scholarly journals Reaction of Broccoli to Isolates of Verticillium dahliae from Various Hosts

Plant Disease ◽  
2001 ◽  
Vol 85 (2) ◽  
pp. 141-146 ◽  
Author(s):  
R. G. Bhat ◽  
K. V. Subbarao
Keyword(s):  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Cropping Systems ◽  
Severe Disease ◽  
Disease Symptoms ◽  
Inoculation Method ◽  
Vascular Discoloration ◽  
Root Tissues ◽  
Rotation Crop

Isolates of Verticillium dahliae from 15 different hosts and V. albo-atrum from alfalfa were tested for their ability to cause wilt on broccoli using a root-dip inoculation method. None of the isolates caused vascular discoloration in broccoli except those from cabbage and cauliflower that were weakly pathogenic. Broccoli cultivars Baccus, Greenbelt, Parasol, Patriot, and Symphony showed resistance to Verticillium infection. Re-isolated strains from fresh samples of internally discolored broccoli and cauliflower root tissues were unable to cause disease symptoms on re-inoculation of broccoli, but caused severe disease on cauliflower. Inoculation of 5-, 7-, 9-, or 11-week-old plants did not alter the resistance in broccoli or the susceptibility in cauliflower against Verticillium. Immunity of broccoli against infection by isolates of V. dahliae from non-crucifer hosts, its resistance against crucifer isolates, and as previously described, attrition of V. dahliae microsclerotia in soil by broccoli residue, coupled with its importance as a commercial vegetable, make broccoli an attractive rotation crop for the management of Verticillium wilt in many cropping systems.

Spatial Patterns of Microsclerotia of Verticillium dahliae in Soil and Verticillium Wilt of Cauliflower

1997 ◽  
Vol 87 (3) ◽  
pp. 325-331 ◽  
Author(s):  
C. L. Xiao ◽  
J. J. Hao ◽  
K. V. Subbarao
Keyword(s):  
Spatial Patterns ◽  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Binomial Distribution ◽  
Disease Incidence ◽  
Soil Samples ◽  
Random Pattern ◽  
Parameter Estimates ◽  
Regular Pattern ◽  
Vascular Discoloration

The spatial patterns of microsclerotia of Verticillium dahliae in soil and wilt symptoms on cauliflower were determined at three sites in each of two fields in 1994 and 1995. Each site was an 8 × 8 grid divided into 64 contiguous quadrats (2 by 2 m each). Soil samples were collected to a depth of 15 cm with a probe (2.5 cm in diameter), and samples from four sites in each quadrat were bulked. Plants in each quadrat were cut transversely, and the number of plants with vascular discoloration and the number without discoloration were recorded. The soil was assayed for microsclerotia by the modified Anderson sampler technique. Lloyd's index of patchiness (LIP) was used as an indicator to evaluate the aggregation of microsclerotia in the field. Spatial autocorrelation and geostatistical analyses were also used to assess the autocorrelation of microsclerotia among quadrats. The LIP for microsclerotia was greater than 1, indicating aggregation of propagules; however, the degree of aggregation at most sites was not high. Significant autocorrelation within or across rows was detected in some spatial autocorrelograms of propagules, and anisotropic patterns were also detected in some oriented semivariograms from geostatistical analyses for microsclerotia, indicating the influence of bed preparation in the fields on pathogen distribution. The parameter estimates p and θ in the beta-binomial distribution and the index of dispersion (D) associated with the distribution were used to assess the aggregation of diseased plants at each site. A random pattern of wilt incidence was detected at 7 of 12 sites, and an aggregated pattern was detected at 5 of 12 sites. The degree of aggregation was not high. A regular pattern of wilt severity was detected at all sites. The high disease incidence (77 to 98%) observed at 11 of the 12 sites could be explained by high inoculum density.

scholarly journals First Report of Verticillium dahliae Causing Artichoke Wilt in California

