{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/70606"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/70606","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Yield Loss Models for Foliar Diseases of Alfalfa and Evaluation of Chemical and Cultural Disease Control Methods","abstract":"Regression models relating various measures of disease level to yield were developed for the complex of fungi which cause foliar disease on alfalfa (Medicago sativa). The accuracy and precision of the models was evaluated using data other than those from which the models were constructed. Linear models using disease severity one week before harvest (DS1), on the day of harvest (DS0), or area-under-disease-progress curve (AUDPC) to predict yield as percent of maximum explained 52 to 60% of the variation in yield. Models estimated a yield reduction of 2.40, 1.83, and 0.142% for each DS1, DS0, and AUDPC unit, respectively. All models overestimated yield but were more accurate within the range of disease levels commonly observed in alfalfa fields than at higher levels. Field studies were done to determine the economically optimal fungicide application frequency and timing for control of alfalfa leaf spot diseases and identify the predominant fungal pathogens responsible for causing foliar disease. A single application of mancozeb after 10 to 14 days of regrowth was the most profitable treatment schedule with a 215% return on investment and net marginal return of $20.58/ha. Stemphylium botryosum and Phoma medicaginis were the predominant pathogens with Leptosphaerulina and Colletotrichum spp. also present at lower but significant levels. The contribution of an early harvest towards minimizing yield and quality losses due to foliar diseases of alfalfa was evaluated. High and low levels of disease were established using inoculations and fungicides. Fungicide protected plots yielded more dry matter, crude protein, and digestible dry matter. Differences between disease level treatments for these variables increased with time. However, even at high disease levels, values for these response variables increased over time. Hay digestibility was reduced when disease levels were high and decreased with time regardless of the disease level treatment. Therefore, early harvesting of alfalfa affected by foliar disease may improve hay quality but not the quantity of dry matter and quality constituents.","abstract_html":"Regression models relating various measures of disease level to yield were developed for the complex of fungi which cause foliar disease on alfalfa (Medicago sativa). The accuracy and precision of the models was evaluated using data other than those from which the models were constructed. Linear models using disease severity one week before harvest (DS1), on the day of harvest (DS0), or area-under-disease-progress curve (AUDPC) to predict yield as percent of maximum explained 52 to 60% of the variation in yield. Models estimated a yield reduction of 2.40, 1.83, and 0.142% for each DS1, DS0, and AUDPC unit, respectively. All models overestimated yield but were more accurate within the range of disease levels commonly observed in alfalfa fields than at higher levels. Field studies were done to determine the economically optimal fungicide application frequency and timing for control of alfalfa leaf spot diseases and identify the predominant fungal pathogens responsible for causing foliar disease. A single application of mancozeb after 10 to 14 days of regrowth was the most profitable treatment schedule with a 215% return on investment and net marginal return of $20.58/ha. Stemphylium botryosum and Phoma medicaginis were the predominant pathogens with Leptosphaerulina and Colletotrichum spp. also present at lower but significant levels. The contribution of an early harvest towards minimizing yield and quality losses due to foliar diseases of alfalfa was evaluated. High and low levels of disease were established using inoculations and fungicides. Fungicide protected plots yielded more dry matter, crude protein, and digestible dry matter. Differences between disease level treatments for these variables increased with time. However, even at high disease levels, values for these response variables increased over time. Hay digestibility was reduced when disease levels were high and decreased with time regardless of the disease level treatment. Therefore, early harvesting of alfalfa affected by foliar disease may improve hay quality but not the quantity of dry matter and quality constituents.","abstract_has_math":false,"creators":["Broscious, Steven Charles"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Plant Pathology","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2014,"date_issued":"2014-12-15T23:52:23Z","date_published":"2014-12-15T23:52:23Z","updated_at":"2026-07-22T22:26:03Z","subjects":["Agriculture, Plant Pathology"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["(UMI)AAI8701442"],"render_values":[{"text":"(UMI)AAI8701442","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/70606","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Broscious, Steven Charles"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2014-12-15T23:52:23Z","10000-01-01","1986"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Plant Pathology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Agriculture, Plant Pathology"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/70606","(UMI)AAI8701442"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Regression models relating various