How Does Your Sprinkler System Know It Has Rained?

How Does Your Sprinkler System Know It Has Rained?

Although it has been very hot this summer throughout the Florida Panhandle, many areas have been blessed with afternoon showers several day in a row.  Historically, this has been the typical Northwest Florida weather pattern known as the ‘Dog Days’. green-grass-with-drops-raining

Yet, many landscape sprinkler systems were still running.  One has to ask, “Where are all the rain shut-off devices?”.  Florida is one of just a few states with a rain sensor statute.  Since May 1991, new installations of irrigation systems have been required to include a rain shut-off device.  However, no wording was included to cover installation or maintenance.  The 2010 statute change now states the following: “Any person who operates an automatic landscape system shall properly install, maintain and operate technology that inhibits or interrupts operation of the system during periods of sufficient moisture.” (Florida Statute 373.62).

Thus, ALL automatic landscape irrigation systems require rain sensors, or other shut-off devices such as soil moisture sensor irrigation controllers.  No “grandfather clause” was included for existing systems.  Regardless of when it was installed, every sprinkler system must have an operational rain shut-off device.  Irrigation contractors can be fined for working on a system without checking out and/or connecting a device.

Moisture sensing technology conserves water, saves money, reduces wear on irrigation system components, reduces disease and helps protect water resources from runoff.  Previous research has shown that homeowners using in-ground, automatic irrigation systems, typically in Florida, apply 47% more water for landscape irrigation than homeowners without automatic irrigation systems.  This over-irrigation is largely due to a “set it and forget it” mentality despite seasonal fluctuations in plant water needs.  If the water costs and the amount of water applied per watering cycle are known, it is easy to calculate how much money is being saved each time the sensor interrupts the program.  For example, if a system irrigates ½ acre of turf and is set to deliver ½ inch of water to each zone, approximately 13,576 gallons of water will be used during each watering event.  If the cost of the water is $2.00 per thousand gallons, every time the sprinkler system comes on the water bill will be $27.15.  A significant amount of money and water can be saved by maintaining a rain shut-off device.

RainSensor_1Irrigation is common in Florida landscapes because of sporadic rainfall and the low water holding capacity of sandy soils.  Water conservation is a growing issue due to increased demands from a growing population.  The least expensive and most common rain sensor device is the expansion disk rain shut-off.  Expanding cork disks trigger a pressure switch.  The expansion space can be easily adjusted by rotation of the disk cover to a predetermined amount of rain required to trigger the switch.  The amount of rain that will interrupt the irrigation system is marked on the adjustment cap.  A rain sensor must be mounted where it will be exposed to unobstructed rainfall, typically installed near the roofline on the side of a building.

Irrigation control technology that improves water application efficiency is now available.  Soil moisture sensors (SMS) can reduce the number of unnecessary irrigation events.  Most soil moisture sensors are designed to estimate soil volumetric water content based on the soil’s ability to transmit electricity, which increases as the water content of the soil increases.  Bypass type soil moisture irrigation controllers use water content information from the sensor to either allow or bypass scheduled irrigation cycles on the irrigation timer.  Another type of control technique with SMS devices is “on-demand” where the controller initiates irrigation at a low threshold and terminates irrigation at a high threshold.  A single sensor can be used to control the irrigation for many zones or multiple sensors can be used to irrigate individual zones.  In the case of one sensor for several zones, the zone that is normally the driest, or most in need of irrigation, is selected for placement of the sensor in order to ensure adequate irrigation in all zones.  Sensors should be buried in the root zone of the plants to be irrigated.  For turfgrass, the sensor should typically be buried at about three inches deep.  The placement of SMS should be at least 5 feet from hard surfaces and sprinkler heads.  The sensor needs to be calibrated and/or the soil water content threshold needs to be selected.SMS

The amount of water that can be saved using rain shut-off devices is substantial since water use increases substantially during summer months. Remember that every drop that hits the ground will be picking up pollutants as it flows to our groundwater.  Nonpoint source pollution is the leading cause of water quality problems.  These pollutants have harmful effects on drinking water supplies, recreation, fisheries and wildlife. By only irrigating when the soil needs it, you are also preventing contamination of drinking water.

