Zamir Punja

Simon Fraser University · Department of Biological Sciences

The increased cultivation of high THC-containing Cannabis sativa L. (cannabis), particularly in greenhouses, has resulted in a greater incidence of diseases and molds that can negatively affect the growth and quality of the crop. Among them, the most important diseases are root rots (Fusarium and Pythium spp.), bud rot (Botrytis cinerea), powdery m...

The increased cultivation of high THC-containing Cannabis sativa L. (cannabis), particularly in greenhouses, has resulted in a greater incidence of diseases and molds that can negatively affect the growth and quality of the crop. Among them, the most important diseases are root rots (Fusarium and Pythium spp.), Botrytis bud rot (Botrytis cinerea),...

The increased cultivation of Cannabis sativa L. in North America, represented by high Δ9-tetrahydrocannabinol-containing (high-THC) cannabis genotypes and low-THC-containing hemp genotypes, has been impacted by an increasing number of plant pathogens. These include fungi which destroy roots, stems, and leaves, in some cases causing a build-up of po...

The increased cultivation of Cannabis sativa L. in North America, represented by high Δ9-tetrahydrocannabinol-containing (high-THC) cannabis genotypes and low THC-containing hemp genotypes, has been impacted by an increasing number of plant pathogens. These include fungi which destroy roots, stems and leaves, in some cases causing a build-up of pop...

Medicinal and recreational uses of Cannabis sativa , commonly known as cannabis or hemp, has increased following its legalization in certain regions of the world. Cannabis and hemp plants interact with a community of microbes (i.e., the phytobiome), which can influence various aspects of the host plant. The fungal composition of the C. sativa phyto...

We established transformation technologies using Agrobacterium tumefaciens (Smith & Townsend) Conn to insert foreign genes into high THC-containing cannabis (Cannabis sativa L.). The Arabidopsis non-expressor of pathogenesis-related protein 1 (AtNPR1) gene was selected as a potentially useful agronomic gene, which was linked to the bar gene from St...

Total yeast and mold (TYM) levels in inflorescences of high THC-containing Cannabis sativa (cannabis) are regulated to ensure that medicinal and recreational users, especially those with immunocompromised systems, are not exposed to potentially harmful levels. In North America, the limits imposed range from 1,000-10,000 cfu/g of dried product to 50...

Botrytis cinerea is a widespread necrotrophic plant pathogen that causes diseases on >1000 plant species, including vegetables and ornamental greenhouse crops. On cannabis (Cannabis sativ a L.), the pathogen is responsible for causing “bud rot”, a major disease affecting the inflorescences (compound flowers), as well as seedling damping-off and lea...

Background: Glandular capitate trichomes which form on bract tissues of female inflorescences of high THC-containing Cannabis sativa L. plants are important sources of terpenes and cannabinoids. The influence of plant age and cannabis genotype on capitate trichome development, morphology, and maturation has not been extensively studied. Knowledge...

Raspberry root rot and wilting complex (RRWC), primarily caused by Phytophthora rubi, is the most important disease for raspberry producers in Canada. There is currently little to no information on phenotypic diversity or sensitivity to metalaxyl-m of P. rubi isolates affecting raspberry in Canada. This study was conducted to understand the diversi...

Damping-off, crown rot, and root rot caused by Fusarium oxysporum and Pythium spp. are important diseases that reduce the growth of cannabis plants and cause mortality. There are currently limited management options available to producers in the absence of registered chemical fungicides. The comparative efficacy of five biological control agents in...

We investigated the diversity of fungal species present on inflorescences as epiphytes and in stem tissues as endophytes in flowering plants of cannabis grown organically in British Columbia during 2019–2021. Fresh and dried inflorescence samples were obtained at various times during production while stems were obtained at harvest. Fungal species i...

Cannabis (Cannabis sativa L.) is cultivated by licensed producers in Canada for medicinal and recreational uses. The recent legalization of this plant in 2018 has resulted in rapid expansion of the industry, with greenhouse production representing the most common method of cultivation. Female cannabis plants produce inflorescences that contain brac...

Cannabis (Cannabis sativa L., marijuana) plants grown at indoor and outdoor production sites in British Columbia (BC) and Ontario with stem canker symptoms were sampled and affected tissues were surface-sterilized and plated onto potato dextrose agar. Isolates were identified by colony and spore morphology as well as PCR amplification and sequencin...

