleppo, Syria; and D.-E. Lesemann, Federal Biological Research Centre for Agriculture and Forestry, Institute for Plant Virology, Microbiology and Biosafety, Messeweg 11-12, D-38104 Braunschweig, Germany. Plant Dis. 88:424, 2004; published on-line as D-2004-0204-01N, 2004. Accepted for publication 11 Nov 2003. During May 2003, a high incidence of symptoms suggestive of virus infection in spring chickpea were observed in many fields in Al-Ghab Valley, Syria, the ICARDA farm (near Aleppo, Syria), as well as in other locations in northern Syria, including the Idleb governorate. Symptoms observed were yellowing, stunting, and necrosis. A total of 1345 chickpea samples with these symptoms (331 from Al-Ghab Valley, 269 from the ICARDA farm, and 745 from the Idleb governorate) were collected and tested for the presence of 5 viruses with tissue-blot immunoassay (TBIA) (4) at the Virology Laboratory of ICARDA, using the following antisera: monoclonal antibodies for Faba [Fava?] bean necrotic yellows virus (FBNYV, genus _Nanovirus_) (1); Bean leafroll virus (BLRV, family _Luteoviridae_) (4B10) (3); Beet western yellows virus (BWYV, genus _Polerovirus_, family _Luteoviridae_ [ATCC PVAS-647, American Type Culture Collection, Manassas, VA]); and Soybean dwarf virus (SbDV, family _Luteoviridae_, [ATCC PVAS-650]) and polyclonal antibodies for Chickpea chlorotic dwarf virus (CpCDV, genus _Mastrevirus_, family _Geminiviridae_, provided by H. J. Vetten, BBA, Braunschweig, Germany). The most common virus present was BWYV (detected in 54.1 percent of samples tested), followed by CpCDV (19.2 percent), BLRV (10.2 percent), and FBNYV (5.5 percent). SbDV was not detected in any of the samples tested. Using immunosorbent electron microscopy, infected chickpea samples revealed low numbers of geminivirus-like particles after 15 minutes of incubation on CpCDV antiserum-coated grids. When CpCDV was purified from infected chickpea plants, the virus coat protein was 32 kDa with sodium dodecyl sulfate-polyacrylamide gel electrophoresis typical of CpCDV coat protein (2) and reacted strongly with CpCDV antiserum in western blots. The CpCDV vector in Syria was found to be _Orosius albicinctus_ (Distant), and is thought to be similar to _Orosius orientalis_ (Matsumura), the reported vector of CpCDV (2). FBNYV, BWYV, and BLRV infections of chickpea have been previously reported from Syria, but to our knowledge, this is the 1st report of CpCDV infecting chickpea in Syria. References: (1) A. Franz et al. Ann. Appl. Biol. 128:255, 1996. (2) N. M. Horn et al. Ann. Appl. Biol. 122:467, 1993. (3) L. Katul. Characterization by serology and molecular biology of bean leaf roll virus and faba bean necrotic yellows virus. Ph.D. thesis. University of Gottingen, Germany, 1992. (4) K. M. Makkouk and A. Comeau. Eur. J. Plant Pathol. 100:71, 1994. ------------------------------ ProMED-mail [CpCDV is transmitted only by specific insect vectors (_Orosius_ spp., family _Cicadellidae_). In addition to India and Iran, the virus has been reported on chickpea in Egypt and Iraq. Disease management depends upon an integrated pest management program (IPM). Management options include use of resistant host plants, biological control, suitable agronomic practices, and habitat management. - Mod.DH] [see also: 2002 ---- Faba bean necrotic yellows virus, pulses - Sudan 20021108.5752 Bean common mosaic, Phaseolus sp. - East Africa 20020927.5408 Soybean viruses, first reports - Iran 20020513.4189 Chickpea chlorotic dwarf, sugarbeet & bean - Iran 20020509.4138 2001 ---- Chickpea & lentil viruses, first reports - Iran 20010921.2295] .......................................dh/msp/pg/dk *##########################################################* ProMED-mail makes every effort to verify the reports that are posted, but the accuracy and completeness of the information, and of any statements or opinions based thereon, are not guaranteed. The reader assumes all risks in using information posted or archived by ProMED-mail. ISID and its associated service providers shall not be held responsible for errors or omissions or held liable for any damages incurred as a result of use or reliance upon posted or archived material. ************************************************************ Visit ProMED-mail's web site at . Send all items for posting to: promed@promedmail.org (NOT to an individual moderator). If you do not give your full name and affiliation, it may not be posted. Send commands to subscribe/unsubscribe, get archives, help, etc. to: majordomo@promedmail.org. For assistance from a human being send mail to: owner-promed@promedmail.org. ############################################################ ############################################################ From brian at gweep.ca Wed Apr 7 11:28:44 2004 From: brian at gweep.ca (Brian Edmonds) Date: Sat Jan 15 17:14:03 2005 Subject: PRO/PL> Zucchini yellow mosaic, bottlegourd - India Message-ID: <37u0zvofy0.fsf@lios.aq2.gweep.ca> ZUCCHINI YELLOW MOSAIC, BOTTLEGOURD - INDIA ********************************* A ProMED-mail post ProMED-mail is a program of the International Society for Infectious Diseases Date: 1 Apr 2004 From: ProMED-mail Source: American Phytopathological Society, Plant Disease Notes [edited] 1st Report of Zucchini yellow mosaic virus in Bottlegourd in India. ----------------------------------------------- Raj Verma, Indian Agricultural Research Institute, Regional Station, Agricultural College Estate, P.O. Shivajinagar, Pune- 411 005, India; Y. S. Ahlawat, Plant Virology Unit, Department of Plant Pathology, Indian Agricultural Research Institute, New Delhi- 110 012, India; S. P. S. Tomer and Satya Prakash, Indian Agricultural Research Institute, Regional Station, Agricultural College