Can organics (Urea/nitrogen) cause fungus?

gordon_gardenerJune 23, 2008

IÂve been reading the forums since late last summer, and have learned a lot from the regulars. I am in Easton, PA (eastern), along the NJ border and my lawn is a mix of KBG with perhaps fine Rye mixed in. The problem appears to be with the non-kbg sections.

Last fall I applied Urea which was 46% nitrogen as my last feeding. The application was timed when the top growth stopped and the grass was still very green.

Come spring, the grass awoke nicely. I didnÂt fertilize too early as I wanted the lawn to awaken on its own. On about May 10th, I fertilized with soybean meal at about 15lbs per thousand square feet. On memorial day weekend, I put down cracked corn at about 20lbs per thousand square feet.

Over the last two weeks IÂve noticed dead strands of grass mixed in with the live green grass. When you look close, perhaps 10-20% of the blades are brown (as in not receiving enough water), while the others are green. From what IÂve read, this may be a fungus caused by too much nitrogen. Can this be correct? I didnÂt think I could do damage with organics, but if this is true, then perhaps this was self inflicted.

If this is a fungus, then I will treat with cormeal15lbs per thousand square feet..

Any help or feedback is greatly appreciated.



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rcnaylor(z7 Tex)

Too much fertilizer, especially if hot, humid or watered improperly can increase fungus issues.

In the past I have fertilized just once in the spring for that reason.

I don't think it is caused by the organic choice. It might have even helped it from being worse with the amount of overall nitrogen you put out.

Once it gets going its tough to stop until cool weather arrives.

Using corn meal as your spring fertilizer might help prevent it. Whehter applying it now, if you already have too much fertilizer/nitrogen down is a tougher question. Like I suggested above, once I've gotten it going in the hot months, nothing really helped with stopping it. I've tried corm meal, I've tried fungicides (ugh). And, I've done nothing. Same results for me either way.

    Bookmark   June 23, 2008 at 11:06AM
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The above is correct. Too much nitrogen doesn't *cause* fungus but it tilts the soil balance in the pathogen's favor for a variety of reasons. If the conditions that favor a particular fungus are present then over fertilized grass is more likely to have an issue.

    Bookmark   June 23, 2008 at 6:53PM
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The grains are protein not nitrogen in the sense of chemical fertilizer (at least that is what dchall would tell us - and I believed him). That being the case nitrogen should not be a cause. I assume your urea last fall was about 1#/1000 which should be just right. The cracked corn will offer the same anti-fungal properties as the corn meal just longer to break down and get going. I would tend to say you are fighting the same problem I am which is the late evening thunderstorms and warm humid nights mixed with varying temperatures. I think it is the night rains causing a fungus this year. Is this your first year with grains? Did you put out any chemical herbicides (dimension or such) this spring? Did you have a poa annua attack this year - mine is dying out big time now? Sometimes I wonder if it is the lack of nitrogen direct to the grass that causes some problems.

    Bookmark   June 23, 2008 at 8:27PM
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Thanks for the follow ups.

My soil test last year indicated that I was severely lacking in fertilizers, which is when I decided to follow the organics routine many of you have been following. So this was the first year on organics. Having said that, I did put down a crabgrass preventer (containing no fertilizer) earlier this spring.

Soccer dad, the urea was 1#/1000 (measured for 1# of nitrogen, not 1# of urea).

As repsects Poa, I'm still a bit weak in identifying it for sure. There are times that I see a spot that I think may be poa, but these spots have not yet died off, so perhaps they are not poa..

As always...I appreciate the feedback.



    Bookmark   June 24, 2008 at 8:58AM
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Your problem may be insect .......ID your problem first then proceed. Take samples of damaged turf to nursery or county extension office.

    Bookmark   June 28, 2008 at 9:35AM
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