Tissue culture approaches are widely used in crop plants for the purposes of micropropagation, regeneration of plants through organogenesis, obtaining pathogen-free plantlets from meristem culture, and developing genetically modified plants. In this research, we evaluated variables that can influence the success of shoot growth and plantlet product...

Plants of the cannabis (Cannabis sativa, marijuana) strain ‘Chronic Ryder’ grown outdoors in the Fraser Valley of British Columbia (BC) displayed symptoms of powdery mildew in late July 2019. The disease progressed rapidly under cool, wet conditions to infect leaves, stems, shoot tips and inflorescences by early September. To identify the pathogen,...

Cannabis (Cannabis sativa L., marijuana) plants with symptoms of crown rot, root decay, wilting and plant death were sampled during 2018 and 2019 from seven production greenhouses. Affected tissues from 140 diseased plants were surface-sterilized and plated onto potato dextrose agar. Ninety-five isolates morphologically resembling Pythium species w...

Bud rot pathogens cause diseases on Cannabis sativa L. (cannabis, hemp) worldwide through pre-and post-harvest infection of the inflorescence. Seven indoor or outdoor cannabis production sites and three hemp fields were sampled for bud rot and stem canker presence during 2019-2020. Among 178 isolates recovered from diseased tissues, sequences of th...

Cultivation of cannabis plants (Cannabis sativa L., marijuana) has taken place worldwide for centuries. In Canada, legalization of cannabis in October 2018 for the medicinal and recreational markets has spurned interest in large‐scale growing. This increased production has seen a rise in the incidence and severity of plant pathogens, causing a rang...

Wasabi (Wasabia japonica (Miq.) Matsum) plants are grown over a period of 12-18 months for their valuable rhizomes, and pathogens infecting the rhizome are of economic importance for producers. During 2016 and 2017, symptoms of wilting and internal vascular blackening of rhizomes were observed in two greenhouses in British Columbia, with disease in...

Greenhouse-grown cannabis (Cannabis sativa L., marijuana) plants with yellowing, crown rot and root browning symptoms were sampled from six production facilities during 2019-2020. Among 34 fungal isolates recovered, 28 were identified as Fusarium solani and six isolates were provisionally identified as Cylindrocarpon sp. based on morphology. These...

Powdery mildew on cannabis (Cannabis sativa L., marijuana), caused by Golovinomyces cichoracearum, reduces plant growth and overall quality. To investigate disease management options, biological, chemical and physical approaches were assessed. A mildew-susceptible strain, ‘Copenhagen Kush’, was grown indoors with continual exposure to mildew inocul...

Biological control of plant diseases is important in organic greenhouse vegetable production where fungicide use is limited. Organic producers employ microbially-diverse substrates, including composts, as media for plant growth. Previous research into the impact of vermicompost on the efficacy of applied biocontrol agents is limited. An in vitro as...

Symptoms of ringspots and vein-clearing were observed on wasabi (Wasabia japonica (Miq) Matsum) plants in three greenhouses in British Columbia during 2017. Ten indicator plant species, including four Nicotiana species, were inoculated with sap extracts from symptomatic leaves; after 4–11 days, necrotic lesions developed on all plants. Transmission...

Cannabis (Cannabis sativa L., marijuana) plants grown under greenhouse or controlled environments with symptoms of leaf yellowing, leaf necrosis and defoliation were observed during 2018–2019. Additional symptoms included crown rot and internal browning or blackening of the pith tissues. Stock (mother) plants as well as plants in the vegetative and...

Fusarium oxysporum causes root browning and crown infection on marijuana (Cannabis sativa L.) plants, resulting in stunted growth, yellowing of leaves, and plant death. Pathogen presence and diversity were assessed in samples of diseased crowns, stems, pith tissues and roots from five commercial production facilities in British Columbia and Ontario...

Powdery mildew on wasabi (Wasabia japonica (Miq.) Matsumura)plants reduces photosynthesis and severe infections can result in chlorosis and defoliation, resulting in reduced yields. Erysiphe cruciferarum Opiz ex L. Junell was confirmed as the causal agent using sequence analysis of the ITS1-5.8 S-ITS2 region, along with conidial and conidiophore mo...

