A disease of tomato caused by an Ilarvirus provisionally indicated TI 1 (tomato Ilarvirus 1), serologically related to parietaria mottle ilarvirus, has been observed in different regions of Italy. TI 1 caused necrosis of the apex, leaves and stems and corky rings and brown patches on the fruits. It has been detected in Piedmont, Liguria, Sardinia and Lazio, mostly in field crops. Infection may reach 30% in some fields. Tomato plants infected with TI 1 were often also infected by cucumber mosaic virus, potato virus Y or tomato spotted wilt virus; these viruses were not the agents of the disease, although when present they aggravated the symptoms. The spatial distribution of TI 1 infected plants in the fields appeared to be mostly random. TI 1 was not seed-transmitted to 738 sedlings from seeds of infected tomato plants of six cultivars | Viene segnalata la presenza in diverse regioni italiane di una malattia del pomodoro causata da un Ilarvirus indicato come TI 1 (tomato Ilarvirus 1), sierologicamente correlato a parietaria mottle ilarvirus (virus della maculatura della parietaria) e non ancora completamente caratterizzato. TI 1 causa, su pomodoro, necrosi dell'apice principale, di foglie e di fusti ed anulature suberose o brunastre sui frutti. Il virus e' stato individuato in Piemonte, Liguria, Sardegna e Lazio, soprattutto in coltivazioni in campo, talvolta con percentuali di infezione sino al 30%. Le coltivazioni considerate erano infette anche da cucumber mosaic cucumovirus (virus del mosaico del cetriolo), potato Y potyvirus (virus Y della patata) e tomato spotted wilt tospovirus (virus dell'avvizzimento maculato del pomodoro), i quali aggravavano la malattia ma non erano causa determinante delle alterazioni necrotiche osservate. La distribuzione delle piante infette da TI 1 nelle coltivazioni appariva generalmente causale. Non si e' verificata trasmissione per seme di TI 1 in 738 semenzali di pomodoro derivati da semi prodotti da piante infette di sei cultivar

One of the most severe diseases of cultivated tomato worldwide is caused by tomato yellow leaf curl virus (TYLCV), a geminivirus transmitted by the whitefly Bemisia tabaci. Here we describe the application of antisense RNAs to interfere with the disease caused by TYLCV. The target of the antisense RNA is the rare messenger RNA of the Rep protein, encoded by the C1 gene. Transgenic Nicotiana benthamiana plants expressing C1 antisense RNA were obtained and shown to resist infection by TYLCV. Some of the resistant lines are symptomless, and the replication of challenge TYLCV almost completely suppressed. The transgenes mediating resistance were shown to be effective through at least two generations of progeny.

Fungicide tolcolfos methyl was able to inhibit the disease incidence and pathogenicity of stem rot causal agent of tomato, Sclerotium rolfsii Sacc. Under screen-house and field conditions, using tolcolfos-methyl 750 mg/l showed the disease incidences 6.2 and 18.7 percent while in control treatment disease incidences were 93.7 and 83.3 percent respectively. Compared with pentachloronitrobenzene (PCNB) 500 mg/l, the tolcolfos-methyl was more effective than those PCNB according to disease incidences that were 87.5 percent in screen-house and 75 percent in field experiment. The result suggested that disease incidence of stem rot of tomato can be reduced by soil drench of tolcolfos-methyl 750 mg/l.

A new virus of tomato, tomato infectious chlorosis virus (TICV), has been identified in both field-and greenhouse-grown tomatoes in California, North Carolina and Italy. TICV is transmitted by the greenhouse whitefly (Trialeurodes vaporariorum) in a semipersistent manner. TICV infects a wide range of plant hosts, and has been found naturally infecting Petunia and Ranunculus in greenhouses, and tree tobacco, commercial artichoke and bristly oxtongue in the southern coastal region of California. Because of its wide host range, the prevalence of the greenhouse whitefly in fields and greenhouses, and the movement of susceptible plant hosts within and among countries around the world, TICV is a potential problem for the world's tomato industry. TICV caused an estimated $2 million loss in Orange County in 1993. Control measures include whitefly control, confirmation of TICV infection by a diagnostic test and roguing of infected plants.

A new virus of tomato, tomato infectious chlorosis virus (TICV), has been identified in both field-and greenhouse-grown tomatoes in California, North Carolina and Italy. TICV is transmitted by the greenhouse whitefly (Trialeurodes vaporariorum) in a semipersistent manner. TICV infects a wide range of plant hosts, and has been found naturally infecting Petunia and Ranunculus in greenhouses, and tree tobacco, commercial artichoke and bristly oxtongue in the southern coastal region of California. Because of its wide host range, the prevalence of the greenhouse whitefly in fields and greenhouses, and the movement of susceptible plant hosts within and among countries around the world, TICV is a potential problem for the world's tomato industry. TICV caused an estimated $2 million loss in Orange County in 1993. Control measures include whitefly control, confirmation of TICV infection by a diagnostic test and roguing of infected plants.

