{"id":2468,"date":"2016-08-17T13:37:50","date_gmt":"2016-08-17T20:37:50","guid":{"rendered":"http:\/\/blogs.cdfa.ca.gov\/Section3162\/?p=2468"},"modified":"2024-04-26T11:03:34","modified_gmt":"2024-04-26T18:03:34","slug":"podosphaera-xanthii-castagne-u-braun-shishkoff-2000","status":"publish","type":"post","link":"https:\/\/blogs.cdfa.ca.gov\/Section3162\/?p=2468","title":{"rendered":"Podosphaera xanthii (Castagne) U. Braun & Shishkoff 2000"},"content":{"rendered":"
\"Watermelon<\/a>
Watermelon leaf showing an even distribution of powdery mildew (Podosphaera xanthii) over the entire leaf surface. June 1995. \u00a0Photo by Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org<\/figcaption><\/figure>\n
California Pest Rating for<\/strong><\/h5>\n
Podosphaera xanthii<\/em><\/strong> (Castagne) U. Braun & Shishkoff 2000<\/strong><\/h5>\n
Pest Rating: \u00a0C<\/h5>\n
\n
PEST RATING PROFILE<\/strong><\/h5>\n
Initiating Event:<\/h5>\n

On July 13, 216, diseased leaves of Calibrachoa<\/em> sp. plants exhibiting powdery mildew symptoms were collected during a regulatory nursery inspection, from a nursery in San Luis Obispo County, by San Luis Obispo County officials and sent to the CDFA Plant Pathology Laboratory for diagnoses.\u00a0 Suzanne Latham, CDFA plant pathologist, identified the powdery mildew pathogen, Podosphaera xanthii<\/em>, as the cause for the disease. \u00a0The pathogen was assigned a temporary \u201cZ\u201d rating as it has been reported earlier in California and is considered widely distributed.\u00a0 That rating is reassessed here and a permanent rating is proposed.<\/p>\n

History & Status:<\/strong><\/h5>\n

Background<\/u>:<\/strong> Podosphaera xanthii<\/em> causes powdery mildew disease primarily in cucurbits under field and greenhouse conditions.\u00a0 The pathogen has a wide host range which includes several ornamental plants, including Verbena. There are several pathogenically distinct races of P. xanthii<\/em>, and plant resistance-breaking races are present in California.\u00a0 The pathogen is widely distributed throughout the world (see \u2018Worldwide Distribution\u2019 below) as well as in California.\u00a0 Within California, powdery mildew may be common in coastal and desert production areas, but is more common in fall in the San Joaquin Valley and Sacramento Valley (Davis, et al<\/em>., 2012).<\/p>\n

Podosphaera xanthii<\/em> was previously known by several names including Sphaerotheca fuliginea<\/em> and S. fusca<\/em>.\u00a0 In 2012, P. caricae-papayae<\/em> was synonymized with the morphologically similar species P. xanthii <\/em>(Braun & Cook, 2012) however, the synonymy of P. xanthii<\/em> and P. caricae-papayae<\/em> is in question given the molecular work of Takamatsu et al<\/em>., (2010) who also inferred that further molecular and morphological studies would help to determine the correct taxonomic position of P. caricae-papayae<\/em> within the genus Podosphaera<\/em> in the family Erysiphaceae of the order Erysiphales.\u00a0 (The CDFA risk assessment and rating for <\/em>P. caricae-papayae is published separately.)<\/em><\/p>\n

