Showing papers on "Leaf spot published in 1998"

Mixtures of Plant Growth-Promoting Rhizobacteria Enhance Biological Control of Multiple Cucumber Pathogens

Abstract: Plant growth-promoting rhizobacteria (PGPR) strains INR7 (Bacillus pumilus), GB03 (Bacillus subtilis), and ME1 (Curtobacterium flaccumfaciens) were tested singly and in combinations for biological control against multiple cucumber pathogens. Investigations under greenhouse conditions were conducted with three cucumber pathogens-Colletotrichum orbiculare (causing anthracnose), Pseudomonas syringae pv. lachrymans (causing angular leaf spot), and Erwinia tracheiphila(causing cucurbit wilt disease)-inoculated singly and in all possible combinations. There was a general trend across all experiments toward greater suppression and enhanced consistency against multiple cucumber pathogens using strain mixtures. The same three PGPR strains were evaluated as seed treatments in two field trials over two seasons, and two strains, IN26 (Burkholderia gladioli) and INR7 also were tested as foliar sprays in one of the trials. In the field trials, the efficacy of induced systemic resistance activity was determined against introduced cucumber pathogens naturally spread within plots through placement of infected plants into the field to provide the pathogen inoculum. PGPR-mediated disease suppression was observed against angular leaf spot in 1996 and against a mixed infection of angular leaf spot and anthracnose in 1997. The three-way mixture of PGPR strains (INR7 plus ME1 plus GB03) as a seed treatment showed intensive plant growth promotion and disease reduction to a level statistically equivalent to the synthetic elicitor Actigard applied as a spray.

Characterization of Colletotrichum species responsible for anthracnose diseases of various fruits.

Abstract: ilamentous fungi of the genus Colletotrichum and its teleomorph Glomerella are considered major plant pathogens worldwide. They cause significant economic damage to crops in tropical, subtropical, and temperate regions. Cereals, legumes, ornamentals, vegetables, and fruit trees may be seriously affected by the pathogen (3). Although many cultivated fruit crops are infected by Colletotrichum species, the most significant economic losses are incurred when the fruiting stage is attacked. Colletotrichum species cause typical disease symptoms known as anthracnose, characterized by sunken necrotic tissue where orange conidial masses are produced. Anthracnose diseases appear in both developing and mature plant tissues (4). Two distinct types of diseases occur: those affecting developing fruit in the field (preharvest) and those damaging mature fruit during storage (postharvest). The ability to cause latent or quiescent infections has grouped Colletotrichum among the most important postharvest pathogens. Species of the pathogen appear predominantly on aboveground plant tissues; however, belowground organs, such as roots and tubers, may also be affected. In this article, we deal in particular with methods used to identify and characterize Colletotrichum species and genotypes from almond, avocado, and strawberry, as examples, using traditional and molecular tools. The three pathosystems chosen represent different disease patterns of fruitassociated Colletotrichum. Multiple Species on a Single Host Numerous cases have been reported in which several Colletotrichum species or biotypes are associated with a single host. For example, avocado and mango anthracnose, caused by both C. acutatum and C. gloeosporioides, affect fruit predominantly as postharvest diseases (25,40,41). Strawberry may be infected by three Colletotrichum species, C. fragariae, C. acutatum, and C. gloeosporioides, causing anthracnose of fruit and other plant parts (31). Almond and other deciduous fruits may be infected by C. acutatum or C. gloeosporioides (Table 1) (1,5,46,50). Citrus can be affected by four different Colletotrichum diseases (61): postbloom fruit drop and key lime anthracnose, both caused by C. acutatum, and shoot dieback and leaf spot, and postharvest fruit decay, both caused by C. gloeosporioides. Additional examples of hosts affected by multiple Colletotrichum species include coffee, cucurbits, pepper, and tomato. Single Species on Multiple Hosts It is common to find that a single botanical species of Colletotrichum infects multiple hosts. For example, C. gloeosporioides (Penz.) Penz. & Sacc. in Penz. (teleomorph: Glomerella cingulata (Stoneman) Spauld. & H. Schrenk), which is considered a cumulative species and forms the sexual stage in some instances, is found on a wide variety of fruits, including almond, avocado, apple, and strawberry (Table 2) (6,15,31,46). Likewise, C. acutatum J.H. Simmonds has been reported to infect a large number of fruit crops, including avocado, strawberry, almond, apple, and peach (1,5,16,25,27). Examples of other species with multiple host ranges include C. coccodes, C. capsici, and C. dematium (14,56).

