Plant Disease

@plantdiseasej

The leading international journal for rapid reporting of research on new, emerging, and established plant diseases. Published by The American Phytopathological Society.

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Plant Disease@plantdiseasej· 27d

Lethal wilt is an endemic disease affecting oil palms. Catalina Chaves-Sierra et al. present the first report of ‘Candidatus Liberibacter’ being associated with lethal wilt in oil palms of the Arecaceae family in Colombia: https://doi.org/10.1094/PDIS-10-24-2079-RE #plantdisease

Fig. 4. Venn diagram comparing bacterial genera unique to lethal wilt samples collected in 2019 and 2020 with those shared across both years. Genera were classified based on a confidence threshold cutoff of >97%.

Plant Disease@plantdiseasej· 27d

Cassandra L. Swett et al. identified #Fusarium falciforme, F. noneumartii, and F. martii in association with a current disease outbreak in California processing tomatoes and propose names for the diseases associated with the identified pathogens: https://doi.org/10.1094/PDIS-08-24-1773-RE

Fig. 1. Symptoms and field patterns associated with the Fusarium stem rot and decline outbreak in California (initially detected in 2017).

Plant Disease@plantdiseasej· 28d

Inorbert de Melo Lima et al. provide the first statewide, integrative assessment of root-knot nematodes in black pepper production in Espírito Santo, Brazil. Learn more: https://doi.org/10.1094/PDIS-08-25-1757-RE #plantdisease

Fig. 1. Geographic distribution of 240 Meloidogyne isolates (M. arenaria, M. incognita, and M. javanica) collected from black pepper fields across 16 municipalities in four major producing microregions of Espírito Santo, Brazil: Northeast (São Mateus, Jaguaré, Boa Esperança, Conceição da Barra, Pinheiros, Montanha, Pedro Canário), Sweet River (Sooretama, Linhares, Rio Bananal, Aracruz), Central-West (Vila Valério, São Gabriel da Palha, São Domingos do Norte), and Northwest (Nova Venécia, Vila Pavão).

Plant Disease@plantdiseasej· 29d

Feature: Peter V. Oudemans et al. review the epidemiology, historical management strategies, and recent resurgence of cranberry false blossom disease, with a focus on its causal phytoplasma pathogen and insect vector, and implications for disease control: https://doi.org/10.1094/PDIS-11-25-2382-FE

Fig. 2. Discovery of the blunt-nosed leafhopper as the vector of cranberry false blossom disease (1925-1931). Research was conducted at the Boyce Thompson Institute as well as on commercial cranberry beds in Toms River, New Jersey. Irene Dobroscky (top left, standing) first tested cranberries with leafhoppers contained in lantern globes (top right), and later the research was conducted in portable screen houses located on cranberry beds (bottom).

Plant Disease@plantdiseasej· 29d

Findings from Alejandro K. Llanos et al. provide novel insights into the diversity and pathogenicity of #Lasiodiplodia species affecting avocado and highlight the importance of species-level identification to guide disease management: https://doi.org/10.1094/PDIS-08-25-1691-RE

Fig. 2. Symptoms and signs of avocado stem-end rot (SER) and branch canker (BC) in Peru. A, External symptoms of SER. B, Internal symptoms of SER. C, Sugary exudation associated with BC. D, Dark discoloration of cankered wood. E, Severe canker advancing toward the trunk. F and G, Pycnidia protruding from the bark of a severely affected branch.

Plant Disease@plantdiseasej· Jul 14

Thiago de Aguiar Carraro et al. provide the first detailed report of Alternaria brown spot (ABS)-related #Alternaria species and fungicide resistance in Paraná, Brazil: https://doi.org/10.1094/PDIS-05-25-0971-RE #plantdisease

Fig. 1. A, Collection sites of isolates of Alternaria spp. associated with brown spot symptoms on mandarins and B, their hybrids in the northwest region and metropolitan region of Curitiba in Paraná state, Brazil, and the number of isolates obtained from each susceptible mandarin organ.

Plant Disease@plantdiseasej· Jul 14

Michelle L. Heck et al. present a field-forward experimental framework, “Grove-First,” that reverses the traditional laboratory-to-field pipeline by prioritizing outcome-based screening for huanglongbing. Learn more: https://doi.org/10.1094/PDIS-07-25-1379-RE #HLB 🍊

Fig. 1. The “Grove-First” approach: Screening new HLB therapies in the grove.