Hosts<\/strong>: Podosphaera xanthii<\/em> has a wide host range which includes agricultural crops, ornamentals, few fruit, and weed plant species within eight or more families. Hosts include, Citrullus lanatus<\/em> (watermelon), Cucumis melo<\/em> (melon), C. sativus<\/em> (cucumber), Cucurbita<\/em> (pumpkin), C. maxima<\/em> (giant pumpkin, C. moschata<\/em> (pumpkin), C. mixta<\/em> (pumpkin), C. pepo<\/em> (synonym: C. ovifera<\/em>; ornamental gourd), C. vulgaris<\/em>, Lagenaria siceraria<\/em> (bottle gourd), Luffa acutangula<\/em> (angled luffa), L. aegyptiaca<\/em> (loofah), L. cylindrica, Momordica charantia<\/em> (bitter gourd), M. cochinchinensis<\/em> (gac), Sechium edule<\/em> (chayote), Cyamopsis tetragonoloba<\/em> (guar), Phaseolus aconitifolius<\/em> (synonym: Vigna aconitifolia; <\/em>moth bean), P. coccineus<\/em> (runner bean), P. vulgaris<\/em> (common bean), Vigna mungo<\/em> (black gram), V. radiata<\/em> (mung bean), V. umbellata<\/em> (rice-bean), V. unguiculata<\/em> (synonym: V. catjang<\/em>; cowpea), Cajanus cajan <\/em>(pigeon pea), Sesamum indicum<\/em> (sesame), Capsicum frutescens<\/em> (chili), Solanum melongena<\/em> (eggplant),\u00a0 Hibiscus mutabilis<\/em> (cottonrose), H. syriacus<\/em> (shrubby althaea), Hoheria lyallii<\/em> (synonym: H. populnea<\/em>; lacebark), Malva pusilla<\/em> (round-leaved mallow), Carica papaya<\/em> (papaya), Coriaria arborea<\/em> (tree tutu), Kalanchoe blossfeldiana<\/em> (flaming katy), Petunia x hybrid, <\/em>, Verbena bonariensis<\/em> (purpletop vervain), V. brasilensis <\/em>(Brazilian verbena), V. canadensis<\/em> (clump verbena), Verbena x<\/em> hybrida<\/em> (synonym: V. hortensis<\/em>; garden verbena), V. incisa,<\/em> V<\/em>. lasiostachys<\/em> (western vervain), V. litoralis<\/em> (blue vervain),V. macdougalii<\/em> (MacDougal verbena), V. officinalis<\/em> (common verbena), V. phlogiflora<\/em>, V. rigida<\/em> rigid verbena), Calendula<\/em> sp. C. arvensis (field marigold), C. officinalis<\/em> (pot marigold), C. palaestina <\/em>(Palestine marigold), \u00a0Cosmos bipinnatus<\/em> (garden cosmos), Calibrachoa<\/em> sp.,\u00a0 Cephalotus follicularis (Albany pitcher plant), Farfugium japonicum<\/em> (leopard plant), Glandularia pulchella<\/em> (South American mock vervain), Gynostemma pentaphyllum<\/em> (jiagulan), Gerbera jamesonii<\/em> (African daisy), Gynura bicolor<\/em> (Okinawan spinach), Helianthus annuus<\/em> (sunflower), Heteropogon contortus <\/em>(black speargrass), Jatropha gossypiifolia<\/em> (bellyache bush), Ligularia sibirica<\/em>, Medusagyne oppositifolia<\/em> (jellyfish tree), Melampyrum nemorosum<\/em> (wood cow-wheat), Melothria japonica<\/em> (Japanese wild cucumber), Melothria<\/em> sp. Parasenecio hastatus<\/em> subsp. tanakae<\/em>, Pericallis cruenta<\/em> (common cineraria), Physalis alkekengi<\/em> (Chinese lantern), Pisum sativum<\/em> (pea), Pulicaria dysenterica<\/em> (meadow false fleabane), Senecio chrysanthemoides , S. grahamii, S. hercynicus, S. nemorensis<\/em>, Impatiens hawker<\/em> (New Guinea impatiens), Ageratum conyzoides<\/em> (billy goat weed), Bidens bipinnata<\/em> (Spanish needles), B. cernua<\/em> (nodding beggarticks), B<\/em>. frondosa<\/em> (devil\u2019s beggartick), B. pilosa<\/em> (blackjack), B. tripartita<\/em> (three-lobe beggarticks), Boehmeria nivea <\/em>(Chinese grass), Buddleja brasiliensis, B. salviifolia<\/em>, Xanthium californicum<\/em> (synonym: X. strumarium<\/em> var. canadense<\/em>; Canada cocklebur), Xanthium italicum, X. pensylvanicum, X. spinosum, X. strumarium<\/em> (common cocklebur), X. spinosum<\/em> (spiny cocklebur) Zinnia elegans<\/em> (zinnia), (CABI, 2016; Farr & Rossman, 2016).<\/p>\n