Sibling species of Cercospora associated with gray leaf spot of maize.

Abstract: Monoconidial isolates of the fungus causing gray leaf spot of maize were obtained from diseased leaves collected throughout the United States and analyzed for genetic variability at 111 am...

Effects of crop rotations and fertilizer management on leaf spotting diseases of spring wheat in southwestern Saskatchewan

Abstract: The objective of this study was to determine the effect of crop sequence, summerfallow frequency, and fertilizer application, on the severity of leaf spotting diseases of spring wheat (Triticum aestivum L.). In the field experiment examined, Pyrenophora tritici-repentis (Died.) Drechs. was the pathogen most commonly isolated from lesioned leaf tissue, followed by stagonospora blotch (Phaeosphaeria nodorum [E. Muller] Hedjaroude). The severity of leaf spots in wheat after fallow was greater than in monoculture continuous wheat, or in wheat after a noncereal crop. Percent area with leaf spots in wheat grown after wheat was higher than in wheat grown after flax (Linum usitatissimum L.) or lentil (Lens culinaris Medikus) in years with high disease pressure (1995 and 1996), but not in 1993 or 1994 when overall disease levels were low. Under soil N-deficient conditions, leaf spot levels increased in years with dry summers (1994 and 1996), whereas a P deficiency decreased leaf spot severity in years that had coo...

Identification of QTL involved in field resistance to light leaf spot (Pyrenopeziza brassicae) and blackleg resistance (Leptosphaeria maculans) in winter rapeseed (Brassica napus L.)

Abstract: Quantitative trait loci (QTL), involved in the polygenic field resistance of rapeseed (Brassica napus L.) to light leaf spot disease, were mapped using 288 DNA markers on 152 doubled-haploid (DH) lines derived from the cross ‘Darmor-bzh’בYudal’. Over two years (1995 and 1996), the DH population was evaluated for light leaf spot resistance on leaves (L) and stems (S), and for blackleg disease resistance in same field trials. For the L resistance criterion, a total of five and seven QTL were detected in 1995 and in 1996 respectively, accounting for 53% and 57% of the genotypic variation. For the S criterion, three and five QTL were identified in 1995 and in 1996 respectively, explaining 29% and 43% of the genotypic variation. The locations of the QTL detected were quite consistent over the two years (4- and 2-year common QTL for L and S, respectively). Three genomic regions, located on the DY5, DY10 and DY11 groups, were common to the resistance on leaves and stems. In comparison with the QTL for blackleg resistance described by Pilet et al. (1998), two regions on the DY6 and DY10 groups, were associated with the two disease resistances. These ‘multiple disease resistance’ (‘MDR’) QTL may correspond to genes involved in common resistance mechanisms towards the two pathogens or else to clusters of resistance genes.

Effects of bean line pattern mosaic virus on the monocyclic components of rust and angular leaf spot of Phaseolus bean at different temperatures

Abstract: Monocyclic components (development rate during the incubation period or latent period, lesion density, lesion size and disease severity) of rust (Uromyces appendiculatus) and of angular leaf spot (Phaeoisariopsis griseola) in two bean (Phaseolus vulgaris) cultivars (Rosinha G-2 and Carioca), pre-infected or not with bean line pattern mosaic virus (BLPMV), were determined. Trials were conducted at temperatures in the range from 9 to 27°C for rust and from 12 to 30°C for angular leaf spot. Regardless of viral pre-infection, the effect of temperature on the four monocyclic components followed an optimum curve and could be described by a generalized beta function. Generally, angular leaf spot was favoured by higher temperatures with an optimum for disease severity between 24.2 and 28.3°C compared with 15.9–18.5°C for rust. Pre-infection with BLPMV did not change the shape of the optimum curves for all components, but significantly reduced lesion density and disease severity on both cultivars. The development rates during incubation and latent periods for both fungal diseases were not affected by BLPMV. Pre-infection with virus did not alter the ranking of cultivars with respect to resistance to both fungal diseases.