Cannabis sativa L. (hemp, marijuana) produces male and female inflorescences on different plants (dioecious) and therefore the plants are obligatory out-crossers. In commercial production, marijuana plants are all genetically female; male plants are destroyed as seed formation reduces flower quality. Spontaneously occurring hermaphroditic infloresc...

The objective of this study was to assess harvested dried inflorescences (buds) of cannabis (Cannabis sativa L., marijuana) for fungal presence and diversity. Samples from drying rooms of three licenced facilities in British Columbia were tested repeatedly during 2017–2019. A swab method was used, wherein sterile cotton swabs were gently swabbed ov...

Powdery mildew, caused by Podosphaera xanthii (U. Braun & Shishkoff), is a widespread disease on greenhouse cucumber in many countries, including Canada. The efficacy of seven biological or chemical products to manage powdery mildew was evaluated. These included Rhapsody® (Bacillus subtilis Ehrenberg strain QST 713), Microflora PROTM (B. subtilis,...

Fusarium infection of Cannabis sativa to cause root and crown rot is one of the more problematic diseases in growing facilities in Canada. The disease is understudied and difficult to control with currently available methods. Both Fusarium oxysporum and Fusarium proliferatum have routinely been isolated from plants with wilt symptoms. These pathoge...

Plant pathogens infecting marijuana (Cannabis sativa L.) plants reduce growth of the crop by affecting the roots, crown, and foliage. In addition, fungi (molds) that colonize the inflorescences (buds) during development or after harvest, and which colonize internal tissues as endophytes, can reduce product quality. The pathogens and molds that affe...

Sclerotinia stem rot (Sclerotinia sclerotiorum Lib. De Bary) is one of the most destructive fungal diseases on canola (Brassica napus L.). The effect of a foliar fertilizer containing 3% boron (Active Flower™ [AF]) in reducing disease severity was evaluated. AF at 0.1, 0.3 and 0.5 ml/100 ml was first tested for growth inhibition of S. sclerotiorum...

Diseases of cucumber (Cucumis sativus L.) are a major limiting factor during commercial greenhouse production of the crop. The biological control agent Bacillus subtilis strain QST 713 (Rhapsody, containing 1 × 10⁹ colony-forming units per g) was evaluated for efficacy against four major diseases affecting greenhouse cucumbers grown in British Colu...

Six wasabi greenhouses in the Lower Mainland and Vancouver Island areas of British Columbia were surveyed for disease symptoms during the summers of 2017 and 2018. Disease symptoms were observed at low to moderate levels, depending on the greenhouse sampled. Over the two years, 86 symptomatic plants were collected and a total of 16 potential pathog...

Bacillus subtilis is a potential biocontrol agent for management of fungal diseases on greenhouse crops. Colonization of plant roots by B. subtilis enhances growth and reduces disease incidence and severity to minimize yield losses and improve quality. The mechanisms through which B. subtilis may contribute to control of fungal diseases include com...

Wasabia japonica (Miq) Matsum. is cultivated for its rhizome which is traditionally consumed with Japanese cuisine. In 2017, ringspot and vein-clearing symptoms were observed in a commercial greenhouse in British Columbia. Symptomatic leaves were ground in phosphate buffer and used to mechanically inoculate Nicotiana benthamiana, N. clevelandii, N....

Wasabia japonica (Miq) Matsum. is cultivated for its rhizome which is traditionally consumed with Japanese cuisine. In 2017, ringspot and vein-clearing symptoms were observed in a commercial greenhouse in British Columbia. Symptomatic leaves were ground in phosphate buffer and used to mechanically inoculate Nicotiana benthamiana, N. clevelandii, N....

An increase in the cultivation of Cannabis sativa (cannabis or marijuana) plants in Canada is becoming associated with increased incidence and severity of various diseases, many of which have not been previously reported. In this study, hydroponically grown C. sativa plants were sampled over a 3-year period (2014-2017) to determine the prevalence o...

Flower buds of Cannabis sativa develop as inflorescences (buds) which are harvested and dried prior to sale. The extent to which fungal plant pathogens can colonize the buds prior to harvest has not been previously studied. Flower buds were sampled at various pre-harvest and harvest time periods during 2015-2017 at locations in British Columbia and...

Yellowing and wilting symptoms on field-grown Cannabis sativa (cannabis) plants followed by total plant collapse under conditions of extreme hot weather were observed in northern California in 2017. The crown regions of affected plants were dark and sunken and internal tissue discoloration extended 10-15 cm above the soil surface. Isolations made f...