Plant Disease ◽  
1999 ◽  
Vol 83 (8) ◽  
pp. 782-782 ◽  
Author(s):  
R. G. Bhat ◽  
K. V. Subbarao ◽  
M. A. Bari
Keyword(s):  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Infected Plant ◽  
Potato Dextrose Agar ◽  
The Other ◽  
Central Coast ◽  
Cynara Scolymus ◽  
First Report ◽  
Vascular Discoloration ◽  
Infested Field

In mid-August 1998, artichoke (Cynara scolymus L.) plants of cultivar Imperial Star in a field in the Salinas area of the central coast of California developed wilt symptoms. The plants were stunted with chlorotic, drooping, and dried leaves near the bottom and middle of the plants as previously described in Italy (1). Diseased plants produced smaller edible buds and, in severe cases, buds were discolored with dried outer bracts. Roots exhibited the characteristic vascular discoloration of Verticillium infection. In one part of the infested field, artichoke was near harvest with 85% of plants showing wilt symptoms with vascular discoloration whereas the other part had a 60-day-old crop with 98% of plants infected. Yield in the field was reduced by as much as 50%. Verticillium dahliae was isolated from infected plant samples on NP-10 medium (2), and isolates were single spored before storing on potato dextrose agar at 4°C. Identity of the pathogen was confirmed based on colony morphology and formation of microsclerotia. In root-dip inoculation tests in the greenhouse, two V. dahliae isolates from artichoke infected 1-month-old artichoke seedlings that wilted within 6 weeks of inoculation. V. dahliae was reisolated from plants showing vascular discoloration. Cross-inoculation studies revealed that artichoke isolates caused a moderate level of disease in lettuce, but only a trace of vascular discoloration in cauliflower. Lettuce isolates caused a severe wilt in artichoke. Cauliflower isolates did not cause wilt in lettuce and caused only slight vascular discoloration in artichoke. This is the first report of a Verticillium wilt of artichoke in California. References: (1) M. Cirulli et al. Plant Dis. 78:680, 1994. (2) L. H. Sorensen et al. Phytopathology 81:1347, 1991.

scholarly journals First report of Verticillium wilt and mortality of Ailanthus altissima caused by Verticillium dahliae and V. albo-atrum sensu lato in Spain

Plant Disease ◽  
2021 ◽  
Author(s):  
Concepció Moragrega ◽  
Júlia Carol ◽  
Enric Bisbe ◽  
Enric Fabregas ◽  
Isidre Llorente
Keyword(s):  
Biological Control ◽  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Mediterranean Basin ◽  
Ailanthus Altissima ◽  
First Report ◽  
Vascular Discoloration ◽  
Invasive Tree ◽  
The Mediterranean ◽  
The Mediterranean Basin

