THE NEXT BIG THING
There are more than 9,000 known grass species that grow on the earth, and many that have yet to be discovered. There are more grass species on earth than any other species of plant. Only about 20 different species of grasses are used for turf applications; however, these include hundreds of varieties. As you know, a turf is simply a population of grass plants that are mowed. So why are only 20 grass species used for turf when there are more than 9,000 grass species? A few of the reasons include: most grass plants will not tolerate close mowing; many grasses are only adapted to grow in specific climates; and we have not tried all 9,000 species to see if they would make a good turf. In this article, I will describe what it means to find a “novel” turfgrass, how it is accomplished and what new types of turfgrasses might be developed in the future.
WHAT IS A “NOVEL” TURFGRASS?
To qualify as a new or novel variety, turfgrass must be distinct in some way from what is currently recorded by the U.S. Government. This sounds simple enough, but how different does is need to be is the real question. There are major differences between warm-season and cool-season turfs, many of which you can describe. Major differences also exist among zoysiagrass, St. Augustinegrass and bermudagrass (warm-season grasses), as well as among ryegrass, bluegrass and fescue (cool-season grasses). Grasses that differ in big ways (i.e., they look different), generally have many genetic or DNA differences between them. Quite simply, the reason one grass plant is different from the next is all due to differences in their DNA. What might surprise you is that grass plant DNA is mostly the same in all of the 9,000 species, and only a small fraction of the total DNA in a plant actually accounts for the differences among them. There are grass plants that differ by only one gene, and yet they behave completely differently. How can this be? Is one gene enough to distinguish one turfgrass from another? This may not seem important to you, but it is if you want to make sure the new turfgrass you are buying is really different from what was sold last year. For example, if I took the Kentucky bluegrass variety Merion and put a new gene into it — a dummy gene that did nothing to change the behavior of Merion — would it be new? Technically, yes; but it would not be “different” in terms of how it behaved as a grass plant. Simply put, it could be sold as “new” Merion, but it would be no better than the old Merion.
NEW OR DIFFERENT DOES NOT ALWAYS MEAN BETTER
Is there a required minimum difference between the original plant and an improved grass plant before it can be labeled as “new”? Presently, the rules are not very clear. But the lawyers, not the turfgrass breeders, will probably decide what requirements a grass plant must possess to be called “new.” Right now, in order for a turfgrass variety to be protected by law, much like an invention is protected by a patent, the variety must be morphologically distinct. Grass breeders evaluate and record many different measurements to convince government officials that their “new” grass is really different. However, all this is changing with the advent of GMOs (genetically modified organisms).
So how do you really determine if a “new” turfgrass is really different and better? Here are some guidelines:
- Look beyond the “new” name
A newly named turfgrass variety does not necessarily mean it is better than an older variety.
- Determine exactly what makes the “new” grass plant different
Consider the following traits: dwarfism, disease resistance and quality. Some fescues are marketed as dwarfs, and they are, when allowed to grow unmowed. But they are not when you mow them at 2 or 3 inches. Disease resistance can be measured, but it is difficult to do, so be skeptical of major claims of improvement in this area. Quality is a subjective trait, and evaluation programs often try to split hairs when ranking varieties. Ask yourself: Is a new turf rated 8.2/9.0 actually different than an old one rated 7.8/9.0? Remember: Statistics are used to test experimental data for differences, but statistics do not address the biological importance of the difference — that is up to people!
- Determine how big the difference really is between the old and “new” turfgrass
A difference can be very small and have no practical effect on how the grass behaves. Or it might even be totally unrelated to your need. For example, a grass with an increased level of ergot disease resistance would be both new and better to turf seed producers, but useless to turf managers.
- Do not focus on just one trait of a new grass
When a newly offered grass hits the market, it might have been changed in more than one way but marketed for only one trait. For example, it might be darker in color, but also more susceptible to leaf rust or summer patch. Be careful when you first look at GMO turfs. They will be different, and they will have an easily identifiable trait (e.g. herbicide resistance), but they could also be very susceptible to a disease like brown patch.