Powdery mildew (PM) reduces photosynthesis and can affect yield of cultivated crops. Severe infections can result in chlorosis and defoliation. Disease surveys conducted over the 2016-2018 period indicate that PM is a prevalent foliar pathogen on wasabi (Wasabia japonica (Miq.) Matsum.) in British Columbia. Erysiphe cruciferarum Opiz ex L. Junell w...

Wasabi (Wasabia japonica) is grown primarily for its valuable rhizome which is ground into a paste and used in Japanese cuisine. In British Columbia (BC), wasabi is generally grown semi-hydroponically in beds of river rock with overhead misting within polyethylene-covered greenhouses. However, drip irrigation, with peat or hydroton as substrates, i...

Wasabi (Wasabia japonica (Miq.) Matsum) is grown for its valuable rhizome which is ground into a paste and used in Japanese cuisine. Growers are increasingly interested in marketing leaves and petioles in addition to rhizomes. Consequently, both rhizome-infecting pathogens and foliar pathogens can be quite destructive. In surveys conducted during 2...

Sprouting Damage is a persistent quality control concern in the cereals industry, as sprouting damaged kernels (SDK) contain enzymes that have a detrimental effect on flour quality. Furthermore, the severity of sprouting damage is difficult to detect using standard visual grading methods. In this work, we present Biospeckle Laser Analysis (BLA) as...

Wasabi (Wasabia japonica (Miq.) Matsumura) is a greenhouse crop grown under high humidity conditions, which provide an ideal environment for pathogen development. During a survey of five British Columbia greenhouses conducted in the summer of 2016, a range of disease symptoms were observed, which included powdery mildew, leaf spot, root rot, rhizom...

Cannabis sativa is a multi-use crop valued for its pharmacological properties and as a fibre and seed crop. Biotechnological applications toward Cannabis research and product development are still in their early stages. An important feature of biotechnology is the collection of gene transfer technologies that are used to introduce genetic material...

Cannabis sativa L. represents plants cultivated for their psychoactive and medicinal properties (marijuana) or as a source of fibre, seed and oil (hemp). Breeding and selection efforts have produced marijuana genotypes (strains) with a range of levels of the cannabinoid Δ9-tetrahydrocannabinolic acid (THCA) and other non-psychoactive cannabinoids,...

Diseases of wasabi (Wasabia japonica) are the most important reason for crop failure in commercial greenhouses, and expanding disease issues highlight the importance of identifying the causal agents. Diseased wasabi leaves were collected during 2013-2015 from greenhouses in the Fraser Valley of British Columbia. Isolations from plants showing sympt...

Five wasabi greenhouses in the Lower Mainland and Vancouver Island areas of British Columbia were surveyed for disease symptoms during the summer of 2016. Disease symptoms (Table 1) were observed at low to moderate levels, depending on the greenhouse sampled. Thirty-one plant samples were collected from which 8 potential fungal pathogens, as well a...

Fungi causing post-harvest decay of greenhouse-grown tomato fruits in British Columbia were recovered from diseased samples collected during 2010 and 2011. The most frequently isolated fungi were Penicillium olsonii, Botrytis cinerea, Rhizopus stolonifer and Alternaria alternata, and to a lesser extent Galactomyces geotrichum. Pathogenicity tests s...

Wasabi (Wasabia japonica (Miq.) Matsumura) is grown for its highly valuable rhizome in greenhouses with high humidity, providing ideal conditions for disease development. Symptoms of leaf spot, root rot, rhizome rot and petiole blight are commonly observed. We surveyed five different wasabi greenhouses during 2015–2016 to determine the pathogens th...

Wasabi (Wasabia japonica (Miq.) Matsumura) is grown for its highly valuable rhizome in greenhouses with high humidity, providing ideal conditions for disease development. Symptoms of leaf spot, root rot, rhizome rot, and petiole blight are commonly observed. We surveyed five different wasabi greenhouses during 2015-2016 to determine the pathogens t...

A leaf spot disease on wasabi plants grown in commercial greenhouses in the Fraser Valley of British Columbia was characterized. Mycelial growth and pycnidial formation were observed within lesions when leaves were incubated under conditions of high humidity. Isolation from diseased tissues consistently yielded colonies of a Phoma sp. Sequence anal...