Estate, P.O. Shivajinagar, Pune- 411 005, India; and R. P. Pant, Plant Virology Unit, Department of Plant Pathology, Indian Agricultural Research Institute, New Delhi- 110 012, India. Plant Dis. 88:426, 2004; published on-line as D-2004-0124-01N, 2004. Accepted for publication 17 Dec 2003. In December 2002, bottlegourd (_Lagenaria siceraria_ L.) plants grown as a commercial crop in Pune, India (western Maharashtra) showed severe mosaic, interveinal chlorosis, and leaf deformation that resulted in fernleaf appearance and severe fruit distortion in approximately 70 percent of the plants. Crude sap of collected samples was used to mechanically inoculate uninfected glasshouse-grown bottlegourd plants that reproduced symptoms observed in the field. Sap extracts from these glasshouse-infected bottlegourd plants were used to mechanically inoculate selected indicator hosts. Chlorotic local lesions were produced on _Chenopodium amaranticolor_, and systemic symptoms were produced on _Benincasa hispida_ (Chinese squash), _Citrullus lanatus_ (watermelon), _Cucumis sativus_ (cucumber), _Cucurbita moschata_ (pumpkin), _Luffa cylindrica_, and _Trichosanthes anguina_. The virus was specifically identified with serological testing using direct antigen coating enzyme-linked immunosorbent assay. The virus reacted strongly to Zucchini yellow mosaic virus (ZYMV) antiserum and did not react to Papaya ring spot virus-P (PRSV-P), Cucumber mosaic virus (CMV), or Watermelon mosaic virus (WMV) antisera. Electron microscopic examination of leafdip preparation from infected plants showed flexuous filamentous particles (720 to 760 nm long) that are typical of potyviruses. Natural infection of bottlegourd by ZYMV has been reported in the Hawaiian Islands (1). To our knowledge, this is the first report of this potentially destructive virus in bottlegourd in India. Reference: (1) D. E. Ullman et al. Plant Dis. 75:367, 1991. ------------------------------ ProMED-mail [ZYMV is an aphid-transmitted potyvirus that causes severe diseases in several cucurbit species. Symptoms include mosaic, yellowing, shoestringing, stunting, and fruit and seed deformations. ZYMV is particularly damaging to cucurbit crops in some Mediterranean countries, Central Europe, and the USA. Typical of aphid-transmitted viruses, it is extremely difficult to control with insecticides, reflective mulches, or mineral oils. Disease management involves use of resistant cultivars and control of infected weeds from which aphids can acquire the virus. Application of chemical insecticides is usually not economical. Additional references: -Mod.DH] [see also: 2003 ---- Zucchini yellow mosaic, cucumber - Poland 20031031.2711] .......................................dh/pg/dk *##########################################################* ProMED-mail makes every effort to verify the reports that are posted, but the accuracy and completeness of the information, and of any statements or opinions based thereon, are not guaranteed. The reader assumes all risks in using information posted or archived by ProMED-mail. ISID and its associated service providers shall not be held responsible for errors or omissions or held liable for any damages incurred as a result of use or reliance upon posted or archived material. ************************************************************ Visit ProMED-mail's web site at . Send all items for posting to: promed@promedmail.org (NOT to an individual moderator). If you do not give your full name and affiliation, it may not be posted. Send commands to subscribe/unsubscribe, get archives, help, etc. to: majordomo@promedmail.org. For assistance from a human being send mail to: owner-promed@promedmail.org. ############################################################ ############################################################ From brian at gweep.ca Mon Apr 12 17:05:41 2004 From: brian at gweep.ca (Brian Edmonds) Date: Sat Jan 15 17:14:03 2005 Subject: PRO/PL> High Plains virus, wheat - Australia (Qld) Message-ID: <37fzb8ztj6.fsf@lios.aq2.gweep.ca> HIGH PLAINS VIRUS, WHEAT - AUSTRALIA (QUEENSLAND) ************************************************* A ProMED-mail post ProMED-mail is a program of the International Society for Infectious Diseases Date: 10 Apr 2004 From: ProMED-mail Source: Australian Broadcasting Corporation [edited] New wheat virus discovered in southern Queensland ------------------------ A wheat virus new to Australia has been found at the Leslie Research Centre in Toowoomba, southern Queensland. Scientists say the High Plains virus (HPV) is often found in conjunction with wheat streak mosaic virus (WSMV), discovered for the first time in Australia early in 2003. It has similar characteristics, causing streaking and mottling on leaves, but doesn't cause any major yield loss. Chris Adriaansen from the Queensland Department of Primary Industries, referring to a radio transcript from ABC National Rural Hour, says it's likely HPV has been in Australia for some time. It was found on 1 plant in 1 glasshouse at Leslie Research Centre, and that plant was isolated and destroyed. He says that testing will be done throughout the Leslie Research Centre, as was done with WSMV. The Commonwealth Scientific and Industrial Research Organisation(CSIRO) has also been testing their material in Canberra, and there is an expectation that further testing will reveal HPV in other locations in Australia. ------------------------------ ProMED-mail [The fact that HPV has been detected in Australian wheat is not surprising. It has been recorded in the Americas, and there are unconfirmed reports of its presence in Russia. HPV can cause severe disease in barley, maize, oats, rye, and some grasses. Disease management depends upon interrupting the life cycle of the