Symptoms<\/strong>:\u00a0 Powdery mildew symptoms on cucurbits: the disease first appears as pale yellow spots on stems, petioles, and leaves.\u00a0 These spots enlarge as white powdery fungal growth comprising primarily of asexual spores (conidia) develops on upper and under leaf surfaces, petioles, and stems of infected plants, usually developing first on crown leaves, shaded lower leaves, and leaf undersurfaces.\u00a0 Affected leaves become dull, chlorotic and may wilt and eventually turn brown and papery (Davis et al<\/em>., 2012).\u00a0 Older plants are initially infected and infected leaves usually wither and die.\u00a0 Premature senescence may occur.\u00a0 Fruit infection occurs rarely in cucumber and watermelon.\u00a0 Minute dark brown chasmothecia (sexually produced, closed fruiting structures) have been rarely observed in infected cucurbits in the USA and may be easily overlooked. They may develop late in the season, and the sexual spores within the structures are protected from adverse conditions.\u00a0 Symptoms are less common on cucumber and melon as many commercial cultivars are resistant to the pathogen (McGrath, 2011).<\/p>\n

Disease cycle:\u00a0<\/strong> Podosphaera xanthii<\/em> is an obligate parasite.\u00a0 Primary sources of inoculum include conidia which can be dispersed over long distances and remain viable for 7-8 days.\u00a0 The fungus grows on the surface of plant tissue and invades by sending feeding organs (haustoria) into the plants epidermal cells only in order to obtain nutrients.\u00a0 Mycelium produces conidiophores on the plant surface.\u00a0 Each conidiophore produces chains of conidia (spores) that are dispersed by air currents.\u00a0 Powdery mildew develops quickly under favorable conditions of dense plant growth and low light intensity.\u00a0 High relative humidity is favorable for infection and conidial survival, and infection can occur as low as 50% relative humidity.\u00a0 Dry conditions favor colonization, sporulation, and dispersal, however, rain and free moisture on plant surfaces are unfavorable.\u00a0 Optimum temperature for disease development is 20-27\u00b0C with infection occurring at 10-32\u00b0C.\u00a0 Powdery mildew development is arrested at 38\u00b0C and higher temperatures.\u00a0 As an obligate parasite, P. xanthii<\/em> requires living host plants for survival, however, it may also survive as chasmothecia which have been reported rarely in the United States (CABI, 2016; McGrath, 2011).<\/p>\n

Damage Potential:\u00a0<\/strong> Powdery mildew can diminish the photosynthetic regions of cucurbit leaves. Severely infected leaves turn brown and shriveled.\u00a0 Fruit quality and yield are reduced.\u00a0 In squash, fruit quality is reduced by sunscald and premature ripening resulting in poor storability, in melon, incomplete ripening and poor flavor occurs, and pumpkin fruit may be shriveled and discolored (CABI, 2016).\u00a0 Late fruit usually fail to mature and are small and misshapen.\u00a0 Stress from disease can result in speckling and oedema on fruit rind.\u00a0 Powdery mildew-infected plants can be weakened and predisposed to other diseases.\u00a0 Podosphaera xanthii<\/em> can be a major production problem of cucurbits in field and greenhouse conditions (McGrath, 2011).<\/p>\n

Transmission:<\/strong>\u00a0 Conidia (spores) are airborne and dispersed by wind currents.\u00a0 Laboratory studies have shown that conidia remain viable for 7-8 days. On cucurbits in greenhouses conidia are released and spread from plant to plant via irrigation or air currents.\u00a0 Conidia can overwinter on cucurbit plants in a greenhouse and then be dispersed from greenhouse to field crops during spring and summer.\u00a0 Non-cucurbit hosts are not a major source of inoculum due to pathological specialization (CABI, 2016; McGrath, 2011).<\/p>\n

