Bentgrass problem/Lawn Renovation

Discussion in 'Homeowner Assistance Forum' started by CT John, Aug 14, 2003.

  1. CT John

    CT John LawnSite Member
    Messages: 90

    Hey guys. New to the site and have spent hours reading most of the threads from this forum. What a great deal of info.

    Anyway, heres my problem. Over the last few years I have had my lawn's, approx. 10,000 sq. ft, appearance deteriorate due to what I believe to be a bentgrass infestation. It has taken over approx 40% of my yard. I have decided that in order to effectively eliminate the problem, I will be killing off everything with Round-up this fall and re-seeding. My plans are apply the herbacide in a couple applications over a two week period beginning at the end of this month. I plan on renting a slit seeder to do the seeding. Should I mow the grass down to .5" to 1" or so before applying the round-up or after its dead? Now I planned on renting a core aerator also, so should I aerate after the grass is dead and THEN mow it down to better break up the cores?

    Also, I live in Connecticut. I have decided that I would like to slit seed with a good KBG blend but was hoping to mix in some(30% or so) perennial rye. Now I understand that the rye germinates much quicker than the BG, so what I was thinking was in order to stop the rye from hurting the germination of the BG, I would wait a week or so and just broadcast spread the rye. Is this feasible? Any suggestions? My lawn gets excellent sun and the soil pH is good. The photo below was taken a couple years ago. Looking forward to your responses. Thanks.

    One more thing....There is no way to kill off the bent only without hurting the rest of the lawn, is there?

  2. GroundKprs

    GroundKprs LawnSite Bronze Member
    Messages: 1,969

    Renovation procedure:

    1- Roundup area to be done, ideally a month before seeding date (you then have chance to redo Roundup if some weed grasses come back in that month).

    2- When you are getting close to seeding date, mow the dead areas as short as possible without scalping. (The dead blades will just stand there for months, so the short mowing will hide them after new grasses germinate.)

    3- Core aerate after short mowing - you get better penetration. Should have area irrigated for this step. Aerate in mutiple directions, 3 or 4 passes is best. The more soil pulled up, the more seed/soil contact you are achieving.

    4- Let area dry after aeration, then slit seed. Make two passes, applying seed at 1/2 rate. Don't do a 90º pattern, but a diamond pattern. Plan the pattern depending on how the lawn is viewed. The diamond pattern helps conceal the visible lines of grass just after germination.

    ??- Why mess up KGB with ryegrass. I think the hoopla on the east coast about rye is to provide lawn care services with more reason to apply fungicides, LOL. See (this deals with sports turf, but the disease problems are for all uses of rye). If you do go with rye, and use more than 10-15% rye, you will basically have no KGB survive (from a Purdue study). The rye germinates so quickly, then grows so aggressively, the KGB cannot succeed. The reason for rye in a seed mix is to get quick germination to stabilize the soil; your soil surface is already stabilized by the dead stubble of your former lawn.

    And you're probably going to have the bentgrass coming back, because the seed supply is still there somewhere; also there are probably bent seeds in your lawn now. In my area I found that I can control the spread of bent by powerraking with vertical flails in the early spring. Since bent is stoloniferous (above ground horizontal stems), you will tear up a lot of bent. Then the KGB has a chance to fill in the thin spots, because it starts active growth earlier in spring than bent does.
  3. CT John

    CT John LawnSite Member
    Messages: 90

    Thanks for the reply Jim. I'll take your advice and stick with a good blend of KBG only. I certainly hope the bent doesn't come back. Is there anything additional I can do to increase the chance of it being killed off permanently? I enjoyed a beautiful lawn until this started spreading like wildfire a few years ago. I don't want to go through this again. thanks again for the reply. Any other opinions? Professional/non-professional.....i'll take any advice I can get.

    Also, where can I go to get a good grass seed blend in my area?
  4. GroundKprs

    GroundKprs LawnSite Bronze Member
    Messages: 1,969

    Before you assume you're fighting bentgrass, it would be practical to positively ID the culprit. Is is bent, annual blue (Poa annua), or even poa triv (Poa trivialis)? Your state land grant university diagnostic lab, or even local extension service, can help here.

    As far as best source of seed, I cannot help you there. Ask a good golf course super in your area. He may have a supplier who could help you. Last time I got a good sunny blue blend, it was about $3/# wholesale - but what a beautiful lawn it made. (Same belend went down to half that cost following spring, LOL. Price depends on supply and demand.) A good seed man - a rarity in any area - will have blends and mixes that will do well in his area, and that success varies sometimes from county to county.
  5. CT John

    CT John LawnSite Member
    Messages: 90

    Thanks. I appreciate the replys. From the pictures I've seen and my brother-in-law who has some experience in the area, I'm 95% sure its bent. I can pull up the grass in some areas and the stem runners are 6+ inches long. :eek: Maybe I'll snap a pictire and post it. All I know is that it has destroyed my lawn over the past few years.

    Anyone else fight a bentgrass problem?

    Also, any advice as to how much seed I will need for approx. 10K sq. ft? What rate should I use?
  6. GroundKprs

    GroundKprs LawnSite Bronze Member
    Messages: 1,969

    Normal rate for KBG is 3#/1000 ft². Germination rate when slit seeding is ~65%. With coring also, germ rate will be higher, around 75-80%.

    Seed required = 10 * 3# / 0.75 /(germ rate of seed label)

    And as I stated above, if bent is indeed the problem, it will generally come back in the future. I once spot treated and repaired with sod a lawn starting to be bothered by bent. All lawns in the neighborhood had some bent in them. By using the spring flail raking noted above, during the 7-8 years I continued to manage this lawn there was no great buildup of bent. It was present in the lawn, but did not overtake the KBG. Youy might even experiment with an additional fall flail raking to thin the bent.

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