Full TGIF Record # 33484
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Web URL(s):https://listings.lib.msu.edu/nmtma/1995apr.pdf#page=4
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Publication Type:
Content Type:Abstract or Summary only
Author(s):Vargas, J. M. Jr.
Author Affiliation:Department of Botany and Plant Path, Michigan State University
Title:Demethylation Inhibitor (DMI) resistance update
Source:Turf Times. Vol. 24, No. 4, April 1995, p. 4.
# of Pages:1
Publishing Information:Traverse City, MI: Northern Michigan Turf Managers Association
Keywords:TIC Keywords: Contact fungicides; DMI fungicides; Dollar spot; Fungicide profile; Fungicide resistance; Fungus control; Sclerotinia homoeocarpa; Systemic fungicides
Abstract/Contents:"Strains of Sclerotinia Homoeocarpa, the casual agent of dollar spot, were isolated from several golf courses where demethylation inhibitor (DMI) fungicides had been reported to give little or no control. Laboratory tests provided evidence that the strains of S. homoeocarpa were resistant to the DMI fungicides. ED50 values for 50 isolates of S. Demethylation homoeocarpa, from each of 6 golf courses, were determined for 4 DMI fungicide concentrations based on radial mycelial growth. Isolates collected from golf courses where DMI fungicides were used on a regular basis had higher ED50 values than isolates from golf courses where DMI fungicides had never been used. These studies allowed for the establishment of one fungicide concentration as a monitoring dose to follow shifts in the S. homoeocarpa populations. Fungicide field trials were initiated in the summer of 1991 on a golf course which had reported no control of dollar spot with the use of DMI fungicides such as Bayleton, Rubigan, and Banner. During the next 4 seasons, individual field plots were sampled prior to the first fungicide application and following the last fungicide application. Each individual isolate sampled was tested against the established monitoring dose. From the data collected, the effects of each fungicide treatment on the S. homoeocarpa population was evaluated. The contact fungicides, Daconil 2787 and Dyrene, applied alone provided excellent disease control and were the only treatments to maintain a level of stability within the S. homoeocarpa population when compared to the control. The DMI fungicides applied alone or in combination or alternation with a contact fungicide resulted in a shift in the S. homoeocarpa population towards a higher level of resistance. Based on these results, the old theory that alternating contact and systemic fungicides or applying them together will prevent resistance from occurring will not work. Since most of the problems with resistance to the systemic fungicides has occurred with dollar spot, a system needs to be designed to delay dollar spot from becoming resistant to the DMI fungicides. By limiting the use of DMI fungicides during the time of year when dollar spot is most severe, the selection pressure on the population can be reduced. This should allow the wild-type, DMI sensitive strains of S. homoeocarpa to remain dominant in the population."
Note:This item is an abstract only!
ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Vargas, J. M. Jr. 1995. Demethylation Inhibitor (DMI) resistance update. Turf Times. 24(4):p. 4.
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    Last checked: 10/27/2017
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    Notes: Item is within a single large file
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MSU catalog number: SB 433 .A1 N572
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