Showing papers in "Plant Health Progress in 2016"
Mississippi State University1, University of Kentucky2, Iowa State University3, South Dakota State University4, Michigan State University5, University of Arkansas6, Pennsylvania State University7, Oklahoma State University–Stillwater8, Ohio State University9, University of Florida10, University of Costa Rica11, University of Maryland, College Park12, Louisiana State University13, Texas A&M University14, Kansas State University15, University of Tennessee16, University of Georgia17, University of Delaware18, North Carolina State University19, University of Minnesota20, North Dakota State University21, Virginia Tech22, Clemson University23, DuPont Pioneer24, Auburn University25, University of Wisconsin-Madison26, Ontario Ministry of the Environment27, Purdue University28, University of Missouri29
TL;DR: Annual decreases in corn yield caused by diseases were estimated by surveying members of the Corn Disease Working Group in 22 corn-producing states in the United States and in Ontario, Canada from 2012 through 2015 by finding foliar diseases commonly caused the largest estimated yield loss.
Abstract: Annual decreases in soybean (Glycine max L. Merrill) yield caused by diseases were estimated by surveying university-affiliated plant pathologists in 28 soybean-producing states in the United State...
181 citations
University of Minnesota1, Iowa State University2, Purdue University3, Pennsylvania State University4, Michigan State University5, Ohio State University6, North Dakota State University7, University of Nebraska–Lincoln8, University of Wisconsin-Madison9, South Dakota State University10, Kansas State University11, University of Illinois at Urbana–Champaign12
TL;DR: How soy bean aphid impacts soybean yield, the role of biology and economics in recommendations for soybean aphid management, and the shortand long-term consequences of inappropriately timed insecticide applications are reviewed.
Abstract: Soybean aphid, Aphis glycines Matsumura, remains the key insect pest of soybean, Glycine max (L.) Merrill, in the north-central United States. Management of this pest has relied primarily ...
34 citations
TL;DR: The terms used to describe symptoms of delayed senescence in soybean often are used inconsistently or interchangeably and do not adequately distinguish the observed symptoms in the field, so the terms standardized at the end of this article standardized the terms used.
Abstract: The terms used to describe symptoms of delayed senescence in soybean often are used inconsistently or interchangeably and do not adequately distinguish the observed symptoms in the field. ...
28 citations
TL;DR: The results indicate that although yield increases can occur with foliar fungicide and/or insecticide treatments, current market prices and application costs may limit profitability when disease and/ or insect pressure is low.
Abstract: Foliar disease and insect management on soybean (Glycine max L. Merrill) in the North Central region of the United States has been increasingly accomplished through foliar fungicide and in...
21 citations
TL;DR: Questions from researchers and from agribusiness and extension professionals who advise farmers include: • When will there be a molecular test for HG type (or SCN race)?
Abstract: It has been more than 45 years since the race test was created to describe and differentiate the ability of populations of the soybean cyst nematode (SCN), Heterodera glycines, to reproduce on resistant soybean cultivars (Golden et al. 1970). Nearly 15 years have passed since the updated adaptation of the race test, the HG type test, was established (Niblack et al. 2002). Unfortunately, confusion still exists about the concept of SCN race and HG type. Questions from researchers and from agribusiness and extension professionals who advise farmers include: • When will there be a molecular test for HG type (or SCN race)? • How many HG types (or races) are there in a field? • Do seed treatments work against all HG types (or races)?
16 citations
TL;DR: Growers should be aware that a broad range of ornamental plants, including previously unknown hosts, can be latently infected by non-Race 3 biovar 2 strains of R. solanacearum that are also highly virulent on tomato.
Abstract: A strain of Ralstonia solanacearum was associated with wilting and blight of flowering ornamentals grown from cuttings that originated in Guatemala. This isolate, UW757, could wilt geraniu...
15 citations
TL;DR: A field trial in 2012 indicated a possible disease complex between Pythium aphanidermatum and the root-knot nematode (RKN) Meloidogyne incognita in cucumber as mentioned in this paper.
Abstract: A field trial in 2012 indicated a possible disease complex between Pythium aphanidermatum and the root-knot nematode (RKN) Meloidogyne incognita in cucumber. Two growth chamber trials were conducte...
14 citations
TL;DR: Investigators using artificial methods to phenotype wheat cultivars for reaction to head blast are encouraged to use this protocol to facilitate worldwide communication of data on the reaction of wheat cultivar to this devastating disease.
