This week I'm providing a great schedule for planning out a management program recommended by Kansas State Extension for all the warm-season grasses grown in lawns, on farmsteads and many of the out lots.
Warm-season grasses include bermudagrass, zoysiagrass, blue grama and buffalograss. Of these four, only the blue grama and buffalo are natives to the High Plains. Buffalo prefers growing on the "hard ground" — plains and hills, not on the sandy soils. The blue grama will grow on the plains, hills and on the sandy soils such as the sand hills south of the Arkansas River. Although some of the early season dates have passed, there is still plenty of time to address many of the practices for your warm-season lawn areas.
Lawn calendar for warm-season grasses
* March: Spot treat broadleaf weeds, if necessary. Treat on a day that is 50 degrees or warmer. Rain or irrigation within 24 hours of application will reduce effectiveness.
* April: Apply crabgrass preventer between April 1 and 15, or apply preventer when the Eastern Redbud is in full bloom. If using a product that contains the herbicide Barricade, apply two weeks earlier. Crabgrass preventers need to be watered in before they will start to work.
May through Aug. 15: Fertilize with one pound of nitrogen per 1,000 square feet per application. Remember, more applications will give a deeper green color, but will increase mowing and lead to a build-up of thatch with bermudagrass and zoysiagrass.
On buffalo lawns, too much nitrogen, or if applied too early, will stimulate weed growth.
Bermudagrass — Use two to four applications.
Zoysiagrass — Use one to two applications. Too much nitrogen leads to thatch build-up.
Buffalograss — Use one to two applications.
Apply nitrogen during the following months, depending on the number of applications you wish to make:
One application: Apply in June
Two applications: Apply May and July
Three applications: Apply May, June and early August
Four applications: Apply May, June, July and early August
If grubs have been a problem in the past, apply a product containing Merit or Mach 2. Either product should be applied by mid-July. Merit can be applied as early as mid-May if there are problems with billbugs or May Beetle grubs. Both of these work as grub preventers. These insecticides are effective and safe. They must be watered in before they become active.
June is a good time to core aerate a warm-season lawn. Core aeration will help alleviate compaction, increase the rate of water infiltration, improve soil air exchange and help control thatch.
Late July through August: If you see grub damage, apply an insecticide that is labeled as a grub killer. If Merit or Mach 2 has been applied, this should not be necessary. Grub killers must be watered in immediately.
Late October: Spray for broadleaf weeds if they are a problem. Treat on a day that is at least 50 degrees. Rain or irrigation within 24 hours reduces effectiveness. Use the rates listed on the label for all products mentioned.
Brown patch on tall fescue
The time of year is approaching when brown patch disease will start showing up in tall fescue lawns. This disease is favored by warm night temperatures and extended periods of leaf wetness. When the lawn is covered with dew in the morning, conditions are favorable for brown patch. The fungus is primarily a leaf pathogen and is not known to attack roots. During severe outbreaks, the fungus may invade the lower leaf sheaths and crown and kill plants. But in most cases, the turfgrass can recover from brown patch. This recovery may take two to three weeks depending on weather.
K-State Extension Plant Pathologist Megan Kennelly reports that there is no way to eliminate the brown patch fungus from a lawn. It will persist indefinitely in the soil. It is not likely that the fungus was introduced into the lawn on a contaminated mower or other piece of lawn equipment. In almost all cases, the limiting factor for brown patch development is the weather, not the amount of fungal inoculum. Almost all lawns have plenty of the fungus already present in the soil.
Although the fungus cannot be eliminated, cultural practices can be changed to reduce environmental conditions favorable for infection.
The most important thing is to manage irrigation. Don't water in the evening; instead, water early in the morning. This will help decrease the number of hours the leaf tissue remains wet and susceptible to infection. The frequency of irrigation is not as important as the time of day you do it. Don't over-fertilize and certainly don't fertilize when brown patch is active. Also don't seed or overseed at too high a rate.
Fungicides can be effective in preventing brown patch. Use of fungicides is not recommended unless you want to maintain a blemish-free yard. Remember that, more often than not, turf will recover from brown patch. Nevertheless, fungicides can be applied on a 21- to 35-day interval (depending on fungicide and rate) to prevent infection.
Curative fungicide applications are much less effective because the fungus has already caused substantial injury before you can get the product on the lawn.
Physiological leaf curl in tomatoes
Every year, we have calls from gardeners who have tomato plants with leaves that curl up. When tomato plants grow vigorously in mild spring weather, the top growth often exceeds the root development. When the first few days of warm, dry summer weather hit, the plant "realizes" that it has a problem and needs to increase its root development. The plant tries to reduce its leaf area by rolling leaves. The leaves curl along the length of the leaf (leaflet) in an upward fashion. It is often accompanied by a thickening of the leaf, giving it a leathery texture. Interestingly, leaf roll is worse on some varieties than others.
Though rolling usually occurs during the spring to summer shift period, it also may occur after a heavy cultivating or hoeing, a hard rain or any sudden change in weather. Too much rain or irrigation can saturate the soil and suffocate the roots. A root system lacking in oxygen cannot move water to the upper parts of the plant, resulting in the same symptoms that occur with too little soil moisture or a limited root system. This leaf roll is a temporary condition that goes away after a week or so when the plant has a chance to acclimate, recover from injury or the soil has a chance to dry out.
As the plant matures and the root system develops, it gains the ability to take up moisture from a larger volume of soil, thus resulting in less shock from sudden weather changes. Also, if you grow several tomato varieties, it's common to observe the differences in plant leaves, from course, broad, potato-like leaves to much smaller-fine leaflets.
In addition, K-State Extension has two excellent publications that address many of the disorders that are commonly found across the state, available at no cost at the Extension Office or on the Web. They are "Tomato Leaf and Fruit Diseases and Disorders" (http://www.oznet.ksu.edu/library/plant2/L721.pdf), which covers the following diseases: Septoria leaf spot, early blight, anthracnose, bacterial speck, bacterial spot and bacterial canker. It also discusses the following abiotic disorders: growth cracks, blossom end rot and physiological leaf roll. The other publication is "Wilt, Nematode and Virus Diseases of Tomatoes" (http://www.oznet.ksu.edu/library/plant2/l723.pdf). These are the diseases and disorders found in the root system of tomatoes.