The maize lethal leaf spot 1 mutant has elevated resistance to fungal infection at the leaf epidermis

Abstract: The maize lethal leaf spot 1 (lls1) mutant exhibits enhanced resistance to fungal pathogens. The lls1 resistance to Cochliobolus heterostrophus has two components: (i) lesion number is reduced 40% relative to wild type; and (ii) the lesions that do form often do not contain viable fungus. This lesion sterility is dependent upon leaf maturity and light, whereas reduced lesion number is not. The lls1 lesions express pathogenesis-related proteins at high levels, so lesion sterility likely results from activation of defense systems and necrosis. Reduced lesion number is correlated with a reduction of C. heterostrophus spore germination, hyphal growth, and haustoria formation on the leaf epidermis. The rust pathogen Puccinia sorghi has reduced pustule formation on lls1, and its germination and growth are also slowed on the epidermis. However, after entering the mesophyll through stomata, P. sorghi can form pustules on lls1, and even green islands within necrotic lls1 lesions. In situ mRNA hybridization shows t...

Diagnosis of light leaf spot (Pyrenopeziza brassicae) on winter oilseed rape (Brassica napus) in the UK

Abstract: Light leaf spot lesions were generally first observed as light green areas on leaves of UK winter oilseed rape crops in January or February and later became brittle and bleached. Elongated lesions, which were brown with indistinct edges, developed on stems in the spring and summer, when lesions were also observed on flower buds, pedicels and pods. Development of diagnostic white pustules (spore masses of Pyrenopeziza brassicae, which erupt through surfaces of infected tissues) for confirmation of light leaf spot infection on symptomless plants or plants with indistinct or ambiguous symptoms in the autumn, winter or spring was enhanced by incubating plants in polyethylene bags. In experiments with artificially inoculated plants, glasshouse-grown plants exposed in infected crops and plants sampled from crops, white pustules developed at all incubation temperatures from 2 degrees C to 20 degrees C on infected leaves of different cultivars. The period of incubation required before the appearance of pustules decreased as the time that had already elapsed since the initial infection increased. The longest periods of incubation were required at the lowest temperatures (2 degrees C or 5 degrees C) but leaves senesced and abscised from plants most quickly at the highest temperatures (15 degrees C or 20 degrees C), suggesting that the optimal incubation temperature was between 10 degrees C and 15 degrees C.

Effect of a Leaf Spot Disease Caused by Alternaria alternata on Yield of Sunflower in Greece

Abstract: Field experiments were conducted during the 1989 to 1993 growing seasons in order to determine the effect of natural infections of Alternaria alternata on yield of sunflower (Helianthus annuus). Number of seeds produced per head and seed weight were reduced by 16 to 65% and 15 to 79%, respectively. Number and weight of seeds produced per head were correlated negatively with disease intensity before anthesis. The fungus overwinters in sunflower leaf residues and may present a yearly problem for sunflower production in some areas.

Cercospora beticola tolerant to triphenyltin hydroxide and resistant to thiophanate methyl in North Dakota and Minnesota

Abstract: Triphenyltin hydroxide (TP'I H) has been used exten­ sively for control of Cercospora (Cercospora betiola) leaf spot of sugarbeet (Beta vulgaris) in Minnesota and North Dakota foll owing the development of benz­ imidazole resistant strains in t he early 19808. The discovery oftolerance to TPTH in 1994 prompted ex­ tensive sampling throughout the region in 1995 and 1996. In 1995, 60% of the leaf spots in the southern most district were tolerant to 0.2ppm TPTH and 42% tolerant to Ippm. By 1996 these frequencies had increased to 83 and 60%, respectively. More alarm­ ing than this increase in the southern district was the rapid increase in the occurrence of tolerance fu rther north where the disease is generally less severe and fungicide use is less. In four of the seven factory dis­ tricts the frequency of leaf spots tolerant to O.2ppm exceeded 35% and the frequency tolerant to 1 ppm was greater than 15%, in 1996. Resistance to thio­ phanate-methyl, a benzimidazole-type fungicide, per­ sisted in local populations even though TPTB has been the predominant fungicide for control of Cer­ cospora leaf spot for about 15 years.

Integrated Management Practices for the Control of Maize Grey Leaf Spot

Abstract: Grey leaf spot of maize, (Zea maydis L.) (Cercospora zeae-maydis) Tehon and Daniels, is one of the most destructive leaf diseases of maize. The distribution and severity of grey leaf spot has increased over the past 10 to 15 years. The United States and South Africa are main areas where research on the disease has been concentrated. The research results have provided valuable and significant insight into pathogen epidemiology and allowed an integrated management system to be developed. However, management options are a result of the agricultural system under which maize is produced. The pathogen survives only on maize, so crop rotation and stubble management are major factors in disease management, but resistant hybrids offer the best option for economic control. Many other factors, such as soil fertility, plant density, irrigation and chemical control, can significantly influence a grey leaf spot epidemic, although a single management practice will not control the pathogen effectively.