Abstract: Wheat blast, caused by the Triticum pathotype of Magnaporthe oryzae, poses a significant threat to wheat production worldwide. Because this pathotype does not occur in the United States, it is impo...
13 citations
TL;DR: Discrete microsclerotia of C. pseudonaviculata from culture were treated with eight commercially available sanitizers and were found to be more sensitive regardless of size, suggesting differences between the species should be elucidated.
Abstract: Discrete microsclerotia of C pseudonaviculata from culture were treated with eight commercially available sanitizers (ZeroTol 20, Oxidate, Sanidate, X³, Greenshield, and Lysol Concentrate at maximum label rates, plus 70% Ethanol and 06% sodium hypochlorite) to determine effective methods of disinfestation of nursery beds and benches Ethanol proved most effective, killing microsclerotia in less than 5 min ZeroTol, 10% bleach, and 70% ethanol were used in comparison tests of microsclerotia of C pseudonaviculata and C henricotiae Microsclerotia of C henricotiae were found to be more sensitive regardless of size This finding, along with other research that has found differences in fungicide sensitivity and thermotolerance between the two species, suggests that differences between the species should be elucidated
13 citations
TL;DR: Two commercial woody ornamental nurseries were sampled for the presence of Phytophthora over a period of 3 years, and puddles on the pathways had the highest percentage of positive samples.
Abstract: Two commercial woody ornamental nurseries were sampled for the presence of Phytophthora over a period of 3 years. The samples were taken every 2 months at different sections of propagation (greenhouses, plastic tunnels) and cultivation (container stands) as well as from nearby pathways and from a water recycling system with slow sand filter. Different materials like soil, substrates, residues, wind-carried leaves, and water and sediment were sampled. In total 12 known Phytophthora species could be detected. Three isolates did not match any of the known species. P. ramorum, P. gonapodyides, and P. plurivora were the species with the highest detection rates. P. ramorum could be detected at all seasons of the year. In total, puddles on the pathways had the highest percentage of positive samples. Residues, wind-carried leaves, and water and sediment from the runoffs were also good places for Phytophthora survival. In both nurseries, the plant samples showed very low infection rates. Ideas for surveys and management are discussed.
13 citations
TL;DR: Recommendations are made that appropriate fungicide resistance management measures should be employed in strawberry growing areas of the Central Coast region of California.
Abstract: Grey mold, caused by Botryis cinerea, is one of the most important diseases of strawberry in California. Management of grey mold typically relies on repeated fungicide applications. The oc...
TL;DR: This research quantified the impact of these three management strategies, alone and in combination, on BYD disease progress and grain yields in Kansas and found integrating management practices can result in high levels of control of BYD in Kansas.
Abstract: Barley yellow dwarf (BYD) is one of the most important wheat diseases in the state of Kansas. Several methods of disease management have been recommended to mitigate losses from BYD includ...
TL;DR: A survey of Christmas tree farms in southern Sweden to identify prominent disease and pest problems found dead tops of Norway spruce and Neonectria fuckeliana, the first report of N. neomacrospora in Sweden, causing top dieback on young spruce.
Abstract: In May 2015, a Christmas tree disease and pest survey was carried out in southern Sweden. Neonectria canker found on spruce and fir was the most prominent disease problem. Accepted for publication ...
TL;DR: The present survey results indicates that research efforts should be directed towards developing solutions for managing important watermelon diseases.
Abstract: Watermelon is an important crop grown for its fruit in the United States and many other countries across the world. A survey of members of the Watermelon Research and Development Group was...
TL;DR: The best sources of downy mildew resistance seems to be found in cultivars from the United Kingdom and continental Europe, and such cultivars are typically lower yielding and lack distinctive aroma and flavor characteristics presently desired by craft brewers.
Abstract: Hop downy mildew (caused by Pseudoperonospora humuli) is a yield-limiting disease in many hop-production regions of the world. In this research, 110 cultivars that are or were widely grown...
TL;DR: The ability to import and process large datasets and the multiplatform nature of the ECX package overcomes limitations presented in other software can increase the use of the spiral plating technique for sensitivity studies.
Abstract: Spiral plating technique is reliable, repeatable, and more efficient than dilution plating methods in studying the efficacy of antimicrobial products. In this method, the concentration of ...
TL;DR: A cost/ benefit analysis showed deferred fungicide application after VT hail, and immediate and deferred applications after VT for non-hail plots did provide positive economic returns, and results will help inform decisions about fungicide use in hail-damaged corn when foliar diseases are not present at high levels.
