The Facts

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  Dog urine is waste. It is, basically, nitrogen-rich fertilizer. Unfortunately, the nitrogen is ammonia-based rather than useable nitrate or organic nitrogen and is so concentrated that a heavy dose cannot be converted easily. A flood of it burns plants, just like commercial fertilizer applied too heavily. If Max were a tiny dog or just "marking," his spots would show up as little spots of fast-growing dark green spots for a few mowings. But since he's a 120-pound "puppy" that hasn't learned to lift a leg yet, he's left a puddle that takes five minutes to soak in.
  
  

Identification

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  Look for brown, thin spots that dot a lawn and look like isolated late-season burn-out. Unlike burn-out, the grass will be lying flat. Repeated "accidents" will kill the grass completely, leaving a series of "dead zones."
  
  

Expert Insight

• The best treatment for dog urine is water---lots of it---as close as possible to the time of the offense. Flooding the area with water dilutes the nitrogen and flushes it through the soil faster. Some homespun gardening advice favors dropping a handful of gypsum on dog spots, but, unless you're trying to refurbish a compacted "dead zone," your best bet is the water. Both compounds have oxygen to help disperse the nitrogen, but water is benign---its hydrogen and oxygen do not affect the basic balance of the soil. Gypsum contributes only calcium and sulfur and leaches some other nutrients. Most of the products marketed to cure dog spots--including specially treated grass patch mixes---contain various enzymes that work to convert the ammonia-based nitrogen to a useable form.
  
  

Time Frame

• Time is of the essence. The sooner you flood the area with water, the better. Whether you use water, gypsum or some other alternative, the need for quick action is based on minimizing the effects of the nitrogen overdose by flushing and initiating the conversion process as fast as possible. Sow replacement mixtures exactly as directed at the proper time. Warm weather mixtures should be sown in late spring and early summer when these varieties grow best. Cool-weather grasses grow fastest in early spring and again in early autumn. Match the majority variety to the time you're planting so you can get the quickest recovery.
  
  

Misconceptions

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  Don't blame Max for spots that may be due to some problems that may look like urine spots. Certain viruses attack particular grasses, most notably St. Augustine grass and Kentucky Blue grass, by killing in a circular pattern. Infestations of pests such as billbugs, grubs, chinch bugs, sod webworms may start with circular patterns. Watering practices and heavy rainfall or flooding can also have an effect, particularly if you have a lawn with many low areas where water pools. If you haven't got a dog or haven't noticed one around, check for pests and diseases like leaf spot disease (helminthosporium) or downy mildew with your local extension agent or have your soil tested professionally.