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Leaf smut, caused by Entyloma polysporum, on greenhouse-grown ornamental sunflowers in California. Lesions on upper (A) and lower leaf surface (B). 

Leaf smut, caused by Entyloma polysporum, on greenhouse-grown ornamental sunflowers in California. Lesions on upper (A) and lower leaf surface (B). 

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The majority of United States sunflower production is in seven Midwestern states, but hybrid planting seed is almost exclusively produced in California. Due to the lack of summer rains and furrow irrigation, California-produced seed is relatively disease free and thus it regularly meets phytosanitary restrictions imposed by many countries. For the...

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... have been several unique, infrequent pathogens isolated from sunflower over the 15-year period. For example, in 2010, leaves of ornamental sunflower from two coastal county greenhouses had numerous, small (2 to 4 mm), round necrotic lesions on them, without any chlorotic haloes (Fig. 3). Hyaline, oblong-fusoid conidia measuring 11-20 × 2.5-3.5 µm were seen fruiting hypophyllously on the leaves. The causal agent was identified as Ramularia helianthi, which, while not a first record, has not been noted in California since 1894 (8). Ramularia spp. are foliar pathogens of numerous crops in California, including artichoke, strawberries, sugarbeets, and many ornamental plants, and lesions on sunflower are similar in appearance to those on artichoke (20). Elsewhere in the US, Ramularia helianthi has been noted on sunflower only in Wyoming (9). Another minor, non-quarantine pathogen was found, Phytophthora cryptogea, which causes a girdling black lesion at the soil line (Fig. 4), and causes affected plants to wilt and die. These stalk lesions are similar to that caused by Phoma macdonaldii in Midwestern states (7). Phytophthora lesions are larger, extending up to 15 to 20 cm, and unlike Phoma, Phytophthora causes a black discoloration of the woody tissue of the stalk (Fig. 4). Phytophthora collar rot is seen mainly on plants at the ends of rows where the soil is saturated during irrigation. This pathogen has been noted in California previously (13,19) but has not been identified from any Midwestern state. Another unusual disease, leaf smut caused by Entyloma polysporum, was confirmed several times on ornamental sunflowers in southern California nurseries by the CDFA and others (6) (Fig. 5). This pathogen has not been recorded from field grown sunflowers, either in California or in any other state, although it is seen on ornamental Compositae in other states (17). ...

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Citations

... Bacterial stalk rot of sunflower has been observed occurring sporadically throughout the Great Plains of the United States (Gudmestad et al. 1984;Gulya et al. 2012), but it is generally not considered to be of major concern for production. It is also known to occur throughout Europe, Russia, Turkey, South Africa, and several other central African countries (e.g., Tanzania and Uganda) (Arsenijevic 1970;Baştaş et al. 2009;Gulya et al. 1997;Harveson et al. 2016;Raj and Wati 2005). ...
Article
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This article describes three distinct sunflower stalk diseases that are caused by pathogens that primarily begin as foliar infections. Included are two similar fungal diseases: Phoma black stem and Phomopsis stem canker, caused by Phoma macdonaldii and two species of Diaporthe (helianthi and gulyae), respectively. The bacterial stalk rot disease caused by Pectobacterium carotovorum subsp. carotovorum and Pectobacterium atrosepticum is also included for comparison. We provide information on how to identify the diseases and distinguish them from each other with signs, symptoms, and biological characteristics of the pathogens. It is important to learn to recognize and differentiate these three diseases, because only one (Phomopsis stem canker) is considered to be economically damaging. Misidentification could result in utilizing unneeded disease management techniques.
... Seventy-seven percent of the United States' total sunflower value was for oil production, whereas the rest was for non-oil production, including human and animal consumption and planting seed (USDA National Agricultural Statistics Services 2016). Although most of the sunflower production in the US is concentrated in the Great Plains and surrounding states (USDA Economic Research Service 2017), nearly 95% of the US sunflower production of seed for planting is grown in California, where the warm, dry Mediterranean climate is less favorable for plant diseases (Gulya et al. 2012). ...
... Sunflowers grown in California share many of the same diseases found in the primary growing states, including rust (Puccinia helianthi), sclerotinia stalk rot (Sclerotinia sclerotiorum), charcoal stalk rot (Macrophomina phaseolina), rhizopus head rot (Rhizopus oryzae), powdery mildew (Golovinomyces spp.) and root and stalk rot caused by Phytophthora spp. (Braun and Cook 2012;Gulya et al. 2012;Harveson et al. 2016a). A few other sunflower diseases occur occasionally on ornamental varieties grown for cut flowers in California greenhouses, but not in commercial fields. ...
... A few other sunflower diseases occur occasionally on ornamental varieties grown for cut flowers in California greenhouses, but not in commercial fields. These diseases include leaf spot caused by Ramularia helianthi and leaf smut caused by Entyloma polysporum (Gulya et al. 2012; A c c e p t e d M a n u s c r i p t and severe economic losses under optimal temperatures and high humidity in production systems without an effective chemical control program (Harveson et al. 2016a). ...
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White leaf smut is a minor foliar disease of sunflower (Helianthus annuus) in the United States. The disease occurs primarily in greenhouse-grown sunflowers in California and causes leaf spot, defoliation, and a reduction in yield and crop value. Historically, many Entyloma specimens with similar morphological characters, but infecting diverse plant genera including Helianthus, were called Entyloma polysporum. Recent comparative morphological and molecular work has shown that Entyloma species infect hosts within a single genus or species, suggesting that the sunflower Entyloma species may not be E. polysporum. In 2015, sunflower leaf smut material was collected from ornamental sunflowers in a greenhouse in Santa Barbara County, CA. Morphologically, this species differed from E. polysporum in having smaller, more regular shaped teliospores and prominently developed conidiophores with cylindrical conidia. The rDNA ITS 1-5.8S-ITS2 region of the sunflower leaf smut was phylogenetically distinct from all previously sequenced Entyloma species and found only on H. annuus. This study confirms that the sunflower leaf smut pathogen represents a novel species, Entyloma helianthi. Possible misidentification of the anamorphic stage of Entyloma helianthi as another leaf spot pathogen, Ramularia helianthi, is also discussed.
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This datasheet on Diaporthe helianthi covers Identity, Overview, Distribution, Dispersal, Hosts/Species Affected, Diagnosis, Biology & Ecology, Seedborne Aspects, Impacts, Prevention/Control, Further Information.