Field Performance of Banana Micropropagules and Somaclones

Abstract: Banana and plantain (Musa spp. L.) are giant perennial herbs that thrive in the humid tropics and subtropics. The cultivated banana is mostly triploid (2n = 3x = 33), although diploid and tetraploid cultivars occur in much lower numbers. Its fruit provides one of the major commodities in international trade, but is far more important as a starchy staple food in local economies (Stover and Simmonds, 1987). However, production is threatened by pest and disease pressure, which have been increasing during the past 20 years. Most alarming has been the spread of more virulent forms of the fungal diseases black sigatoka leaf spot (Mycosphaerella fijiensis Morelet) and fusarium wilt (Fusarium oxysporum Schlecht, f.sp. cubense (E.F. Smith) Snyd. & Hans.). In response to these production constraints, efforts aimed at the genetic improvement of Musa have gained renewed interest (Persley and De Langhe, 1987; Rowe and Rosales, 1996; Vuylsteke et al, 1993a, 1997). Musa genetic improvement by conventional hybridization is, however, complex and difficult as it is burdened with obstacles typical of polyploid, vegetatively propagated crops, among which the trisomie pattern of gene inheritance, low seed fertility, and slow propagation are most conspicuous. Hence, biotechnology has been investigated for Musa germplasm handling and improvement (INIBAP, 1993; Novak, 1992; Vuylsteke, 1989).

Methods for assessment of light leaf spot (Pyrenopeziza brassicae) on winter oilseed rape (Brassica napus) in the UK

Abstract: Summary. Light leaf spot (Pyrenopeziza brassicae) was assessed as % plants with light leaf spot, % leaves with light leaf spot or % leaf area with light leaf spot in winter oilseed rape field experiments done at different sites (Rothamsted, Hertfordshire; Boxworth, Cambridgeshire; near Aberdeen, Scotland), with different cultivars (e.g. Bristol and Capitol), different fungicide treatments, on plants sampled at different dates. Regression analyses on data from these experiments showed that there were consistently good relationships between % leaves with light leaf spot and % plants with light leaf spot for plants sampled during the autumn and winter, until the % plants with light leaf spot approached 100%. The slopes and positions of regression lines were sometimes affected by cultivar, fungicide treatment or sampling date, but not by site. The relationship between % leaf area with light leaf spot (square root-transformed) and % leaves with light leaf spot was less consistent than that between % leaves with light leaf spot and % plants with light leaf spot and was sometimes affected by cultivar, fungicide treatment or sampling date but not by site. The relationship between % leaf area with light leaf spot (square root-transformed) and % plants with light leaf spot was also inconsistent and was sometimes affected by cultivar, fungicide treatment, sampling date and site.

Peanut (Arachis hypogaea L.) cultivar response to leaf spot disease development under four disease management programs

Abstract: Peanut (Arachis hypogaea L.) pod yield and response to early and late leaf spots [caused by Cercospora arachidicola S. Hori and Cercosporidium personatum (Berk. & M. A. Curtis) Deighton, respectively] were evaluated on six runner-type cultivars under four leaf spot spray programs using tebuconazole at 0.23 kg ai/ha and chlorothalonil at 1.26 kg ai/ha. The four leaf spot spray programs included unsprayed, 14-d schedule, 21-d schedule, and 28-d schedule. With the 14- and 21-d schedule, chlorothalonil was applied at the first and last applications with a maximum of four tebuconazole applications for the middle sprays. On the 28-d schedule, tebuconazole was applied four times. Under conditions of heavy leaf spot disease pressure where no fungicide was applied, Southern Runner and Georgia Browne were slightly less susceptible (although not significantly) to early or late leaf spot than Florunner, GK-7, Georgia Runner, or Sunrunner. Less leaf spot was present in the 14-d schedule compared to 21- or 28-...