Survival:\u00a0<\/strong> During cool weather, conidia production ceases and powdery mildew fungi overwinter as chasmothecia and mycelium in weeds and dormant plant tissue. However, the sexual (teleomorph) stage has only been found in California greenhouses and reported for the first time in greenhouse grown squash and melons in Salinas, California (Ramos et al.,<\/em> 2010-2011).\u00a0 Constant greenhouse growth conditions could perpetuate the asexual stage of the fungus.<\/p>\n

Worldwide Distribution<\/u>:<\/strong> Asia<\/em>: Armenia, Azerbaijan, Bangladesh, China, Republic of Georgia, India, Iran, Iraq, Israel, Japan, Republic of Korea, Kyrgyzstan, Lebanon, Myanmar, Oman, Pakistan, Saudi Arabia, Singapore, Taiwan, Turkey, Turkmenistan Uzbekistan, Vietnam; Africa<\/em>: Egypt, Ethiopia, Libya, Somalia, South Africa, Sudan, Tunisia; North America<\/em>: Canada, Mexico, USA; Central America and Caribbean<\/em>: Cuba, Puerto Rico; South America<\/em>: Argentina, Bolivia, Brazil, Nicaragua, Uruguay, Venezuela; Europe<\/em>: Austria, Bulgaria, Czech Republic, (former) Czechoslovakia, Denmark, Estonia, Finland, Former USSR, Romania, France, Germany, Greece, Hungary, Ireland, Italy, Lithuania, Netherlands, Norway, Poland, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, United Kingdom, Ukraine, Yugoslavia (Serbia and Montenegro); Oceania<\/em>: Australia, New Zealand, Samoa (CABI, 2016; Farr & Rossman, 2016).<\/p>\n

Official Control<\/u>:<\/strong> Podosphaera xanthii<\/em> is on the \u2018Harmful Organism List\u2019 for Guatemala (USDA-PCIT, 2016).<\/p>\n

California Distribution<\/u>:<\/strong> San Luis Obispo, Solano, and Yolo (CDFA Pest and Damage Records)<\/em>; San Joaquin Valley and Sacramento Valley counties, coastal and desert cucurbit production areas (Davis, et al<\/em>., 2012).<\/p>\n

California Interceptions<\/u>:\u00a0<\/strong> None reported.<\/p>\n

The risk Podosphaera xanthii<\/em> would pose to California is evaluated below.<\/p>\n

Consequences of Introduction:\u00a0 <\/strong><\/h5>\n

1) Climate\/Host Interaction<\/span>:<\/strong> Evaluate if the pest would have suitable hosts and climate to establish in California. Score:<\/p>\n

– Low (1) Not likely to establish in California; or likely to establish in very limited areas.<\/p>\n

– Medium (2)<\/strong> may be able to establish in a larger but limited part of California.<\/span><\/p>\n

– High (3) likely to establish a widespread distribution in California.<\/p>\n

Risk is Medium (2)<\/em><\/strong> \u2013 Powdery mildew of cucurbits <\/em>Podosphaera xanthii can occur in coastal and desert production regions, and is common in fall in the San Joaquin Valley and Sacramento Valley. Powdery mildew thrives in warm and humid environments. Low light levels, high humidity, and moderate temperature enhance disease development.\u00a0 Dry conditions favor conidia production and dispersal.\u00a0 The pathogen is already widely distributed within cucurbit production regions of the state. \u00a0\u00a0<\/em><\/span><\/p>\n

2) Known Pest Host Range<\/span>:<\/strong> Evaluate the host range of the pest. Score:<\/p>\n

– Low (1) has a very limited host range.<\/p>\n

– Medium (2) has a moderate host range.<\/p>\n

– High (3)<\/strong> has a wide host range.<\/span><\/p>\n

Risk is High (3) <\/em><\/strong>\u2013 Podosphaera xanthii has a wide host range that includes agricultural crops \u2013 primarily cucurbits, ornamentals, few fruit and weed plants.<\/em><\/span><\/p>\n

