Magazine - Professional Turf Diaries With Jerry. Pt. 2

By Jerry Spencer in Consultancy on 16th Feb 2008 18:00

In Jerry's diaries we will look at ethofumesate.  Ethofumesate has been available for years but is seldom used as other ‘easier’ options are now available which are not always the best option.


Poa annua control in perennial ryegrass.
Perennial ryegrass can tolerate ethofumesate treatments better than any of the other cool-season grasses. However, rates and frequency of ethofumesate application needed for effective control will depends on usage of the grass.

Seed fields.
In Oregon, ethofumesate applied as PRE (preemergence) at 0.85 kg/Ha in early October or early POST (postemergence) in November at 1.12 kg/Ha to ryegrass fields for seed production controlled Poa annua completely the following March or early April before rapid ryegrass growth began. However, Poa annua was not as good from single applied ethofumesate treatment in September (autumn) to field grown ryegrass in England. Over a 3- year period, ethofumesate applied at 0.85 kg/Ha did not reduce dry weight of Poa annua the following June (summer). The differences in control between locations may be in part to the different rating dates for March or early April in Oregon and June (summer) in England.

Fairways.
Poa annua control in perennial ryegrass fairway in Maryland varied with ethofumesate rates and frequency of application. Ethofumesate applied once at 1.12 kg/Ha (September) controlled < 40% the following April compared to < 93% when applied twice at 1.12 kg/Ha (September and October). The control was improved to 99% when herbicide rate was increased to 2.24 kg/Ha and applied in each of two applications. At this location Poa annua control was similar whether applied once at 2.24 kg/Ha or twice at 1.12 kg/Ha

Summary.
Optimum Poa annua control can be obtained in perennial ryegrass in the United States with the 1.12 kg/Ha. However, frequency of application depends on where the grass is grown. A single application controlled Poa annua effectively in ryegrass field used for seed production while two applications were needed at a 30 day interval when perennial ryegrass was used on fairways or on overseeded couch greens.

Poa annua control in Kentucky bluegrass.
The tolerance of Kentucky bluegrass is not as good as perennial ryegrass and creeping bentgrass.
In Nebraska Poa annua control in Kentucky bluegrass was 93% when final ratings were made at 6 months after treatment with ethofumesate at 1.12 kg/Ha in each of two applications. The control with bensulide applied at 18.75kg/Ha ranged from 51% at one month to 58% by 6 months after treatment. There was no advantage in control when ethofumesate was applied alone at 2.24 kg/Ha or when the 2.24 kg/Ha rate was followed by 1.12 kg/Ha four weeks later.
Poa annua control in Virginia, was effective in a mixed Kentucky bluegrass and perennial ryegrass fairway when treated either with ethofumesate at 0.56 kg/Ha in three applications or with 1.12kg/Ha in two applications. Ethofumesate applied at 0.85 kg/Ha in each of two applications in the autumn reduced Poa annua the first year, but the control after the second year was near complete. The control was 80% when 1.7 kg/Ha was applied once in each of two years.

Summary. Poa annua control in Kentucky bluegrass was consistent when ethofumesate was applied at 1.12 kg/Ha in each of two autumn applications. It is also necessary to retreat the turf for Poa annua control the second year regardless of rates used during the first year.

Article supplied by E.T.P www.etpturf.com.au

Read more articles in Consultancy, by Jerry Spencer or from February 2008.