Abstract: To test if fungicide applied to hail-injured corn improves yield and reduces disease, we simulated hail at VT and R2 growth stages for three years at three Iowa locations for a total of fi...
TL;DR: In the field trials, copper oxychloride + copper hydroxide plus famoxadone + cymoxanil plus an extract from Reynoutria sachalinensis (Regalia), and B. subtilis (Serenade ASO) were more effective in reducing incidence and severity of bacterial spot on both leaves and fruit compared to controls.
Abstract: Bacterial spot, caused by Xanthomonas cucurbitae, has become one of the most important diseases of pumpkin. Seventeen chemical compounds and five biocontrol agents were evaluated for their...
TL;DR: This poster presents a probabilistic procedure to identify the phytochemical properties of nitrogen-fixing insects that can be passed off to animals as well as to humans.
Abstract: Cercospora leaf blight and purple seed stain are economically important diseases of soybean throughout the Lower Mississippi River Valley and Gulf South USA. Fungicide resistance was documented in ...
TL;DR: This research presents a new approach to plant pathology that combines a high-resolution 3D model, 3D image analysis, and a simple 2D model that allows for real-time analysis of the response of the immune system to pesticides.
Abstract: Melissa D. Irizarry, Department of Plant Pathology, Iowa State University, Ames 50011; Carol L. Groves, Department of Plant Pathology, University of Wisconsin-Madison 53706; Manjula G. Elmore, Department of Plant Pathology, Iowa State University, Ames 50011; Carl A. Bradley, Department of Crop Sciences, University of Illinois, Urbana 61801 (current address: Department of Plant Pathology, University of Kentucky, Princeton 42445); Ranjit Dasgupta and Thomas L. German, Department of Entomology, University of WisconsinMadison 53706; Douglas J. Jardine, Department of Plant Pathology, Kansas State University, Manhattan 66506; Erika Saalau Rojas, Department of Plant Pathology, Iowa State University, Ames 50011 (current address: UMass Cranberry Station, University of MassachusettsAmherst, East Wareham 02538); Damon L. Smith, Department of Plant Pathology, University of Wisconsin-Madison 53706; Albert U. Tenuta, Ontario Ministry of Agriculture, Food, and Rural Affairs; University of Guelph, Ridgetown N0P 2C0, Canada; Steven A. Whitham and Daren S. Mueller, Department of Plant Pathology, Iowa State University, Ames 50011
TL;DR: Polyoxin D could be used to prevent outbreaks of gummy stem blight on watermelon and muskmelon seedlings grown for use as transplants and as effective as mancozeb.
Abstract: Keinath, A. P. 2016. Polyoxin D and other biopesticides reduce gummy stem blight but not anthracnose on melon seedlings. Plant Health Prog. 17:177-181. Biopesticides may be useful to prevent fungal foliar diseases on cucurbit seedlings in greenhouses because of the short re-entry intervals, normally 4 h. Bacillus subtilis QST 713 (Serenade ASO), root extract of Reynoutria sachalinensis (Regalia), hydrogen dioxide (Oxidate), paraffinic oil (JMS Stylet Oil), polyoxin D (Oso), and 92% edible fish oil + 5% sesame oil (Organocide) were evaluated against gummy stem blight on muskmelon seedlings and anthracnose on watermelon seedlings. Polyoxin D applied alone, B. subtilis QST 713 followed by polyoxin D, and R. sachalinensis extract followed by B. subtilis QST 713 reduced the severity of gummy stem blight and were as effective as mancozeb. None of the biopesticides applied alone or sequentially were effective against anthracnose. Polyoxin D could be used to prevent outbreaks of gummy stem blight on watermelon and muskmelon seedlings grown for use as transplants.
TL;DR: Artificial inoculation of logs, and later, trees, confirmed that P. ramorum caused phloem cankers on canyon live oak, but cankers showed either no or minuscule external bleeding.
Abstract: Mortality of large canyon live oaks suddenly appeared in natural stands in San Mateo, CA, starting in 2007. A survey of affected stands showed that symptomatic trees were spatially associa...
TL;DR: A quantifiable rating scale may be useful to stakeholders in making FLS management decisions and may be used in developing thresholds for FLS action in cultivar screenings and foliar fungicide efficacy trials.