3) Pest Dispersal Potential<\/span>:<\/strong> Evaluate the natural and artificial dispersal potential of the pest. Score:<\/p>\n

– Low (1) does not have high reproductive or dispersal potential.<\/p>\n

– Medium (2) has either high reproductive or dispersal potential.<\/p>\n

– High (3)<\/strong> has both high reproduction and dispersal potential.<\/span><\/p>\n

Risk is High (3) <\/em><\/strong>\u2013 Under suitable climate conditions, airborne conidia are produced in abundance and readily spread by wind currents to non-infected sites.\u00a0 Within and outside greenhouse environments, the pathogen is capable of rapidly spreading to non-infested host plants as well as other sites where host plants are grown.<\/em><\/span><\/p>\n

4) Economic Impact<\/span>:<\/strong> Evaluate the economic impact of the pest to California using the criteria below. Score:<\/p>\n

A. The pest could lower crop yield.<\/p>\n

B. The pest could lower crop value (includes increasing crop production costs).<\/p>\n

C. The pest could trigger the loss of markets (includes quarantines).<\/p>\n

D. The pest could negatively change normal cultural practices.<\/p>\n

E. The pest can vector, or is vectored, by another pestiferous organism.<\/p>\n

F. The organism is injurious or poisonous to agriculturally important animals.<\/p>\n

G. The organism can interfere with the delivery or supply of water for agricultural uses.<\/p>\n

– Low (1) causes 0 or 1 of these impacts.<\/p>\n

– Medium (2) causes 2 of these impacts.<\/p>\n

– High (3)<\/strong> causes 3 or more of these impacts.<\/span><\/p>\n

Risk is High (3)<\/em><\/strong> \u2013 The pathogen can potentially cause significant losses in plant growth and crop yield. Powdery mildew infections could lower crop yield and value causing significant losses in production \u2013 especially with use of protective and eradicative fungicides.\u00a0 It could result in loss of markets, and change in cultivation practices to prevent the spread of inocula to non-infected, healthy plants.<\/em><\/span><\/p>\n

5) Environmental Impact<\/span>:<\/strong> Evaluate the environmental impact of the pest on California using the criteria below.<\/p>\n

A. The pest could have a significant environmental impact such as lowering biodiversity, disrupting natural communities, or changing ecosystem processes.<\/p>\n

B. The pest could directly affect threatened or endangered species.<\/p>\n

C. The pest could impact threatened or endangered species by disrupting critical habitats.<\/p>\n

D. The pest could trigger additional official or private treatment programs.<\/p>\n

E. The pest significantly impacts cultural practices, home\/urban gardening or ornamental plantings.<\/p>\n

Score the pest for Environmental Impact. Score:<\/p>\n

– Low (1) causes none of the above to occur.<\/p>\n

– Medium (2)<\/strong> causes one of the above to occur.<\/span><\/p>\n

– High (3) causes two or more of the above to occur.<\/p>\n

Risk is <\/em><\/strong>Medium (2)<\/em><\/strong> \u2013 <\/em>The powdery mildew pathogen could significantly impact home\/urban gardening and\/or ornamental plantings. \u00a0<\/em><\/span><\/p>\n

Consequences of Introduction to California for Podosphaera xanthii:<\/em><\/strong><\/h5>\n

Add up the total score and include it here. (Score)<\/p>\n

-Low = 5-8 points<\/p>\n

-Medium = 9-12 points<\/p>\n

–High<\/strong> = 13-15 points<\/span><\/p>\n

Total points obtained on evaluation of consequences of introduction of P. xanthii <\/em>to California = (13).<\/strong><\/span><\/p>\n

6) Post Entry Distribution and Survey Information<\/span>:<\/strong> Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included. (Score)<\/p>\n

-Not established (0) Pest never detected in California, or known only from incursions.<\/p>\n