Black Rot of Crucifers and Sources of Resistance in Brassica Crops

Abstract: Since the early 1990s, diseases caused by Xanthomonas campestris have been spreading on new host plants and in new regions, that had not been previously affected by the pathogen. Still, vegetable crops of Brassica oleracea are the most damaged plants by black rot. Recent achievements in the studies on resistance to black rot were reviewed. For the first time resistance genes were identified based on gene-for-gene interaction with different races of the pathogen. Some East Asian cabbage and Portuguese Penca kale cultivars seemed to carry the homologous genes for race-specific resistance. Their origin in Asian cabbages was traced to the Flat Dutch group of varieties and to heading Mediterranean kale. It is suggested that novel non-specific stem resistance found in Chinese kale, broccoli and cabbage might be an alternative means of genetic protection against the pathogen. Discipline: Plant disease/Plant breeding Additional key words: race-specific resistance, race structure, leaf spot diseases

Some factors affecting infection of citrus by Phaeoramularia angolensis

Abstract: Fruit and leaf spot disease caused by Phaeoramularia angolensis is the most important disease of citrus in Kenya. Current control recommendations are to apply copper fungicide sprays every 2 weeks during the main rainy season. Factors affecting lesion production on attached and detached citrus leaves and fruit were studied in order to provide the background information to target the spray timing to periods of maximum susceptibility. Results showed that leaf infection was dependent on high inoculum levels, periods of high humidity in excess of 24 h and moderate temperatures of around 25°C. Although all the citrus species tested were susceptible, the degree of susceptibility varied. Marsh seedless grapefruit was the most susceptible and Tahiti lime the least susceptible of those tested. Spore germination on the leaf, germ-tube penetration and sporulation capacity of the lesions were independent of cultivar/species and the determinant of susceptibility appeared to be the length of the incubation and latent periods. Fruit infection required a shorter wetting period than did leaf infection, but the period required for successful infection increased with increasing fruit age. The implications of these findings for improved fungicide spray recommendations are discussed.

Occurrence of Gibbago trianthemae Simmons on Horse Purslane Trianthema portulacastrum L. in India

Abstract: During the surveys conducted in Haryana, a leaf spot disease creating epiphytotics was observed in 1990 on horse purslane at Kurukshetra. Infected leaves had dark-brown, round to irregular, necrotic lesions with maroon margins. The fungus was identified as Gibbago trianthemae Simmons, a phaeodictyoconidial hyphomycete. Its pathogenicity was confirmed, both in vitro and in vivo . This is the first report of occurrence of G. trianthemae on horse purslane in India.

Effects of light leaf spot (Pyrenopeziza brassicae) on yield of winter oilseed rape (Brassica napus)

Abstract: Summary The relationship between development of light leaf spot and yield loss in winter oilseed rape was analysed, initially using data from three experiments at sites near Aberdeen in Scotland in the seasons 1991/92, 1992/93 and 1993/94, respectively. Over the three seasons, single-point models relating yield to light leaf spot incidence (% plants with leaves with light leaf spot) at GS 3.3 (flower buds visible) generally accounted for more of the variance than single-point models at earlier or later growth stages. Only in 1992/93, when a severe light leaf spot epidemic developed on leaves early in the season, did the single-point model for disease severity on leaves at GS 3.5/4.0 account for more of the variance than that for disease incidence at GS 3.3. In 1991/92 and 1992/3, when reasonably severe epidemics developed on stems, the single-point model for light leaf spot incidence (stems) at GS 6.3 accounted for as much of the variance. Two-point (disease severity at GS 3.3 and GS 4.0) and AUDPC models (disease incidence/severity) accounted for more of the variance than the single-point model based on disease incidence at GS 3.3 in 1992/93 but not in the other two seasons. Therefore, a simple model using the light leaf spot incidence at GS 3.3 (x) as the explanatory variable was selected as a predictive model to estimate % yield loss (yr): yr= 0.32x– 0.57. This model fitted all three data sets from Scotland, When data sets from Rothamsted, Rosemaund and Thurloxton in England were used to test it, this single-point predictive model generally fitted the data well, except when yield loss was clearly not related to occurrence of light leaf spot. However, the regression lines relating observed yield loss to light leaf spot incidence at GS 3.3 often had smaller slopes than the line produce, by the model based on Scottish data.

