UVM Theses and Dissertations
Format:
Print
Author:
Zirkle, Jonathon W.
Dept./Program:
Plant and Soil Science
Year:
2012
Degree:
M.S.
Abstract:
Little is known about how clover interseeding of organic wheat affects disease dynamics of Fusarium head blight (FHB) of wheat, a significant disease concern for organic wheat producers in northern New England. A study was conducted to examine impacts of two seeding rates of red clover (RC) (Trifolium pratense L.) and white clover (WC) (Trifolium repens L.) interseeded with winter and spring wheat on FHB incidence, FHB severity, FHB index, and accumulation of the garin mycotoxin deoxynivalenol (DON) at Fusarium spp. propagule concentration (CFUc), splash volume (mL), and total Fusarium spp. propagules (CFUt) splashed at collection heights of 100 and 30 cm during rain events occurring between wheat anthesis and soft dough stages. Grain yield and crude protein data were collected from spring and winter wheat study sites. Clover, weeds, and total understory biomass was collected and quantified in spring wheat sites at grain harvest.
Significant (P <0.01) height effects were found across all site-years and events for CFUc, splash volume, and CFUt with values at 100 cm higher than at 30 cm. Looking at site-years individually, significant treatment effects (P <0.05) were seen at South Burlington (SBUR) 2011 for CFUc and CFUt as well as treatment x height interactions. Conditions at SBUR 2011 where ground coverage was much lower in no clover (NC) controls plots during splash events may have been the cause of significantly higher (P <0.01) CFUc and CFUt in NC treatments at 30 cm compared to RC 28 kg ha⁻¹ at 30 cm, enabling greater splash potential from the soil or crop residue. Significant treatment effects were not seen across site-years for DON, FHB incidence, FHB severity, FHB index, yield, or protein. WC 14 kg ha⁻¹was the highest yielding clover treatment, though not significant.
Weeds biomass was significantly reduced (P <0.001) in clover treatments compared to control, and total understory biomass was significantly different by treatment (P <0.05) with highest biomass in WC 14 kg ha⁻¹ and lowest in NC. Positive correlation was found between total understory biomass (TUB) and grain yield as well as between TUB and crude wheat protein. Findings indicate that FHB of wheat is likely not favored by clover interseeding, nor is grain quality and yield significantly reduced. Further studies are suggested to examine Fusarium spp. community dynamics in organic wheat-clover systems, as conditions created by clover interseeding may alter Fusarium spp. community structure and thus have implications for FHB and mycotoxin dynamics in interseeded organic wheat.
Significant (P <0.01) height effects were found across all site-years and events for CFUc, splash volume, and CFUt with values at 100 cm higher than at 30 cm. Looking at site-years individually, significant treatment effects (P <0.05) were seen at South Burlington (SBUR) 2011 for CFUc and CFUt as well as treatment x height interactions. Conditions at SBUR 2011 where ground coverage was much lower in no clover (NC) controls plots during splash events may have been the cause of significantly higher (P <0.01) CFUc and CFUt in NC treatments at 30 cm compared to RC 28 kg ha⁻¹ at 30 cm, enabling greater splash potential from the soil or crop residue. Significant treatment effects were not seen across site-years for DON, FHB incidence, FHB severity, FHB index, yield, or protein. WC 14 kg ha⁻¹was the highest yielding clover treatment, though not significant.
Weeds biomass was significantly reduced (P <0.001) in clover treatments compared to control, and total understory biomass was significantly different by treatment (P <0.05) with highest biomass in WC 14 kg ha⁻¹ and lowest in NC. Positive correlation was found between total understory biomass (TUB) and grain yield as well as between TUB and crude wheat protein. Findings indicate that FHB of wheat is likely not favored by clover interseeding, nor is grain quality and yield significantly reduced. Further studies are suggested to examine Fusarium spp. community dynamics in organic wheat-clover systems, as conditions created by clover interseeding may alter Fusarium spp. community structure and thus have implications for FHB and mycotoxin dynamics in interseeded organic wheat.