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By Jerry Spencer in {CATEGORY} on 8 Feb 2012

Following is a brief guide to over-sowing warm season grasses like couch and kikuyu with turf-type perennial ryegrasses.

Reasons for Over-seeding Warm Season Grasses:
Often when growing warm season grasses, it can be noticed that some areas of the turf can become dormant and loss of turf quality when winter arrives. To overcome the detrimental appearance and improve the functionality of turf playing surfaces during the colder months, a cool season grass can be planted in its place for the duration of the winter. Whilst this practice not only enhances winter colour it also improves the quality of the playing surface and protects couch grass & kikuyu from winter wear.

The major advantage in over-seeding playing fields is the ability for wear recovery during the high usage winter months. The addition of a cool-season ryegrass not only protects the established warm-season grass from excessive wear but also provides some cushioning for players using that surface.

Planning for Over-seeding Warm Season Grasses:
When beginning a program of over-seeding warm season grasses, all efforts must be made to give this every chance to successfully establish and gain a good cover, exhibiting strong root growth before any high frequency of play occurs.

What you need to look for in an over-sowing ryegrass is:
Fast germination & establishment;Good cold tolerance & wear tolerance;A quality seed variety with a minimum germination of 90% and minimum purity of 98%;A dwarf growth habit with good lateral stability;Tolerant of required mowing height & good colour;

When carrying out over-sowing aim to use one of the higher quality newer dwarf turf type cultivars. Many of these varieties have been subject to Australian testing under the ANTEP Program (Australian National Turf grass Evaluation Program) and are proven performers. Some suitable cultivars could be Zero, Pennant II & III, Divine or Indy Ryegrass sown at a rate of between 2-4kg/100m2.

Optimum temperature & moisture for over-sowing ryegrass:
The optimum time for over-seeding is late autumn so the warm season grass growth has slowed by lower temperatures but early enough that temperature are still favourable for germination of the turf - type ryegrass sown. Ideal timing for over-seeding is when night time temperatures are close to 13ºC and daytime temperatures are between 21-29ºC.

*Average temperature dates for Melbourne, Sydney & Canberra are shown below:

	Feb		March		April
Temp °C	Min	Max	Min	Max	Min	Max
Melbourne	14.6	25.8	13.2	23.9	10.7	20.3
Sydney	18.6	25.9	18.8	25.7	17.5	24.7
Canberra	13.1	27.1	10.7	24.5	6.6	20.0

To promote good seed establishment at this critical time, soil moisture conditions should be maintained at optimum levels without creating localized dry spots or over wet conditions.

The surface of the over-seeded area should be kept uniformly and consistently moist during the initial two week germination and establishment period.

Some additional key factors to consider when over-sowing:

• Stop N fertilisation 10-20 days before carrying out over-seeding to help reduce competition from the existing kikuyu or couch.
• Lower mowing height 25 to 30% for last mowing before over-seeding.
• Ideally light verticutting (if possible) before over-sowing. Even better remove thatch present entirely or use a disc drill or super seeder to place the seed through this.
• Reduce irrigation by 30% at 1 to 2 weeks before over-seeding.
• Stop watering 2 to 3 days before over-sowing.
• Consider an application of Clipless® (growth regulator) prior to over-seeding.
• Over-seed in two directions and drag the seed into the turf to ensure good soil seed contact.
• Aim to use a small seed ryegrass as this has a better chance at making good soil contact and not getting caught up in any overlying thatch.

Many, if not most, over-seeding failures are due to too little or too much water and poor planning. If you can used a good quality ryegrass supplied and applied by a professional turf contractor using precision seeders and following a few of the key issues raised above, then your project will be successful and you will be able to not only improve the appearance of your turf surface but also increase the quality and frequency of play on that surface.

Contact Details

Office Phone 03 8555 0641

www.etpturf.com.au

Read more articles in {CATEGORY}, by Jerry Spencer or from February 2012.