Abstract: A quantifiable rating scale based on disease severity was developed for frogeye leaf spot (FLS) using image analysis software. The scale may be useful for estimating FLS severity in producer fields...
TL;DR: The western tarnished plant bug, Lygus hesperus Knight (Hemiptera: Miridae), can be a serious pest of celery, Apium graveolens dulce (Mill.) Pers.
Abstract: The western tarnished plant bug, Lygus hesperus Knight (Hemiptera: Miridae), can be a serious pest of celery, Apium graveolens dulce (Mill.) Pers. in the Central Coast region of California. Little is known about injury symptoms caused by L. hesperus adults on celery. When celery seedlings were exposed to L. hesperus adults, their crown area was found destroyed with necrotic dead tissue. Destroyed crowns of dead seedlings were observed when seedlings were exposed to five or more L. hesperus adults for ≥24 h but was not observed on seedlings exposed ≤12 h. In addition, elongated lesions were noticed on the celery petiole and were significantly greater when exposed to five or more L. hesperus adults for as little as 4 h. Number of elongated lesion injuries and number of eggs recovered from elongated lesions was correlated (r = 0.66; P < 0.001). Data provide key diagnostic symptoms of L. hesperus feeding and ovipositional injury on celery seedlings. Also, this study expands our understandings on the effects of L. hesperus adult density and duration of exposure which reinforces the need for regular scouting, and immediate management decisions and action to reduce losses from L. hesperus injury in both celery seedlings and mature plants in greenhouse and field settings, respectively
TL;DR: Examples of instances in which newly described taxa differ from the original (“parent”) in phenotypic traits of importance to plant disease management: host range, fungicide sensitivity, environmental niche, metabolite production, regulatory status, or other attributes are provided.
Abstract: Multiple traditional species names for plant pathogenic fungi have been supplemented with new names that delimit formerly cryptic species. In separate instances, isolates within a species ...
TL;DR: This study established the presence of Phytophthora spp.
Abstract: Phytophthora nicotianae and P. palmivora are common soilborne oomycete pathogens that affect tree health in citrus groves by infecting fibrous roots. Recent evidence indicates that trees affected by huanglongbing (HLB), caused by ‘Candidatus Liberibacter asiaticus’, have higher chances of increased propagule counts of Phytophthora spp. (Graham et al. 2003). In response to the discovery of HLB in Texas in January 2012, we initiated this study on the distribution of Phytophthora spp. in soils of South Texas citrus orchards. Soil samples were collected from 61 citrus groves (Fig.1), from four quadrants of a single tree selected arbitrarily. The sample area was about a 3-m-diameter circle under the canopy of the tree and in the root zone of each tree. Five replicate samples were collected from each quadrant. Those samples were pooled prior to analysis and the propagule density determined for each of the four quadrants and then averaged for the site. Phytophthora spp. was first identified by following a standard soil plating protocol (Timmer et al. 1988). The medium used was supplemented with 10 mg/liter of rifampicin. DNA was extracted from all 61 soil samples using PowerSoil DNA Isolation Kit (Catalog No. 12888-50, MO BIO Laboratories, Inc. DNA), and was amplified by PCR using primers common to 16 species of Phytophthora (Drenth et al. 2006) and also species-specific primers (Drenth et al. 2006; Ippolito et al. 2002). No Phytophthora spp. was detected at Sites 60 and 41 using universal primers, indicating the absence of the 16 species. Phytophthora citrophthora was restricted to 13 sites (Fig. 1; Table.1). Phytophthora citrophthora usually occurs in cooler sites near coastal areas (Graham and Timmer 1992). Phytophthora nicotianae was identified from most of the sites. Phytophthora spp. isolates from Site 11 and Site 15 showed morphological features resembling P. ramorum, but that species was not detected by PCR. Phytophthora palmivora was not identified in any soil sample; P. palmivora is a pathogen of citrus and many fruit crops primarily in the humid tropical areas (Zitko et al. 1991). Data were analyzed by calculating the proportion of orchards that had soil populations above or below 10 to 20 propagules/cm, a value that is considered of concern (Graham et al. 2003). Since our data were not normally distributed, a nonparametric statistical test, signed rank, was used. The tests were one-sided and conducted against baseline values of 10 or 20 propagules/cm (α ≤ 0.05). Twenty-four sites had a P value of ≤0.05. Our results indicated that 18 sites were significantly higher than the baseline of 20 propagules/cm. Though counts of 10 to 20 propagules/cm are considered important, establishment of firm threshold levels are not simple or easy because of the complex relationship between fungal populations, fibrous root densities, and yield (Zitko et al. 1991). Prior evaluations of presence of Phytophthora spp in the Lower Rio Grande Valley (Timmer 1973) identified only P. parasitica (now P. nicotianae). In our study, we have now established the presence of P. citrophthora in the Valley. In addition, we have quantified populations in that area for the first time. Growers with orchards with propagule counts greater than 10 to 20 propagules/cm should consider treatment with an appropriate fungicide such as mefenoxam or fosetyl-Al (Zitko et al 1991).