Efficacy of Fungicide Treatments for Control of Common Rust and Northern Leaf Spot in Hybrid Corn Seed Production

Abstract: Field experiments were conducted during the 1992 and 1993 growing seasons in 13 commercial fields in Iowa to assess the efficacy of foliar applications of fungicides to seed corn for control of common rust, Puccinia sorghi, and northern leaf spot, Bipolaris zeicola. Chlorothalonil, mancozeb, and/or propiconazole sprays were initiated at growth stage (GS) 2.5, GS 4.0, or approximately 2 weeks before detasseling, and applications were repeated up to five times at various growth stages. The majority of fungicide treatments resulted in an increase in salable seed units (1 unit = 80,000 seeds) compared to untreated control treatments. The greatest increase in salable seed occurred in the large and medium seed size units. Although disease severity on the final assessment date in both years and standardized area under the disease progress curve in 1993 were significantly higher (P ≤ 0.05) in untreated control plots than in fungicide-treated plots in all experiments, the best disease control was provided by 5 applications of chlorothalonil or 2 to 4 applications of chlorothalonil, mancozeb, or propiconazole initiated on the first spray date.

Susceptibility of Crapemyrtle Cultivars to Powdery Mildew and Cercospora Leaf Spot in Alabama

Abstract: Reaction of 43 cultivars in three crapemyrtle taxa (Lagerstroemia indica, L. indica x fauriei and L. fauriei) to powdery mildew (Erysiphe lagerstroemia) and Cercospora leaf spot (Cercospor...

Sigatoka leaf spot diseases of bananas and plantains in Central and West Africa. Distribution - impact on banana productions field susceptibility of wild and cultivated bananas to BLSD control strategies

Abstract: Sigatoka Leaf Spot Disease of bananas involve two related ascomycetous fungi : Mycosphaerella fijiensis,which causes Black Leaf Streak disease (BLSD) and M Musicola which causes Sigatoka disease (SD) In Africa, the first records of BLSD were noted in Zambia in 1973 and, between 1973 and 1993, the disease spread along the West coast to Cameroon, Nigeria, Benin, Togo, Ghana and Ivory Coast The local dissemination of BLSD within the same country or the long distance spread of the disease can vary significantly depending on epidemiological factors (climatic conditions and host reactions) Competitivity problems can appear between SD and BLSD at altitudes over 1200 - 1400 m

Regeneration of late leaf spot-resistant groundnut plants from Cercosporidium personatum culture filtrate-treated callus

Abstract: Cotyledon callus cultures of groundnut (Arachis hypogaea L.) derived from tikka late leaf spot disease-susceptible and resistant genotypes were exposed to various concentrations of fungal culture filtrate (FCF) of Cercosporidium personatum, the causal fungal agent of tikka late leaf spot disease. Fresh weight and cell viability of calli were determined after exposure to various concentrations of FCF. Sensitive calli have failed to increase in fresh weight and lost viability after exposure to media containing the FCF whereas insensitive calli retained growth and maintained viability similar to controls, viz, calli not exposed to FCF, Insensitive calli were selected by culturing on growth medium containing various concentrations of the FCF. Resistant calli obtained by selection survived three subcultures under the same conditions and were used for plantlet regeneration, Regenerated plants when transferred to soil-sand mixture in plastic cups and subsequently shifted to field conditions, set few viable seeds. Plants of R-2 generation exhibited enhanced resistance to tikka late leaf spot disease.

Bacterial Blight of Broccoli Raab: A New Disease Caused by a Pathovar of Pseudomonas syringae.

Abstract: Bacterial blight is a new disease of broccoli raab or rappini (Brassica rapa subsp. rapa) that has developed on commercially grown crops in the Salinas Valley (Monterey County) in California. Symptoms consist of small, angular, water-soaked flecks on lower foliage that are visible from both adaxial and abaxial sides of the leaves. These flecks expand and become surrounded by bright yellow borders. With time, multiple leaf spots coalesce and result in large, irregular necrotic areas, extensive leaf yellowing, and eventual leaf death. If symptoms develop on the uppermost leaves attached to the inflorescence, the shoot loses market quality and will not be harvested. Pseudomonas syringae was consistently isolated from symptomatic plants, and selected strains caused similar symptoms when inoculated onto broccoli raab test plants. Broccoli raab strains caused leaf spot symptoms on nine other Cruciferous plants, as well as on three grass species (California brome, oat, and common timothy). Conversely, broccoli raab was not infected by P. syringae pathovars coronafaciens, maculicola, and tomato. Broccoli raab strains were positive for coronatine toxin production. Fatty acid analyses indicated that the P. syringae from broccoli raab was most closely related to P. syringae pvs. coronafaciens and maculicola, but its distinct host range suggests that it may be considered a separate pathovar.