Plant Disease@plantdiseasej· Jul 13

Editor’s Pick: Braham Dhillon, Sushmita Sapkota, and Navi Gill Dhillon generated an interactive tool (https://robigus.rc.ufl.edu/) to visualize verified plant diseases published in Plant Disease Notes over the last 45 years and conducted a meta-analysis: https://doi.org/10.1094/PDIS-09-25-1900-RE

Fig. 6. Network analysis of top 10 flowering plant hosts and associated pathogens. One-to-one and one-to-many connections were observed between the pathogen and host genera. Pathogens along the edge were seen to form connections to one host (narrow-host range) versus pathogens in the center that connected to many hosts (broad-host range). The host nodes were labeled using a one-letter code derived from the first initial of the host genus name, G - Glycine, C - Capsicum, A - Allium, S - Solanum, Z - Zea, P - Prunus, V - Vitis, Ci - Citrus, F - Fragaria, and B - Brassica, and their color represented a “community” of hosts that shared connections to more pathogens among themselves than other hosts. The node size was proportional to the number of plant disease notes for that genus.

Plant Disease@plantdiseasej· Jul 5

“Differential Infection by Barley Yellow Mosaic Disease and Its Impact on Key Agronomic Traits in Barley,” by Mengna Zhang et al. Learn more: https://doi.org/10.1094/PDIS-08-25-1656-RE #plantdisease

Fig. 4.
Line graph of daily temperature for 2 years. The orange and blue lines represent data for 2022 to 2023 and 2023 to 2024, respectively.

Plant Disease@plantdiseasej· Jul 4

Gray mold disease, caused by #Botrytis cinerea, can lead to severe economic losses. Hong-Jie Liang et al. report neocryptolepine derivative Z24 has good fungicidal activity against B. cinerea and has potential for managing pyrimethanil-resistant strain: https://doi.org/10.1094/PDIS-06-25-1322-RE

Fig. 1.
Structure of neocryptolepine and its derivative compound Z24.

Plant Disease@plantdiseasej· Jul 3

Lefan Pu et al. developed a hydroponic inoculation method for #wheat seedlings and an integrated crown rot resistance assessment system that combines disease index and in planta fungal biomass: https://doi.org/10.1094/PDIS-08-25-1773-SR #plantdisease #Fusarium

Fig. 5.
Disease symptoms (A to G), disease index (H), and fungal in planta biomass (Fusarium pseudograminearum [Fp] DNA/wheat DNA) (I) of seven wheat varieties infected with Fp. by the hydroponic inoculation method at 12 days postinoculation. A, Xinong979. B, EGA Hume. C, Xiaoyan22. D, Fielder. E, Suwon11. F, Mingxian169. G, Sunco. H, Disease index of seven varieties. I, Biomass of seven varieties. The error bar represents the standard deviations among three independent replicates. Different letters indicate statistical significance (Duncan’s multiple range test, P < 0.05).

Plant Disease@plantdiseasej· Jul 3

“Identification of Root Rot Pathogens, Biological Control, and the Mechanism Analysis Underlying Polygonatum kingianum Response to Pathogen Stress,” by Rong Liu et al. Learn more: https://doi.org/10.1094/PDIS-07-25-1436-RE #plantdisease #Fusarium #Aspergillus

Fig. 1.
Comparison of the phenotypes of pathogens from root rot diseased rhizome of Polygonatum kingianum (A). Colony morphology and phenotype of major root rot pathogens isolated and purified on solid media (B). Identification of microscopic structures of spores and mycelia of three root rot pathogens (C). Fusarium oxysporum (Fo), Fusarium redolens (Fr), and Aspergillus awamori (Aw).

