Effects of sowing date on severity of blight caused by <Emphasis Type="Italic">Ascochyta rabiei</Emphasis> and yield components of five chickpea cultivars grown under two climatic conditions in Tunisia

Five chickpea cultivars, Chitoui, Neyer, Kasseb, Beja 1 and Bouchra, were planted on three sowing dates at two Experimental Stations in Tunisia: Bou Salem in the north and the more southerly Mornag, where the climate is drier. Severity of blight, caused by Ascochyta rabiei, was measured on a 1–9 scale (defined) on vegetative parts and on pods as percent infected and percent infected that were empty. At both locations, disease was essentially absent on plants sown on the third dates but present on plants sown on the two earlier dates. At Bou Salem, disease severity was highest for the second sowing date whereas at Mornag it was highest for the first sowing date; but for each sowing date, disease severity was lower at Mornag than at Bou Salem. Yield components were measured as number of pods per plant, number of seeds per plant, number of seeds per 100 pods, 100 seed weight and weight of seeds per plant. Both disease severity and yield differed significantly among sowing dates (differently at each location) and also among cultivars for each sowing date, these differences depending both on sowing date and location. A lower yield was always associated with a higher disease severity, although the quantitative relationship differed between cultivars and locations. Cultivar Beja 1 had the lowest vegetative disease scores at both locations and both sowing dates 1 and 2. Beja 1 also scored well for all yield components. Plants sown on the third (latest) date gave the highest yields for all cultivars at both locations (except for an unusually high yield of Neyer at Mornag on sowing date 2), in some instances being more than double those from the earlier sowing dates. Thus, in contrast to other studies, late sowing did not result in yield loss.     

Residual effects of cultivation methods on weed seed banks and weeds in Cambodia

The effects of the planting method (transplanting vs. direct seeding), rice cultivar (Sen Pidao vs. Phka Rumduol), and herbicide application (admixture of bentazone and cyhalofop‐butyl) on weeds and weed seed banks were quantified in unflooded, shallowly flooded, and deeply flooded paddy fields in Cambodia in 2005 and 2006. Broad‐leaved weeds infested more toward maturity in 2006 than in 2005, particularly in directly seeded plots. Weed dry weights at pre‐heading and/or maturity were consistently reduced by herbicide application and Phka Rumduol cultivar, while weed numbers increased under unflooded condition. The proportion of sedges was consistently larger in directly seeded and non‐herbicide plots at pre‐heading. Larger numbers and dry weights of sedges and total weeds in 2005 caused larger seed bank sizes of sedges and total weeds in 2006, which further caused their infestation in 2006. A greater weed dry weight at 62 days after sowing in 2005 resulted in larger seed banks of Cyperus iria and Fimbristylis miliacea, which were most severe under non‐herbicide, direct‐seeded treatment, while that at rice maturity resulted in larger seed banks of Cyperus difformis, Scirpus juncoides, and Lindernia antipoda. Overall, sedges shared the majority of the total weed seed bank, followed by broad‐leaved weeds and then grasses. A lower yield in 2005 led to significantly larger seed bank sizes of sedges, but not of grasses or broad‐leaved weeds. Rice yield reduction was consistently related to larger numbers of sedges by heading and those of grasses at maturity.     

Determination of agronomic practices for the management of blight of chickpea caused by <Emphasis Type="Italic">Ascochyta rabiei</Emphasis> in Turkey: 1. Appropriate sowing date

In order to determine the most appropriate dates for planting chickpea in central Anatolia, Turkey, six cultivars were planted at three sites that differed in disease pressure. In two of the sites, disease pressure from Ascochyta rabiei was promoted by spreading infected chickpea debris on the soil surface at the time of planting and, at one of these, sprinkle irrigation was applied. In the third site, where conditions were dryer, no artificial inoculum was provided. Plants from seeds sown in early March had the most disease and in the sprinkle irrigated plots the disease severity ranged from 7.8 on the most susceptible cv. Canitez to 3.3 on the least susceptible Gokce as scored on the 1–9 scale where 1 = no disease and 9 represents a plant killed by the fungus. There was an inverse relationship between disease severity and yield, production from blight resistant cultivars of around 2,000 kg ha⁻¹ being more than twice that of susceptible ones. Delaying planting for 3–5 weeks reduced the severity of ascochyta blight but also reduced the yields in four of the six cultivars. In contrast, reduction in disease severity by delayed sowing resulted in yield increases for the susceptible cvs Canitez and Local, although yield level was not as much as those of the less susceptible cvs sown early. Delay of 6–9 weeks almost eliminated ascochyta blight but yields of all cultivars were seriously compromised by drought stress. In consequence, chickpea farmers are recommended to use resistant or tolerant cultivars and sow early in March. For less resistant cultivars, sowing in early April is recommended. Further delay is not recommended unless irrigation is provided and fungicide spraying is recommended where signs of infection are present under conditions conducive to the disease.     