mite vector (_Aceria tosichella_) by plowing down volunteer wheat seedlings at least 2 weeks before seeding the next crop. The mite cannot survive in the absence of susceptible hosts for more than 24 hours. At present there is no information on how HPV presence will affect wheat production in Australia. Time will tell. An intriguing aspect of this report is that HPV appears to share some properties of a group of filamentous, eryiophyid mite-transmitted viruses (fig mosaic, thistle mosaic, rose rosette, redbud yellow ringspot, and wheat spot mosaic, all transmitted by _A. tosichella_ ) and possibly pigeonpea sterility mosaic, transmitted by _A. cajani_, and known to infect pigeonpea crops in India. There is little information about the structural properties of HPV and others in the group. Relevant information about this group would be welcome. Let me know, please. References: - Mod.DH] [see also: 2001 --- High Plains virus, maize - USA (Washington) 20010603.1096] ....................mpp/dh/pg/sh *##########################################################* ProMED-mail makes every effort to verify the reports that are posted, but the accuracy and completeness of the information, and of any statements or opinions based thereon, are not guaranteed. The reader assumes all risks in using information posted or archived by ProMED-mail. ISID and its associated service providers shall not be held responsible for errors or omissions or held liable for any damages incurred as a result of use or reliance upon posted or archived material. ************************************************************ Visit ProMED-mail's web site at . Send all items for posting to: promed@promedmail.org (NOT to an individual moderator). If you do not give your full name and affiliation, it may not be posted. Send commands to subscribe/unsubscribe, get archives, help, etc. to: majordomo@promedmail.org. For assistance from a human being send mail to: owner-promed@promedmail.org. ############################################################ ############################################################ From brian at gweep.ca Thu Apr 15 22:35:08 2004 From: brian at gweep.ca (Brian Edmonds) Date: Sat Jan 15 17:14:03 2005 Subject: PRO/PL> Potato purple top disease - USA (WA, OR) Message-ID: <3765c07d73.fsf@lios.aq2.gweep.ca> POTATO PURPLE TOP DISEASE - USA (WASHINGTON, OREGON) **************************************************** A ProMED-mail post ProMED-mail is a program of the International Society for Infectious Diseases http://www.isid.org Date: 14 Apr 2004 From: ProMED-mail Source: American Phytopathological Society, Plant Disease Notes [edited] Clover Proliferation Group (16SrVI) Subgroup A (16SrVI-A) Phytoplasma is a Probable Causal Agent of Potato Purple Top Disease in Washington and Oregon. I.-M. Lee and K. D. Bottner, Molecular Plant Pathology Laboratory, USDA, ARS, Beltsville, MD 20705; J. E. Munyaneza, USDA, ARS, YARL, Wapato, WA 98951; and G. A. Secor and N. C. Gudmestad, North Dakota State University, Department of Plant Pathology, Fargo 58105. Plant Dis. 88:429, 2004; published on-line as D-2004-0204-02N, 2004. Accepted for publication 14 Jan 2004. An epidemic of purple top disease of potato (_Solanum tuberosum_) occurred in the Columbia Basin Region of Washington and Oregon in 2002 and 2003, causing great economic loss in the potato industry (1). Symptoms of potato purple top (PPT) were upright terminal shoots, upward leaf rolling, chlorosis, red or purplish discoloration of new leaves, proliferation of axillary shoots with basal swelling, and the formation of aerial tubers. Preliminary studies on PPT disease suggested phytoplasma as a possible cause (1). In this study, 78 potato samples (including 5 asymptomatic) were collected from 5 fields throughout the region. A nested polymerase chain reaction (PCR) with primer pair P1/P7 in the first amplification followed with primer pair R16F2n/R16R2 was performed to detect the presence of phytoplasmas in infected plants (2). Restriction fragment length polymorphism (RFLP) and phylogenetic analyses of amplified 16S rDNA sequences were used for phytoplasma identification. 84 percent (63 percent in the first amplification) of the symptomatic samples and 60 percent (0 in the first amplification) of the asymptomatic samples tested positive. Low phytoplasma titers and the presence of PCR inhibitors account for the low detection rate in the 1st PCR amplifications. RFLP analyses of 16S rDNA with enzymes MseI, AluI, HhaI, RsaI, and HpaII indicated that the phytoplasma associated with PPT belonged to the clover proliferation (CP) group (16SrVI) subgroup A (16SrVI-A) (2). 16SrVI-A currently consists of 3 members, CP (GenBank Accession No. AY500130), potato witches'-broom (GenBank Accession No. AY500818), and vinca virescence (VR) (GenBank Accession No. AY500817), a strain of beet leafhopper-transmitted virescence agent (BLTVA) phytoplasma (2). The taxonomic affiliation of PPT phytoplasma was confirmed by phylogenetic analysis of cloned 16S rDNA (GenBank Accession Nos. PPT4, AY496004; PPT8, AY496005). The 16S rDNA sequences of the PPT strains were closely related to VR with 99.7 percent sequence homology compared with 99.2 percent with CP. A high correlation between the symptoms and the presence of 16SrVI-A phytoplasmas in the potato plants suggests that these phytoplasmas play an etiological role in PPT disease. To gain further evidence, a modified test of Koch's postulates was conducted. Infected tissues from four phytoplasma-positive potato samples (including PPT4 and PPT8) were grafted onto healthy potato seedlings. Within 60 days after grafting, the potato seedlings developed symptoms similar to those in the original diseased samples. The newly infected plants were maintained through cuttings. RFLP analysis of 16S rDNA indicated that the phytoplasmas detected in each of the seedlings and cuttings were identical to those in the scions. These results confirmed the probable etiological role of CP group, subgroup 16SrVI-A phytoplasma strains in PPT disease in Washington and Oregon. There are 2 other confirmed cases of phytoplasmas (BLTVA and aster yellows phytoplasma) associated with PPT disease in Utah (4) and Mexico (3). References: (1) P. B. Hamm et al. Potato Prog. Vol. 3, No. 1, 2003. (2) I.