 

This article is being reissued as part of our ‘Best Of” series, from August 2013 .

A Robotic Mower Debuts at the Gulf Coast Turfgrass Expo & Field Day

A new research project at the West Florida Research and Education Center in Jay, FL is looking into the quality of turfgrass cut with a robotic mower.  The study is to determine whether the quality of St. Augustinegrass can be improved by continuous mowing with a robotic mower at 2.4″ height instead of the traditional mowing height of 3.5″, removing only a third of leaf blade material per mowing.

Dr. Shaddox discusses the Miimo mower.

Dr. Shaddox talking to participants at the 2018 Gulfcoast Expo & Turfgrass Field Day. Photo Credit: Matt Lollar, University of Florida/IFAS Extension.

The mower being tested is the Miimo manufactured by Honda.  This particular model mows and charges on its own and can mow up to 0.37 acres on one charge.  It can mow in three programmable cutting patterns: directional; random; or mixed.  The study is utilizing the random cutting pattern.

Miimo Mower Docking

A Miimo Mower pulling into its docking station. Photo Credit: American Honda Motor Company, Inc.

The mower’s three, two-sided blades are mounted on a circular head that can rotate both clockwise and counter-clockwise.  The head automatically switches between clockwise and counter-clockwise rotation to reduce wear on the blades.  The blades are basically just two-sided razor blades.  A buried guide wire is installed on the perimeter of the lawn to serve as a boundary.

Mower Blades

A close-up shot of the Miimo mower blades. Photo Credit: Matt Lollar, University of Florida/IFAS Extension.

So far, the plots cared for by the robotic mower look promising!  The blades on the robot are much finer than those found on a common rotary mower.  Because of this, they cut more cleanly and tend to tear the grass blades less often than the rotary mower.  Other robotic mowers on the market include the Worx Landroid, Husqvarna Automower, and Bosch Indego.  Please stay tuned for future robotic mower evaluations on other products, energy consumption, and nutrient evaluation.

Is Your Lawn Drowning?

A healthy lawn is a joy to stroll, relax and play on. It can also be part of an environmentally friendly landscape. But, sometimes it can seem to be a mystery on how to achieve that lush, healthy lawn in the Florida environment. Since we have lots of sandy soils and experience long periods of warm and hot weather, many suppose that giving the lawn lots of water will help do the trick. Not so.

Photo credit: UF/IFAS.

But what harm can it cause to give the lawn plenty of water all the time? Isn’t that a good thing? No! Overwatering your lawn can lead to the following problems:

  • Development of fungal diseases (fungi love a moist environment!)
  • Increased insect pest pressure
  • More rapid thatch development
  • More weeds (those little emerging weed seedlings thrive on consistent moisture!)
  • Some weeds, like dollarweed and sedges, can be an indication of overwatering
  • A shallow root system when frequent, light watering is applied
  • Washing away of fertilizer down into the soil past the root system
  • Higher water bills.

Our lawns need, on average, about 1/2 to 3/4 “of water a week during the summer. This recommendation changes depending on soil type, shade, temperature, wind, and season. To figure out how long to run your sprinklers, watch this YouTube video from UF/IFAS.

We recommend running your automated system only when your lawn shows signs of needing water such as:

  • Leaf blades fold
  • The lawn looks ‘off-color’
  • Footprints remain and are visible

 

For more information:

Watering Your Florida Lawn

Gardening Solutions: Irrigation

Your Florida Lawn

 

The Mystery of Florida Betony

Figure 1: Florida Betony, Stachys floridana. Credit: UF/IFAS Range Cattle Research & Education Center.

If you look closely at your yard, there is a good chance that you will find a plant that, depending on who you ask, is considered either a native wildflower or a weed and there are more than a few species that fit this description. If, upon even closer inspection, you find a plant with root tubers that resemble egg casings or even a rattlesnake’s rattle, you’ve stumbled upon Florida Betony.