Striga seed avoidance by deep planting and no-tillage in sorghum and maize

The possibility of reducing Striga hermonthica (Del.) Benth. parasitism in severely infested fields, by means of deep planting - thereby reducing the root length in the upper layers of the soil where Striga seeds are predominantly found - was tested in field trials with maize and sorghum in western Kenya. Sorghum seeds were planted in Striga-infested fields approximately 2.5 cm deep in the soil or at the bottom of conically-shaped plant holes (15-20 cm deep). Depth of plant holes for maize varied from 0 to 30 cm, in un-tilled soil. Deep planting in un-tilled soil gave higher (up to double) grain yields, compared with standard planting in tilled soil. Parasite emergence was related negatively to planting depth of maize (p< 0.05). Deep planting in tilled soil gave 74% more sorghumgrain yield relative to standard planting. In this treatment Striga seed production was not reduced but in un-tilled fields with deeply planted sorghum Striga seed production was completely suppressed. Therefore, a combination of zero-tillage and deep planting seems to be the most effective treatment. The probable mechanism causing these results is avoidance of Striga seed by the host root system, resulting in a delay in the onset of Striga attachment and the formation of smaller numbers of attachments.     

<Emphasis Type="Italic">Ulocladium atrum</Emphasis> as a biological control agent for white mold of bean caused by<Emphasis Type="Italic">Sclerotinia sclerotiorum</Emphasis>

Field studies were conducted near Lethbridge, Alberta, Canada, in 2001, 2004 and 2005 to determine the efficacy of the antagonistic fungusUlocladium atrum for control of white mold of bean caused bySclerotinia sclerotiorum. Results of the 3 years of field trials showed that, compared with the untreated control, foliar application of a spore suspension ofU. atrum (300 ml m⁻² of 10⁶ spores ml⁻¹ suspension) significantly reduced incidence and severity of white mold, increased seed yield and reduced contamination of bean seed by sclerotia ofS. sclerotiorum. The level of control of white mold observed in the treatment ofU. atrum was similar to that of the mycoparasitic fungusConiothyrium minitans, but lower than the fungicide treatments of Ronilan (vinclozolin) at the rate of 1200 g ha⁻¹ per application in 2001, or Lance (boscalid) at the rate of 750 g ha⁻¹ per application in 2004 and 2005. The potential for use ofU. atrum as a biological control agent for sclerotinia diseases is discussed. http://www.phytoparasitica.org posting Nov. 12, 2006.     

Effect of Winter Planting Date on Oil Yield and Fatty Acids of New Spring Canola (Brassica napus L.) Cultivars Under Foliar Zinc Spray

Canola (Brassica napus L.) oil yield and fatty acid composition are the function of genotype, climate conditions, morphology, and physiology as well as crop management. In this study, the reaction of different canola cultivars—in terms of seed oil content and fatty acids—to different planting dates and foliar zinc application during two experimental years (2016–2017) was investigated in the field in arid and semi-arid regions of Karaj, Iran. The experiment was performed as a factorial split plot in a randomized complete-block design with three replications. Three sowing dates (February 9, 19, 29) and two foliar zinc applications (non-application as control and zinc application; spraying in the stem elongation stage) were factorially randomized to main plots, and canola cultivars (Sarigol, Dalgan, Salsa, and Solar) were allocated to sub-plots. The results indicated that the effect of year, planting date, zinc application, cultivar, and the interaction effect of planting date and cultivar on quality traits (glucosinolate and fatty acids) and seed yield were significant (p?<?0.01). The delay in winter planting of spring canola cultivars caused a significant reduction in seed yield, oil yield, and the content of oleic, linoleic, and palmitic fatty acids and increased the content of linolenic, erucic, stearic, arachidic, and behenic fatty acids and glucosinolate. The highest seed yield (4732.2?kg/ha), oil yield (2066?kg/ha), and oleic acid content (66.52%) were observed in the Dalgan cultivar in the zinc application treatment with normal planting date (February 9). The Salsa cultivar had the highest content of erucic acid (0.46%) and glucosinolate (17.3?μmol/g meal) in the control treatment with the last planting date. Because the quality of edible canola oil depends on the increase in unsaturated fatty acids, particularly oleic and linoleic acids, and the reduction of erucic acid and glucosinolate, planting Dalgan cultivar with zinc application at the normal planting date is recommended for the study area and similar areas.