Plant Disease@plantdiseasej· Jul 2

Research from Bo-Yi Lee et al. validates the role of fusaricidins in #Paenibacillus polymyxa TP3-mediated induction of systemic resistance and facilitates the application of P. polymyxa as a health enhancer for sustainable crop production: https://doi.org/10.1094/PDIS-07-25-1374-RE #plantdisease

Fig. 1.
Comparison of the antifungal activity of Paenibacillus polymyxa wild-type strain TP3 and its fusA-disrupted mutant. A, The wild-type strain TP3 and its fusA-disrupted mutant (ΔfusA) were confronted with Botrytis cinerea (Bc) W2 and Colletotrichum siamense (Cs) ML133. Sterile water (H2O) was used as a control treatment. B, The inhibition rates of mycelial growth were shown. The error bar represents standard deviation of a dataset relative to the mean, N = 3. On each incubation period for Bc W2 (upper panel) and Cs ML133 (lower panel), different letters indicate significant difference of the inhibition rate for different treatments (ANOVA followed by Tukey’s HSD test, P < 0.05).

Plant Disease@plantdiseasej· Jul 2

#Pyrrhoderma noxium is an entry quarantine tree pathogenic fungus in China. Haiyue Yin et al. established a rapid, specific, and visible detection method for P. noxium by integrating recombinase-aided amplification with a lateral flow dipstick: https://doi.org/10.1094/PDIS-11-24-2521-SR

Fig. 3.
Specificity of the RAA-LFD assay. The assay was tested against different phytopathogen genomic DNA. Lane 1, Cryphonectria parasitica; Lane 2, Colletotrichum gloeosporioides; Lane 3, Gymnosporangium yamadai; Lane 4, Pseudocryphonectria elaeocarpicola; Lane 5, Verticillium dahliae; Lane 6, Cytospora chrysosperma; Lane +, Pyrrhoderma noxium; Lane −, H2O (negative control); C, control line; T, test line. RAA, recombinase-aided amplification; LFD, lateral flow dipstick.

Plant Disease@plantdiseasej· Jul 1

Glen Groben et al. quantified the concentration of #Clarireedia in a tolerant and a susceptible cultivar of creeping bentgrass throughout the growing season to determine the effect of host tolerance on dollar spot development in the field. Learn more: https://doi.org/10.1094/PDIS-02-25-0348-RE

Fig. 4.
Top: Representative pictures of an ‘Independence’ (susceptible cultivar) creeping bentgrass plot from 2 July 2020. Bottom: Representative pictures of a ‘Declaration’ (tolerant cultivar) creeping bentgrass plot from 2 July 2020. Each plot had three areas sampled representing different dollar spot symptom intensity levels. Left: No dollar spot symptoms. Middle: Disease onset (initial infections). Right: Developed lesion. In each image, a 1-cm-diameter × 2.5-cm-deep core was collected below the micro centrifuge tube in each photo and represents one of the five replicate plots on each sampling date.

Plant Disease@plantdiseasej· Jul 1

R. J. Harkness et al. report the most sensitive and specific assay for #Caliciopsis pinea detection for our current understanding of species diversity within the genus. Learn more: https://doi.org/10.1094/PDIS-06-25-1152-SR #plantdisease

Fig. 1.
Typical symptom development of a Caliciopsis pinea infection on Pinus strobus. A, Sunken, red cankers and the damage they cause to lumber. B, “Flagging,” or when the needles on individual branches brown and the whole branch may eventually die. C, Pitching and profuse resin bleeding from cankers that form on the trunk and branches of the tree.

Plant Disease@plantdiseasej· Jun 30

#Venturia inaequalis affects apple production worldwide. Giuliana Maddalena et al. provide evidence that fungicide-resistant V. inaequalis strains in northern Italy can maintain competitive fitness under a variety of environmental conditions: https://doi.org/10.1094/PDIS-07-25-1586-RE #plantdisease

Fig. 1.
Frequencies of Venturia inaequalis isolates classified as sensitive (green), intermediate-resistant (light blue), or resistant (purple) to the five fungicides tested.

Plant Disease@plantdiseasej· Jun 30

Fresh Japanese plums are highly susceptible to postharvest diseases caused by fungal pathogens. Ricardo Lima de Souza et al. evaluated the potential of immature-thinned apples ultrasound-assisted extracts for disease control: https://doi.org/10.1094/PDIS-07-25-1589-RE #plantdisease

Fig. 2.
Growth inhibition of Botrytis cinerea (BC), Geotrichum candidum (GC), Monilinia fructicola (MF), Penicillium expansum (PE), and Rhizopus stolonifer (RS) exerted by immature-thinned apple extracts from ‘Gala’, ‘Golden Delicious’ (GD), and ‘Opal’ cultivars. Results were calculated from optical density values of suspensions incubated in microtiter plates at 25°C for 4 days. Values are mean ± standard deviation of four replicates per extract from two independent experiments (n = 8). The dashed line at 80% inhibition indicates the threshold for selecting treatments to be further evaluated in in vivo trials.