-M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (3) N. E. Leyva-Lopez et al. Can. J. Microbiol. 48:1062, 2002. (4) C. D. Smart et al. Phytopathology 83:1399, 1993. ------------------------------ ProMED-mail [Phytoplasma-induced diseases are being recognized as significant pathogens of food crops. PPT (a.k.a. aster yellows [haywire, purple dwarf and Purple-top wilt]) disease in Washington is somewhat ephemeral. It has been a factor in disease losses for many years in Washington state but is seldom a major factor affecting potato crops in the Columbia Basin. However, PPT is endemic in potato crops in Mexico, where it ranks 2nd to late blight caused by _Phytophthora infestans_. 2 phytoplasma diseases have been recognized in Mexico; PPT and potato hair sprouts (PHS). PHS has the greater impact, since infected, but symptomless, tubers generally fail to sprout or may sprout poorly. Moreover, PHS-infected stems are weakened because they are deficient in chlorophyll (etiolated). Moreover, psyllid nymphs inject a toxin into potato tissue, causing PPT-like symptoms, which confounds diagnosis. Disease management basically depends upon planting certified seed in areas free of phytoplasmas or, in the case of areas infested with infected weeds and leafhoppers, use of insecticides to reduce vector numbers. Development of resistance to phytoplasmas may offer a measure of control. Useful references: - Mod.DH] [see also: 2001 ---- Potato stolbur phytoplasma, potato - Austria 20011124.2877 2000 ----- Potato stolbur phytoplasma - Poland: EPPO report 20001127.2063] .......................................dh/pg/jw *##########################################################* ProMED-mail makes every effort to verify the reports that are posted, but the accuracy and completeness of the information, and of any statements or opinions based thereon, are not guaranteed. The reader assumes all risks in using information posted or archived by ProMED-mail. ISID and its associated service providers shall not be held responsible for errors or omissions or held liable for any damages incurred as a result of use or reliance upon posted or archived material. ************************************************************ Visit ProMED-mail's web site at . Send all items for posting to: promed@promedmail.org (NOT to an individual moderator). If you do not give your full name and affiliation, it may not be posted. Send commands to subscribe/unsubscribe, get archives, help, etc. to: majordomo@promedmail.org. For assistance from a human being send mail to: owner-promed@promedmail.org. ############################################################ ############################################################ From brian at gweep.ca Fri Apr 16 12:36:44 2004 From: brian at gweep.ca (Brian Edmonds) Date: Sat Jan 15 17:14:03 2005 Subject: This Month in Plant Disease Message-ID: <37llkv3h3b.fsf@lios.aq2.gweep.ca> As a subscriber to APS news, you are receiving this update to keep you informed on the latest plant disease information as published in Plant Disease, an official APS publication. This Month in Plant Disease... May 2004 New Breakthroughs Aid in Controlling "Green Plague" of Important Indian Legume http://www.apsnet.org/pd/summaries/dmy04sum.asp#Jones Highly-destructive Onion Disease Found in Colorado http://www.apsnet.org/pd/summaries/dmy04sum.asp#Gent Length of Storage an Important Factor in Pear Diseases http://www.apsnet.org/pd/summaries/dmy04sum.asp#Lennox Researchers Study Methods of Preventing Post-harvest Decay of Pears http://www.apsnet.org/pd/summaries/dmy04sum.asp#Lennox2 Real-Time Diagnostic Tools Aid in the Detection of Pathogens in Crucifier Seeds http://www.apsnet.org/pd/summaries/dmy04sum.asp#Guillemette Researchers Look for Non-chemical Means of Managing Jujube Fruit Diseases http://www.apsnet.org/pd/summaries/dmy04sum.asp#Qin Study Evaluates the Use of Disinfectants to Control Mold http://www.apsnet.org/pd/summaries/dmy04sum.asp#Fermin Engineered Papaya Found Resistant to Papaya Ringspot Virus http://www.apsnet.org/pd/summaries/dmy04sum.asp#Fermin Test Weighs Risk of Possible Year-Round Soybean Rust Outbreak http://www.apsnet.org/pd/summaries/dmy04sum.asp#Pivonia New Computer Program to Improve Identification of Race-Specific Resistance Genes in Wheat http://www.apsnet.org/pd/summaries/dmy04sum.asp#Wamishe To view interpretive summaries of the articles, please click on the corresponding links. For more information, or to receive a full copy of the article, please contact Amy Steigman at mailto:asteigman@scisoc.org or call +1.651.454.7250. Plant Disease is a leading international journal of applied plant pathology, published by The American Phytopathological Society. It publishes original research articles focusing on practical aspects of plant disease diagnosis and control. Each issue also includes a monthly feature article summarizing a significant topic in plant pathology. The Disease Notes section contains timely reports of new diseases, outbreaks, and other pertinent observations. For a full list of contents, visit http://www.apsnet.org/pd/current/. The American Phytopathological Society 3340 Pilot Knob Road St. Paul, MN 55121-2097 Phone: +1.651.454.7250 Fax: +1.651.454.0766 E-mail: mailto:aps@scisoc.org From brian at gweep.ca Wed Apr 21 14:30:45 2004 From: brian at gweep.ca (Brian Edmonds) Date: Sat Jan 15 17:14:03 2005 Subject: PRO/PL> Dry bean phyllody disease - USA (WA): 1st report Message-ID: <37isftdqfk.fsf@lios.aq2.gweep.ca> DRY BEAN PHYLLODY DISEASE - USA (WASHINGTON): 1ST REPORT ******************************************************** A ProMED-mail post ProMED-mail is a program of the International Society for Infectious Diseases Date: 15 Apr 2004 From: ProMED-mail Source: American Phytopathological Society, Plant Disease Notes [edited] Clover Proliferation Group (16SrVI) Subgroup A (16SrVI-A) Phytoplasma is a Probable Causal Agent of Dry Bean Phyllody Disease in Washington. I.