Commercial plantings of Wasabia japonica (Miq.) Matsu. are expanding in the Pacific Northwest, where it is utilized in the culinary market and in sushi restaurants. The high moisture environment required to cultivate the crop has led to an increasing incidence of disease and occurrence of a number of destructive root and foliar pathogens. In 2015,...

Commercial plantings of Wasabia japonica (Miq.) Matsu. are expanding in the Pacific Northwest, where it is utilized in the culinary market and in sushi restaurants. The high moisture environment required to cultivate the crop has led to an increasing incidence of disease and occurrence of a number of destructive root and foliar pathogens. In 2015,...

Tomato plants in two commercial greenhouses were treated with Rhapsody (Bacillus subtilis strain QST 713, rate of 1.45%) once every 4 weeks during 2012–2013 to determine effects on post-harvest fruit infection. Populations of Bacillus and disease incidence were monitored weekly from harvested fruit over an 18-week period. Population levels of Bacil...

Wasabia japonica (Miq.) Matsu. is grown in the Pacific Northwest for the culinary market and use in sushi restaurants. The high moisture environments required to successfully cultivate the crop and a 15-18 month crop cycle are conducive for growth and infection by pathogens. In 2014, a commercial crop grown in a greenhouse in Maple Ridge, BC showed...

Wasabia japonica (Miq.) Matsu. is grown in the Pacific Northwest for the culinary market and use in sushi restaurants. The high moisture environments required to successfully cultivate the crop and a 15-18 month crop cycle are conducive for growth and infection by pathogens. In 2014, a commercial crop grown in a greenhouse in Maple Ridge, BC showed...

A unique symptom of longitudinal red stripes on the surface of one-year-old ginseng roots was studied to determine the morphological and biochemical changes taking place. Light and scanning electron microscopy, measurements of phenolic and mineral element content, and enzyme activity, were compared between healthy and stripe-affected root tissues....

Double-stranded (ds) RNA elements are commonly present in strains of the plant pathogenic fungus Thielaviopsis basicola which infects a wide range of plant species. To characterize a novel 12 kb dsRNA in strain NC1527 of this fungus, reverse transcription-polymerase chain reaction (RT-PCR) was used to obtain an 11,602 bp cDNA sequence from overlapp...

Ginseng roots with reddish-brown to black surface discolourations were collected from eight farms in British Columbia during 2005–2007. Affected tissues predominantly yielded colonies of Fusarium spp. and Rhexocercosporidium panacis when plated onto half-strength PDA. Percentage recovery of these fungi was influenced by root age, with Fusarium spec...

When western boxelder bugs, Boisea rubrolineata (Barber) (Hemiptera: Rhopalidae), form aggrega-tions in warm sunlight, they release from their posterior dorsal abdominal gland an odorous blend of monoterpenes with heretofore unknown biological function. In laboratory analyses and experiments, we show that bugs in warm sunlight, but not in shade, ex...

A previously undescribed spotting of tomato fruit was observed in the packinghouse and storage facility of a commercial organic grower in the Fraser Valley of British Columbia during 2009–2011. Symptoms initially appeared as small black spots on the tomato fruit, barely visible after harvest. The black spots expanded to form larger grey-black lesio...

The ecological requirements for the colonization of geranium leaves by the biocontrol agent Clonostachys rosea f. catenulata strain J1446 were investigated. Although this biocontrol agent is a soil-inhabiting fungus, treatment of geranium foliage with the agent can reduce grey mould caused by Botrytis cinerea in the greenhouse. To characterize the...

Four commercially formulated biological control products, containing Gliocladium catenulatum (Prestop® WP), Trichoderma harzianum (PlantShield®) and Bacillus subtilis [Serenade® MAX™ (wettable powder) and Rhapsody® ASO™ (liquid)] were evaluated for control of rose powdery mildew (Podosphaera pannosa) on outdoor, container-grown roses and botrytis b...

American ginseng (Panax quinquefolius L.) is grown in some regions of the USA and Canada and marketed for its health promoting attributes. While cultivation of this plant species has taken place in North America for over 100 years, there are many challenges that need to be addressed. In this article, the current production method used by growers is...

There are a range of vegetable crop species that are grown worldwide to provide humans with a source of nutrients, vitamins, and ‰ber. These vegetables are usually consumed fresh, e.g., carrot, cucumber, lettuce, and tomato, while others may be eaten after cooking, e.g., broccoli, cabbage, peas, and squash. Vegetable crops are usually grown under ‰...

