Integration of Chemical Control with Restoration Techniques for Management of Fallopia japonica Populations

Effective management of invasions by Fallopia japonica are currently limited to repeated annual herbicide applications and research efforts are needed to determine integrated cost‐ effective treatments that result in greater management success. We evaluated several different herbicides for F. japonica control in the greenhouse and under field conditions and coupled chemical control with restoration activities at an invaded site. Results suggest that: 1) glyphosate applied at 4.21 kg ae/ha is the most cost effective treatment option, 2) the standard rate for F. japonica control with aminocyclopyrachlor is approximately equivalent to the 0.56 kg ai/ha, 3) restoration with grasses can be coupled with targeted chemical control.

However, vegetation surrounding treated sites can quickly re-colonize many sites (Ford 2004;Miller 2005).While this can result in desirable native plants being restored to the site (Ford 2004), the possibility for undesirable plant species to re-infest the area is also a management concern.
Restoration to ecologically desirable species may increase the

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Especies invasoras, plantas nativas, manejo de malas hierbas o malezas aminocyclopyrachlor, may be a useful chemical tool to manage F. japonica in the future.A greenhouse study was conducted to quantify the potential of this new herbicide active ingredient for F. japonica control.

Native Grass Establishment
The 40 kg/ha seeding rate resulted in significantly higher grass seedling establishment (  1. Native grass percent cover 30 days after seeding (DAS) and grass density 45 and 176 DAS.Means (plus/minus the standard error of the means) within a column followed by the same lower-case letter are not significantly different (p < 0.05).
Table 2. F. japonica percent injury and percent leaf drop resulting from herbicide treatments applied on October 13, 2008, and quantified by visual rating 11, 32, 210, and 378 days after treatment (DAT).Means (plus/minus the standard error of the means) within a column followed by the same lower-case letter are not significantly different (p < 0.05). .Percent injury to F. japonica was evaluated during the next Table 3.Growth and biomass parameters of F. japonica 196 days after herbicide treatment (DAT).Means (plus/minus the standard error of the means) within a column followed by the same lower-case letter are not significantly different as indicated by 95% individual confidence intervals.4. F. japonica percent injury and percent leaf drop resulting from tank mix herbicide treatments applied on October 13, 2008, and quantified by visual rating 11, 32, 210, and 378 days after treatment (DAT) Means (plus/minus the standard error of the means) within a column followed by the same lower-case letter are not significantly different (p < 0.05).0.035, 0.07, 0.14, 0.28, 0.56 kg ai/ha rates (Table 9).However, at 186 DAT the 0.28 and 0.56 kg ai/ha rates aminocyclopyrachlor treatments had no regrowth after clipping.

Fig. 1 .
Fig. 1.Dense infestation of F. japonica growing in a floodplain of a coastal river watershed in western Oregon, U.S., with very few other plant species established under the F. japonica canopy .
resilience of these sites to future infestations.A diverse mixture of native tree and shrub species is most suitable for riparian sites in the PNW, but it is difficult to restore a site dominated by F. japonica to these species due to the altered site conditions caused by F. japonica M. Rudenko & A. Hulting.Fallopia japonica: Chemical Management Resumen El manejo efectivo de las invasiones de Fallopia japonica está actualmente limitado a la aplicación anual repetida de herbicidas, y se necesita realizar esfuerzos de investigación para determinar los tratamientos integrados con mejor balance coste-efectividad que conllevan un mayor éxito en el manejo.En este trabajo evaluamos diferentes herbicidas para el control de F. japonica en invernadero y condiciones de campo, y acoplamos el control químico con trabajos de restauración en las parcelas invadidas.Los resultados sugieren que: 1) el glifosato aplicado a razón de 4.21 kg equivalentes ácido/ha es la opción con mayor balance coste-efectividad, 2) la tasa estándar para el control de F. japonica control con aminocyclopiraclor es de 0.56 kg ai/ha, 3) la restauración con herbáceas perennes puede ser acoplada a un los trabajos de control químico.

FieldFig. 2 .Fig. 3 .
Fig. 2. Location of experimental studies where a large infestation of F. japonica grows along the Nehalem River near Garabaldi, Oregon, U.S.A. shown here in spring (2a) and during the winter months (2b) after leaf drop with only primary canes of plants remaining after flooding events at the site.
of injury to F. japonica evaluated a year after treatment was equal with these two products (81 to 89%) we conclude adapted to the unique conditions at any F. japonica management site.Based on the results from this study, it does appear to be plausible, with some modification to our methods, to establish a native grass community at a F. japonica restoration site that can be used as a stepping stone community before proceeding to restoration with tree and shrub species.Further experiments designed to test both spring and fall grass seeding before and after herbicide application should be conducted in order to determine the most effective means of the integration of restoration with herbicide control of F. japonica.We were able to establish a mixture of native grasses at a site with a dense F. japonica population by planting the grasses in early spring.The grasses grew through the summer but did not survive the winter conditions at the site.Though the causes of this failure are u n k n o w n , site in a given year.Fall planting may also be feasible at some sites depending on environmental conditions and other range of 0.28 kg ai/ha to 0.56 kg/ha should be further examined under field conditions to determine a standard application rate of this product for F. japonica control.

Table 5 .
Growth and biomass parameters of F. japonica 196 days after herbicide tank mixture treatments (DAT).Means (plus/minus the standard error of the means) within a column followed by the same lower-case letter are not significantly different (p < 0.05).

Table 6 .
F. japonica percent injury from herbicide treatments in combined greenhouse experiments A and B 7, 21, and 63 days after treatment (DAT).Means (plus/minus the standard error of the means) within a column followed by the same lower-case letter are not significantly different (p < 0.05).

Table 7 .
F. japonica above ground biomass 70 DAT and above ground biomass of regrowth 186 DAT (after clipping) expressed as a percentage of control biomass in combined greenhouse experiments A and B. Means (plus/minus the standard error of the means) within a column followed by the same lower-case letter are not significantly different (p < 0.05).

Table 8 .
F. japonica percent injury from herbicide treatments in greenhouse experiment C 7, 21, and 63 days after treatment(DAT).Means (plus/minus the standard error of the means) within a column followed by the same lowercase letter are not significantly different (p < 0.05).
kg ai/ha).Applications rates in the factors including the dynamics of the water table or surface water.