• What does RPR stand for?
• What sets RPR apart from all other perennial ryegrasses?
• What’s in a name?
• What is a determinate stolon[1]?
• What is ‘Regeneration Potential’?
• Seeding rates. What’s the difference?
• Why is RPR so traffic tolerant?
• Will RPR’s density provide added weed control?
• Will RPR tolerate lower mowing heights?
• How will RPR perform in ‘non-traditional’ ryegrass climates?
• How will RPR perform in residential situations?
• How will RPR mix with other turfgrasses?
• Can RPR be successfully over-seeded into existing turf?
• Does RPR exhibit good drought tolerance?
• Should RPR be used in the Fall over-seeding of warm season grasses?

[1] Patent 

 What does RPR stand for? [Top]

RPR means ‘Regenerating Perennial Ryegrass’ and is representative of Barenbrug’s commitment to develop turfgrasses that combine excellence of turf quality, traffic tolerance, recovery from intense traffic events, disease resistance, insect tolerance, and overall turf performance. As of Spring, 2013, Barenbrug has developed 3 unique varieties of regenerating perennial ryegrass: Baralpha, Barbeta, and Bargamma, with future varieties in development.

What sets RPR apart from all other perennial ryegrasses? [Top]

Barenbrug’s RPR varieties are the very first turf perennial ryegrasses to be classified Lolium perenne L. subsp. stoloniferum (Lawson) Wipff[1].  The ‘stoloniferum’ indicates these perennial ryegrass varieties produce ‘determinate stolons’. ‘Determinate stolons’ form quickly and aggressively at the crown of the plant forming a dense, extremely traffic tolerant turf. Within a single growing season, one plant will often cover a somewhat circular area with a 3 ft. perimeter.

Further separation from other perennial ryegrasses was also determined by genetic fingerprinting. Using SSR Analysis in a blind trial evaluated by an independent analyst, RPR cultivars were shown to be genetically different from traditional perennial ryegrass, including C.S.I. perennial ryegrass.  

What’s in a name? [Top]

Since the release of RPR, other perennial ryegrasses are now being marketed as spreading and creeping with further descriptions of ‘secondary tillers’ or ‘pseudo-stolons’ or even exhibiting ‘rhizomes’. Rhizomes are underground stems capable of spreading as seen in Kentucky bluegrass and creeping red fescue. Perennial ryegrass does not, nor has ever shown to be capable of producing rhizomes.

RPR is the only perennial ryegrass exhibiting determinate stolons.   To many, that may seem a moot point. Determinate stolons, tillers, rhizomes, etc……….what difference does it make?  For an individual managing a sports turf facility, golf course, or any area where traffic and heavy use are significant issues, the difference is traffic tolerance and recovery versus severely damaged turf with little ability to recover.

RPR was developed through a novel selection system where intense traffic was applied with a 2000 lb. traffic simulator on millions of plants. The few plants that survived formed determinate stolons.  Exhibiting significant traffic tolerance, determinate stolons develop significant rooting at the nodes and the ability to quickly regenerate and thrive.

What is a determinate stolon[2]? [Top]

A determinate stolon is an above ground, horizontal stem produced from the crown of the RPR plant within nine months of seeding.  They elongate 6-8” where it roots firmly to the soil, establishing new foliage, seed head, and forming a new crown. Each year, these new crowns will produce many more new determinate stolons, each spreading in different directions before once again rooting firmly to the soil.  Within 2-3 years, a single RPR plant may be as wide as 36”, with stolons firmly rooted to the soil and producing a uniform, dense area of turf.

In the Fall of 2011, in Albany, OR a traffic study was conducted on one year old space plants in order to simulate the effects of 5 games per week and to assist in determining the ‘Regeneration Potential’ of ryegrasses.  Comparing both RPR plants and a standard perennial ryegrass variety, Pinnacle II, the data confirmed the presence of both determinate stolons and secondary peripheral tillers on the RPR plants. The perennial ryegrass standard, Pinnacle II, exhibited only peripheral tillers with no determinate stolons.  The number of determinate stolons present ranged from 16-35 per plant with a spread of 5-8” per determinate stolon. The Pinnacle II plants exhibited a spread of 3” based on tiller growth.

What is ‘Regeneration Potential’? [Top]

The ‘Regeneration Potential’ of turf is a measurement of data that allows the turf researcher to determine a variety’s true ability to recover from an extreme traffic situation. This potential is a physical measurement of a plant’s perimeter, either proving a variety’s ability or inability to recover from traffic. In determining the regeneration potential for RPR varieties, 8 month old RPR space plants and those of Pinnacle II P.R. and C.S.I. Per. Rye (Natural Knit) were subjected to weekly traffic events for 4 months and then allowed to recover for 2 months. The data below clearly shows that even when including the L.S.D. factors, the RPR varieties exhibit a positive (+) ability to recover from serious traffic damage while the Pinnacle II and C.S.I. ( Natural Knit ) exhibit a negative (-) ability. The end result being, when the turf is heavily damaged, RPR will recover and regenerate while traditional ryegrasses, such as Pinnacle II, and spreading ryegrasses such as C.S.I. and L.S. ‘Lateral Spread’ will offer no such recovery.