Ailanthus altissima (Mill.) swingle is a highly invasive tree that has become established worldwide, especially in the Mediterranean Basin because of its good drought resistance. Ailanthus altissima is included in the list of Invasive Alien Species of the EU, so measures for eradication and management are required. Assessment for potential biological control agents is of great interest to manage this invasive tree in natural ecosystems. Verticillium dahliae Kleb. and Verticillium nonalfalfae Inderb. et al. (formerly V. albo-atrum Reinke & Berthold) have been reported as the causal agents of Verticillium wilt and mortality of ailanthus (Shall and Davis 2009; Rebbeck et al., 2013; Snyder et al., 2013; Brooks et al. 2020). Ailanthus trees with Verticillium wilt symptoms (wilt, premature defoliation, terminal dieback, yellow vascular discoloration, and mortality) were detected for the first time in 2007 in Celrà (42.040466N, 2.864436E) (Catalonia, Northeastern Spain), then spread to neighboring ailanthus populations. In 2018, ailanthus trees in a 570 km2 area in Catalonia were surveyed for disease symptoms. The incidence of wilt disease in ailanthus trees in forest ecosystems ranged from 50 to 90%, and the severity, 60 to 92%. One hundred and fifty branch samples showing wilt symptoms were collected and disinfected by immersion in 1% sodium hypochlorite for 2 min, then cut into 5mm pieces. These were placed onto PDA plates and incubated at 22.5 °C and 12 h light photoperiod for 7-10 days. Eighty-four tentative Verticillium sp. isolates were recovered and subcultured on modified water agar (WA-p) and PDA for identification (Inderbitzin et al. 2011, 2013). The majority of isolates (77 %) were identified as V. dahliae based on morphology; production of brown-pigmented microsclerotia and conidia features and dimensions (5.7 ± 0.9 μm long). Sequencing of mycelial DNA using primer pair ITS1-F and ITS4, resulted in consensus sequences of 503 bp. BLASTn analysis of ITS sequence of native isolate VdGi688 gave 100% identity to the ITS sequences of V. dahliae type strain PD322 (92% coverage) and Vd16_9 (100% coverage). In addition, 23% isolates morphologically corresponded to V. albo-atrum or V. nonalfalfae; melanized resting mycelia and round to oval-shaped conidia (5.2 ± 0.9 μm × 2.2 ± 0.5 μm). The ITS consensus sequence (544 bp) of native isolate VaaGi02 gave 99% identity (90-100 % coverage) to V. albo-atrum isolates CBS 127169, PSU 140, Vaa_TN1 and to V. nonalfalfae type PD592, CBS5451.88 and Vert 18. Sequences from isolates VdGi688 and VaaGi02 were deposited in GenBank as MW624723 and MW624724, respectively. Koch’s postulates for seven V. dahliae isolates and eight V. albo-atrum isolates were fulfilled by injection of 1 mL of 1 x 107 conidia/mL suspension into the stem of A. altissima seedlings under greenhouse conditions. Six plants were inoculated per isolate in two independent experiments. Control plants were inoculated with sterile distilled water. All isolates caused leaf chlorosis, defoliation, and apical stem death, as well as internal necrosis and vascular discoloration. Control plants remained asymptomatic. The pathogens were re-isolated from internal symptomatic tissues of inoculated plants. To our knowledge, this is the first report of V. dahliae and V. albo-atrum sensu lato causing Verticillium wilt on A. altissima in Spain. The study suggests the potential of native isolates of Verticillum spp. in the biological control of ailanthus in the Mediterranean Basin. This work was funded by the Diputació de Girona (Spain) (2017/8719, 2019/3091, 2020/7565, and 2021/1468).

scholarly journals Efficacy of resistance selection to Verticillium wilt in strawberry (Fragaria x ananassa Duch.) tissue culture

2012 ◽  
Vol 64 (3) ◽  
pp. 3-12 ◽  
Author(s):  
Jadwiga I. Żebrowska
Keyword(s):  
Tissue Culture ◽  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Pathogenic Fungus ◽  
Genetic Resistance ◽  
Fragaria X Ananassa ◽  
Post Inoculation ◽  
Disease Symptoms ◽  
Resistance Selection