     

Detection of Dickeya spp. latent infection in potato seed tubers using PCR or ELISA and correlation with disease incidence in commercial field crops under hot‐climate conditions

Over a 5‐year period (2006–2010), 277 certified, visually healthy potato seed lots, imported from Europe to Israel for commercial use, were tested for Dickeya spp. latent infection by PCR analysis (277 seed lots) and ELISA (154 seed lots). Seeds from these lots were grown in commercial potato fields which were inspected twice a season by Plant Protection and Inspection Services (PPIS). Stem samples were tested for the presence of Dickeya spp. by PCR analysis. PCR and ELISA results from seed lot testing correlated with disease expression in 74 and 83·8% of the cases, respectively. Positive laboratory results with no disease symptoms in the field (‘+lab/?field’ results) comprised 24·7 and 9·7% of the PCR and ELISA analyses, respectively, whereas negative laboratory results with disease symptoms in the field results (‘?lab/+field’) were obtained in 1·3 and 6·5%, of cases respectively. Maximum disease incidence, as well as the number of cultivars expressing disease symptoms, increased over the years of this study, indicating an increase in the prevalence of the disease. Severe disease incidence was observed on cvs Dita, Rodeo, Desiree, Mondial, Tomensa and Jelly. Of the 55 imported seed lots from which disease was recorded in the field, 49 originated from the Netherlands, four from Germany and two from France. None originated from Scotland.     

Factors affecting the temporal progress of stem canker (Rhizoctonia solani ) on potatoes (Solanum tuberosum)

The effects of different densities of tuber-borne inoculum, selected agronomic treatments (date of planting, irrigation and size of seed tubers) and their interactions on the temporal progress of stem canker ( Rhizoctonia solani ) on potato plants ( Solanum tuberosum ) were investigated in a multifactorial experiment. Data comprising stem number and the incidence and severity of stem canker from planting until tuber initiation in two consecutive growing seasons were analysed using linear contrasts, quadratic contrasts and the area under the disease progress or host growth curve. Differences in the incidence and severity of stem canker were dominated by the effect of different densities of tuber-borne inoculum. The majority of disease progress curves were nonmonotonic for the incidence and severity of stem canker with a rapid rise in disease up to stem emergence and a decline thereafter. Most treatments affected the area under the curve and to a lesser extent the average rate of increase in disease. Of the agronomic treatments, later dates of planting and pre-emergence irrigation reduced the levels of stem canker whereas size of seed tubers did not affect the progress of disease. Little additional information was revealed by scoring for the severity rather than the incidence of stem canker.     

White mould of sweet basil: conditions influencing its development in greenhouses and cultural measures for disease management

During the winter season, Sclerotinia sclerotiorum infects the stem bases of greenhouse‐grown sweet basil plants and, in severe epidemics, it may also infect the shoots. Sclerotia of S. sclerotiorum, and the ascospores that are released from the apothecia that form on them, serve as the inoculum for white mould epidemics. This research aimed to identify cropping parameters associated with lower incidence of white mould in a survey of the main basil‐growing region in Israel, and study cultural methods that might suppress the disease. The survey revealed that this mould, in the main growing area in Israel, has one cycle of infection. Factors associated with increased moisture in the greenhouse were found to be associated with increased levels of the disease. The use of a lower planting density reduced the incidence of white mould in semi‐commercial experimental plots, as well as the severity of the disease on shoots infected by S. sclerotiorum after harvest, in comparison to the commonly used higher planting density, with no negative effect on yield. Mulching the beds with polyethylene effectively reduced disease, and a combination of polyethylene mulch and increased plant spacing reduced disease severity on cut shoots in a synergistic manner. In conclusion, cultural control methods reduced disease incidence under field conditions and severity of the disease on cut shoots.     

