After a slow start, spring may actually be here. Because of the seasonally below average temperatures, turf has been slow to grow. Our schedule, a week late based on what we had planned, will actually reflect a more typical year now that some sense of normal spring weather is occurring. Our second round of pre-emergent will begin during the week of May 6, and we will be spraying any weeds that have sprouted.
- It is not too late to aerate. This a recurring theme. Twice a year will improve the overall condition of your turf.
- Overseeding should be completed soon to ensure sufficient time to develop grass plants healthy enough to withstand the summer temperatures especially given what we have experienced the last two summers in the Omaha area. For turf that is dead, we can put a plan in place to address the problem in the late summer
- It might be beneficial to take a leaf rake to smaller areas of that do not appear to be responding. A gentle raking along with aeration may stimulate some re-growth if any of the root zone survived
Wait as long as possible to provide supplemental irrigation. We have had more than adequate spring rain to carry most turf for some time. Turf provides more than enough hints when supplemental irrigation is needed.
We are indebted to the University of Nebraska for its ongoing support of optimal turf care practices and the turf care profession.
It is sometimes hard to believe that we are thinking about fall already, but it is a reality for those of us in this business as well as for homeowners with an interest in the long-term well-being of their lawns.
We have experienced unusually high temperatures in June, and there has not been much rain. The cool season grasses have reacted as one might expect. The University of Nebraska-Lincoln is nice enough to provide periodic updates on climate and its impact on turf. Dr. Zac Reicher, Professsor, Turfgrass Science, recently sent us the following:
High temperatures cause problems both above and below ground. Above ground, photosynthesis or energy production of cool-season turfgrasses starts to decline once daytime air temperatures exceed 70-75F. At the same time, respiration (the energy-consuming process to maintain the plant) is increasing with higher temperatures. At air temperatures greater than 80-85F, cool-season turfgrass plants are in an energy debit where energy demand is higher than energy production. Short periods of an energy debit are normal and the plant uses stored energy to meet its needs. However,energy stores are depleted with extended heat, and the plant weakens. This energy depletion is further exaggerated during warm nights when the plant uses up far more stored energy for respiration than during cool nights. Since the energy reserves of cool-season plants are fairly high early in the summer (June), they are usually capable of withstanding early summer heat like we are expecting. However, this early summer heat depletes energy reserves that may be needed later in the summer.
Below ground, root growth of cool-season turfgrass is optimal between 50 and 65F and declines quickly above 70F. At the same time, root death increases at elevated temperatures, especially in wet soils with limited ability to hold oxygen. The end result is that root systems become shallow and spindly with prolonged heat and thus have limited ability to take up water and nutrients.
Following are management suggestions to help the cool-season grasses cope with the heat:
The almost immediate response to high temperatures is to increase irrigation, which makes sense and is needed since most water is used for cooling the plant. However, saturated soils from over irrigation limits oxygen leading to root death and thus severely compromises the grass plant over the rest of the season. Therefore, we still want to keep turf on the dry side to maximize soil oxygen, but at the same time enough water should be applied to allow the plant to cool itself.
As you can see, the processes are complex. Dr. Reicher goes on to talk about mowing strategies as well.
So, how do we build that healthy lawn that is best able to withstand the rigors of Nebraska weather, turf disease, and insects? We cannot stress enough the importance of aerating lawns twice a year. We believe that periodic overseeding, following a double-plug aeration, is a way to introduce newer varieties of turf cultivars in addition to thickening up the lawn. In the case of lawns that have significant damage, we would add power-raking to remove excess damaged turf material. Fall fertilization is extremely important as well. It is not the time to skimp on applications.
By mid-July, we will have completed our applications for grub control. Healthy turf (there is that word healthy again) can withstand the presence of grubs at below treatment level thresholds. Some grubs may always be present at some stage of development. We do have products for insect break-through later in the season.
We try to minimize our use of post-emergent weed control products when the temperatures are high. These are products we spray, and we like to avoid damaging healthy turf surrounding the weeds. Additionally, the products simply don’t work as well in extreme heat. Optimal control for most broad-leaf weeds occurs in the fall.
What can you say about a spring that has yet to arrive? Sure the grass is green, there are buds on the trees and shrubs, and birds are making nests at the angle of the house and downspout (I have three trees in my yard; you think they could find one of them). The temperatures, on the other hand, are hardly something in which you can revel. You are probably wondering where I am going with this. The cool season grasses - Kentucky blue, the fescue and rye - thrive in the cooler seasons of the year, typically now into June and again in the fall. I encourage you to enjoy the experience. I also urge you to be thinking about those months in between when heat and humidity take the measure of these same grasses. Last season’s experience led us to rethink our typical advice on dealing with fungus in turf.
While we can’t control temperature and humidity, we can do some things to minimize their effect on your turf. Healthy, dense turf withstands most adverse occurrences better than turf that is not so healthy. That is always the first thing we aim for. If you have a lawn that is on the thin side, overseeding is a must until it thickens up.
A well-aerated turf resists disease better. We recommend aerating twice a year.
Pay attention to irrigation amounts and timing. Right now, we are getting more than adequate moisture for turf. As the seasons change, so do rainfall amounts; there is a tendency to overwater. There is no hard and fast rule as to the number of times per week or the number of minutes per zone. It is all about how your turf absorbs the water at the root zone. On slopes, longer irrigation times lead to run-off; break your irrigation into shorter cycles to maximize absorption and minimize run-off. Morning is always the best time for watering turf. Winds are calmer, and the turf canopy has the chance to dry out during the rest of the day.
We never tire of reminding you about keeping you mower blades sharp. We want to cut the grass, not beat it into submission. Disease is more likely to enter a plant through a grass leaf with a ragged edge. We also believe in leaving the clippings where they fall; bagging removes nutrients that you have paid for. The only time you should bag is when you have an active disease process in your turf. Frequency is also important. Turf growth determines when you mow, not trash pick-up. Mow so that you never remove more than one third of the crown at any one mowing. When turf is growing more rapidly, you mow more frequently.
That brings me to fungicides. As a rule, most disease outbreaks end in recovery in the fall with cooler, drier weather. Last year, the rule was broken. We have done a great deal of overseeding since last fall to repair damaged turf. We have fungicides available. We will look for the appearance of disease as the seasons progress, and we will offer you the option of treating or not.
Call or email us with your questions. Check our website, blog and Facebook page for more information about how we help you care for your turf.
Did you know that dandelion greens are considered a delicacy? They are a slightly more bitter than spinach, but with a little olive oil and balsamic vinegar, you have a salad. Of course, you have to find greens which have not been sprayed this spring by well-meaning, but misinformed chemical applicators (or homeowners). It is a misconception that a pre-emergent herbicide will control dandelions. The dandelion is a perennial which is best controlled in the fall when they more actively translocate herbicide to the plants root system as they store energy for the winter. We do have some success killing the flower of the plant which helps keep the seed from spreading. If you have a great number of dandelions, the problem is a lack of turf density. The thicker your turf, the more difficult it is for any weeds to become established in your lawn (think overseeding).
We make a concerted effort in the fall to hunt dandelions down to reduce the population. As we see flowering plants during our fertilizer applications, we will spray those.
Pre-emergents are used for the control of grassy weeds such as crabgrass, foxtail, goose grass, and barnyard grass (grassy weeds). There is an even longer list of broadleaf weeds which they control. The mode of action is directed at the shoots and roots of plants as they emerge.