First record of the tomato leafminer,Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) in Sudan

An outbreak of larvae and adults of a devastating moth was noted to be causing severe damage in tomato grown in greenhouses at Khartoum State, Sudan during June 2010. Symptoms included foliage mining and leaves drying. Photographs of symptoms and larvae and adults of the pest (and subsequently specimens) were sent to Russell IPM, UK and the Finnish Museum of Natural History for identification. The pest was identified as Tuta absoluta (Meyrick), (Lepidoptera: Gelechiidae). This is the first official record of T. absoluta in Sudan, based on surveys in tomato production areas in Khartoum, Gezira, Red Sea and North Kordofan States and eggplant and potato in Khartoum State. Severe yield loss due to the serious feeding damage on foliage and fruits infestation was reported on tomato and eggplant fields at Khartoum State.     

Displacement of Tomato Yellow Leaf Curl Virus (TYLCV)-Sr by TYLCV-Is in Tomato Epidemics in Spain

ABSTRACT A progressive displacement of tomato yellow leaf curl virus (TYLCV)-Sr by TYLCV-Is was observed in tomato epidemics in southern Spain based on incidence data of both virus species obtained during surveys conducted between 1996 and 1998. Ecological factors that might be involved in such a displacement, such as competition of TYLCV-Sr and TYLCV-Is in tomato, transmission by local biotypes (B and Q) of Bemisia tabaci, and presence in weeds and alternate crops, have been analyzed. No selective advantage is observed for TYLCV-Sr or TYLCV-Is in tomato plants either infected via Agrobacterium tumefaciens or via B. tabaci. However, TYLCV-Is is more efficiently vectored by local biotypes of B. tabaci; and common bean, a bridge crop between tomato crops, is a host for TYLCV-Is but not TYLCV-Sr. Therefore, common bean acts as a reservoir for TYLCV-Is. These two factors are probably responsible for the displacement of TYLCV-Sr by TYLCV-Is as the causative agent of epidemics in tomato in southern Spain.     

云南怒江番茄种植新区番茄病毒检测及病毒种传特性

病毒病对番茄生产造成严重危害, 近年来在番茄种植新区发生严重, 疑似为种子带毒传播。本研究通过对云南省怒江州番茄种植新区的番茄病毒病样品采用RNA-seq高通量测序, RT-PCR验证的方法检测病毒种类;对番茄病果种子进行超薄切片制样透射电子显微镜观察, 将病果种子播种后对种苗进行RT-PCR带毒检测。结果表明, RNA-seq高通量测序及RT-PCR检测到的病毒有番茄环纹斑点病毒(tomato zonate spot orthotospovirus, TZSV)、番茄黄斑驳相关病毒(tomato yellow mottle-associated virus, TYMaV)、辣椒脉斑驳病毒(chili veinal mottle virus, ChiVMV)、南方番茄病毒(southern tomato virus, STV)。透射电镜观察到种胚细胞及胚乳细胞中分布典型的正番茄斑萎病毒属Orthotospovirus病毒粒体。病果种子播种28 d后的种苗具有病毒病症状, 通过RT-PCR检出TZSV、ChiVMV、STV, 检出率分别为60%、100%、80%。上述研究结果为TZSV通过种子传播提供了有利的证据, 并为源头防控番茄病毒病提供了依据。     

Tomato early blight (Alternaria solani): the pathogen, genetics, and breeding for resistance

Alternaria solani causes diseases on foliage (early blight), basal stems of seedlings (collar rot), stems of adult plants (stem lesions), and fruits (fruit rot) of tomato. Early blight is the most destructive of these diseases and hence receives considerable attention in breeding. For over 60 years, breeding for early blight resistance has been practiced, but the development of cultivars with high levels of resistance has been hampered by the lack of sources of strong resistance in the cultivated tomato and by the quantitative expression and polygenic inheritance of the resistance. In some accessions of wild species, high levels of early blight resistance have been found, but breeding lines still have unfavorable horticultural traits from the donor parent. Recently, the first linkage maps with loci controlling early blight resistance have been developed based on interspecific crosses. These maps may facilitate marker-assisted selection. This overview presents the current knowledge about the A. solani–tomato complex with respect to its biology, genetics, and breeding.     