The soil-borne pathogenic fungus <i>Verticillium dahliae</i> Kleb. causes economic losses in crops in temperate regions of the world and hence is the most studied species. Strawberry (<i>Fragaria x ananassa</i> Duch.) belongs to plant species susceptible to <i>Verticillium dahliae</i>, although the response to infection caused by this pathogen is varied and depends on the cultivar. Due to a lack of efficient methods in Verticillium wilt elimination, the selection of genetically resistant plant material is a priority direction in breeding programs. Efficacy of resistance selection to <i>Verticillium dahliae</i> Kleb. in strawberry tissue culture was examined on the basis of response to <i>in vitro</i> infection by this pathogenic fungus in two tissue cultured strawberry cultivars, i.e. 'Filon' and 'Teresa'. Culture was conducted for 16 months in an environmentally controlled growth room at 18-20°C, 60-70% relative humidity and light intensity of 100 µm E × m<sup>-2</sup> × s<sup>-1</sup> on a 16h light / 8h dark cycle. Subcultures were proliferated every 6 weeks on modified Murashige and Skoog medium. Four hundred microplants from each tissue cultured cultivar were inoculated under <i>in vitro</i> conditions at the 4-leaf stage with a homogenate of liquid mycelium of <i>Verticillium dahliae</i> serving as the selecting agent. Disease symptoms were observed at 15, 30, 45, 60, and 75th days post inoculation. The extent of leaf chlorosis was rated on a scale of 0-4. At day 75<sup>th</sup> post inoculation, the percentage of totally chlorotic plants in micropropagated cv. Teresa reached the value of 76.27%, whereas the proportion of such plants in inoculated tissue cultured cv. Filon reached the value of 89.40%. Also, the index of infection calculated for very severe disease symptoms in the subclone 'Teresa' reached the mean value lower when compared with that calculated for subclone 'Filon' (0.0962 and 0.1150, respectively). These results suggested that the micropropagated cv. Teresa exhibited higher genetic resistance to the selecting agent in comparison with the tissue cultured cv. Filon, and it was consistent with field resistance of both cultivars to this pathogen. Therefore, the procedure of <i>in vitro</i> selection used in this study was quite efficient to distinguish varying genetic resistance to <i>Verticillium dahliae</i> in the two examined strawberry subclones, and can be recommended as a suitable method for the estimation of susceptibility to Verticillium wilt in different strawberry genotypes.

scholarly journals Cryptic Infection and Systemic Colonization of Leguminous Crops by Verticillium dahliae, the Cause of Verticillium Wilt

Plant Disease ◽  
2019 ◽  
Vol 103 (12) ◽  
pp. 3166-3171 ◽  
Author(s):  
M. G. Lloyd ◽  
N. McRoberts ◽  
T. R. Gordon
Keyword(s):  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Warm Season ◽  
Field Trials ◽  
Cool Season ◽  
Common Vetch ◽  
Rotation Scheme ◽  
Sunn Hemp ◽  
Leguminous Crops ◽  
Rotation Crop

Verticillium dahliae, the cause of Verticillium wilt, is a widespread pathogen that affects many crops in California and throughout the world. Cover cropping with leguminous species is often integrated into a rotation scheme for its contribution to soil nitrogen, and can contribute to management of Verticillium wilt provided the chosen crop does not support development of V. dahliae. Seven cool season legumes (faba bean, bell bean, field pea, hairy vetch, common vetch, purple vetch, and woollypod vetch), and three warm season legumes (sesbania, sunn hemp, and black-eyed pea) were evaluated as hosts for reproductive growth of V. dahliae. All 10 legumes were colonized by V. dahliae, while remaining symptomless, when subjected to a root-dip inoculation. Similar results were obtained when plants were grown in infested potting soil, albeit with a lower frequency of infection than in root-dip assays. All tested legumes were also infected in field trials, with the exception of bell bean. Overall, warm season legumes sustained higher rates of infection than cool season legumes. Common vetch was the most extensively colonized of the cool season legumes. Based on the results of this study, legumes may not be an appropriate rotation crop in fields where Verticillium wilt is a problem.

scholarly journals Symptomless Host and Nonhost Responses of Paulownia (Paulownia spp.) to Olive-Defoliating Verticillium dahliae

Plant Disease ◽  
2015 ◽  
Vol 99 (7) ◽  
pp. 962-968 ◽  
Author(s):  
Daniel Jiménez-Fernández ◽  
Concepción Olivares-García ◽  
José L. Trapero-Casas ◽  
Jaime Requena ◽  
Jesús Moreno ◽  
...  
Keyword(s):  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Severe Disease ◽  
Infested Soil ◽  
Conidial Suspension ◽  
Nested Polymerase Chain Reaction ◽  
Soil Mixture ◽  
Practical Applications ◽  
Dahliae Isolate ◽  
First Time

