Clipping date
Control of Medusahead (Taeniatherum caput-medusae) and barbed goatgrass (Aegilops triuncialis) with precision defoliation Jimin Zhang1,2, Montague W. Demment1 ,Craig Schriefer1, Corey Cherr1 and Emilio A. Laca1 , 1 Department of Plant Sciences, University of California, Davis, CA 95616; 2Department of Plant Sciences, Northwest A & F University, Yangling, Shaanxi 712100, China Medusahead clipped at height 3 cm
8M ay 12 -M ay 16 -M ay
Seedhead productions responces (Figure 2): All defoliations significantly reduced
reproduction of medusahead and goatgrass under three intensities. Medusahead is more sensitive to defoliation than goatgrass. Late vegetative phenological stage of Goatgrass seems to be the best time for starting defoliation. Defoliation to 3 cm prevented reproduction of Medusahead very well at all dates. Canopy height of goatgrass after clipping at height 3 cm
Canopy height of medusahead after clipping at height 6 cm
8M ay 12 -M ay 16 -M ay
4M ay
Canopy height of medusahead after clipping at height 9 cm
4M ay
1M ay
15 -A pr 19 -A pr 25 -A pr 28 -A pr
8M ay 12 -M ay 16 -M ay
P < 0.01
40 30 20 10 0 Un cli pp ed
Canopy height (cm)
4M ay
1M ay
Clipping date
8M ay 12 -M ay 16 -M ay
P < 0.01
15 -A pr 19 -A pr 25 -A pr 28 -A pr
Figure 1. Medusahead and Goatgrass plots after clipping (50 cm X 50 cm).
Un cli pp ed
Clipped at 9 cm height
Canopy height (cm)
Clipped at 6 cm height
1M ay
Clipping date
Canopy height of goatgrass after clipping at height 9 cm
Clipped at 3 cm height
15 -A pr 19 -A pr 25 -A pr 28 -A pr
P < 0.0001
Un cli pp ed
Canopy height (cm)
8M ay 12 -M ay 16 -M ay
4M ay
1M ay
15 -A pr 19 -A pr 25 -A pr 28 -A pr
40 30 20 10 0
Clipping date
60 50 40 30 20 10 0
4M ay
15 -A pr 19 -A pr 25 -A pr 28 -A pr 1M ay
Clipping date
P < 0.01
60 50 40 30 20 10 0
Un cli pp ed
Medusahead
Canopy height (cm)
Clipped at 9 cm height
8M ay 12 -M ay 16 -M ay
P < 0.0001
40 30 20 10 0 Un cli pp ed
Canopy height (cm)
4M ay
1M ay
15 -A pr 19 -A pr 25 -A pr 28 -A pr
8M ay 12 -M ay 16 -M ay
P < 0.05
60 50 40 30 20 10 0
Canopy height of medusahead after clipping at height 3 cm
Canopy height of goatgrass after clipping at height 6 cm
Clipped at 6 cm height
8M ay 12 -M ay 16 -M ay
Clipping date
Clipping date
Clipped at 3 cm height
8M ay 12 -M ay 16 -M ay
Un cli pp ed
P < 0.0001
4M ay
Seedhead No. after clipping (/50 cm2)
8M ay 12 -M ay 16 -M ay
4M ay
15 -A pr 19 -A pr 25 -A pr 28 -A pr 1M ay
Un cli pp ed
P < 0.01
1000 800 600 400 200 0
Figure 2. Seedhead numbers of Medusahead and Goatgrass after clipping (/50 cm2).
