Other Plant Sciences Commons^™

Incidence Of Wheat Streak Mosaic Virus, Triticum Mosaic Virus, And Wheat Mosaic Virus In Wheat Curl Mites Recovered From Maturing Winter Wheat Spikes, E. Byamukama, S. Tatineni, G. Hein, J. Mcmechan, S. N. Wegulo

Department of Plant Pathology: Faculty Publications

Wheat curl mites (WCM; Aceria tosichella) transmit Wheat streak mosaic virus (WSMV), Triticum mosaic virus (TriMV), and Wheat mosaic virus (WMoV) to wheat (Triticum aestivum L.) in the Great Plains region of the United States. These viruses can be detected in single, double, or triple combinations in leaf samples. Information on incidence of viruses inWCM at the end of the growing season is scant. The availability of this information can enhance our knowledge of the epidemiology ofWCM-transmitted viruses. This research was conducted to determine the frequency of occurrence of WSMV, TriMV, and WMoV in WCM populations on fieldcollected maturing …

Developing The Framework For A Risk Map For Mite Vectored Viruses In Wheat Resulting From Pre-Harvest Hail Damage, Anthony L. Nguy-Robertson, Arthur Zygielbaum, Anthony J. Mcmechan, Gary L. Hein, Stephen N. Wegulo, Abby R. Stilwell, Travis M. Smith

Department of Plant Pathology: Faculty Publications

There is a strong economic incentive to reduce mite-vectored virus outbreaks. Most outbreaks in the central High Plains of the United States occur in the presence of volunteer wheat that emerges before harvest as a result of hail storms. This study provides a conceptual framework for developing a risk map for wheat diseases caused by mite-vectored viruses based on pre-harvest hail events. Traditional methods that use NDVI were found to be unsuitable due to low chlorophyll content in wheat at harvest. Site-level hyperspectral reflectance from mechanically hailed wheat showed increased canopy albedo. Therefore, any increase in NIR combined with large …

Sequence Variation In Two Genes Determines The Efficacy Of Transmission Of Citrus Tristeza Virus By The Brown Citrus Aphid, S. J. Harper, N. Killiny, Satyanarayana Tatineni, S. Gowda, S. J. Cowell, T. Shilts, W. O. Dawson

Department of Plant Pathology: Faculty Publications

Vector transmission is an important part of the viral infection cycle, yet for many viruses little is known about this process, or how viral sequence variation affects transmission efficacy. Here we examined the effect of substituting genes from the highly transmissible FS577 isolate of citrus tristeza virus (CTV) in to the poorly transmissible T36-based infectious clone. We found that introducing p65 or p61 sequences from FS577 significantly increased transmission efficacy. Interestingly, replacement of both genes produced a greater increase than either gene alone, suggesting that CTV transmission requires the concerted action of co-evolved p65 and p61 proteins.

Field Damage Of Sorghum (Sorghum Bicolor) With Reduced Lignin Levels By Naturally Occurring Insect Pests And Pathogens, Patrick F. Dowd, Deanna L. Funnell-Harris, Scott E. Sattler

Department of Plant Pathology: Faculty Publications

Sorghum (Sorghum bicolor (L.) Moench) brown midrib (bmr) mutant lines have reduced levels of lignin, which is a potentially useful trait for bioenergy production, but the effects of this trait on insect and plant pathogen interactions are unknown under field conditions. Field-grown bmr6, bmr12, and wild-type (WT) plants were examined for insect and disease damage. In most cases, observed frequency, population, or leaf area damage caused by insects or pathogens on bmr6 or bmr12 plants were not greater than those observed on WT plants in the field or laboratory assays. European corn borers [Ostrinia nubilalis (Hübner)(Lepidoptera: …

What's New In Plant Pathology, Anthony O. Adesemoye, Loren Giesler, Robert M. Harveson, Tamra A. Jackson-Ziems, Kevin Korus, Stephen N. Wegulo

Department of Plant Pathology: Faculty Publications

Changes to the Disease Management Section of the 2016 Guide for Weed, Disease, and Insect Management in Nebraska

Biological control Products

Trivapro Fungicide

Priaxor D. Fungicide

Table 1. Foliar products for disease control that were updated in the 2016 Guide for Weed, Disease and Insect Management in Nebraska.