Stachys floridana is a perennial broadleaf commonly referred to as rattlesnake weed due to it’s fleshy, white, segmented underground tubers. The plant has an erect stem with leaves that are opposite, shovel-shaped and coarsely serrated. The plant structure is very similar to mint. Flowers, emerging in late spring, are pinkish-purple in color. These inflorescences will also produce fruit, consisting of four nutlets. However, reproduction of the plant and it’s propensity to spread through lawns and gardens primarily occurs through dense root tuber development. Florida Betony’s growing range was originally confined to the state of Florida, but the commercial nursery trade played a major hand in dispersing the plant across the Southeast in the mid-1900’s. It can now be found as far west as Texas and as far north as North Carolina.

Figure 2: Tubers of the Florida Betony. Credit: Jill Bebee, UF/IFAS Gulf County Master Gardener.It can now be found as far west as Texas and as far north as North Carolina.

This time of year is when Florida Betony thrives. The moderate temperatures of fall and spring are the prime growing periods for Betony. In the heat of the summer, the above-ground structure of the plant will struggle and often disappear completely, only to reemerge in the fall. As a lawn weed, managing tuber development is key to controlling this plant. Applying herbicide to the leaves and stalk may seem at first to have conquered the weed. However, in most cases the tuber will simply regenerate. Glyphosate (Roundup) can be used effectively for control in ornamental plant beds where no turf is present. Be careful when spraying herbicides around trees, shrubs and other desirable plants as any foliar contact will cause phytotoxicity. If you have an infestation of Florida Betony in your turfed areas, there are a few options for control.  Regular applications of three way broadleaf herbicides, such as mixtures of 2-4D, Dicamba and Mecoprop, are effective at suppressing this pesky plant. For more information and options, please contact your local county extension office or see the supporting information links below. Always refer to the product label for specific uses, precautions and application rates when using any herbicide.

Supporting information for this article can be found in the following the UF/IFAS EDIS publication, “Florida Betony Biology and Management in Turf” by J. Bryan Unruh, Ramon G. Leon, and Darcy E. P. Telenko: http://edis.ifas.ufl.edu/pdffiles/EP/EP38800.pdf

 

 

 

 

 

 

 

Have Patience with Spring Lawn Problems

Cold injury to lawn. Photo Credit: Larry Williams

Patience, warmer soil temperature and correct lawn management will solve many spring lawn problems.

Many spring dead spots in lawns are caused by something that happened the previous growing season or winter. For example, a late application of a high-nitrogen fertilizer can decrease winter survival. It’s best to not fertilize our lawns after early September.

An insect or disease problem during fall many times goes unseen as the grass is beginning to go dormant. The following spring, as the lawn begins to green up, evidence of a fall pest is clearly visible by brown dead, grass. The pest may not be present or active during spring.

Poor maintenance practices may be to blame for spring dead spots. Over-watering, shallow watering (watering frequently for short periods), mowing too low, too much fertilizer and herbicide injury can result in poor lawn performance come springtime.

Regardless of cause, problem areas within lawns are slow to recover during spring due to frequent cool night temperatures. Frequent cool nights keep the root zone cool.

Cool soil temperature doesn’t allow rapid root regeneration in spring, which inhibits top growth in your lawn. Cool soil also decreases availability of some needed nutrients. For example, poor availability of iron because of cool soil is a common cause for bright yellow areas within lawns, especially in centipedegrass. Cool soil also decreases availability of phosphorus and potassium, which can result in reddish-purple grass blades, intermingled throughout the yard. As soil temperature increases, availability of nutrients improves and the yellow and purple areas turn green.

Have patience with your lawn and follow good maintenance practices this spring. Provide ½ to 1 inch of water when the grass shows signs of wilt. Fertilize and lime based on the results of a reliable soil test. And, mow at a high setting. Good lawn maintenance info is provided at the YourFloridaLawn website.

Consistently warmer nights will allow the soil temperature to warm, which will improve turf root growth, nutrient availability and lawn recovery. During many years in North Florida, it’s well into the month of May before our lawns begin to recover.

If the lawn has not made a comeback by late spring or early summer, it may be time to consider reworking and replanting the dead areas or maybe consider replacing them with something other than grass, if practical.