The first day of summer/longest day of the year for 2012 has come and gone and just this past week a new National Drought Monitor Map was published (see below). The city of West Lafayette in Tippecanoe County has now fallen into the “Severe Drought” category. In fact 36% of Indiana is now in severe drought, while > 5% (the southwestern counties) are now in “extreme drought”.
Frankly, if you have been paying attention to landscape conditions, it doesn’t take an expert to declare it a severe drought out there. The overall appearance of unirrigated lawns and most turf areas is straw brown and dormant with a “crunchy” leaf canopy. Many of these areas have been that way for several weeks now.
 |
| This newer lawn is very “dormant”, the small green areas are patches of tall fescue that are still surviving and green. |
The dry conditions combined with typical “above average” summer temperatures, > 90 F, have led to a number of people contacting us and asking… “Is my lawn dead?” The answer to this question is complicated, and honestly, it is difficult to truly tell until many of these areas fully rehydrate. Regardless, we are clearly pushing the edge of the envelope on what many turfgrass species can tolerate. Some of our weaker cool-season lawn grasses like the ryegrasses, annual bluegrass and roughstalk bluegrass (See Images) are most likely not to recover. Other common turfgrasses like Kentucky bluegrass or the fescues are more likely to survive. If you are fortunate to have a warm-season lawn (e.g. zoysiagrass or bermudagrass) these lawns are likely not dead.
 |
|
This finer textured patch of turf above is most likely roughstalk bluegrass it will look “dead” but may actually recover, there are still some green shoots.
|
Relative drought tolerance and irrigation requirement rankings of turfgrass lawn species commonly grown in Indiana.
1. Relative Drought Tolerance
2. Relative Irrigation Requirement
(to look their best)
Turfgrass Lawn Species
Zoysiagrass
Excellent
Low
Bermudagrass
Excellent
Low
Turf-type tall fescue
Very good
Low-Medium
Kentucky bluegrass
Good – Very good
Medium – High
Fineleaf fescue
Good
Low
Perennial ryegrass
Poor – Good
High
Annual bluegrass
Poor
Very high
Roughstalk bluegrass
Poor
Very high
Annual ryegrass
Poor
Very high
The other issue to consider is the maturity of the turf and growing environment. Well maintained, mature lawns with a deep root system will be faring much better than recent plantings. Furthermore, turf growing in severely compacted soils or very coarse textured sandy soils may really struggle and not recover. The driving factors for survival during severe drought have to do with rooting depth and the “reservoir” of available water. Sandy soils have less reserve water than fine textured soils and will need more supplemental irrigation.
Now what???
A friend recently asked me recently what to do about their lawn during these very dry conditions. I told them, honestly we will really just need to wait and see. I told him if he has not been irrigating and the lawn is brown then the plant is likely doing it’s best to conserve moisture during this “survival mode”, protecting the crown or growing point. He said, “So I should just accept “a little bit of brown?”, I responded “accept a whole lot of brown!”
Should I water my lawn?
If you have been regularly watering your lawn you should continue, the turf has been conditioned to this practice and shutting off the water may be damaging to survival. Remember the rule of thumb for lawn irrigation is to “water deeply and infrequently”. In other words, you should not be watering lawn grasses every day but every 3 days or so.
On the other extreme, if you have not been watering your lawn it is probably not worth starting at this point. Allow the turfgrass to remain dormant. There is no guarantee that your lawn will survive these conditions of 2012, but… heavily watering at this time may actually shift the competitive edge toward some of the warm-season grassy (e.g. crabgrass, etc.) and broadleaf weeds that thrive during the summer months. Furthermore, the amount of water to help the turf recover and then continue to sustain healthy growth may be cost prohibitive. Allow the turf to remain dormant, some grasses like Kentucky bluegrass have a dormancy mechanism and regrowth may occur from underground stems/rhizomes when more favorable weather returns. If you feel like you need to do something… applying about ½ inch of water every few weeks to keep the crown alive and hydrated. This will help down the road. The turf leaves will not turn green, but this practice will increase the chance for future survival.
 |
|
Light irrigation may help this dormant Kentucky bluegrass survive
|
Will my lawn recover?
While many lawns might not be “dead”, one major factor that will kill drought stressed turf is when the plant is subject to intense traffic and the crown is damaged. Those areas likely will not recover from that abrasive stress of heavy foot traffic or wheel traffic. Therefore, avoid heavy use during this drought period.
What if I need to replant?
The plus side of all of this is there is a lot of time to plan for a better lawn for the future (generally mid-August is the suggested time to begin turf seeding for the cool-season turf species (e.g. ryegrasses, fescues, bluegrasses). If you lawn does severely thin or large areas do not survive this is a perfect opportunity to replant with an improved species or cultivar/variety.
|
| This area has severely thinned and may require replanting. |
One group that I am collaborating with is the Turfgrass Water Conservation Association (TWCA: http://www.tgwca.org/). The stated mission of this organization is “The main goal of the TWCA program is to combat the rising concern of our depleting water resources. To accomplish this goal, the TWCA program is designed to recognize plants and other live goods products in the lawn and garden industry that provide a clear benefit in water conservation. Products that become TWCA qualified will have successfully met a stringent set of criteria.” In this program we are testing and learning about new varieties of various common lawn grass species that are most drought tolerant. Several new very drought tolerant cultivars are listed on the program’s website. One characteristic of these varieties compared to prior generations are these grasses are simply are able to retain their green color for a much longer period of time even though they are drought stressed. Additionally, I participate with another species/cultivar evaluation program, the National Turfgrass Evaluation Program (NTEP) http://www.ntep.org/ This organization also has information regarding the relative drought tolerance of many commercially available cultivars.
If you need to replant immediately, Sodding damaged areas is certainly another option, but the availability of the aforementioned drought tolerant cultivars may be limited. Furthermore, unless it can be regularly watered, it may not survive.
What about fertilizing?
One of the suggested water conservation practices is to stop or reduce (decrease amount) nitrogen fertilization during periods of drought. There is no need to push shoot/leaf growth in the plant when other resources like water are limited. Hence, if your lawn is brown and “crunchy”, certainly do not fertilize at this time.
The partial silver lining…
The upside to this very slow growth and dry conditions is that drought stressed turf does not grow vigorously and thus will require fewer mowings. Furthermore, turfgrass disease incidence is also very low.Consider the current state of your lawn a “more sustainable” turf cover.
Cale A. Bigelow Purdue – Agronomy