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Sunday, June 15, 2014

Turfgrass Dead Spots. Irrigation Problem?

Brown spots or dead areas in lawns can be common during summer months. It might be a disease, but then again, it could be something else.
There is a sprinkler head in the center of the green spots.

The three primary reasons that lawns develop brown spots or dead areas are due to irrigation problems, the development of diseases and insect damage.

Irrigation Problems. How many times have I heard, “I know the sprinkler system was installed right. I did it myself.” Just because you did it yourself, does NOT mean it was done correctly. If it was done correctly did you design it for “head to head” coverage? Did you size your pipe taking into account all of your nozzles gpm and friction losses? Did you make sure the pressure of your 
First sign of an irrigation problem is that smokey-grey color in your lawn when it gets hot.
system falls within the manufacturers recommended pressure range for your nozzles? I can go on. If you understood these terms and took them into account then maybe you did it right.

Pressure too high. Sprinkler in the center of that little green spot of grass
Any weaknesses in your sprinkler system will show up when temperatures hit 110F and 15% humidity. Lawn water use will exceed 4/10 of an inch of water every day. The first thing you will notice when temperatures start to get hot are smoky-grey patches start to show up in your lawn. Then the brown spots or patches start to appear and they are often not clearly defined. Oftentimes they are smack dab between the irrigation heads when heads are not spaced appropriately, nozzles are mismatched, heads are not perpendicular to the lawn or you use 2 inch popups when you should use 4 inch. Sometimes these brown patches can be right next to the head if the pressure of your system is too high and the sprinklers “fog”. In order to clear up the problem or you use the wrong type of nozzles.

Little bit of drought and disease mixed in this lawn.

·       Know the operating pressure of your sprinkler system.
·       If mowing at two inches or above use four inch popup sprinklers.
·       Space sprinkler heads and select the right nozzles to provide head to head coverage (water from one nozzle should reach the neighboring nozzle and vice versa).
·       Size irrigation pipe to provide water flow through the pipe not to exceed 7 feet per second when operating.
·       Use a system pressure regulator (if operating pressure is to high) or a booster pump (if operating pressure is too low) so that operating pressure falls within pressure range recommended by sprinkler nozzle manufacturers.

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