-Low (-1) Pest has a localized distribution in California, or is established in one suitable climate\/host area (region).<\/p>\n

-Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate\/host areas.<\/p>\n

–High (-3)<\/strong> Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate\/host areas.<\/span><\/p>\n

Evaluation is High (-3).\u00a0 <\/em><\/strong>Powdery mildew of cucurbits caused by <\/em>Podosphaera xanthii is widely distributed in California.<\/em>\u00a0<\/em><\/strong><\/span><\/p>\n

Final Score:<\/h5>\n

7) The final score is<\/strong> the consequences of introduction score minus the post entry distribution and survey information score: (Score)<\/p>\n

Final Score: <\/em><\/strong>\u00a0Score of Consequences of Introduction \u2013 Score of Post Entry Distribution and Survey Information =<\/strong> 10<\/strong><\/span><\/em><\/p>\n

Uncertainty: <\/strong><\/h5>\n

None.<\/p>\n

Remark<\/strong>:<\/h5>\n

The assessment of risk of Podosphaera xanthii<\/em> distinctly documents its economic importance to California agriculture and environment and its widespread distribution within cucurbit production regions of the State.\u00a0 Due to its biological capacity for rapid spread and its current widespread instate status, it is highly unlikely that the powdery mildew pathogen of cucurbits can be eradicated from California.\u00a0 However, control measures, including use of protectant fungicides and resistant varieties, have proven successful in significantly reducing disease intensities and spread (CABI, 2016).\u00a0 Therefore, a \u2018C\u2019 rating is proposed for this pathogen.<\/p>\n

Conclusion and Rating Justification: <\/strong><\/h5>\n

Based on the evidence provided above the proposed rating for Podosphaera xanthii<\/em> is C.<\/strong><\/p>\n

References:<\/strong><\/h5>\n

B<\/strong>raun, U. and R. T. A. Cook.\u00a0 2012.\u00a0 Taxonomic manual of the Erysiphales (Powdery Mildews).\u00a0 Centraalbureau voor Schimmelcultures, vol. 11, 707 p.<\/p>\n

C<\/strong>ABI.\u00a0 2016.\u00a0 Podosphaera xanthii <\/em>(powdery mildew of cucurbits) full datasheet.\u00a0 http:\/\/www.cabi.org\/cpc\/datasheet\/50922<\/a>.<\/p>\n

D<\/strong>avis, R. M., T. A. Turini, B. J. Aegerter, and J. J. Stapleton.\u00a0 2012.\u00a0 Cucurbits powdery mildew pathogens: Sphaerotheca fuliginea (=Podosphaera xanthii) and Erysiphe cichoracearum (=Golovinomyces cichoracearum)<\/em>.\u00a0 UC IPM Pest Management Guidelines: Cucurbits UC ANR Publication 3445. http:\/\/ipm.ucanr.edu\/PMG\/r116100711.html<\/a> .<\/p>\n

F<\/strong>arr, D.F., and A. Y. Rossman.\u00a0 2016.\u00a0 Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA.\u00a0 Retrieved January 28, 2016, from http:\/\/nt.ars-grin.gov\/fungaldatabases\/<\/a>.<\/p>\n

Mc<\/strong>Grath, M. T.\u00a0 2011.\u00a0 Vegetables: powdery mildew of cucurbits.\u00a0 Vegetable MD Online, Cooperative Extension, New York State, Cornell University.\u00a0 Fact sheet Page: 732.30 Date: June 2011.\u00a0 http:\/\/vegetablemdonline.ppath.cornell.edu\/<\/a><\/p>\n

R<\/strong>amos, C. B., K. Maruthachalam, J. D. McCreight, and R. S. Garcia Estrada.\u00a0 2010-2011. Podosphaera xanthii<\/em> but not Golovinomyces cichoracearum<\/em> infects cucurbits in a greenhouse at Salinas, California.\u00a0 Cucurbit Genetics Cooperative Report 33-34: 24-28.<\/p>\n