Relationships between stem canker, stolon canker, black scurf (Rhizoctonia solani) and yield of potato (Solanum tuberosum) under different agronomic conditions

Relationships between diseases caused by Rhizoctonia solani on different parts of potato plants ( Solanum tuberosum ) at different stages of crop growth were investigated under selected agronomic conditions. The effects of different densities of tuber-borne inoculum, date of planting, irrigation, size of seed tubers and their interactions on the incidence of stem and stolon canker during crop growth, the incidence and severity of black scurf and the yield of progeny tubers at harvest were quantified in a multifactorial experiment. Differences in the incidence of stem canker, stolon canker and black scurf were dominated by the effect of density of inoculum on seed tubers at planting. Highly positive correlations between the disease variables indicated a close relationship between the incidence of disease at each stage of crop growth although the degree of association between variables measured at an early growth stage and those measured at progressively later stages of crop growth weakened as the time interval increased. Total yield of progeny tubers was not affected by the density of tuber-borne inoculum although there was a shift in the size distribution, with a decrease in the yield of main-sized tubers and an increase in the yield of baker- and oversized tubers at the higher density of inoculum. Of the remaining factors, the effect of season tended to be more pronounced than any of the agronomic treatments although the use of irrigation and later dates of planting did influence the incidence of infection to a limited extent.     

Integration of soil application and seed treatment formulations of Trichoderma species for management of wet root rot of mungbean caused by Rhizoctonia solani

BACKGROUND: The efficacy of seed dressing and soil application formulations from the isolates of Trichoderma viride (IARI P1; MTCC 5369), T. virens (IARI P3; MTCC 5370) and T. harzianum (IARI P4; MTCC 5371) were evaluated individually and in combination in pot and field experiments during the rainy seasons of 2005, 2006 and 2007 for the management of wet root rot (Rhizoctonia solani) and improvement in the yield of mungbean. RESULTS: A seed dressing formulation, Pusa 5SD, and soil application formulations, Pusa Biogranule 6 (PBG 6) and Pusa Biopellet 16G (PBP 16G), based on Trichoderma virens, were found to be superior to other formulations in reducing disease incidence and increasing seed germination and shoot and root lengths in mungbean. In field experiments, a combination of soil application with PBP 16G (T. virens) and seed treatment with Pusa 5SD (T. virens) + carboxin was superior to any of these formulations individually in increasing seed germination, shoot and root lengths and grain yield and reducing wet root rot incidence in mungbean. Seed treatment was more effective than soil application for all the evaluated parameters. The combined application of Pusa 5SD and carboxin was also superior to individual treatment. CONCLUSION: The efficacy of the evaluated formulations against wet root rot of mungbean proved that the integration of soil application of PBP 16G and seed treatment with Pusa 5SD + carboxin is highly effective for the management of wet root rot, increasing plant growth and grain yield of mungbean Copyright © 2011 Society of Chemical Industry     

Assessment of the impact of mid-season late blight infection on disease development and yield of potato variety Russet Norkotah in Maine

Development of late blight of potatoes caused by Phytophthora infestans (US 8 fungal genotype, A2 mating type) was monitored in two Russet Norkotah commercial fields at Fort Fairfield in 1996 and Duncan Farm in 1997. Experimental plots representing various disease treatments (low, moderate, high and random late blight severity levels) were established in two fields in 1996. In 1997, only low and high disease treatments were established. The application of fungicides for late blight control was conducted in both years. Late blight incidence and severity were assessed in each plot of each treatment. Components of late blight disease development, tuber blight incidence and tuber yields were determined from each plot. Progress of late blight disease was rapid in 1996 but not in 1997. During the 1996 cropping season, mean disease incidence and severity in the random disease treatment plots were 84 and 21% respectively within 10 days of disease detection. In 1997, low levels of late blight severity were detected in the field plots. Average numbers of late blight leaf and stem lesions on infected plant and fungal sporangia on the diseased leaf were not significantly affected by disease treatment. Late blight foliar severity significantly affected potato tuber yields. Lowest tuber yield was obtained in plots with high disease levels and highest yields were recorded in plots with low late blight severity in 1996. Late blight severity was significantly correlated with tuber yield but not with per cent tuber blight.     