Symptomless host and nonhost responses of Paulownia spp. to olive-defoliating (D) Verticillium dahliae is reported for the first time. Two paulownia clones, Paulownia elongata ‘PC-2’ and P. elongata × P. fortunei ‘PC-3’, were inoculated with a V. dahliae isolate representative of the D pathotype by either root dip or stem injection with a conidial suspension, repeated transplanting to a V. dahliae-infested soil mixture, or root dip in the conidial suspension followed by transplanting to the infested soil mixture. ‘Picual’ olive and ‘Sugar Baby’ watermelon were included in all experiments as susceptible standards to show that the inoculation procedures and incubation conditions were successful. Plants were incubated under conditions optimal for Verticillium wilt that caused severe disease in ‘Picual’ olive and ‘Sugar Baby’ watermelon in the growth chamber, shade house, and field microplots for 30 to 57 weeks in three independent experiments. No foliar symptoms developed on paulownia, whose stems were found free of V. dahliae both by isolation on semiselective NP-10 medium as well as by a nested-polymerase chain reaction assay using total genomic DNA from inoculated plants that effectively detected D V. dahliae in olive stems. V. dahliae was isolated to a limited extent from roots of PC-3 paulownia plants after 30 weeks of growth in the infested soil mixture but not from those that were root-dip inoculated or from PC-2 plants regardless the method of inoculation. The symptomless host and nonhost responses of Paulownia spp. to D V. dahliae may have practical applications in the use of fertile soils in southern Spain, particularly in those that are highly infested with the highly virulent D pathotype, as well as a replacement crop for Verticillium wilt-affected olive orchards in that region.

scholarly journals Verticillium Wilt of Spineless Safflower Caused by Verticillium dahliae in California

Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1383-1383 ◽  
Author(s):  
S. T. Koike ◽  
A. Baameur ◽  
K. Maruthachalam ◽  
K. V. Subbarao
Keyword(s):  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Vascular Tissue ◽  
Aerial Mycelium ◽  
Molecular Data ◽  
Carthamus Tinctorius ◽  
Peat Moss ◽  
Oilseed Crop ◽  
Specific Pcr ◽  
Vascular Discoloration

Spineless selections of Carthamus tinctorius (safflower) are grown as commercial field grown cutflower crops in coastal California. In 2010, field plantings of spineless safflower in Santa Clara County developed symptoms of a wilt disease. Affected plants were stunted and slow to develop. As plants developed flower buds, lower leaves turned yellow and wilted. As disease developed, lower leaves turned tan and desiccated; in extreme cases, the entire plant wilted and died. Examination of the taproot and stem vascular tissue revealed a tan to light brown, longitudinal, vascular discoloration. Disease distribution was patchy but in some plantings up to 50% of the plants were unharvestable due to loss of quality or plant death. Isolation from symptomatic vascular tissue consistently resulted in the recovery of a fungus with white aerial mycelium, verticillate conidiophores, single-celled, ovoid to ellipsoid, hyaline conidia, and solitary black microsclerotia that were rounded to elongated or irregular in shape. Three single conidial isolates were chosen for species and race identification after DNA extraction using the FastDNASPIN Kit (MP Biomedicals, Solon, OH). Verticillium species-specific PCR amplified a 500-bp amplicon that is specific to Verticillium dahliae from all three isolates. All three isolates also amplified the race 2-specific 270-bp band in PCR. No amplification was observed in race 1-specific PCR. Based on morphological and molecular data, the fungus was identified as V. dahliae (1,3). Pathogenicity of two isolates was tested individually by soil drench inoculations using 10 ml of conidial suspensions (7 × 106 conidia/ml) for each of 10 containerized plants grown in a peat moss mix in 7.6 cm diameter pots. Five safflower selections were inoculated and maintained in a greenhouse. After 6 weeks, as plants began to form flowers, inoculated plants showed lower leaf dieback and plant wilting. Vascular discoloration was observed when plants were dissected. V. dahliae was consistently recovered from symptomatic tissue. Control plants that only received water did not develop symptoms. The experiment was repeated and the results were consistent. To our knowledge, this is the first report of Verticillium wilt of ornamental, spineless safflower. This disease has been reported previously on agronomic safflower grown as an oilseed crop (2). This finding has significance for coastal crop rotation decisions as ornamental safflower is yet another host that could augment V. dahliae soil inoculum levels for crops such as strawberry and vegetables. References: (1) P. Inderbitzin et al. PLoS One 6: e28341, 2011. (2) J. M. Klisiewicz. Plant Dis. 65:237, 1981. (3) Maruthachalam et al. Phytopathology 100:1222, 2010.

