The price of perennial ryegrass seed seems high this year, should I overseed this fall with something else? With our warmer winters the past few years, is overseeding even necessary if the field will not get heavy use until spring?

Overseeding options

The price of perennial ryegrass seed seems high this year, should I overseed this fall with something else? With our warmer winters the past few years, is overseeding even necessary if the field will not get heavy use until spring?

North Carolina

At the end of each summer the North Carolina STMA has a meeting and the suggested topics always include “overseeding.” This year was no different. Overseeding is one of those annual rituals that many turf managers growing bermudagrass go through each fall. Some love it, but most do not. And nobody likes the added expense. With perennial ryegrass prices up 20 to 35% this year, turf managers are again wondering if they could do something different.

In a climate like North Carolina’s, a turf manager should expect their bermudagrass being dormant by late-November through early-March most years. I have seen green, actively growing bermudagrass the first week in March in central North Carolina, but generally I would not expect it to be fully out of dormancy until at least April. So, spring use of a bermudagrass field most often includes time on a dormant field.

Bermudagrass will suffer damage from too much play under harsh winters, especially during extended wet periods. Normally, overseeding a field can protect the bermudagrass turf and help maintain the field’s integrity by providing a wearable playing surface. Recent studies at University of Tennessee quantified a 12 to 56% increase in turf coverage after 20 events when a bermudagrass field was overseeded versus not overseeded.

Despite promising research results, there is still no guarantee that overseeding will prevent damage to the field surface. Events played during severe cold and wet conditions can still easily wear through overseeded turf and damage to bermudagrass crowns, stolons, and rhizomes.

Then there is the issue of overseeding competing with the bermudagrass in the spring. Perennial ryegrass can dramatically slow down green-up of bermudagrass. And with a cool spring many of the ryegrass plants may survive into summer, leaving clumpy ryegrass that result in poor uniformity (aka, ankle breakers) for field users. This has led to the popularity of chemical removal of perennial ryegrass stands, most often with an herbicide in the sulfonylurea family.

While chemical removal does have some downsides (primarily cost and determining the best time to spray), it does offer a great alternative to just taking a chance and hoping for a good natural transition. Most field managers have experienced at least one bad natural transition and would prefer to not have another.

Considering these issues, it is no wonder that turf managers seek alternative grasses for overseeding. The major cool-season grasses that have been mentioned as potential candidates include: annual ryegrass, roughstalk bluegrass, and tall fescue. While an extensive justification why someone would not want to use these could be written, in the end the only grass among these three that has seen appreciable use as an overseeding grass on tall-mown bermudagrass is annual ryegrass.

Annual ryegrass has enjoyed a rich history. There was a time that it was the go-to grass for all overseeding needs—even getting widespread use on golf greens. But new perennial ryegrass cultivars provided better color, more controlled growth, better density, and better tolerance to stresses resulted in its widespread acceptance. With these improved qualities, the use of annual ryegrass for overseeding dropped significantly.

Plant breeders responded with considerable development efforts towards produce better quality annual ryegrasses as well as intermediate ryegrasses. I’ve tested some of these grasses and they certainly have much better quality than the older annual ryegrass cultivars. In fact, many have early-season quality that is similar to good perennial ryegrasses. These annual and intermediate types also have the benefit of quicker transitioning. Some noted downsides have been these new grasses may cost as much as a perennial ryegrass, often have poor late-spring growth habits, and the sulfonylurea herbicides are not nearly as effective at removing them compared to perennial ryegrasses. Look for the gap between these ryegrass types to continue narrowing.

The new trend the last few years is to forego overseeding and just “paint” the turfgrass green. This can provide a nice color but offers only marginal improvement in wear tolerance (via encouraging growth later in the fall and earlier in the spring). This can be a great alternative if heavy traffic is not an issue, but it is certainly not a good option for every situation. With a mild winter and good spring growing conditions, a turf manager that painted rather than overseeding can really come out ahead. But too much traffic without any overseeding protection can result in field failure.

There are limited overseeding grass alternatives to perennial ryegrass. For high-use field for spring sports not overseeding is a risky option. As a turf manager you will have to base your overseeding decision on the past while considering the implications if things do not go as planned. If it were only a money decision, it would be easy. But the health of the existing turfgrass and the playability of the field are also part of the mix.

Dr. Grady Miller is a professor in the crop science department at North Carolina State University.