-M. Lee and K. D. Bottner, Molecular Plant Pathology Laboratory, USDA, ARS, Beltsville, MD 20705; P. N. Miklas, Vegetable and Forage Crop Research, USDA, ARS, Prosser, WA 99350; and M. A. Pastor-Corrales, Vegetable Laboratory, USDA, ARS, Beltsville, MD 20705. Plant Dis. 88:429, 2004; published on-line as D-2004-0128-01N, 2004. Accepted for publication 6 Jan 2004. During 2003, a new disease, dry bean phyllody (DBPh), was observed in the Columbia Basin of Washington in dry bean (_Phaseolus vulgaris_ L.) cultivars of Andean origin grown in Mattawa and Paterson, WA that caused great reduction in dry bean production. Symptoms of DBPh became apparent during mid-to-late pod development and were characterized by leafy petals (phyllody) and aborted seed pods resembling thin, twisted, and corrugated leaf-like structures. Deformed sterile pods that were small, sickle-shaped, upright, and leathery were also observed. The infected plants generally exhibited chlorosis, stunting, or bud proliferation from leaf axils. Symptoms of DBPh were indicative of possible infection by phytoplasmas. Restriction fragment length polymorphism (RFLP) and phylogenetic analyses of amplified 16S rDNA sequences were used for phytoplasma identification. 4 symptomatic bean plants were analyzed and tested positive for phytoplasma infection on the basis of results of initial polymerase chain reaction (PCR) and subsequent nested-PCR amplifications (2). RFLP analyses of 16S rDNA sequences with restriction enzymes, MseI, AluI, HhaI, RsaI, and HpaII indicated that the phytoplasma strains associated with DBPh belonged to the clover proliferation group (16SrVI) subgroup A (16SrVI-A) (2). This subgroup currently consists of 3 members, clover proliferation (CP; GenBank Accession No. AY500130), potato witches'-broom (PWB; GenBank Accession No. AY500818), and vinca virescence (VR; GenBank Accession No. AY500817), a strain of beet leafhopper-transmitted virescence agent (BLTVA) phytoplasmas (1,2). The taxonomic affiliations of the DBPh phytoplasma strains were confirmed by phylogenetic analysis of cloned 16S rRNA gene sequences (GenBank Accession Nos. DBPh2, AY496002; DBPh3, AY496003). Among the existing members of subgroup 16SrVI-A, the 4 DBPh strains were closely related to the VR strain with 99.7 percent 16S rDNA sequence homology and to the CP strain with 99.2 percent sequence homology. To gain further evidence on the role of 16SrVI-A phytoplasma strains in DBPh disease, a modified test of Koch's postulates was conducted. Infected tissue from one phytoplasma-positive dry bean sample was grafted onto 3 Pinto UI-114 bean seedlings in the greenhouse. Within 60 days, the bean seedlings exhibited corrugated leaflike structures from aborted seedpods, a lack of flower formation, general chlorosis, and stunting similar to the original diseased plants. The lower leaves of the inoculated bean plants became epinastic and leathery. The transmitted phytoplasma was detected in each of the grafted symptomatic seedlings, and the RFLP patterns of its 16S rRNA gene sequences were identical to those of the phytoplasmas in the scions. A high correlation between the presence of disease symptoms and the presence of subgroup 16SrVI-A phytoplasmas in the bean plants suggests that these phytoplasmas play an etiological role in DBPh disease. To our knowledge, these findings provide the first confirmed case of phytoplasma-associated DBPh in the United States. References: (1) D. A. Golino et al. Plant Dis. 73:850, 1989. (2) I.-M. Lee et al. Int. J. Syst. Bacteriol. 1153, 1998. ------------------------------ ProMED-mail [Phyllody describes a retrograde metamorphosis of the floral organs to the condition of leaves. Because floral tissues in phytoplasma-infected plants revert to vegetative tissues, no seeds are produced, and crop losses due to phyllody can be very high. Phyllody-affected crop plants can be cured of phytoplasmas by heat treatment or by subjecting cuttings to tissue culture. The beet leafhopper, _Circulifer tenellus_ (Ct), is the only known vector of BLTVA, although not much is known about other vectors. Phytoplasmas infect and multiply in their leafhopper vectors. The BLTVA is vectored in the same manner as other phytoplasmas are by other leafhoppers. Ct acquires BLTVA only by feeding on infected plants. Prophylactic use of insecticides is the only known means to prevent transmission of BLTVA. The Washington vegetable seed industry has been plagued with BLTVA for years, and even the prophylactic use of insecticides has not always successfully managed it. Some vegetable seed crops are no longer grown in the Columbia basin due to inadequate control of BLTVA. Useful references: - Mod.DH] .......................................dh/pg/jw *##########################################################* ProMED-mail makes every effort to verify the reports that are posted, but the accuracy and completeness of the information, and of any statements or opinions based thereon, are not guaranteed. The reader assumes all risks in using information