Seeding rates. What’s the difference? [Top]

Spreading perennial ryegrass, such as C.S.I and L.S. have a published recommended seeding rate of 3 lb per 1000 sq.ft.   RPR’s recommended rate is 7 lbs per 1000 sq.ft.  That’s considerably more seed for the RPR……….and considerably faster establishment and cover, fewer weeds, and a much shorter time for putting your new turf into play. A 3 lb rate versus a 7 lb rate is less expensive, at the time of seeding. However, the added cost of increased establishment time, a loss of field use, and increased weed control will be far greater during the first season of growth than the added 4 lbs of RPR seed. Be mindful that a spring planted spreading perennial rye, such as C.S.I. and L.S., may require close to a year before establishing that first ‘pseudo stolon’ or peripheral tiller. A fall planting, 6 months or longer.

RPR…...why wait…….why be disappointed…….RPR………it’s worth the seed!      

 Why is RPR so traffic tolerant? [Top] 

All 3 current RPR varieties were discovered at Barenbrug’s East Coast Research Center in Virginia under an extensive selection process.  Selections were made from areas where the abuse from both tractor and traffic simulator was at its worst. Those RPR selections distinguished themselves as unique, as they produced ‘determinate stolons’ and regenerated turf over the damaged, bare soil.

 Coupled with their selection from the extremes of Virginia’s summer climate, these RPR varieties take ‘extreme’ performance to a new level.

Will RPR’s density provide added weed control? [Top]

The combination of fast establishment and regenerative growth potential provides significantly improved weed control over traditional bunch-type perennials. RPR’s extreme traffic tolerance also minimizes damage which results in a denser stand of turf with reduced opportunity for weed establishment.  

Will RPR tolerate lower mowing heights? [Top]

In a mowing trial conducted to include a fairway cutting height of 3/8ths inch, RPR exhibited excellent turf quality, maintained excellent density and its ability to regenerate and recover from wear.

How will RPR perform in ‘non-traditional’ ryegrass climates? [Top] 

Perennial ryegrass traditionally performs best in areas with cooler temps and milder summers. One current selection of “spreading” perennial ryegrass, C.S.I., was selected from turf in the cool, wet climate of Oregon’s Willamette Valley. However, RPR’s ‘Virginia heritage’ allows for its use in climates where other perennial ryegrasses struggle to survive. Turfgrass researchers from transition zone climates have expressed surprise at its ‘survival characteristics’ and RPR’s ability to perform under adverse conditions of drought, heat, and humidity.

How will RPR perform in residential situations? [Top] 

There’s no doubt that RPR thrives on abuse. That being said, there are many residential situations that require its durability, ‘repair’ characteristics, and natural ability to resist many weeds from establishing.  Active families, larger family pets, and backyard play areas all take their toll on traditional lawns where perennial ryegrass is an important component of the turf. RPR provides the traffic tolerance, resiliency, and density needed for these demanding situations.

How will RPR mix with other turfgrasses? [Top]

For decades, perennial ryegrass has been frequently mixed with Kentucky bluegrass and Fine fescues. RPR is no different; in fact its ability to regenerate provides a more uniform mixture of species than traditional, clumping perennial ryegrass. Barenbrug’s Turf Blue with RPR combines 20% RPR with its finest Kentucky bluegrasses in just such a mixture.

Can RPR be successfully over-seeded into existing turf? [Top]

Ideally over-seeded in late August thru October, RPR’s quick germ and aggressive establishment serve it well when competing with existing perennial ryegrass and other species. With time, it will become a strong component of your turf area, benefitting overall turf quality and performance.

Does RPR exhibit good drought tolerance? [Top]

When compared with other perennial ryegrasses, RPR exhibits superior drought tolerance. The keys to drought tolerance will be ‘a well-established RPR lawn with a developed root system’ prior to the onset of summer heat and ‘a loamy soil’ capable of good water retention.

Should RPR be used in the Fall over-seeding of warm season grasses? [Top]

RPR is not recommended for use in Fall over-seeding programs. Its aggressive growth habit and durability in heat make it too persistent for use.

[1] Journal of the Botanical Research Institute of Texas. 2010. Vol 4 (683-684)

[2] Patent Publication Number is US2012/0124687 A1. Lolium perenne subs stoloniferum ; Perennial Ryegrass with Determinate-Stolon.