The importance of the infected seed tuber and soil inoculum in transmitting Potato mop‐top virus to potato plants

Potato mop‐top virus (PMTV), the cause of spraing in potato tubers, is transmitted by Spongospora subterranea, the cause of powdery scab, and by planting infected seed tubers. This study was undertaken to determine the relative importance of these sources of infection in seed potato production in Scotland. The transmission of PMTV from tested seed tubers to daughter plants was examined over 2 years and six cultivars. The development of foliar symptoms varied with year and cultivar. Infection of daughter tubers derived from PMTV‐infected seed tubers was more prevalent on plants affected by foliar symptoms than those without symptoms. The rate of transmission of PMTV from infected seed tubers to daughter tubers ranged from 18 to 54%. Transmission was affected by cultivar and by origin of seed tubers used for a cultivar, but not by a cultivar's sensitivity to PMTV infection. The incidence of PMTV in daughter tubers of cv. Cara grown from seed potatoes from one source (common origin) by more than 25 seed producers was examined over two successive generations. The incidence of PMTV in daughter tubers was not correlated with that in the seed tubers but appeared to be strongly associated with soil inoculum. The incidence of PMTV was correlated with powdery scab in those crops in which both were present. There was some evidence from soil tests conducted in 2006 using a tomato bait plant and real‐time RT‐PCR that planting PMTV‐infected seed potatoes could increase the risk of introducing the virus into land not infested by PMTV.     

PUCREC/PUCTRI – a decision support system for the control of leaf rust of winter wheat and winter rye*

During a three‐year project from 2003 to 2006, two models have been developed to predict leaf rust (Puccinia recondita and P. triticina) occurrence and to simulate disease incidence progress curves on the upper leaf layers of winter rye (PUCREC) and winter wheat (PUCTRI). As input parameters the models use air temperature, relative humidity and precipitation. PUCREC and PUCTRI firstly calculate daily infection favourability and a cumulative infection pressure index and, in a second step, disease incidence is estimated. An ontogenetic model (SIMONTO) is used to link disease predictions to crop development. PUCREC and PUCTRI have been validated with data from 2001 to 2005. Both models give satisfactory results in simulating leaf rust epidemics and forecasting dates when action thresholds for leaf rust control are exceeded.     

Ecophysiological study on weed seed banks and weeds in Cambodian paddy fields with contrasting water availability

Weed infestations are a major cause of yield reduction in rice (Oryza sativa) cultivation, particularly with direct‐seeding methods, but the relationship between weed dynamics and water availability in Cambodian paddy fields has not been documented previously. We surveyed the weed abundance and weed seed banks in the soil of paddy fields with inferred differences in their water regime in 22 farm fields in three provinces of Cambodia in the 2005 and 2006 rainy seasons. We studied rain‐fed lowland fields in upslope and downslope topographic positions and fields at different distances from the irrigation water source inside an irrigation rehabilitation area. The weed seed banks were estimated by seedling emergence in small containers and weed abundance and vigor were estimated by a simple scoring system. The estimated weed seed bank in the top 5 cm of soil ranged from 52.1 to 167 × 10³ seeds m^?2 (overall mean of 8.5 × 10³ seeds m^?2) and contained a high proportion (86%) of sedge species, such as Fimbristylis miliacea L. and Cyperus difformis. Several fields had particularly large seed banks, including one near the reservoir. No clear difference was found in the weed seed banks between the irrigated fields that were located close to (upstream) and distant from (downstream) the water source or between the irrigated and rain‐fed lowland fields, but the weed scores were larger in the rain‐fed fields and the downstream fields within the irrigated area. A water shortage during the late growing season in 2005 led to a proliferation of weeds in some fields and an associated increase in weed seedbank size in 2006. However, the weed scores in 2006 were more strongly associated with that year's water conditions than with the weed seedbank size.     

Incomplete systemic movement of Xanthomonas campestris pv. musacearum and the occurrence of latent infections in xanthomonas wilt‐infected banana mats

Management of banana xanthomonas wilt (XW) (caused by Xanthomonas campestris pv. musacearum, Xcm) has been impeded by poor adoption of control options that are complex, cumbersome and costly. To improve XW management, this study investigated Xcm survival and latent infections in subsequent generations, survival of latently infected planting materials (suckers), incidence of latent infections in symptomless plants in mats having diseased plants, and XW status across farms and markets in districts previously devastated but currently endemic. On‐station experiments were protected from new infections. Latent bacteria at low levels were detected in up to 20% of the third generation suckers, with a significant (P < 0·05) reduction (43–20%) in subsequent generations. Only 3–6% of latently infected suckers succumbed to XW. Incidence of Xcm in symptomless suckers from farmers' fields (with up to 70% incidence) was low (3%) while it increased (8–25%) with disease severity in mats in controlled experiments. In the surveyed districts, incidence had significantly declined with yields observed to have recovered relative to earlier reports, although latent infections remained high. This study provides evidence that if new infections are prevented, fields with high XW incidence can be rejuvenated. It showed incomplete systemic movement of Xcm in mats coupled to a gradual decline of bacterial load in subsequent generations to levels that cannot initiate disease. These studies explain the current successes in farms practising single diseased plant removal instead of whole mat rouging, and gives hope to farmers lacking access to clean planting material.     