posted or archived by ProMED-mail. ISID and its associated service providers shall not be held responsible for errors or omissions or held liable for any damages incurred as a result of use or reliance upon posted or archived material. ************************************************************ Visit ProMED-mail's web site at . Send all items for posting to: promed@promedmail.org (NOT to an individual moderator). If you do not give your full name and affiliation, it may not be posted. Send commands to subscribe/unsubscribe, get archives, help, etc. to: majordomo@promedmail.org. For assistance from a human being send mail to: owner-promed@promedmail.org. ############################################################ ############################################################ From brian at gweep.ca Wed Apr 21 14:31:27 2004 From: brian at gweep.ca (Brian Edmonds) Date: Sat Jan 15 17:14:03 2005 Subject: PRO/PL> Banana bunchy-top disease - USA (HI) Message-ID: <37ad15dqec.fsf@lios.aq2.gweep.ca> BANANA BUNCHY-TOP DISEASE - USA (HAWAII) ********************************* A ProMED-mail post ProMED-mail is a program of the International Society for Infectious Diseases Date: 20 Apr 2004 From: ProMED-mail Source: The Star Bulletin, 17 Apr 2004 [edited] Banana disease confirmed on eastern Big Isle Agriculture officials are examining the extent of the bunchy-top virus --------------------------------------------------- Banana bunchy-top virus (BBTV) has been confirmed for the 1st time on the Big Island's east side, the state's main banana-producing region. The state Department of Agriculture is checking banana plants at Keaau Banana Plantation, one of the state's largest banana growers, and at surrounding banana farms to determine the extent of the disease, said Kyle Onuma, of the department's Hilo office. Richard Ha, president of Keaau Banana Plantation, believes that about 35 acres of Williams bananas on his 200-acre plantation might have the disease. Ha will meet with Agriculture Department and University of Hawaii experts on how to cope with the disease next week. "I think we can deal with it," he said. According to state Agriculture Chairwoman Sandra Lee Kunimoto, if BBTV is found to be widespread in Keaau, it could severely impact the state's $8.4-million banana industry. Commercial banana plantings and plants in backyards will be assessed by Department of Agriculture personnel to determine the extent of the problem. BBTV stunts growth in the banana plant's crown, hence the bunchy appearance. Younger leaves might have yellowish, curling edges; and lower leaf stems and midribs might have streaks, blotches or a "Morse code" pattern, according to the Agriculture Department. Infected plants produce deformed and stunted fruit and eventually fail to produce fruit. The disease is transmitted by banana aphids, and there is no known cure. Infected plants disease are treated for aphids and destroyed, Onuma said. Since 1999 more than 175 000 banana plants have been eradicated in North Kona after BBTV was discovered there. The virus also is present on Kauai from Hanalei to Lawai; on Maui in Pukalani and Makawao; and is widespread on Oahu. Sales figures for banana production in 2002, the most recent year for which figures were available, were: Big Island, 815 acres, $6.34 million; Oahu, 460 acres, $1.46 million; Maui, 85 acres, $330 000; and Kauai, 80 acres, $256 000. Statewide production of bananas was 19.5 million pounds in 2002. Oahu production is less per acre than that of the Big Island because of BBTV, said agriculture spokeswoman Janelle Saneishi. [Byline: Diana Leone] ------------------------------ ProMED-mail [BBTV is a member of the genus Nanovirus, not the genus Nanavirus named earlier. Other members are Faba bean necrotic yellows, Milk vetch dwarf and Subterranean clover stunt (type species). Their genomes consist of multiple circular ssDNAs of about 1 kb. BBTV, transmitted by the banana aphid (_Pentalonia nigronervosa_), is the most destructive viral disease of banana [_Musa x paridasiaca_, _M. acuminata_ and _M. textilis_, a Philippine plant known as abaca (Manila hemp)]. BBTV spreads in the African region and the Pacific region; Australia, Burundi, Egypt, Gabon, the Philippines, and Taiwan. BBTV epidemics of the disease have devastated many plantations in the Bicol Region of the Philippines for more than 50 years. Disease management involves eradication of diseased plants, planting of virus-free material, and heat treatment of infected tissue cultures to provide virus-free plantlets. Useful references: - Mod.DH] [see also: 2002 ---- Banana bunchy top virus, banana - Pakistan (Sindh) 20020813.5035 2001 ---- Banana bunchy top nanovirus - New Caledonia (02) 20010516.0951 Banana bunchy top nanovirus - New Caledonia 20010510.0904 2000 ---- Bunchy top virus - USA (Hawaii) 20000505.0688] ......................................mpp/dh/pg/dk *##########################################################* ProMED-mail makes every effort to verify the reports that are posted, but the accuracy and completeness of the information, and of any statements or opinions based thereon, are not guaranteed. The reader assumes all risks in using information posted or archived by ProMED-mail. ISID and its associated service providers shall not be held responsible for errors or omissions or held liable for any damages incurred as a result of use or reliance upon posted or archived material. ************************************************************ Visit ProMED-mail's web site at . Send all items for posting to: promed@promedmail.org (NOT to an individual moderator). If you do not give your full name and affiliation, it may not be posted. Send commands to subscribe/unsubscribe, get archives, help, etc. to: majordomo@promedmail.org. For assistance from a human being send mail to: owner-promed@promedmail.org. ############################################################ ############################################################ From brian at gweep.ca Fri Apr 23 13:24:18 2004 From: brian at gweep.ca (Brian Edmonds) Date: Sat Jan 15 17:14:03 2005 Subject: Disease Threatens Cucumbers, Pumpkins, and Other Vine Crops Message-ID: <37hdva5wgz.fsf@lios.aq2.gweep.ca> PRESS RELEASE For immediate release Contact: Amy Steigman American Phytopathological Society E-mail: mailto:asteigman@scisoc.org Phone: +1.651.454.7250 / Web: http://www.apsnet.org / Disease Threatens Cucumbers, Pumpkins, and Other Vine Crops St. Paul, Minn. (April 23, 2004) - Plant pathologists with The American Phytopathological Society (APS) are reporting a significant increase in the occurrence of Phytophthora blight of vine crops, including cucumbers, pumpkins, and squash, in many vegetable-growing regions of the United States. This devastating disease, caused by a soilborne pathogen called Phytophthora capsici, often results in nearly total yield loss. According to Mohammad Babadoost, a plant pathology professor at the University of Illinois, Phytophthora blight has become one of the most serious threats to production of vine crops, or cucurbits, both in the United States and worldwide. "Recent outbreaks of Phytophthora blight have threatened pumpkin and other cucurbit industries in Illinois, where approximately 90 percent of processing pumpkins produced in the U.S. are grown," said Babadoost. "Because of heavy crop losses, growers often have to abandon their own farms and move into different areas, sometimes traveling more than 50 miles, to find fields not infested with Phytophthora capsici," said Babadoost. Phytophthora blight can strike cucurbit plants at any stage of growth. The infection usually appears first in low areas of the fields where the soil remains wet for longer periods of time. The pathogen infects seedlings, vines, leaves, and fruit. The disease is usually associated with heavy rainfall, excessive-irrigation, or poorly drained soil. Frequent irrigation increases the incidence of the disease. Currently, there are no cucurbit cultivars with measurable resistance to Phytophthora blight. Plant pathologists are working to find new methods of controlling this disease. "In addition to exploring cultural management strategies, plant pathologists are assessing the possibilities of using induced resistance in plants, biocontrol agents, and fungicides for control of this disease in cucurbits and other crops," said Babadoost. More on this subject including details on the disease, the pathogen that causes it, and current control methods can be found in this month's APS feature article at http://www.apsnet.org/online/feature/cucurbit/. The American Phytopathological Society (APS) is a non-profit, professional scientific organization dedicated to the study and management of plant disease with 5,000 members worldwide. From brian at gweep.ca Thu Apr 29 10:51:34 2004 From: brian at gweep.ca (Brian Edmonds) Date: Sat Jan 15 17:14:03 2005 Subject: PRO/PL> Wheat stripe rust - China Message-ID: <37pt9qn2wf.fsf@lios.aq2.gweep.ca> WHEAT STRIPE RUST - CHINA ************************* A ProMED-mail post ProMED-mail is a program of the International Society for Infectious Diseases Date: 26 Apr 2004 From: ProMED-mail Source: Xinhuanet [edited] Emergency prevention against wheat disease urged ------------------------------------------------ The Ministry of Agriculture revealed on Thursday that 2 million hectares of wheat in China have been plagued by stripe rust and the infected acreage might reach 6.7 million hectares by the end of 2004. Minister Du Qinglin urged local governments to strengthen the early-warning system and to enhance efficiency in preventing and controlling the disease, hoping to restrain the infected areas within 5 per cent of the total wheat yield. The ministry set the wheat production goal for the summer of 2004 at an average rise of 5 kilograms per mu (0.067 hectare) over the same period of 2003. Du stressed that both governments and farmers should improve defensive abilities against other disasters, such as drought, plant lodging [the bending or falling over of a crop plant], and hot wind. He also reminded farmers to focus on irrigation to ensure a sufficient water supply for wheat, which was now at its key growth period for the year. ------------------------------ ProMED-mail [Wheat stripe rust (also known as yellow rust) is caused by _Puccinia striiformis_. It occurs worldwide at higher altitudes in wheat production zones of the southern and northern areas of temperate regions. Yield losses can be considerable, ranging from about 40 per cent to complete destruction of the crop. Survival of the fungus is threatened by high temperature and dry weather. It survives primarily in dormant mycelium and uredinia on infected volunteer wheat. It also infects some barley cultivars. Disease management involves the use of resistant cultivars, control of seeding dates, elimination of volunteer seedlings and use of chemical fungicides. Useful references: I also included 2 references from CIMMYT that deal with the disease in China. - Mod.DH] [see also: 2003 --- Wheat stripe rust, new strains - Australia (SA) 20030930.2465 Wheat stripe rust - Australia (WA) 20030624.1553 Wheat stripe rust, first report - USA (Florida) 20030516.1220 2002 --- Wheat stripe rust - Australia (Western): alert 20020831.5198 2001 --- Wheat stripe rust - USA (Great Plains) 20010715.1366 Wheat stripe rust - USA (Central) 20010629.1236 1999 --- Stripe rust, barley - Australia (Victoria & NSW) 19991116.2043] ..........................mpp/dh/pg/sh *##########################################################* ProMED-mail makes every effort to verify the reports that are posted, but the accuracy and completeness of the information, and of any statements or opinions based thereon, are not guaranteed. The reader assumes all risks in using information posted or archived by ProMED-mail. ISID and its associated service providers shall not be held responsible for errors or omissions or held liable for any damages incurred as a result of use or reliance upon posted or archived material. ************************************************************ Visit ProMED-mail's web site at . Send all items for posting to: promed@promedmail.org (NOT to an individual moderator). If you do not give your full name and affiliation, it may not be posted. Send commands to subscribe/unsubscribe, get archives, help, etc. to: majordomo@promedmail.org. For assistance from a human being send mail to: owner-promed@promedmail.org. ############################################################ ############################################################ From brian at gweep.ca Thu Apr 29 10:51:32 2004 From: brian at gweep.ca (Brian Edmonds) Date: Sat Jan 15 17:14:03 2005 Subject: PRO/PL> Phytophthora blight, vine crops - USA Message-ID: <37u0z2n2wi.fsf@lios.aq2.gweep.ca> PHYTOPHTHORA BLIGHT, VINE CROPS - USA ************************************* A ProMED-mail post ProMED-mail is a program of the International Society for Infectious Diseases Date: 23 Apr 2004 From: ProMED-mail Source: Eurek Alert [edited] Disease threatens cucumbers, pumpkins, and other vine crops ----------------------------------------------------------- US plant pathologists are reporting a significant increase in the occurrence of Phytophthora blight [Pb] of vine crops, including cucumbers, pumpkins, and squash, in many vegetable-growing regions of the United States. This devastating disease, caused by the soilborne fungus _Phytophthora capsici_ [Pc], often results in nearly total yield loss. According to Mohammad Babadoost, a plant pathology professor at the University of Illinois, Pb has become one of the most serious threats to production of vine crops, or cucurbits, in the US and worldwide. Recent outbreaks of Pb have threatened pumpkin and other cucurbit industries especially in Illinois, which produces about 90 per cent of processing pumpkins grown in the US. According to Babadoost, heavy crop losses often force growers to abandon their own farms, and move into different areas, sometimes traveling more than 50 miles, to find fields free of Pc. Pb can strike cucurbit plants at any stage of growth. Infection usually appears first in low areas of fields where the soil remains wet for longer periods of time. The pathogen infects seedlings, vines, leaves, and fruit. The disease is usually associated with heavy rainfall, excessive irrigation, or poorly drained soil. Frequent irrigation increases disease incidence. Currently, there are no cucurbit cultivars with measurable resistance to Pb. Plant pathologists are working to find new methods of controlling the disease. Babadoost says that in addition to exploring cultural management strategies, plant pathologists are assessing the possibilities of biocontrol agents, fungicides for control of the pathogen in cucurbits and other crops as well as using induced resistance in plants. ------------------------------ ProMED-mail [A comment is required regarding the phenomenon of induced resistance in plants. For example, lower leaves of a plant, when inoculated with a necrotizing pathogen, will express typical symptoms in leaves of susceptible plants. At a later time (a few days) when newly developed upper leaves are inoculated with the same or a related pathogen, fewer lesions and/or reduced lesion size are observed, relative to control plants not previously inoculated. This phenomenon is described as systemic acquired resistance (SAR), and the inducing agent is considered to be salicylic acid [SA]. SAR is associated with systemic expression of pathogenesis-related proteins (PR proteins) in infected plants. Moreover, application of exogenous SA induces both PR proteins and resistance to attack by pathogens. SAR is a hot topic in plant pathology and plant molecular biology, and I have provided a number of references for those who wish to delve further. You may also wish to contact Amy Steigman for more information. Some useful references: - Mod.DH] [see also: 2003 --- Phytophthora capsici, tomato - South Africa 20031130.2971 Phytophthora capsici, tomato - Mexico (Michoacan) 20030711.1708 2002 --- Phytophthora capsici, cucurbits - Spain (Granada) 20020608.4440] .....................mpp/dh/pg/sh *##########################################################* ProMED-mail makes every effort to verify the reports that are posted, but the accuracy and completeness of the information, and of any statements or opinions based thereon, are not guaranteed. The reader assumes all risks in using information posted or archived by ProMED-mail. ISID and its associated service providers shall not be held responsible for errors or omissions or held liable for any damages incurred as a result of use or reliance upon posted or archived material. ************************************************************ Visit ProMED-mail's web site at . Send all items for posting to: promed@promedmail.org (NOT to an individual moderator). If you do not give your full name and affiliation, it may not be posted. Send commands to subscribe/unsubscribe, get archives, help, etc. to: majordomo@promedmail.org. For assistance from a human being send mail to: owner-promed@promedmail.org. ############################################################ ############################################################