TL;DR: To determine if LiRMoV was present in the symptomatic lilacs, total nucleic acids (TNA) were extracted from symptomatic leaf tissues using a procedure modified from Hughes and Galau (1988).
Abstract: In May 2015, the Oregon Department of Agriculture investigated a report of potential virus symptoms being observed on lilac plants (Syringa vulgaris L.) produced by a nursery in Marion County. Simultaneously, symptomatic lilac plant samples were received by the Oregon State University Plant Clinic from a customer of the same nursery. Lilac ‘President Grevy’ plants inspected at the nursery showed symptoms of leaf deformation, reduction in leaf size, ring spots, and line patterns (Fig. 1). Two months later, similar foliar symptoms were observed on lilac ‘Krasavitsa Moskvy’ plants at the same nursery (Fig. 2). Symptoms on both cultivars resembled those reported for Lilac ring mottle virus (LiRMoV) (Van Der Meer et al. 1976). LiRMoV is an isometric RNA virus within the family Bromoviridae and genus Ilarvirus (Scott and Ge 1995; Scott and Zimmerman 2008) and has only been reported from the Netherlands. The virus was sap transmissible to herbaceous hosts under experimental conditions and was seed transmissible in the experimental hosts Chenopodium quinoa, C. amaranticolor, and Celosia argentea (Van der Meer et al. 1976). Symptom expression in infected lilac is influenced by environmental conditions and may be erratic; thus, infections may remain cryptic for years (Van der Meer et al. 1976). To determine if LiRMoV was present in the symptomatic lilacs, total nucleic acids (TNA) were extracted from symptomatic leaf tissues using a procedure modified from Hughes and Galau (1988). The TNA was used in ONE-STEP PCR reactions (Qiagen, Germantown, MD) at a melting temperature of 55°C and with primers (downstream: 5′-GAGACCGAAGTCTTCTTCC-3′ and upstream: 5′-CCACGTGCTTCTCACCC-3′) specific for the movement protein of the RNA3 of LiRMoV (GenBank Accession No. U17391) (Scott and Zimmerman 2008). In addition to the TNA from the samples, a positive control (plasmid pLRMV-7) (Scott and Zimmerman 2008) and negative controls (healthy plant tissue and water) were analyzed in concurrent PCR reactions. The anticipated 649-bp amplicon was produced in the lilac samples and in the positive control, but not in the negative controls. The amplicons from seven lilac samples were cloned using the pGemT Easy Vector (Promega, Madison, WI), selected by blue-white screening, and then sequenced using the primer M13F. The contiguous sequence generated was deposited into GenBank (Accession No. KX090269). Six of the seven clones contained an FIGURE 1 Foliar symptoms caused by Lilac ring mottle virus on lilac ‘President Grevy.’
TL;DR: To complete Koch's postulates, Calonectria pseudonaviculata’s conidia were produced as previously described and genomic DNA was extracted from fungal mycelium using the DNeasy Plant Mini Kit and amplified through PCR using β-tubulin primers.
Abstract: To the authors' knowledge, this is the first report of Boxwood blight in Florida. Accepted for publication 22 September 2016.
TL;DR: It is demonstrated that fluopyram seed treatment is effecttive at controlling early season brown spot in soybean through reducing the Area Under Disease Progress Curve of brown spot.
Abstract: Early season brown spot caused by Septoria glycines was compared in Illinois, Indiana, Iowa, Michigan, and Ontario, Canada, soybean fields planted with differing commercial seed treatments...
TL;DR: During the fall of 2015, Knock Out roses growing in a commercial landscape in Bossier City, LA, exhibited symptoms similar to those reported for rose rosette disease caused by Rose ro sette virus (RRV).
Abstract: To the authors' knowledge, this is the first report of rose rosette disease caused by Rose rosette virus on Knock Out roses in Louisiana. It is difficult to assess the total value of roses in Louis...