Whitefly-transmitted geminiviruses have increased in their distribution and importance during the last decade, apparently due to a wider distribution of their vector Bemisia tabaci (Gennadius). In Cuba, symptoms of geminivirus disease have been observed since the early 1990s. A survey of geminivirus-caused diseases in tomato plants has been conducted since 1994 in the province of La Habana. The most severe symptoms were observed in the commercial varieties Campbell 28, Criollo Quivican, and HC 3880. In some plants the Israeli strain of tomato yellow leaf curl geminivirus (TYLCV) was detected (1). In other cases, a viral DNA with a genome size smaller than that of TYLCV that could not be amplified with primers specific for the Israeli strain was also detected by hybridization. In these samples a polymerase chain reaction amplification with broad-spectrum, degenerate primers designed for whitefly-transmitted bipartite geminivirus (2) was carried out. Two fragments of about 1.1 and 0.6 kb, corresponding to components A and B, respectively, were amplified, indicating that a bipartite geminivirus was present. The 1.1-kb fragment amplified from a sample showing strong leaf yellowing and slight curling was cloned and sequenced. A sequence of 1,174 nucleotides was obtained and compared with geminivirus sequences deposited in the GenBank, by multiple alignment (CLUSTAL W, European Bioinformatics Institute, Hinxton Hall, UK). Genetic distances were calculated by Kimura's two parameters method. Percentages of similarities obtained with the sequence were as follows tomato mottle virus 78%, abutilon mosaic virus 73.8%, and tomato golden mosaic 61.8%. Partial sequences of the open reading frames AL1 and AR1 and the intergenic region were present. Percentages of similarities obtained with the intergenic region were as follows tomato mottle virus 78.1%, sida golden mosaic virus 63%, bean dwarf mosaic virus 62.6%, abutilon mosaic virus 57.1%, and tomato golden mosaic virus 32%. These results suggest that we have detected in Cuban tomatoes a new bipartite geminivirus related to tomato mottle virus, and we propose that it be named Havana tomato virus. Frequency of distribution of viruses in commercial varieties and their relationship with the presence of whiteflies are currently being studied.

Late blight caused by the oomycete pathogen Phytophthora infestans is a devastating disease of potato and tomato worldwide. A rapid and accurate method for specific detection of P. infestans is necessary for determination of late blight in infected fruit, leaves, and tubers. Ribosomal DNA (rDNA) from four isolates of P. infestans representing the four genotypes US1, US6, US7, and US8 was amplified using polymerase chain reaction (PCR) and the universal primers internal transcribed spacer (ITS) 4 and ITS5. PCR products were sequenced using an automated sequencer. Sequences were aligned with published sequences from 5 other Phytophthora species, and a region specific to P. infestans was used to construct a PCR primer (PINF). Over 140 isolates representing 14 species of Phytophthora and at least 13 other genera of fungi and bacteria were used to screen the PINF primer. PCR amplification with primers PINF and ITS5 results in amplification of an approximately 600 base pair product with only isolates of P. infestans from potato and tomato, as well as isolates of P. mirabilis and P. cactorum. P. mirabilis and P. cactorum are not pathogens of potato; however, P. cactorum is a pathogen of tomato. P. infestans and P. cactorum were differentiated by restriction digests of the amplified product. The PINF primer was used with a rapid NaOH lysis technique for direct PCR of P. infestans from infected tomato and potato field samples. The PINF primer will provide a valuable tool for detection of P. infestans in potatoes and tomatoes.

A study on the extraction of palm oil dry solids (PODS) was conducted to identify the water-soluble compounds involved in the phytotoxicity of PODS. The aqueous extract of PODS was sequentially partitioned using various organic solvents. Each of the dried extracts was bioassayed for inhibitory activity on the growth of tomato radicles.Maximum inhibition of radicle growth was observed in the diethyl ether extract, resulting in 53.3% growth compared with control. Further separation of the ether fraction using column chromatography resulted in a single toxic fraction, RM10, which caused only 30% radicle growth. The fraction was compared with 14 synthetic phenolic compounds using thin-layer chromatography and was observed to be similar to four of the compounds. Further analysis by highperformance liquid chromatography revealed that the RM10 fraction comprised vanillic acid. However, the RM10 fraction was more inhibitory to the growth of tomato radicles than synthetic vanillic acid.