scholarly journals Recovery of Verticillium dahliae from Tall Morningglory (Ipomoea purpurea) in New Mexico and its Pathogenicity on Chile Pepper

Plant Disease ◽  
2009 ◽  
Vol 93 (4) ◽  
pp. 428-428 ◽  
Author(s):  
S. Sanogo ◽  
B. F. Etarock ◽  
M. Clary
Keyword(s):  
New Mexico ◽  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Common Disease ◽  
Infested Soil ◽  
Conidial Suspension ◽  
Chile Pepper ◽  
Ipomoea Purpurea ◽  
Vascular Discoloration ◽  
Pepper Plants

Verticillium wilt, caused by Verticillium dahliae, is a common disease of chile pepper (Capsicum annuum) in New Mexico. In August of 2007, wilted plants with vascular discoloration in the stem typical of infection by V. dahliae occurred in several fields in Luna County in southern New Mexico. In one field, Verticillium wilt incidence was between 60 and 70%. Approximately 30% of the field was infested with Physalis wrightii (Wrights groundcherry) and Anoda cristata (spurred anoda), and 60% of the field was infested with Ipomoea purpurea (tall morningglory). Except for vascular discoloration found in a few plants of Wrights groundcherry and spurred anoda, there were no other symptoms observed in the weeds present. Previously, Wrights groundcherry and spurred anoda were demonstrated as hosts to V. dahliae (2); however, to our knowledge, tall morningglory was not. A 5-cm segment was cut from the lower part of the stems and upper part of the tap roots of six tall morningglory plants and two chile pepper plants. The segments were washed, surface disinfested for 2 min in 0.5% sodium hypochlorite, and cut into pieces that were plated onto water agar. Mycelial colonies emerging from the pieces were transferred to either potato dextrose agar, prune extract agar, or Czapek-Dox agar medium. Putative V. dahliae isolates from tall morningglory and chile pepper plants were identified based on characteristic morphological features when cultured on prune extract medium (2,3). In addition, PCR of fungal DNA and sequencing the amplicons using primer pair ITS4/ITS6 showed a 99% homology with the sequence of the rDNA ITS of V. dahliae (1). Pathogenicity tests were conducted with two isolates of V. dahliae from tall morningglory and one from chile pepper. In the first of two methods, four pots were infested with conidia of each isolate (2 × 107 conidia per 500 cm3 of soilless mix) and planted (five seeds per pot, thinned to three seedlings) with chile pepper cv. AZ-20, which is susceptible to V. dahliae. Three noninfested pots served as the control. Pots were placed in a growth chamber at 26/20°C day/night temperature. In the second method, plants (cv. AZ-20) at the 6- to 8-leaf stage were inoculated in a greenhouse with V. dahliae by dispensing 5 ml of a conidial suspension (4 × 106 conidia/ml) into the root plug prior to transplanting. Four root plugs were inoculated per isolate and there were three noninoculated root plugs. Both experiments were repeated once. Isolates of V. dahliae recovered from tall morningglory and chile pepper were pathogenic on chile pepper. Leaf chlorosis, leaf drop, wilting, and vascular discoloration were observed within 8 weeks after sowing into infested soil or within 6 weeks after inoculation into the root plugs of transplants. No symptoms were observed on noninoculated plants. V. dahliae was reisolated from the stems of all symptomatic plants. To our knowledge, this is the first report to document the recovery of V. dahliae from tall morningglory and its pathogenicity on chile pepper. References: (1) P. V. Pramateftaki et al. J. Fungal Genet. Biol. 29:19, 2000. (2). S. Sanogo and M. Clary. Plant Dis. 87:450, 2003. (3) P. W. Talboys. Plant Pathol. 9:57, 1979.