Plant Disease@plantdiseasej· Jun 30

“Transferring the Psathyrostachys huashanica 5Ns Chromosome into Wheat Genetic Background to Enhance Powdery Mildew Resistance,” by Jiachuang Li et al. Learn more: https://doi.org/10.1094/PDIS-04-25-0895-RE #plantdisease #wheat #Psathyrostachys

Fig. 1.
Symptoms in response to wheat powdery mildew and plant, spikelet morphology of WPh13-2, and its wheat parent 7182. A, Reaction to wheat powdery mildew at the seedling stage. B, Reaction to wheat powdery mildew at the adult stage. C, Comparison of adult plants. D, Comparison of kernels. 1, Control: common wheat cultivar Huixianhong (HXH); 2, alien parent Psathyrostachys huashanica; 3, wheat parent 7182; 4, wheat–P. huashanica derivative WPh13-2.

Plant Disease@plantdiseasej· Jun 29

Grape white rot, caused by #Coniella vitis, affects grape production in China and worldwide. Lichun Yan et al. developed a rapid and highly sensitive LAMP assay targeting the translation elongation factor 1-alpha gene of C. vitis: https://doi.org/10.1094/PDIS-04-25-0861-SR #plantdisease

Fig. 1.
Location of the loop-mediated isothermal amplification primers in TEF-1α gene sequences. Arrows indicate the direction of the primers initiating amplification.

Plant Disease@plantdiseasej· Jun 28

#Puccinia striiformis f. sp. tritici and P. striiformis f. sp. hordei cause stripe rust epidemics on wheat and barley, respectively. Hannah Merrill et al. explored the dynamics of Cyp51 mutants in the P. striiformis populations in the United States: https://doi.org/10.1094/PDIS-03-25-0578-RE

Fig. 1.
Separations of Puccinia striiformis isolates collected from the United States in 2019 to 2021 into the allelic genotypes (AA, AT, and TT) of the KASP marker for the demethylation inhibitor fungicide targeting gene Cyp51. AA = wild type; AT = heterozygous; KASP = Kompetitive allele-specific PCR; TT = the homozygous genotypes.

Plant Disease@plantdiseasej· Jun 28

Ashrafou Ouro-Djobo et al. revealed a greater diversity of wheat-infecting viruses in Texas than previously reported and confirmed #wheat streak mosaic virus and #Triticum mosaic virus as the main etiological agents of wheat viral diseases in the state: https://doi.org/10.1094/PDIS-06-25-1277-RE 🌾

Fig. 1.
Virus-like symptoms present on samples used during the study (A) and map of Texas showing the counties where the sampled wheat fields were located (B). The blue shading represents counties where samples were collected, and samples collected from counties marked with a white star were used for high-throughput sequencing (HTS) analysis.

Plant Disease@plantdiseasej· Jun 28

The pathogenic soilborne and postharvest fungus #Berkeleyomyces basicola is a newly reported pathogen in Serbia. Miljan Grkinić et al. elucidate the pathogenic characteristics of B. basicola causing black root rot of carrot: https://doi.org/10.1094/PDIS-07-25-1516-SC #plantdisease

Fig. 1.
Morphology and symptoms caused by Berkeleyomyces basicola: A, naturally infected mechanically washed carrot roots after 7 days incubation at room temperature with symptoms of black root rot; B, grayish round 10-day-old colony on potato dextrose agar (PDA); C, dark gray 30-day-old colony on PDA; D, chains of 2 to 6 chlamydospores; E, conidiophores; F, secondary conidia with endoconidia on malt extract agar; G, artificially inoculated carrot roots (from left to right: cuts, sprayed, injection) and resembling cross sections; H, control carrot roots and resembling cross sections; I, wilting of wounded seedlings sprayed with a spore suspension (left) and control seedlings (right); J, stem necrosis of wounded seedlings (left) and control seedlings (right); K, detail of necrotic stem tissue with photomicrography of chlamydospores formed in the diseased plant tissue 10 days postinoculation; and L, control seedling (bar = 20 μm).

