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Characterization And Management Of Auxin-Resistant Palmer Amaranth In Tennessee, Delaney C. Foster

Doctoral Dissertations

Palmer amaranth has a long history of evolving resistance to herbicides to the point it has become a significant row crop production obstacle. Cotton and soybean growers were offered new technologies in 2016, expanding in-crop herbicide options to include dicamba or 2,4-D. Within three years of commercialization, dicamba use in these crops increased ten-fold and growers began to report Palmer amaranth escapes in west Tennessee auxin-tolerant production systems. A survey of Palmer amaranth escapes in dicamba and 2,4-D-tolerant cotton and soybean fields in Tennessee was conducted in the fall of 2021 with the objective of determining if poor control was …

Fungicide Sensitivity Screening Of Corynespora Cassiicola In Us Soybean And Cotton, Tyler Miles Smith

Doctoral Dissertations

Target spot, caused by the fungus Corynespora cassiicola, is a foliar disease of cotton and soybean. Target spot has become a disease of concern in soybean and cotton production systems. Data for fungicide sensitivity and understanding potential impact on yield is lacking for C. cassiicola. Fungicide resistance is also a concern in C. cassiicola with the increase in resistant pathogens in soybean. With the lack of knowledge about baseline fungicide sensitivity and the concern of fungicide resistance the objectives of this study were: (i) to evaluate fungicide products and mixes in small plot soybean and cotton trials, (ii) …

A Site-Specific And Dynamic Modeling System For Zoning And Optimizing Variable Rate Irrigation In Cotton, Amir Haghverdi

Doctoral Dissertations

Cotton irrigation has been rapidly expanding in west Tennessee during the past decade. Variable rate irrigation is expected to enhance water use efficiency and crop yield in this region due to the significant field-scale soil spatial heterogeneity. A detailed understanding of the soil available water content within the effective root zone is needed to optimally schedule irrigation. In addition, site-specific crop-yield mathematical relationships should be established to identify optimum irrigation management. This study aimed to design and evaluate a site-specific modeling system for zoning and optimizing variable rate irrigation in cotton. The specific objectives of this study were to investigate …

Giant Ragweed (Ambrosia Trifida L.) Biology, Competition, And Control In Cotton (Gossypium Hirsutum L.), Kelly Anna Barnett

Doctoral Dissertations

The objectives of this research were to evaluate control options and investigate the biology and competitiveness of glyphosate-resistant (GR) giant ragweed in cotton. Our results determined that glufosinate followed by glufosinate, glufosinate plus pyrithiobac, and glufosinate plus fluometuron at 0.56 or 1.12 kg ai ha^-1 resulted in the highest level of visual control and the highest yield. However, glufosinate followed by glufosinate was the only treatment that resulted in the highest yield and > 90% control of GR giant ragweed.

The development of glufosinate-tolerant, 2,4-D tolerant, and dicamba-tolerant crops may provide growers with new opportunities for difficult-to-control weeds such as …