This study examined the effects of Stimplex™, a marine plant extract formulation from Ascophyllum nodosum, on some common cucumber fungal pathogens. Greenhouse cucumber plants were sprayed and/or root drenched using Stimplex™ at 0.5% or 1% concentration twice at 10-day intervals. Treatments also included application of fungicide (chlorothalonil, 2g...

The mitochondrial DNA (mtDNA) of Chondrostereum purpureum (Pers.:Fr.) Pouzar was extracted and purified, and the size ranged from 51.8 to 66.4 kb. One isolate each from British Columbia, Alberta, Finland, the Netherlands, and New Zealand were found to have identical BamHI mtDNA restriction patterns, resulting in a mitochondrial genome of 63.8 kb. A...

The extent of variation in colony morphology and chlamydospore size, septation, and pigmentation was studied in 50 isolates of Chalara elegans Nag Raj et Kendrick (syn. Thielaviopsis basicola (Berk. et Br.) Ferr.) originating from 12 different geographic areas and substrates. In addition, the extent of genetic variation among these isolates was det...

Mycelial growth, both linear extension and biomass accumulation, and phialospore production in three Chalara elegans strains from diverse geographical areas were greatest at 20–25 °C. Growth and sporulation were minimal at 10 °C and nil at 35 °C. The optimal pH range for growth was 4.0–6.5, and no growth was observed at pH 3.0 or 7.75. Phialospore...

Three strains of Chalara elegans from diverse geographical areas that contained multiple (4 or 5) double-stranded RNA fragments were compared with spontaneously derived cultures from these strains that were either partially cured or completely free of dsRNA. In the wild-type strains, presence of the dsRNAs was found to significantly enhance phialos...

The influence of low (70%) and high (90%) relative humidity on epiphytic growth, development, and survival of Tilletiopsis pallescens, a ballistospore-forming yeast-like fungus, on cucumber leaves was investigated. In addition, survival of the fungus in the presence or absence of powdery mildew (Sphaerotheca fuliginea) colonies was determined. Grow...

Crystals produced during growth of Sclerotium rolfsii on cellophane overlaying water agar were identified as calcium oxalate based on their solubility characteristics in certain acids, positive staining reaction with silver nitrate – dithiooxamide, and characteristic energy-dispersive X-ray emission spectrum. Addition of calcium salts to water agar...

Three composts (Ball, dairy, and greenhouse) were tested for the ability to suppress the development of Fusarium root and stem rot (caused by Fusarium oxysporum f. sp. radicis-cucumerinum) on greenhouse cucumber. Dairy and greenhouse composts significantly reduced disease severity (P = 0.05), while Ball compost had no effect. Assessment of total cu...

Plant class III peroxidases are involved in numerous responses related to pathogen resistance including controlling hydrogen peroxide (H(2)O(2)) levels and lignin formation. Peroxidases catalyze the oxidation of organic compounds using H(2)O(2) as an oxidant. We examined the mechanisms of disease resistance in a transgenic carrot line (P23) which c...

We review the current and future potential of genetic engineering strategies used to make fungal and bacterial pathogen-resistant GM crops, illustrating different examples of the technologies and the potential benefits and short-falls of the strategies. There are well- established procedures for the production of transgenic plants with resistance t...

A previously undescribed fungal disease, coined daphne sudden death syndrome (DSDS), was reported on Daphne cneorum from several nurseries and research centres in British Columbia, Canada. Diseased and healthy plants were obtained from several sources, and from these plants, the following fungi were isolated: Fusarium roseum, Fusarium oxysporum, Tr...

Blueberry scorch virus (BlScV), first discovered in British Columbia, Canada, in 2000, causes a potentially serious disease on highbush blueberry (Vaccinium corymbosum). The epidemiology of BlScV was studied over four consecutive years (2001–2004) in British Columbia. In 2001, leaf tissue sampled from 40 commercial fields tested positive for BlScV,...

Chalara elegans (syn. Thielaviopsis basicola) is a soilborne plant pathogen with a wide host range, which initially establishes a hemibiotrophic relationship, following infection of its host. To assess the differences in virulence among isolates and to study colonization of host tissues, detached bean leaves were used in an inoculation assay. Two-w...