抑制蒸腾对番茄生长及植株镁、钾、钙吸收的影响

北方日光温室生产中蔬菜频繁出现营养失调,导致产量、品质明显下降,为探明番茄养分失调是否与蒸腾受到抑制有关,通过2个水培试验分别研究了短期（24 h）及长期（24 d）喷施蒸腾抑制剂对中杂9号和改良毛粉两个番茄品种蒸腾、生物量和镁、钾及钙养分吸收的影响。结果表明：短期（24 h）抑制蒸腾,蒸腾量减少20.6%、镁吸收量减少4.5%,蒸腾与番茄镁吸收呈显著正相关关系;长期（24 d）喷施蒸腾抑制剂减少了番茄生长量、光合速率,蒸腾量减少47.5%时镁吸收量减少17.1%,钾、钙吸收量分别减少12.9%和44.1%,不同番茄品种间对钾、钙、镁的吸收无显著差异。可见,抑制蒸腾减少番茄对镁、钾、钙的吸收。北方日光温室冬茬栽培中高湿、寡照等不良环境因子会诱导番茄营养失调症的发生。     

Comparison of pheromone lures used in mass trapping to control the tomato leafminer Tuta absoluta (Meyrick, 1917) in industrial tomato crops in Kairouan (Tunisia)

An experimental trial of integrated pest management against Tuta absoluta (Meyrick) based on mass trapping with a density of 32 traps per hectare was conducted in a 5 ha open‐field tomato crop. During this trial, the efficiency of three brands of sex pheromone dispenser commercialized in Tunisia was tested. The ‘superdosed’ pheromone lure type TUA‐Optima^® (Russell IPM, Deeside, Flintshire, CH5 2LA, United Kingdom) loaded with 0.8 mg of synthetic pheromone was more attractive to males of T. absoluta, and these lures should be used with high populations. Standard lures Pherodis^® and TUA‐500^® containing 0.5 mg of pheromone were less attractive, and can be used in open‐field tomato crops with lower populations of T. absoluta. An assessment of the susceptibility of crop borders to T. absoluta, based on data collected from traps, revealed that levels of adult T. absoluta were similar between borders with either tomato or cereal crops. Particular attention should thus be paid to crop borders even when not adjacent to other tomato crops.     

Identification of Rhizoctonia solani AG 1-IB in Lettuce, AG 4 HG-I in Tomato and Melon, and AG 4 HG-III in Broccoli and Spinach, in Brazil

Fungi isolated in Brazil, from lettuce, broccoli, spinach, melon and tomato, were identified as Rhizoctonia solani. All lettuce isolates anastomosed with both AG 1-IA and IB subgroups and all isolates from broccoli, spinach, melon and tomato anastomosed with AG 4 subgroup HG-I, as well as with subgroups HG-II and HG-III. DNA sequence analyses of ribosomal internal transcribed spacers showed that isolates from lettuce were AG 1-IB, isolates from tomato and melon were AG 4 HG-I, and isolates from broccoli and spinach were AG 4 HG-III. The tomato isolates caused stem rot symptoms, the spinach, broccoli and melon isolates caused hypocotyl and root rot symptoms on the respective host plants and the lettuce isolates caused bottom rot. This is the first report on the occurrence in Brazil of R. solani AG 4 HG-I in tomato and melon, of AG 4 HG-III in broccoli and spinach and of AG 1-IB in lettuce.     

Persistence,metabolism and safety evaluation of thiamethoxam in tomato crop

BACKGROUND: Thiamethoxam, a neonicotinoid insecticide, has been widely accepted for use in various crops, including vegetables, owing to its high efficacy against various chewing and sucking insect pests. In this particular study, the authors examined the residue dynamics of this insecticide in tomato and soil and calculated a safety index for this insecticide in an Indian context. RESULTS: In tomato fruits, the insecticide dissipated from 82 to 87% in 10 days with a half‐life of 4 days, whereas dissipation in soil, under tomato crop, varied between 72 and 75% in 15 days with a half‐life of 9 days. Total residues reached below detectable level in 15 days in tomato fruits and 20 days in soil. Maximum damage (30%) was found in control plots, as opposed to 8–10% of fruit damage in treated plots. One degradation product was detected on the tomato fruit surface, and three metabolites were identified in tomato fruits by the LC‐MS technique. The metabolites have been reported for the first time in tomato fruits. CONCLUSION: Thiamethoxam at normal and double the recommended use rate effectively controlled aphids, whiteflies and Helicoverpa, as the insect population decreased to a minimum within 10 days of spraying in comparison with the control. There was no significant difference between the two rates of application, and both thiamethoxam treatments significantly increased tomato fruit yield compared with the untreated control. A maximum residue limit (MRL) of 0.05 mg kg^?1 for tomato has been proposed, with a corresponding preharvest interval (PHI) of 8 days. These parallel advances in toxicology and analytical chemistry have strengthened the observations that thiamethoxam can be used safely and efficiently in crop protection programmes. Copyright © 2009 Society of Chemical Industry     