Table 2. Seed treatment products for disease control that were updated in the 2016 Guide for Weed, Disease and Insect Management in Nebraska.

Table 3. Seed treatment nematicide product that was updated in the 2016 Guide for Weed, Disease and Insect Management in Nebraska.

Fungicide Application Timing And Disease Control, Tamra A. Jackson-Ziems, Loren J. Giesler, Robert M. Harveson, Stephen N. Wegulo, Kevin Korus, Anthony O. Adesemoye

Department of Plant Pathology: Faculty Publications

Wet weather that persisted during much of the 2015 growing season proved to be very favorable for disease development in several crops across Nebraska. In particular, diseases caused by fungi were favored by repeated rainfall events and high relative humidity, fog, etc., that supported the production of more spores and continuous plant infection. On some susceptible varieties and hybrids, diseases developed early and quickly eventually reaching moderate to severe levels. Foliar fungicides were applied one or more times to some crops in an effort to mitigate losses due to disease. However, low crop prices and narrow profit margins made foliar …

Corn Disease Update, Tamra A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

The 2015 corn crop was impacted by several corn diseases from the beginning to the end of the season and in all areas of Nebraska. The increased severity and incidence of some diseases was largely due to the extended periods of favorable weather conditions in varying parts of the state that supported the increase in some diseases. In particular, frequent rainfall and high relative humidity were especially favorable for several fungal diseases. Unfortunately, almost all diseases of corn (except rusts) are caused by pathogens that can successfully overwinter in Nebraska. For this reason, making detailed notes on disease development and …

Trivapro A + Trivapro B Application Timing And Disease Efficacy In Field Corn In Nebraska, 2015, J. D. Harbour, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

The objective of the trial was to evaluate foliar fungicides and application timings for crop response and foliar disease efficacy. Irrigated corn was grown based on Nebraska Extension irrigation recommendations at the South Central Ag Lab near Clay Center, NE. Soils were a silt loam with 6.7 pH and 1.8 % OM and the previous crop was soybean. Reduced tillage was performed to the field prior to planting. Corn (DKC 65-79 RIB, tolerant to grey leaf spot (GLS)) was planted at approximately 34,000 seed/A on 26 May. Seven treatments were arranged in a randomized complete block design with six replications. …

Fungicide And Herbicide Effects On Grey Leaf Spot In Nebraska Field Corn, 2015, J. D. Harbour, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

The objective of the trial was to compare foliar fungicides applied to three growth stages of corn for grey leaf spot (GLS) efficacy. Irrigated corn was grown based on Nebraska Extension irrigation recommendations at the South Central Ag Lab near Clay Center, NE. Soils were a silt loam with 6.7 pH and 1.8 % OM and the previous crop was soybean. Reduced tillage was performed to the field prior to planting. Corn (DKC 65-79 RIB, tolerant to gray leaf spot (GLS)) was planted at approximately 34,000 seed/A on 26 May. Five treatments were arranged in a randomized complete block design …

A Foliar Fungicide Plus Herbicide Tank Mixture Evaluation In Field Corn In Nebraska, 2015, J. D. Harbour, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

The objective of the trial was to evaluate the tank mixture of Laudis herbicide plus Stratego YLD fungicide for corn response. Irrigated corn was grown based on Nebraska Extension irrigation recommendations at the South Central Ag Lab near Clay Center, NE. Soils were a silt loam with 6.7 pH and 1.8 % OM and the previous crop was soybean. Reduced tillage was performed to the field prior to planting. Corn (DKC 65-79 RIB, tolerant to gray leaf spot (GLS)) was planted at approximately 34,000 seed/A on 26 May. Four treatments were arranged in a randomized complete block design with six …