Un cli pp ed
Goatgrass
Medusahead clipped at height 9 cm
Clipping date
Canopy height (cm)
Study Sites: This study is conducted in 2 sites ((38 34’21.61” N, 121 51’49.21” W) and (38 34’21.21” N, 121 51’57.54” W) in Antibodies ranch. Plots were 50 cm X 50 cm each for a total of 108 plots (for 2 species). Treatments: Three intensities (Clipping height) : 3 cm, 6 cm, 9 cm above ground were done with electrical clipper on April 15, 19, 25, 28 and May 1, 4, 8, 12, 16, 2007. Two replicates were conducted of each date. Evaluations: The botanical composition and canopy height of each plot were observed before clipping and at maturity. Five plants of each plot were collected before clipping to identify phenological stage. Clipped vegetative portion of each plot was collected for nutrition analysis. Seedhead No., canopy height and botanical composition of each plot were measured on July 12, 2007 Analysis: Data were analyzed by one way ANOVA statistical software JMP (SAS; Cary, North Carolina, USA). Means were separated using Tukey-Kramer HSD (p
8M ay 12 -M ay 16 -M ay
Seedhead productions responces (Figure 2): All defoliations significantly reduced
reproduction of medusahead and goatgrass under three intensities. Medusahead is more sensitive to defoliation than goatgrass. Late vegetative phenological stage of Goatgrass seems to be the best time for starting defoliation. Defoliation to 3 cm prevented reproduction of Medusahead very well at all dates. Canopy height of goatgrass after clipping at height 3 cm
Canopy height of medusahead after clipping at height 6 cm
8M ay 12 -M ay 16 -M ay
4M ay
Canopy height of medusahead after clipping at height 9 cm
4M ay
1M ay
15 -A pr 19 -A pr 25 -A pr 28 -A pr
8M ay 12 -M ay 16 -M ay
P < 0.01
40 30 20 10 0 Un cli pp ed
Canopy height (cm)
4M ay
1M ay
Clipping date
8M ay 12 -M ay 16 -M ay
P < 0.01
15 -A pr 19 -A pr 25 -A pr 28 -A pr
Figure 1. Medusahead and Goatgrass plots after clipping (50 cm X 50 cm).
Un cli pp ed
Clipped at 9 cm height
Canopy height (cm)
Clipped at 6 cm height
1M ay
Clipping date
Canopy height of goatgrass after clipping at height 9 cm
Clipped at 3 cm height
15 -A pr 19 -A pr 25 -A pr 28 -A pr
P < 0.0001
Un cli pp ed
Canopy height (cm)
8M ay 12 -M ay 16 -M ay
4M ay
1M ay
15 -A pr 19 -A pr 25 -A pr 28 -A pr
40 30 20 10 0
Clipping date
60 50 40 30 20 10 0
4M ay
15 -A pr 19 -A pr 25 -A pr 28 -A pr 1M ay
Clipping date
P < 0.01
60 50 40 30 20 10 0
Un cli pp ed
Medusahead
Canopy height (cm)
Clipped at 9 cm height
8M ay 12 -M ay 16 -M ay
P < 0.0001
40 30 20 10 0 Un cli pp ed
Canopy height (cm)
4M ay
1M ay
15 -A pr 19 -A pr 25 -A pr 28 -A pr
8M ay 12 -M ay 16 -M ay
P < 0.05
60 50 40 30 20 10 0
Canopy height of medusahead after clipping at height 3 cm
Canopy height of goatgrass after clipping at height 6 cm
Clipped at 6 cm height
8M ay 12 -M ay 16 -M ay
Clipping date
Clipping date
Clipped at 3 cm height
8M ay 12 -M ay 16 -M ay
Un cli pp ed
P < 0.0001
4M ay
Seedhead No. after clipping (/50 cm2)
8M ay 12 -M ay 16 -M ay
4M ay
15 -A pr 19 -A pr 25 -A pr 28 -A pr 1M ay
Un cli pp ed
P < 0.01
1000 800 600 400 200 0
Figure 2. Seedhead numbers of Medusahead and Goatgrass after clipping (/50 cm2).
Un cli pp ed
Goatgrass
Medusahead clipped at height 9 cm
Clipping date
Canopy height (cm)
Study Sites: This study is conducted in 2 sites ((38 34’21.61” N, 121 51’49.21” W) and (38 34’21.21” N, 121 51’57.54” W) in Antibodies ranch. Plots were 50 cm X 50 cm each for a total of 108 plots (for 2 species). Treatments: Three intensities (Clipping height) : 3 cm, 6 cm, 9 cm above ground were done with electrical clipper on April 15, 19, 25, 28 and May 1, 4, 8, 12, 16, 2007. Two replicates were conducted of each date. Evaluations: The botanical composition and canopy height of each plot were observed before clipping and at maturity. Five plants of each plot were collected before clipping to identify phenological stage. Clipped vegetative portion of each plot was collected for nutrition analysis. Seedhead No., canopy height and botanical composition of each plot were measured on July 12, 2007 Analysis: Data were analyzed by one way ANOVA statistical software JMP (SAS; Cary, North Carolina, USA). Means were separated using Tukey-Kramer HSD (p