陕西杨凌番茄褪绿病毒的分子检测

近年来在陕西番茄生产区出现了一种新病害,病株表现为叶片褪绿,叶脉颜色变深及叶片增厚,果实变小发白,严重影响番茄产量及经济效益,2016年发病极为严重,部分产区甚至绝收。该病疑似由番茄褪绿病毒Tomato chlorosis virus(ToCV)引起。利用ToCV特异引物对感病番茄样品进行RT-PCR检测,结果从所采集的4份病样中均检测到ToCV预期大小的特异片段。对ToCV外壳蛋白CP基因和类热激蛋白HSP70h基因进行克隆与序列分析,ToCV-YL1 CP基因774个核苷酸序列与已报道的ToCVCP基因有较高的一致性,与山东青岛和山西晋中分离物同源性为100%。ToCV-YL1 HSP70h基因1 665个核苷酸序列与已报道的ToCV HSP70h基因有较高的同源性,与中国、韩国、日本、美国、希腊分离物同源性达到99%以上。研究表明ToCV已传播至陕西地区。     

Evaluation of the pathogenicity of microorganisms isolated from Egyptian broomrape (Orobanche aegyptiaca) in Israel

Diseased Egyptian broomrape ( Orobanche aegyptiaca ) inflorescences were collected from a heavily broomrape-infested tomato ( Lycopersicon esculentum ) field in Israel. The microorganisms that were isolated from the diseased inflorescences were passed through Koch's postulates on Egyptian broomrape-parasitizing tomato roots in a polyethylene bag system and pots under greenhouse conditions. The fungi, Alternaria alternata , Macrophomina phaseolina , Rhizoctonia solani , and Fusarium solani , and the bacterium, Bacillus sp., were newly isolated from the diseased inflorescences of Egyptian broomrape and were found to be pathogenic to the parasite. Fusarium solani damaged all of the developmental stages of broomrape and prevented the damage that Egyptian broomrape causes to tomato plants. The level of pathogenicity and the damage of M. phaseolina , A. alternata , and Bacillus sp. to Egyptian broomrape in greenhouse experiments were relatively low. All the tested microorganisms are known as pathogens of tomato, yet none caused disease symptoms on the tomato plants grown in the inoculated polyethylene bags or in the pots. Fusarium solani demonstrated the highest potential for further development as a mycoherbicide for Egyptian broomrape control in tomato.     

Reduction of Bacterial Speck (Pseudomonas syringae pv. tomato) of Tomato by Combined Treatments of Plant Growth-promoting Bacterium, Azospirillum brasilense, Streptomycin Sulfate, and Chemo-thermal Seed Treatment

Inoculation of tomato seeds with the plant growth-promoting bacterium Azospirillum brasilense, or spraying tomato foliage with A. brasilense, streptomycin sulfate, or commercial copper bactericides, separately, before or after inoculation with Pseudomonas syringae pv. tomato, the casual agent of bacterial speck of tomato, had no lasting effect on disease severity or on plant height and dry weight. Seed inoculation with A. brasilense combined with a single streptomycin foliar treatment and two foliar bactericide applications at 5-day intervals (a third or less of the recommended commercial dose) reduced disease severity in tomato seedlings by over 90% after 4 weeks, and significantly slowed disease development under mist conditions. A. brasilense did not induce significant systemic resistance against the pathogen although the level of salicylic acid increased in inoculated plants. Treatment of tomato seeds that were artificially inoculated with P. syringae pv. tomato, with a combination of mild chemo-thermal treatment, A. brasilense seed inoculation, and later, a single foliar application of a copper bactericide, nearly eliminated bacterial leaf speck even when the plants were grown under mist for 6 weeks. This study shows that a combination of otherwise ineffective disease management tactics, when applied in concert, can reduce bacterial speck intensity in tomatoes under mist conditions.     