Control of common bunt of wheat under field conditions with the biofumigant fungus <Emphasis Type="Italic">Muscodor albus</Emphasis>

Field experiments were conducted to evaluate the biological control potential of the fungus Muscodor albus, when applied as a seed treatment or an in furrow soil treatment, for control of common bunt (CB) of wheat caused by Tilletia caries. For seed treatments, dry rye grain culture of M. albus was ground into powder and applied, at a rate of 125 mg/g seed, to wheat seed infested with T. caries teliospores. The culture was also cracked into particles and applied in furrow at the rate of 4 g/m of row, along with teliospore infested seed during planting. Treatments were evaluated during two growing seasons and two planting dates beginning in early spring when soil temperatures were optimal for disease development (5–10°C), and then approximately 3 weeks later. In the first year, treatments in the first seeding date reduced CB from 44% diseased spikes in untreated controls to 12% and 9% in seed and in furrow treatments respectively, and from 6% in controls to 0% in both treatments in the second seeding date. In the second year, CB was reduced from 8% in controls to 0.5% and 0.25% for seed and in furrow treatments respectively in the first seeding date, and from 0.75% in controls to 0% in both the treatments in the second seeding date. M. albus may have potential for CB control in organic wheat production where options for managing the disease are very limited.     

A model of plant virus disease epidemics in asynchronously-planted cropping systems

A mathematical model was developed of the dynamics of a plant virus disease within a spatially-referenced lattice of fields of a host crop. The model can be applied to crops in continuous, contiguous cultivation such as tropical irrigated rice. Disease progress in each field of the host crop was assumed to be logistic and determined by incidence within the field itself as well as incidence in neighbouring fields, depending on the gradient of disease spread. The frequency distribution of planting dates (represented by the proportion of the total number of fields planted in successive months) was assumed to follow a normal distribution and the variance of planting date was used as a measure of cropping asynchrony. Analysis of the model revealed that disease incidence within the lattice (i.e. mean incidence over all fields) depended upon the infection efficiency, the slope of the dispersal gradient, and the variance in planting date. Disease endemicity depended mainly on planting date variance and disease persisted in the lattice if this variance exceeded a certain threshold. Above the threshold for persistence, the response of mean disease incidence to planting date variance was non-linear and the region of greatest sensitivity was closest to the threshold. Thus, disease systems that show moderate rather than high cropping asynchrony are more likely to be influenced by changes in the variance of planting date. Implications for the area-wide management of rice tungro virus disease are discussed.     

Uptake of iprodione and control of diseases on potato stems

When applied to the roots of potato plants growing in different soils iprodione became systemic in the plants. Although iprodione was adsorbed on the soils tested, sufficient fungicide was present in potato stems to prevent infection by Phoma exigua var. foveata on all plants except those grown in peat soils. The amount of fungicide present in the aerial parts of the plant was related to the soil/water distribution coefficients. Application of iprodione to the sprouts of seed potato tubers prior to planting decreased the incidence and severity of infection by Rhizoctonia solani (stem canker) and Polyscytalum pustulans on stem bases.     

Incidence of Verticillium wilt of artichoke in eastern Spain and role of inoculum sources on crop infection

Surveys of 94 artichoke fields throughout the artichoke production areas of Comunidad Valenciana (eastern Spain) were conducted from 1999 to 2002 to determine the incidence and distribution of Verticillium wilt.Verticillium dahliae was isolated from 80.9% of the sampled fields, and detected in all artichoke-growing areas, with a mean disease incidence of 53.8% infected plants. The disease was found to cause severe damage to cv. ‘Blanca de Tudela’, which is the most important artichoke cultivar grown in Spain, and was also observed on the seed-propagated cv. ‘Imperial Star’. In field trials to study the role of infected planting material and soil inoculum on infection of artichoke plants during the cropping season,V. dahliae was transmitted from infected stumps to the plants, confirming that the use of infected stumps could have greatly contributed to the dissemination of the pathogen. Inoculum density ofV. dahliae in soil had an effect on crop infection, in that a higher number of microsclerotia per gram of soil resulted in a higher percentage of infected plants. In addition, yield of cv. Blanca de Tudela was significantly affected byV. dahliae infection, showing that a higher percentage of infection corresponded with lower yield. http://www.phytoparasitica.org posting July 21, 2005.