scholarly journals Verticillium dahliae Infects, Alters Plant Biomass, and Produces Inoculum on Rotation Crops

2016 ◽  
Vol 106 (6) ◽  
pp. 602-613 ◽  
Author(s):  
D. L. Wheeler ◽  
D. A. Johnson
Keyword(s):  
Host Range ◽  
Crop Rotation ◽  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Plant Biomass ◽  
Inoculum Density ◽  
Symptomatic Infection ◽  
Wide Host Range ◽  
Rotation Crops ◽  
Rotation Crop

Verticillium wilt, caused by Verticillium dahliae, reduces yields of potato and mint. Crop rotation is a potential management tactic for Verticillium wilt; however, the wide host range of V. dahliae may limit the effectiveness of this tactic. The hypothesis that rotation crops are infected by V. dahliae inoculum originating from potato and mint was tested by inoculation of mustards, grasses, and Austrian winter pea with eight isolates of V. dahliae. Inoculum density was estimated from plants and soil. Typical wilt symptoms were not observed in any rotation crop but plant biomass of some crops was reduced, not affected, or increased by infection of specific isolates. Each isolate was host-specific and infected a subset of the rotation crops tested but microsclerotia from at least one isolate were observed on each rotation crop. Some isolates were host-adapted and differentially altered plant biomass or produced differential amounts of inoculum on rotation crops like arugula and Austrian winter pea, which supported more inoculum of specific isolates than potato. Evidence of asymptomatic and symptomatic infection and differential inoculum formation of V. dahliae on rotation crops presented here will be useful in designing rotations for management of Verticillium wilt.

scholarly journals Impact of Seed Lot Infection on the Development of Black Dot and Verticillium Wilt of Potato in Washington

Plant Disease ◽  
2012 ◽  
Vol 96 (8) ◽  
pp. 1179-1184 ◽  
Author(s):  
Jeremiah K. S. Dung ◽  
Jason T. Ingram ◽  
Thomas F. Cummings ◽  
Dennis A. Johnson
Keyword(s):  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Root Colonization ◽  
Colletotrichum Coccodes ◽  
Potato Field ◽  
Black Dot ◽  
Plant Debris ◽  
Disease Symptoms ◽  
Field Soils ◽  
Potato Rotation

The fungi Colletotrichum coccodes and Verticillium dahliae are two pathogens of potato which are prevalent in potato field soils and seed tubers. The objective of this study was to investigate the influence of seed lot infection by C. coccodes and V. dahliae on disease severity and yield using infested seed lots and fields with and without potato in their recent cropping histories. Greater incidence of C. coccodes in seed led to more root colonization in 2008 (both field types) but not in 2007 and did not influence tuber quantity or yield. Incidence of infection in seed lots by V. dahliae was not related to canopy necrosis, infection of progeny tubers, or yield. However, seed lots exhibited more V. dahliae aboveground vascular colonization, canopy necrosis, infested plant debris, and infected progeny tubers in 5-year potato rotation fields compared with long potato rotation fields. In general, foliar disease symptoms and yield reductions were not related to levels of either pathogen in seed lots. Symptoms of both diseases were more severe and yields were lower in fields with potato in their recent cropping histories, emphasizing the importance of soilborne inoculum in the development of black dot and Verticillium wilt of potato.

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