Effect of host plants on developmental and population parameters of invasive leafminer, <Emphasis Type="Italic">Tuta absoluta</Emphasis> (Meyrick) (Lepidoptera: Gelechiidae)

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is one of the most serious pests of tomato, capable of causing 100% crop losses under favourable conditions. We studied the effect of different host plants on developmental and population parameters of this pest at 25?±?0.5 °C temperature, 70?±?5% relative humidity and 12 L: 12D photoperiod. Host plant had significant effect on the developmental biology and the population growth parameters of the pest. The leafminer developed fastest on tomato leaves and slowest on potato tubers. Population growth parameters like intrinsic rate of increase, net reproductive rate, finite rate of increase, doubling time and weekly multiplication rate of T. absoluta were highest on tomato leaves and lowest on potato tubers. Mean generation time was minimum on tomato leaves and maximum on potato tubers. Females developed on tomato leaves were more fecund than other hosts. Though, tomato was found to be the most suitable host plant of T. absoluta, yet, the pest developed and grew successfully on other alternate hosts like potato (Solanum tuberosum L.), brinjal (Solanum melongena L.) and pepino (Solanum muricatum Aiton). These hosts can, therefore, play an important role in the survival, population build up and overwintering of the miner. Further, under favourable conditions the miner can become a serious pest on these crops and need to be monitored on these crops as well.     

Host plant induction of microsomal monooxygenase activity in relation to diazinon metabolism and toxicity in larvae of the tobacco budworm Heliothis virescens (F.)

The effect of the wild tomato, Lycopersican hirsutam F. glabratam (accession PI 134417), on susceptibility to and metabolism of diazinon, 0,0-diethyl-0-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate, in larvae of the tobacco budworm, Heliothis virescans F., was studied. The larvae were over 4-fold more tolerant to diazinon toxicity when fed on leaves of wild tomato than when fed on an artificial diet. Diazinon injected into fifth instar larvae is converted into two chloroform-soluble and five water-soluble metabolites. Degradation of diazinon was faster in larvae fed tomato leaves (88.1%) than in larvae fed on the artificial diet (68.4%). Some oxon (13.0%) was detected in the latter case but none in larvae fed tomato leaves. The major metabolite was hydroxypyrimidine and its formation was higher (73.2%) in larvae fed tomato leaves than in larvae fed the artificial diet (49.2%). In vitro studies revealed that both diazinon and its oxon were metabolized primarily by the microsomal cytochrome P-450-dependent monooxygenase system which was induced 2.5- to 3.7-fold by feeding on tomato leaves. It was concluded that diazinon was degraded in H. virescens larvae through desulfuration, hydroxylation of the ring-alkyl side chain, and oxidative dearylation reactions, all of which were increased by varying amounts after feeding on tomato leaves. Treatment of the larvae with 2-tridecanone, a naturally occurring toxin in tomato leaves, resulted in increased tolerance to diazinon and increased in vitro degradation of diazinon and its oxon, the induction being dependent on the magnitude of 2-tridecanone treatment. The microsomes of tomato fed larvae had a 1.5- to 2.1-fold higher concentration of cytochrome P-450, accompanied by a 1–2 nm shift in the λmax of the cytochrome P-450 carbon monoxide complex.     

Determination of famoxadone, fenamidone, fenhexamid and iprodione residues in greenhouse tomatoes

BACKGROUND: Greenhouse tomato production is intended exclusively for fresh consumption. Typical greenhouse conditions provide a conducive environment for the development of different fungi, principally late blight and grey mould, that can destroy plants and fruits. For this reason, different fungicides with different sites of action are used in integrated pest management strategies. Famoxadone, fenamidone, fenhexamid and iprodione (fig. 1 ) are fungicides of difference classes with different actions that could be used to control tomato pests. RESULTS: The QuEChERS method showed good recoveries, and the analytical method allowed good separation of the fungicides selected. Good results were obtained in terms of repeatability and intermediate precision, with a coefficient of variation of < 9.8%. The limits of determination and quantification of the method were far below the maximum residual levels (MRLs) set by the EU for these fungicides in tomatoes. The analysis of fungicide residues showed that cv. Shiren accounted for higher residue levels than cv. Caramba. The dissipation curves were similar in the two cultivars, indicating that the decrease in pesticides was not related to the tomato type. CONCLUSIONS: Care should be taken when using pesticides in greenhouse conditions, because degradation mainly affects fruit growth. The size of the tomato, in particular its surface/weight ratio, is very important for defining pesticide residues. All fungicides used showed residue levels below the MRLs at the preharvest interval. Copyright © 2011 Society of Chemical Industry     

