Pine trees competing for moisture? Some brown areas


#1

Our lawn is mostly doing well but a recent shift to not much rain and many 90* (F) days has a few areas near pine trees a bit brown. I think I shared this last year and someone suggested the pine trees are probably sucking up the nearby moisture.

I’m on Flex daily. What would you suggest as tweaks to the zones covering this area? Perhaps bumping allowed depletion to a slightly lower number? All zones covering the challenged spots are…

  • Cool season grass
  • Sandy loam
  • Lots of sun
  • Flat
  • Rotor heads
  • 0.12 available water
  • 6" root depth
  • 50% allowed depletion
  • 70% efficiency
  • 80% crop coefficient


#2

Does it have anything to do with shade cover? I have a few areas of my yard that pretty much get 100% shade all day long thanks to some very healthy trees, and I can’t grow grass there AT ALL…

Gorgeous yard BTW…


#3

I’ll probably considered increasing the AWC to 15-16
And the crop coefficient to 86 or 90


#4

Thank you. It may not be easy to see but directly under the pine trees are flower beds with pine bark mulch. No grass there on purpose. :slightly_smiling_face: It is only the areas just outside these beds where the browning is.


#5

Hmmm. Are these pine tree roots shallow? Then perhaps they’re drinking up the water within their drip line. Usually in deep soils they’re deep rooted. I normally don’t see grass under pine trees in the wild, but I do see grass under large oak trees — and with the shade, that grass tends to stay green longer during harsh summers. Oaks are deep rooted. Soil conditions could be different, maybe more compacted if the shade is enjoyed by humans. Pine needles do not acidify soil— just got to put that out there :slight_smile: Great for mulch though!


#6

I made the following changes for the two zones covering the troubled areas. I’ll keep an eye on them the next couple weeks and see how things go.

  • AWC from 0.12 to 0.15
  • Crop Coefficient from 80% to 86%
  • Allowed Depletion from 50% to 40%

#7

Top rooted pines will compete for the water supply. From the appearance of the photo, I noticed 2 things.

  1. Your depletion area is proximal to the drip line of the trees.

  2. You have the pre-signs of subterranean fungus.

This can easily be treated and you must treat the entire lawn area.

In a 4 gallon back pack sprayer, dissolve1/2 cup of sodium bicarbonate and apply the complete 4 gallons of sollution at the rate of 1 gallon per 1,000 sq ft. Water it in immediately, irrigate on your normal schedule and repeat in 2 weeks.

This solution can be applied between 50 and 100 degrees F and just about any time of year that you are within these temperature ranges.