Corn Disease Profiles: Diseases Favored By Dry Conditions, Tamra A. Jackson-Ziems, Anthony O. Adesemoye, Loren J. Giesler, Robert M. Harveson, Kevin A. Korus, Stephen N. Wegulo

Department of Plant Pathology: Faculty Publications

Extension Circular 1910 (EC1910)

Extreme weather events are predicted to become increasingly common and could bring periods of drought as well as intense rainfall events. Wet conditions are favorable for many plant pathogens and the development of diseases, but some diseases may also develop during or following dry weather. The timing during the season when dry conditions occur, as well as other factors, such as temperature, impact which diseases develop and when. The list summarizes some of the most common corn diseases that can develop during dry conditions: Seedling Root Rot Diseases, Nematodes, Common Smut, Rust Diseases Charcoal Rot, Stalk …

Corn Disease Profiles: Diseases Favored By Wet Conditions, Tamra A. Jackson-Ziems, Anthony O. Adesemoye, Loren J. Giesler, Robert M. Harveson, Kevin A. Korus, Stephen N. Wegulo

Department of Plant Pathology: Faculty Publications

Extension Circular 1909 (EC1909)

Extreme weather events are predicted to become increasingly common and could bring periods of more intense rainfall. Wet conditions are favorable for many plant pathogens and the development of diseases. Seasonal timing when these conditions occur, as well as other factors such as temperature, impact which diseases develop and when. Listed, described, and illustrated are some common corn diseases favored by wet conditions: Pythium Root Rot, Eyespot, Northern Corn Leaf Blight, Gray Leaf Spot, Physoderma Brown Spot, Rust Diseases (Puccinia spp.), Stalk and Crown Rot Diseases (such as those caused by Fusarium and Diplodia spp.), …

From Seed To Sky: Impacts Of Explosive Compounds On Vegetation Across Spatial And Developmental Scales, Stephen M. Via

Theses and Dissertations

Explosive compounds are broadly distributed across the globe as a result of nearly two centuries of munitions use in warfare and military activities. Two explosive compounds have seen disproportionate use; RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) and TNT (2-methyl- 1,3,5-trinitrobenzene), being the most commonly found explosives in the environment. The effects of explosives on biota have been studied in great detail; however, there is a general lack of understanding with regard to broader ecological impacts of these contaminants. My dissertation objective was to follow the impacts of explosive compounds on vegetation across scales. Impacts on vegetation at the species scale alter community composition via …

Plant Functional Trait And Hyperspectral Reflectance Responses To Comp B Exposure: Efficacy Of Plants As Landmine Detectors, Paul V. Manley Ii

Theses and Dissertations

At least 110 million landmines have been planted since the 1970s in about 70 nations, many of which remain in place today. Some risk of detection may be mitigated using currently available remote sensing techniques when vegetation is present. My study focused on using plants as phytosensors to detect buried explosives. I exposed three species representing different functional types (Cyperus esculentus (sedge), Ulmus alata (tree), Vitis labrusca (vine)) to 500 mg kg^-1 of Composition B (Comp B; 60/40 mixture of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and 2,4,6-trinitrotoluene (TNT)), a commonly used explosive mixture, and measured functional traits and reflectance over …

Transcriptional Regulation Of Specialized Metabolites In Arabidopsis Thaliana And Catharanthus Roseus, Craig M. Schluttenhofer

Theses and Dissertations--Plant and Soil Sciences

For millennia humans have utilized plant specialized metabolites for health benefits, fragrances, poisons, spices, and medicine. Valued metabolites are often produced in small quantities and may command high prices. Understanding when and how the plant synthesizes these compounds is important for improving their production. Phytohormone signaling cascades, such as jasmonate (JA) activate or repress transcription factors (TF) controlling expression of metabolite biosynthetic genes. TFs regulating specialized metabolite biosynthetic genes can be manipulated to engineer plants with increased metabolite production.

