Irrigation Techniques During Summer Months for Weed and Disease Management
Irrigation systems are crucial to a healthy and vibrant lawn during the summer months. Weather conditions are constantly changing, and periods of drought are common. Dry periods are inevitable, and irrigation helps sustain your lawn through these periods. Just as important is not over watering your lawn. Improper irrigation can lead to problems with diseases and weeds, so understanding some basic information can reduce the chances of serious problems and damage to your lawn. Several factors we will be discussing today include –
1. Irrigation components and sprinkler heads
2. Irrigation scheduling and run times
3. Soil types, terrain, thatch, and other factors
4. Recognizing drought stress and “hot spots”
5. Common causes of “hot spots”
6. Disease and weed issues from irrigation problems
Irrigation components and sprinkler heads
The control panel is where you will set up the programming for your system. There are many different styles and varieties on the market today. We will be mostly concerned with the program times and schedule. Additional information about how to program can be found in your instruction manual or we can help if needed.
We will be talking about the 3 main types of sprinkler heads seen here. We also refer to them as –
Gear drive – rotor sprinkler
MP – rotary nozzle
Stationary – spray head
Irrigation scheduling and times
On average, we receive around 50 to 52 inches of rainfall per year here in the CSRA. Unfortunately, this rainfall does not happen on a weekly basis. Most lawns require 1 inch of water per week for optimum health during the active growing season. Dormant lawns require less. Transition periods during the spring and fall also do not need as much water for your lawn.
This chart is just a starting point. We will discuss some factors that will have an impact on this schedule. Also, active growth and green grass is present. The best time for watering your lawn is during the dew hours of the early morning. Ideally, you want your last zone to end at sunrise. Prime time would be 3:00am to 7:00am. The number of zones and the run time of each zone will determine your start and end times.
Again, this chart is just a starting point. We will discuss the factors that will affect these run times. The basic idea of irrigation is deep, infrequent waterings that improve root development for drought tolerance. We want the lawn to dry out during the day.
Soil types
Our typical soil type here in the CSRA is a combination of sand and clay. As you get closer to the Savannah River and into Georgia, we typically see higher concentrations of clay. The further away from the river we see more sandy soils. Rarely do we see a loamy soil type here.
If you are ever in Hitchcock Woods either walking or riding a horse, locate the area referred to as the Aiken Grand Canyon. It is an interesting area that shows the local structure of our native soil here in the area. If you live near new home construction, go look at the land as the builder is excavating and grading the property.
Another great resource is with the US Department of Agriculture. They have soil survey charts that show native soil types throughout the United States.
Understanding what type of soil you have is very helpful in determining how much water to put out during each cycle. Most plants and lawns like well-drained soil.
Seems simple enough if you know the native soil type you have in your area; however, building construction changes everything.
Honestly, I have no idea! I am not Bob the Builder!
Builders bring in whatever soil type is best for what they are constructing. Once the landscape is installed and the grass is planted it becomes nearly impossible to find out what lays under the surface. To make it even more difficult; chances are the soil brought in changes throughout the property!
Digging holes is one way of finding out. Have fun with that! Soil testing can help without backbreaking work.
Visual cues like excessive puddling can be a tell-tell sign of clay, while consistent dry spots could signify sandier soils.
Types of Terrain
The terrain of your property will affect your watering as well. A perfectly flat property will keep the water within that area and evenly spread it out. Rolling properties with small hills and valleys will have areas of puddling with dry spots on the crest of the hills. Steep slopes will allow the water to run off quicker than it can absorb.
You may have a combination of terrains on your property which will require you to run each zone just a little differently.
Steep slopes may require multiple waterings at short intervals during a period to allow water to absorb and not create erosion issues. Terracing may be needed in some cases.
Thatch and Soil Compaction
Depending on your grass type, up to a ¼” layer of thatch is acceptable. Bermuda and wide blade zoysia keep it less, fine blade zoysia absolutely no thatch, and centipede and St Augustine can handle the ¼”.
Bag your clippings as much as possible or mow your lawn often and regularly to avoid large amounts of clippings at one time. For Bermuda you may have to mow every 5 days to minimize clippings.
Thatch layers can harden and become water repellent or hydrophobic. This will not allow water, chemicals, fertilizers and oxygen to reach the roots where it is needed.
Soil compaction is very similar. Roots cannot penetrate and spread into areas of heavy compaction. Water will not penetrate into the soil.
Core aeration on a regular basis will help solve these problems.
Drought conditions
It takes around 27,154 gallons of water to equal 1” of rain per acre. It is roughly 617 gallons per 1000 sqft of area. That is what you need to provide during periods of drought per week. Irrigation is only meant to sustain your lawn, not keep it a lush green. Fertilizer and irrigation cannot replace mother nature!
Monitor your local weather or follow the US Drought Monitor through the US Department of Agriculture.
Recognizing drought stress and “hot spots”
Watering efficiency and conservation practices go hand in hand. A good rule of thumb is to only water when your lawn tells you it needs it. Of course, it will visually tell you and not actually yell at you! Long term drought conditions will necessitate scheduled watering.
Color test – your lawn will develop a bluish-gray appearance as the leaves curl up to minimize water loss. The blades will appear small and thin. Brown patches will begin to develop as the grass goes dormant to protect itself.
Footprint test – a properly hydrated lawn will bounce back from treading across it. Walk across your lawn first thing in the morning after a good watering. Time how quickly your footprints disappear. Walk across it late in the day after a hot and sunny period and see if there is a difference.
Screwdriver/soil probe test – Take a screwdriver and push it into the ground. If it is hard to push, your lawn may be too dry. Use a soil probe to remove a sample of soil and feel for wetness between 6” to 8” deep.
By far, in my opinion, the best method is the color test. Walk through your lawn and look for patches and areas that just do not look the same. When those leaves start to curl and look smaller than other areas that shows you where you have the start of a “hot spot”. You will also notice areas that are not growing the same. Investigate these areas as quickly as you see them.
A “hot spot” does not necessarily mean your entire lawn is dry. You may just need some adjustments in that one area.
Disease problems
Just like us, the best way to protect against disease is to maintain a healthy lifestyle. A strong and vibrant lawn is more likely to resist and repair disease damage. A stressed lawn is more susceptible to a variety of diseases such as pythium, dollar spot, and many others.
Overwatering can be just as problematic as underwatering. Root rot issues and leaf spot diseases are just as damaging to your landscape.
Weed Problems
Thin and stressed grass can increase the ability of weeds to establish in your lawn. Weeds have a remarkable way of growing in some of the most inhospitable areas. Once weeds establish themselves, they easily out compete the stressed lawn for water and nutrients. This can lead to larger and larger bare spots.
Overwatering can also help weeds establish. Weeds such as nutsedge, kyllinga, dove weed and poa all love wet environments. Puddling areas around flower beds, curbs, low spots are all areas where these weeds establish and spread.
A strong, thriving, and healthy lawn is the best defense against pest issues. Irrigation is just one of the integrated parts of the pest management program. Not all recommendations will work in every situation. Constant monitoring and adjustment is needed to stay on top of lawns overall health. We are always here to help!
The Cold Creek Lawn and Shrub Care Department offers the following programs that you can consider in maintaining your lawn and landscape-
Lawn Weed and Insect Management Spray
Lawn Fertilization
Lawn Disease Management Spray
Growth Regulator Spray
Mole Cricket Management
Shrub Disease and Insect Management Spray
Shrub Fertilization
Core Aeration
Soil Testing and Analysis
Thank you- Chris Clement
chris.clement@coldcreek.net