Diversity,distribution and prevalence of vegetable-infecting geminiviruses in Burkina Faso

In West and Central Africa, as in many regions of the world, vegetables are severely affected by geminivirus diseases. In Burkina Faso, observation of various virus-like symptoms, especially on tomato, suggests the involvement of several geminiviruses and underlines the pressing need for additional information on their diversity, distribution, prevalence and host plant reservoirs. Large-scale surveys conducted in Burkina Faso confirmed the presence of tomato (yellow) leaf curl diseases (ToLCD-TYLCD) and geminiviruses in all localities with mean prevalences of 25% and 45%, respectively. Five geminiviruses including four begomoviruses (pepper yellow vein Mali virus (PepYVMLV), tomato leaf curl Burkina Faso virus, tomato leaf curl Mali virus and tomato leaf curl Ghana virus) and a dicot-infecting mastrevirus (chickpea chlorotic dwarf virus) were characterized on tomato. In addition, PepYVMLV and cotton leaf curl Gezira virus (CLCuGeV) were characterized on pepper and okra, respectively, in combination or not with alphasatellites and betasatellites for CLCuGeV. The most severe, prevalent and widely distributed virus on vegetables was PepYVMLV, which was characterized for the first time in combination with a genetically divergent DNA-B component that may constitute a key factor of PepYVMLV pathogenicity. Of the eight weeds identified as potential reservoir hosts of begomoviruses, four host PepYVMLV. The results confirm the importance of geminivirus diseases on vegetable crops in Burkina Faso and highlight the complex association of geminiviruses and satellites. The detection of begomoviruses in weeds growing close to crops points to the increasing necessity to consider reservoir plants and virus communities in the control of virus diseases.     

The use of antioxidants (free radical scavengers) to control grey mould (Botrytis cinerea) and white mould (Sclerotinia sclerotiomm) in various crops

Eighteen free radical scavengers (antioxidants) were tested for their ability to control grey mould. Most of the compounds reduced disease significantly in at least one of the test hosts–leaves of tomato, pepper, Senecio sp., bean, eggplant, or rose flowers; however, the effective concentration varied between 0.1 and 100 m m . Selected antioxidants were tested further. Butylated hydroxy toluene (BHT), tannic acid, ascorbic acid and dimethyl sulfoxide (DMSO) at a concentration of 1 .0 m m controlled grey mould of tomato fruits. All these compounds except BHT controlled the disease on cucumber fruits. Antioxidants affected Rhizopus stolonifer on grape berries but not Botrytis cinerea or Aspergillus spp. Some combinations of antioxidants were found to be more effective than either compound alone when tested on pepper or tomato. The synergists ascorbic acid and citric acid improved the control activity of BHT, propyl gallate, benzoic acid and tert -butylhydroquinone on tomato leaves. Ethylene production was inhibited in tomato leaves treated with propyl gallate, ascorbic acid and benzoic acid, but not in pepper leaves. Ethephon or H₂O₂ increased the severity of grey mould on leaves of Senecio sp. Their effect was controlled by BHT and benzoic acid or by BHT, respectively. Four to six compounds reduced linear growth of B. cinerea isolates in culture at a concentration of 1.0 m m , and six more compounds were effective at 10.0 m m . However just five compounds inhibited conidial germination at the high concentration alone. Gluconic acid lactone, thiourea and propyl gallate reduced Sclerotinia sclerotiomm on lettuce by 51-76%. The multiple activity of antioxidants on the host plant interaction is discussed.     

Possible rôle of allelopathy in the competition between tomato, Senecio vulgaris L. and Chenopodium album L.

