Entomology Commons^™

Rapid Molecular Detection And Population Genetics Of Pityophthorus Juglandis, A Vector Of Thousand Cankers Disease In Juglans Spp., Emel Oren

Masters Theses

Thousand Cankers Disease (TCD) is a disease complex involving the fungal pathogen Geosmithia morbida, an insect vector Pityophthorus juglandis, and the hosts, Juglans spp. and Pterocarya spp. Signs and symptoms of TCD include crown thinning due to branch dieback, yellowing and wilting of the leaves, appearance of epicormic shoots, numerous entrance/exit holes, gallery formation by P. juglandis, and the development of small, dark brown cankers underneath the bark. TCD originally described from western U.S., has now expanded to eastern U.S. and northwestern Italy. The disease complex is often difficult to diagnose due to the absence of symptoms …

Over-Summering Ecology Of The Wheat Curl Mite (Aceria Tosichella Keifer), Anthony J. Mcmechan

Department of Entomology: Dissertations, Theses, and Student Research

The wheat-mite-virus complex is a consistent and significant threat to winter wheat production in the western Great Plains. This complex consists of three viruses (Wheat streak mosaic virus, Triticum mosaic virus, and Wheat mosaic virus that are transmitted by the wheat curl mite (Aceria tosichella Keifer). Yield impacts from this complex are typically associated with the presence of volunteer wheat that emerges prior to harvest as a result of hail occurring during the heading stages of wheat in early summer. Historical literature on pre-harvest germination has been primarily focused on accelerating breeding programs; however, critical gaps in knowledge exist on …

Corn Following Corn In 2008, Mahdi Al-Kaisi, Roger W. Elmore, Antonio P. Mallarino, Palle Pedersen, Alison E. Robertson, John E. Sawyer, Jon J. Tollefson

John E. Sawyer

Corn following corn is in rough shape in areas across Iowa. Many wonder what is happening. The crop’s condition in general is not normal for this time of year. For example, last Sunday the USDA rated this year’s Iowa corn crop as 54 percent in ‘Good’ to ‘Excellent’ condition and 15 percent is ‘Poor’ or ‘Very Poor.’ Last year 72 percent was rated ‘Good’ to ‘Excellent’ and 5 percent was in ‘Poor’ or ‘Very Poor’ condition during the same week. Average plant height as of Sunday was 24 inches compared to 40 inches at end of the same week last …

Exploration Of Chemical And Biological Management Strategies For Diaphorina Citri The Primary Vector Of Candidatus Liberibacter Asiaticus, Gretta Marie Sharp

Biology Theses

Diaphorina citri (Hemipteran: Psyllidae), the Asian citrus psyllid, is a phloem-feeding, invasive species endemic to southern Asia that was first identified in the United States in Florida in 1998. Since introduction, D. citri has spread across the major citrus growing regions of the United States. This is of great concern to the citrus industry because D. citri is the primary vector of Candidatus Liberibacter asiaticus the causal agent of Haunglongbing (HLB). Haunglongbing is the most economically devastating disease of citrus causing an estimated 8.92 billion dollars lost in revenue and 4.62 billion dollars lost in gross domestic product between 2006-2007 …

A Brief History Of Corn: Looking Back To Move Forward, Jon Derek Pruitt

Doctor of Plant Health Program: Dissertations and Student Research

Maize was domesticated from teosinte in Mexico some 7,000 to 10,000 years ago and quickly spread through the Americas. It has become one of the most important crops at a local and global level. Two types, Northern Flint corn and Southern Dent corns provided the basis of the genetic background of modern maize hybrids. The development of hybrids, first double-cross and later single-cross hybrids, along with a transition to high input farming provided huge yield increases, which have continued to improve with improving technology.

Increase in maize production also caused a rise in Western corn Rootworm (Diabrotica virgifera virgifera …

Managing Drought Stress In California Agricultural Systems, Gregory D. Brittain Jr.

Doctor of Plant Health Program: Dissertations and Student Research

California is currently facing a historic drought, and this has led many farmers in the state to severely cut back on irrigation. Optimal use of water for irrigation requires a comprehensive understanding of how plants respond physiologically to water stress (Chapter 1). By monitoring water requirements in crops and managing irrigation to meet those requirements, growers can significantly reduce water use (Chapter 2). This can be done through improving application efficiency of irrigation technology as well as increasing the water use efficiency of the crops themselves. Deficit irrigation practices can be used to manipulate the physiology of water use in …

Ecological Risks Of The Conventional Insecticide/Fungicide Seed Treatment Mixture Of Thiamethoxam And Mefenoxam In Soybean On Beneficial Insects, Carolina Camargo

Department of Entomology: Dissertations, Theses, and Student Research

The impact of neonicotinoid seed treatments on beneficial insects has been a controversial topic during the last years. While neonicotinoids are usually used as mixtures with systemic fungicides, few studies have examined the impact of the mixtures on beneficial insects. Pesticide mixtures can have synergistic, additive, or antagonistic effects on the toxicity of neonicotinoids on non-target species.

Thiamethoxam with mefenoxam is the most used neonicotinoid insecticide/fungicide mixture applied to soybean. Based on the systemic nature of thiamethoxam and mefenoxam, residues of this insecticide/fungicide mixture can be present in soybean vegetative and floral tissue with potential impacts to beneficial insects. This …