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Take on all centipede

The Grass is Greener

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POSTED: April 26, 2012 6:00 a.m.

We are just to the calendar date when our turf fertilization usually starts, and the turf disease year already is off to a new and rousing start.

We hit and held our trigger soil temperature of 65 degrees at a 4-inch depth five weeks early this year on March 12. If we had two legitimate mowings on the lawn, the earliest date for application of any fertilizer, whether it is straight fertilizer or a weed and feed mix of fertilizer and herbicide, was March 26 for Bryan County this year. One could also have waited until May to start fertilization of lawns, but then we Americans are an impatient lot. We want to see results now, not next week, and if this company cannot give me overnight results, why I’ll just fire them and get another company that will tell me what I want to hear.

Of course, anyone is free to disregard the research-based advice from Cooperative Extension, and they are free to suffer the consequences as well. For those of you who disregarded good, solid, research-based information and instead listened to a pitch man who told you to “Feed your lawn — feed it!” back in February and early March, I say thank you for giving me grist for today’s column and ensuring others in the green industry will be doing more business this year at your expense. Those who fertilized early have brought me samples of their lawn and wondered why their grass is dying.

Early fertilization is a common thread. The other is using rapidly available nitrogen sources. Fast-release nitrogen gets a big slug of nitrogen out on the lawn and gives rapid response from the grass. Homeowners like that. It proves to them that the fertilizer is working. Lawn-care companies use it so the homeowner will know the company applied fertilizer. Homeowners don’t pay the fertilizer bill unless they see the plants push on new green leaves. So lawn companies push out the fast-release fertilizer not because it is the best thing to put out or even the best time to put it out, but because you, the customer, demand them to do it. Given the almost non-existent winter this year and early warm-up, there was an overwhelming push to start fertilizing early. That now has started reaping the predictable rewards of accelerated fungus-disease development. Putting out a fast-release fertilizer is like putting out a huge buffet in a crowded park when you only want to feed two people. There is too much food for two people to eat in one sitting, so soon everybody else in the park is feasting on the bounty spread before them. Yes, the grass gets all the nitrogen it can handle, but there is so much left over that the fungi, insects and weeds get fed as well. If the grass was awake and able to defend itself, this might not be so bad, but the grass still is waking up, and the soil has not been warm very long, so the fungi and weeds quickly can get the upper hand.

This is one reason why I have been recommending slow-release fertilizers on coastal lawns. Slow-release nitrogen sources cost more than fast-release sources, but that is taking too narrow a view. Slow-release sources that do not exacerbate disease, weed and insect problems cost a whole lot less than cheaper fast-release sources PLUS the cost of disease control PLUS the added weed control PLUS the added insect control the excess nitrogen causes. It is one of those “an ounce of prevention being worth a pound of cure” situations.

The most interesting trend for the early season turf problems this year is Take All Patch attacking centipede lawns. In the past 10 years, I have been able to diagnose Take All Patch on centipede lawns twice. This past week, I found Take All on centipede twice in the same day. This is important because Take All is only poorly controlled with fungicides. Cultural controls work far better than fungicides on this disease but must be used in concert to get the best results. The Take All fungus attacks grasses. It attacks all grasses, but it only attacks grasses. St. Augustine turf seems to have the least resistance to Take All. Now it seems that if one abuses centipede lawns enough, one can tip the balance away from the turf and in favor of the fungus. When one makes a mistake applying too much early season or autumn nitrogen, Rhizoctonia Large Patch often becomes a problem. Rhizoc clips off a few leaves but does not kill the runners or roots.

Rhizoc also is effectively suppressed with fungicides, giving the turf a chance to recover in a week to 10 days. The pathogen for Take All, Gaeumannomyces graminis graminis, represents a much more serious threat to a lawn because, as its name states, it takes it all: leaves, runners and roots. Recovery takes months or years instead of days. Centipede does best on 1 pound of nitrogen per 1,000 square feet per year. If you put out a weed-and-feed already, please check the bag and figure out how much nitrogen you applied per thousand square feet. Many weed-and-feed products provide 1 pound of nitrogen per 1,000 square feet when applied at the recommended rate. If your weed-and-feed was one of these, then you are done fertilizing your lawn this year. One pound of nitrogen per 1,000 is all the centipede really can handle.

Of course, there will be those who read this who will ignore my recommendation and they will apply fertilizer to their centipede once or twice more this year. Then they will call me next spring wondering why their lawn did not green up and is dead. I will try to explain what happened, but of course it could not have been something they did. They will resod their lawn or fire their lawn-care company when the guilty party was staring back at them in the mirror this morning.

 

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