Summary. The allelopathic effect of Chenopodium album L. (fat-hen) and Senecio vulgaris L. (groundsel) on tomato ( Lycopersicon esculentum Mill cv. Ailsa Craig) plants was investigated under glasshouse conditions. A new technology was used to separate competitive from allelopathic effects. These experiments suggested that C. album had an effect on tomato through allelopathy. C. album leach-ates significantly reduced shoot fresh and dry weights and the accumulation of N, P, K, Ca and Mg of tomato shoots. No effect was found on the quantities of these elements in tomato roots. Leachate of five plants of C. album per pot was sufficient to reduce tomato growth. Addition of 10 or 20 g kg⁻¹ of C. album dried shoots to the soil mixture significantly decreased the fresh and dry weights of tomato plants. S. vulgaris leachates did not show significant effects on the growth or nutrient accumulation of tomato plants.     

Tomato yellow leaf curl virus in the Dominican Republic: Characterization of an Infectious Clone, Virus Monitoring in Whiteflies, and Identification of Reservoir Hosts

ABSTRACT Epidemics of tomato yellow leaf curl disease (TYLCD) in the Dominican Republic in the early to mid-1990s resulted in catastrophic losses to processing tomato production. As part of an integrated management approach to TYLCD, the complete nucleotide sequence of a full-length infectious clone of an isolate of Tomato yellow leaf curl virus (TYLCV) from the Dominican Republic (TYLCV-[DO]) was determined. The TYLCV-[DO] genome was nearly identical in sequence (>97%) and genome organization to TYLCV isolates from Israel and Cuba. This established that TYLCV-[DO] is a bonafide TYLCV isolate (rather than a recombinant virus, such as isolates from Israel [Mild], Portugal, Japan, and Iran), and provided further evidence for the introduction of the virus from the eastern Mediterranean. A reduction in the incidence of TYLCV in the northern and southern processing tomato production areas of the Dominican Republic has been associated with the implementation of a mandatory 3-month whitefly host-free period (including tomato, common bean, cucurbits, eggplant, and pepper). Monitoring TYLCV levels in whiteflies, by polymerase chain reaction with TYLCV-specific primers, established that the incidence of TYLCV decreased markedly during the host-free period, and then gradually increased during the tomato-growing season. In contrast, TYLCV persisted in whiteflies and tomato plants in an area in which the host-free period was not implemented. Surveys for TYLCV reservoir hosts, conducted to identify where TYLCV persists during the host-free period, revealed symptomless infections in a number of weed species. The implications of these findings for TYLCV management in the Dominican Republic are discussed.     

Incidence and pathogenicity of races and isolates of Verticillium dahliae in Crete, southern Greece

Classification of 32 Verticillium dahliae isolates originating from 19 plant species in eight different botanical families to races and determination of host range pathogenicity were carried out. The physiological races of isolates were identified using the two differential tomato cultivars ??Belladonna?? (susceptible to both races 1 and 2 of V. dahliae) and ??Ace 55VF?? (resistant to race 1, susceptible to race 2 of V. dahliae). Among these isolates, 14 were race 2 (43.8%), 12 race 1 (37.5%) and six nonpathogenic (18.7%) on tomato. The host range pathogenicity of isolates was determined using four differential hosts (eggplant, turnip, tomato (Ve ^? ) and sweet pepper). Among isolates, five were pathogenic to both eggplant and turnip (15.6%), 21 to eggplant, turnip and tomato (65.6%), five to eggplant, turnip, tomato and sweet pepper (15.6%) and one was pathogenic to eggplant, turnip and sweet pepper (3.2%). The pathogenicity of isolates on the aforementioned five hosts was investigated on the basis of external symptoms and by calculating the relative areas under disease progress curves (relative AUDPC). Results showed that eggplant was the most susceptible, followed by turnip and tomato cv. Belladonna, while sweet pepper and tomato cv. Ace 55VF were less susceptible to all the isolates used. The pathogenicity of isolates varied from highly to mildly virulent on eggplant and turnip while on Belladonna, Ace 55VF and sweet pepper it varied from highly virulent to nonpathogenic. Belladonna exhibited a similar level of susceptibility to races 1 and 2 of V. dahliae, but was more susceptible than Ace 55VF to race 2. Interestingly, the isolates originating from eggplant were clearly more virulent than those originating from tomato and black nightshade on all solanaceous plants tested.