measures of disease level to yield were developed for the complex of fungi which cause foliar disease on alfalfa (Medicago sativa). The accuracy and precision of the models was evaluated using data other than those from which the models were constructed. Linear models using disease severity one week before harvest (DS1), on the day of harvest (DS0), or area-under-disease-progress curve (AUDPC) to predict yield as percent of maximum explained 52 to 60% of the variation in yield. Models estimated a yield reduction of 2.40, 1.83, and 0.142% for each DS1, DS0, and AUDPC unit, respectively. All models overestimated yield but were more accurate within the range of disease levels commonly observed in alfalfa fields than at higher levels. Field studies were done to determine the economically optimal fungicide application frequency and timing for control of alfalfa leaf spot diseases and identify the predominant fungal pathogens responsible for causing foliar disease. A single application of mancozeb after 10 to 14 days of regrowth was the most profitable treatment schedule with a 215% return on investment and net marginal return of $20.58/ha. Stemphylium botryosum and Phoma medicaginis were the predominant pathogens with Leptosphaerulina and Colletotrichum spp. also present at lower but significant levels. The contribution of an early harvest towards minimizing yield and quality losses due to foliar diseases of alfalfa was evaluated. High and low levels of disease were established using inoculations and fungicides. Fungicide protected plots yielded more dry matter, crude protein, and digestible dry matter. Differences between disease level treatments for these variables increased with time. However, even at high disease levels, values for these response variables increased over time. Hay digestibility was reduced when disease levels were high and decreased with time regardless of the disease level treatment. Therefore, early harvesting of alfalfa affected by foliar disease may improve hay quality but not the quantity of dry matter and quality constituents.","Made available in DSpace on 2014-12-15T23:52:23Z (GMT). No. of bitstreams: 1 8701442.pdf: 3350310 bytes, checksum: 79b396b8816cd688cab3c960c2f49bf1 (MD5) Previous issue date: 1986","Embargo set by: Seth Robbins for item 70772 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","115 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1986."]},{"key":"dc:title","label":"Title","values":["Yield Loss Models for Foliar Diseases of Alfalfa and Evaluation of Chemical and Cultural Disease Control Methods"]}]}],"canonical_facts":{"dc:creator":["Broscious, Steven Charles"],"dc:date":["2014-12-15T23:52:23Z","10000-01-01","1986"],"dc:description":["Regression models relating various measures of disease level to yield were developed for the complex of fungi which cause foliar disease on alfalfa (Medicago sativa). The accuracy and precision of the models was evaluated using data other than those from which the models were constructed. Linear models using disease severity one week before harvest (DS1), on the day of harvest (DS0), or area-under-disease-progress curve (AUDPC) to predict yield as percent of maximum explained 52 to 60% of the variation in yield. Models estimated a yield reduction of 2.40, 1.83, and 0.142% for each DS1, DS0, and AUDPC unit, respectively. All models overestimated yield but were more accurate within the range of disease levels commonly observed in alfalfa fields than at higher levels. Field studies were done to determine the economically optimal fungicide application frequency and timing for control of alfalfa leaf spot diseases and identify the predominant fungal pathogens responsible for causing foliar disease. A single application of mancozeb after 10 to 14 days of regrowth was the most profitable treatment schedule with a 215% return on investment and net marginal return of $20.58/ha. Stemphylium botryosum and Phoma medicaginis were the predominant pathogens with Leptosphaerulina and Colletotrichum spp. also present at lower but significant levels. The contribution of an early harvest towards minimizing yield and quality losses due to foliar diseases of alfalfa was evaluated. High and low levels of disease were established using inoculations and fungicides. Fungicide protected plots yielded more dry matter, crude protein, and digestible dry matter. Differences between disease level treatments for these variables increased with time. However, even at high disease levels, values for these response variables increased over time. Hay digestibility was reduced when disease levels were high and decreased with time regardless of the disease level treatment. Therefore, early harvesting of alfalfa affected by foliar disease may improve hay quality but not the quantity of dry matter and quality constituents.","Made available in DSpace on 2014-12-15T23:52:23Z (GMT). No. of bitstreams: 1 8701442.pdf: 3350310 bytes, checksum: 79b396b8816cd688cab3c960c2f49bf1 (MD5) Previous issue date: 1986","Embargo set by: Seth Robbins for item 70772 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","115 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1986."],"dc:identifier":["http://hdl.handle.net/2142/70606","(UMI)AAI8701442"],"dc:subject":["Agriculture, Plant Pathology"],"dc:title":["Yield Loss Models for Foliar Diseases of Alfalfa and Evaluation of Chemical and Cultural Disease Control Methods"],"dc:type":["text"],"thesis:degree_discipline":["Plant Pathology"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:26:03Z"}