Plant Disease@plantdiseasej· Jun 28

Jack Mascarenhas et al. present the first study to evaluate the impact of fungicide applications to manage black rot in the field on residues obtained at harvest in sweetpotato: https://doi.org/10.1094/PDIS-05-25-1003-RE #plantdisease 🍠

Fig. 1.
Key time points throughout the sweetpotato production and packaging process for fungicide application to manage fungal sweetpotato diseases. A fungicide can be applied to sweetpotato seed roots from the previous harvest before bedding via a banded application on the surface of the seedbed followed by a second banded application on the surface of the seed roots. After slips have been propagated from seed roots and cut from the beds, fungicides can be applied via a transplant water application during slip setting. Harvested storage roots intended for domestic or export sale can be sprayed with a fungicide during packing and sorting. Figure adapted from Stahr and Quesada-Ocampo (2020).

Plant Disease@plantdiseasej· Jun 26

Cottony leak, a soft rot on fruit of #cucurbit crops, is a concern for pickling cucumber growers in South Carolina and other states. Anthony P. Keinath et al. present the first report of #Pythium deliense as a causal agent: https://doi.org/10.1094/PDIS-04-25-0855-SR #plantdisease

Fig. 2.
Typical symptoms of cottony leak on fruit of cucumber cv. Kirby (bottom) inoculated with Pythium deliense incorporated into the potting soil on which the fruit were laid. Symptomless, noninoculated fruit are shown on the top.

Plant Disease@plantdiseasej· Jun 26

Michael R. Fulcher et al. report the first instance of #Boeremia exigua on a swallow-wort species and highlight the potential for widespread invasive plants to harbor previously undescribed pathogen genotypic diversity: https://doi.org/10.1094/PDIS-03-25-0684-SC #plantdisease

Fig. 1.
Black swallow-wort (Vincetoxicum nigrum) and annular leaf spot symptoms resulting from Boeremia exigua infection. A, An infestation of black swallow-wort. B, Annular ring spots on black swallow-wort caused by Boeremia exigua.

Plant Disease@plantdiseasej· Jun 25

Italian ryegrass is widely cultivated in southern China. Longhai Xue et al. form the basis for the diagnosis, detection, pathogen identification, and scientific control of black leaf spot, caused by #Pestalotiopsis species, on Italian ryegrass: https://doi.org/10.1094/PDIS-09-24-2013-SR

Fig. 1.
Natural symptoms of black leaf spot on Italian ryegrass in the field. A and B, The photos were taken at Dushan, Guizhou, in 2021. C to H, The photos were taken at Yunnan in 2022: C to E, Yiliang; F to H, Xundian.

Plant Disease@plantdiseasej· Jun 25

Findings from Chaydon O’Fallon et al. support the registration of the new Oomycota fungicides ethaboxam, fluopicolide, mandipropamid, and oxathiapiprolin to manage #Phytophthora diseases on almond and other tree crops in the United States: https://doi.org/10.1094/PDIS-05-25-1038-RE #plantdisease

Fig. 1.
Number of isolates of Phytophthora niederhauserii, P. mediterranea, and P. syringae collected from almond in counties of California. Additionally, there were ten, five, and one isolate, respectively, with unknown origins.

Plant Disease@plantdiseasej· Jun 24

“Resistance in Capsicum Species and Cultivars to Colletotrichum scovillei and Implications for Fungicide Applications,” by Anthony P. Keinath and William B. Rutter: https://bit.ly/4ojLuD5 Read the press release by Denise Attaway (@ClemsonUniv), to learn more: https://bit.ly/3RVSV7p

Fig. 1.
Yields of four pepper cultivars affected by green fruit anthracnose caused by Colletotrichum scovillei in fall 2022 and fall 2023. Means with the same letter do not differ significantly; Fisher’s protected least significant difference test, P ≤ 0.01.

Plant Disease@plantdiseasej· Jun 23

James J. Polashock and Wei Wei designed a LAMP assay and developed a quantitative PCR assay to mitigate the impact of false blossom disease on cranberry production: https://doi.org/10.1094/PDIS-08-25-1779-SC #plantdisease