T<\/strong>akamatsu, S., S. Ninomi, M. Harada and M. Havrylenko.\u00a0 2010.\u00a0 Molecular phylogenetic analyses reveal a close evolutionary relationship between Podosphaera<\/em> (Erysiphales: Erysiphaceae) and its rosaceous hosts.\u00a0 Persoonia, 24, 38-48.<\/p>\n

U<\/strong>SDA PCIT.\u00a0 2016.\u00a0 USDA Phytosanitary Certificate Issuance & Tracking System.\u00a0 https:\/\/pcit.aphis.usda.gov\/PExD\/faces\/ReportHarmOrgs.jsp<\/a>.<\/p>\n

\n
Responsible Party:<\/strong><\/h5>\n

John J. Chitambar, Primary Plant Pathologist\/Nematologist, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832. Phone: 916-262-1110, plant.health[@]cdfa.ca.gov.<\/p>\n

\n
\u00a0PEST RATING: \u00a0C<\/h5>\n
\n

Posted by ls<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

California Pest Rating for Podosphaera xanthii (Castagne) U. Braun & Shishkoff 2000 Pest Rating: \u00a0C PEST RATING PROFILE Initiating Event: On July 13, 216, diseased leaves of Calibrachoa sp. plants exhibiting powdery mildew symptoms were collected during a regulatory nursery inspection, from a nursery in San Luis Obispo County, by San Luis Obispo County officials … Continue reading Podosphaera xanthii (Castagne) U. Braun & Shishkoff 2000<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":1117,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[8,4],"tags":[46,45,388],"class_list":["post-2468","post","type-post","status-publish","format-standard","hentry","category-fungi","category-plant-pathology","tag-fungi-2","tag-plant-pathogen","tag-podosphaera-xanthii"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p5l8vQ-DO","jetpack-related-posts":[{"id":1008,"url":"https:\/\/blogs.cdfa.ca.gov\/Section3162\/?p=1008","url_meta":{"origin":2468,"position":0},"title":"Podosphaera caricae-papayae","author":"Admin","date":"June 1, 2015","format":false,"excerpt":"California Pest Rating for Podosphaera caricae-papayae Pest Rating: B PEST RATING PROFILE Initiating Event:\u00a0 In March 2014, Podosphaera caricae-papayae, a powdery mildew fungal pathogen, was identified by morphological and sequence analyses by Suzanne Latham, plant pathologist, CDFA. The symptomatic papaya leaf sample was collected from an ornamental container nursery in\u2026","rel":"","context":"In "Fungi"","block_context":{"text":"Fungi","link":"https:\/\/blogs.cdfa.ca.gov\/Section3162\/?cat=8"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":6079,"url":"https:\/\/blogs.cdfa.ca.gov\/Section3162\/?p=6079","url_meta":{"origin":2468,"position":1},"title":"Erysiphe peckii (U. Braun) U. Braun & S. Takam. 2000","author":"Admin","date":"April 4, 2019","format":false,"excerpt":"California Pest Rating Profile for Erysiphe peckii (U. Braun) U. Braun & S. Takam. 2000Pest Rating: B DOWNLOAD PEST RATING Profile Author\/Responsible Party: John J. Chitambar, Primary Plant Pathologist\/Nematologist, California Department of Food and Agriculture, Phone: 916-738-6693, plant.health[@]cdfa.ca.gov. Pest Rating: B Updated on 7\/10\/2019 by ls","rel":"","context":"In "B-Rated"","block_context":{"text":"B-Rated","link":"https:\/\/blogs.cdfa.ca.gov\/Section3162\/?cat=670"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":7102,"url":"https:\/\/blogs.cdfa.ca.gov\/Section3162\/?p=7102","url_meta":{"origin":2468,"position":2},"title":"Tubakia californica Rooney-Latham & U. Braun 2018","author":"Heather.Martin","date":"May 5, 2020","format":false,"excerpt":"California Pest Rating for Tubakia californica Rooney-Latham & U. Braun 2018 Tubakia leaf spot of oaks Pest Rating: C download pest rating *NOTE: You must be registered and logged in to post a comment. 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