WRKY transcription factor are known components of both JA signaling cascades and regulation of specialized metabolism. The presence of WRKY binding …

Multiple Records Of Monoecy In Dioecious Taxa Of Hawaiian Coprosma Spp. (Rubiaceae)., Jason T. Cantley, Danielle Frohlich, Chris Martine

Faculty Journal Articles

The breeding systems of the 110+ species of Coprosma J.R. Forst. & G. Forst. across the Pacific are largely considered dioecious, with male and female flowers occurring on separate plants (oliver 1935). However, for many species, particularly of New Zealand, the dioecious breeding system is leaky. Coprosma species exhibiting leaky dioecy are primarily dioecious, with male and female flowers on separate plants, but individuals occasionally develop apparently functional bisexual flowers, which sporadically occur among an abundance of unisexual flowers. A putative monoecious Coprosma taxon was once reported for the Macquarie Island individuals of C. perpusilla Colenso (= C. pumila Hook.f.), …

What Would The Babel Fish Say?, Monica Gagliano

Animal Sentience

Starting with its title, Key’s (2016) target article advocates the view that fish do not feel pain. The author describes the neuroanatomical, physiological and behavioural conditions involved in the experience of pain in humans and rodents and confidently applies analogical arguments as though they were established facts in support of the negative conclusion about the inability of fish to feel pain. The logical reasoning, unfortunately, becomes somewhat incoherent, with the arbitrary application of the designated human criteria for an analogical argument to one animal species (e.g., rodents) but not another (fish). Research findings are reported selectively, and questionable interpretations are …

Cryptic Species: A Leitmotif Of Contemporary Mycology Has Challenges And Benefits For Plant Pathologists, Frank M. Dugan, Sydney Everhart

Department of Plant Pathology: Faculty Publications

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 are clearly differentiated by both phylogeny and distinctive pathogenic traits and are assigned sub-specific designations. These new species names and the sub-specific designations are both cases of cryptic species that are, in some instances, relevant and/or critical for plant disease management. Here we provide examples of such 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 …

Foliar Fungicide Comparison For Southern Rust Management, Stay Green, Push Lodging, And Yield In Nebraska, 2015, J. D. Harbour, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

The objective of the trial was to compare foliar fungicides for southern rust (SR) efficacy. Irrigated corn was grown based on Nebraska Extension irrigation recommendations at the South Central Ag Lab near Clay Center, NE. Soils were a silt loam with 6.7 pH and 1.8 % OM and the previous crop was soybean. Reduced tillage was performed to the field prior to planting. Corn (DKC 65-79 RIB, tolerant to gray leaf spot (GLS)) was planted at approximately 34,000 seed/A on 26 May. Eight treatments were arranged in a randomized complete block design with six replications. . . . Stalk lodging …

Association Of Neonectria Macrodidyma With Dry Root Rot Of Citrus In California, A. O. Adesemoye, J. S. Mayorquin, B. B. Peacock, K. Moreno, S. Hajeri, R. Yokomi, A. Eskalen

Department of Plant Pathology: Faculty Publications

During yearly surveys that started in 2010 to identify pathogens associated with dry root rot disease of citrus in California, samples with root rot symptoms were collected in Tulare County. Small pieces of tissue from root samples were plated onto potato dextrose agar amended with 0.01% tetracycline and incubated at 25°C. Pure cultures of fungal isolates were identified by morphology and sequence analysis of the Internal Transcribed Spacer and Beta Tubulin regions. Neonectria macrodidyma (Cylindrocarpon macrodidymum) was first recovered in 2011 and has subsequently been recovered multiple times from citrus samples. The pathogen appeared to be widely distributed …