- Focus on the traits of turf that are important to you (and your customers)
Do not get caught by the lure of marketing. Understand the most important characteristics of the turf you want, and prioritize them. For example, if early spring and late fall color is most important, find varieties that offer this feature — new or old. Then take your second desired trait and find the top five or so in that category. When you do this for each of your desired traits, you will end up with a short list from which to select. You will be surprised to find that “new” varieties often fall out of your list. It takes many years to develop and test new varieties of turf, including their performance in the marketplace after they are initially offered.
HOW ARE NEW TURFGRASS VARIETIES DEVELOPED?
There are a number of different methods that can lead to new grass varieties, but common to all of these is the fact that any change in a plant results from a change in the DNA. So how can the DNA of a grass plant be changed?
- Natural DNA changes
This has been the most important means for developing new turfgrasses. Remember those 9,000 grass species that I mentioned above? They are the work of natural DNA changes. These natural changes occur all the time, but most go unnoticed. It takes many years and many changes for nature to produce a new and better plant. Scientists and turf managers are still finding new grass varieties growing naturally. These are called clonal variants, and they are found all over the world. Keep your eye out for them in older turf areas, like cemeteries, roadways and older golf courses.
- Controlled breeding changes DNA
We are all familiar with the power of breeding, by virtue of corn, rice and soybeans that producer bigger and more nutritious grains. Controlled breeding means that a selected plant is forced to pollinate another plant. The limiting factor is that the two plants must be biologically compatible. For example, you can cross two ryegrasses, but not ryegrass and bluegrass. Breeding allows new grasses to be developed faster than would be developed in nature, and also with a greater degree of control over what characteristics the new plants will have. While it is faster than nature, controlled breeding takes 10 to 15 years and a lot of money to develop and test.
- Genetically Modified Organism (GMO)
This is a fancy way of saying “artificially inserting DNA into a plant that naturally did not have the gene.” GMO technology also avoids some of the problems of incompatibility. Most of us think of GMO technology as a “space-age” method of creating new plants, but that is not the case. Yes, we do put the new DNA into a plant cell with “guns” and needles, but that is only the method of delivery. In fact, Mother Nature has been genetically modifying grass plants and most other forms of life for billions of years. For example, a virus can live in one plant and “pick up” a piece of the plant DNA. The virus is then picked up by an insect sucking on the plant, and deposited into another plant that the insect lands on and feeds on. The virus then delivers the new DNA to the second plant, and, voila: The plant is now a GMO. Aha! You think that the insect will only feed on the same type of plant? Not so! Most insects test and taste many different plants in order to find just the right one for feeding. In the meantime, they are depositing viruses all over the place.
The bottom-line for evaluating a “new” turfgrass variety is not how it was created, but what its characteristics are as a turfgrass.
TURF OF THE FUTURE
In the coming decade, what will the new turfgasses be like, and where will they come from? Here are my top picks, in order of their predicted availability.
- Herbicide resistance
These will come mainly from GMOs, but some with slightly less tolerance will emerge through natural selection. The reason this type of plant will be developed first is simple: Herbicide resistance is controlled by a single gene; i.e., the DNA change is small.
- Heat or cold tolerance
These will come mainly from GMOs, but again, some will emerge from natural selection. Heat and cold tolerance are controlled by only a few genes, so changing a grass plant will be fairly straightforward, but not simple.
- Disease resistance
For many diseases, this will change slowly and through natural selection. The reason is that disease resistance is generally controlled by a number of different genes, most of which we have not identified. For example, summer patch, necrotic ring spot, and take-all patch all require multiple genes to confer resistance. This is more likely to have developed during the past billion years, so keep looking for natural clones. On the other hand, look for big, new changes against a disease like rust, which requires only one gene to confer resistance.
- Root-chewing insect resistance
This is a guess, but I believe that GMO technology could result in grasses that produce a nasty tasting chemical in the roots to deter insect feeding.
Caution! New and better turfgrass varieties will be produced, but this will take time. Beware of “overnight” miracle grasses or grass varieties that are ranked superior but are actually not any better than the industry standards.
Henry T. Wilkinson is professor of plant pathology at the University of Illinois (Urbana. III.).
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