Friday, May 17, 2013

Growing Zoysia (warm season grass) in Illinois

Whether you are thinking of starting a Zoysia lawn or just looking for some pointers on maintenance, proper cultural practices are important. This is especially true here in Illinois, towards the northern limit of Zoysia’s zone hardiness. The things you can do to properly establish and maintain your turf include:

1. Establishing Zoysia can be difficult do to because of its slow growth habit.  Most Zoysia is plugged. Zoysia establishment via seed is virtually impossible as seed only germinates about 33% of the time. It is also difficult to establish Zoysia within a lawn that already has an existing grass. It is recommended to set on bare soil to reduce competition and remember to give it time to establish. Zoysia generally spreads about 6 inches per year, so even if you are setting plugs, it may take several years to completely cover the lawn. Dave Robson, U of I PSEP Specialist, recommends an annual or perennial ryegrass in the meantime to green up the bare lawn during the establishment of Zoysia.  He also said that Zoysia established bluegrass lawn can take forever and you probably will not get a good stand.

2. Zoysia prefers a slightly acidic pH of around 6.0 to 6.5. It is a good idea to conduct periodic soil testing every 2 to 3 years for necessary lime and fertilizer application. For information on soil testing in Illinois visit:

3. For minimum maintenance, it is necessary to apply at least 1 to 3 pounds of nitrogen per 1000 sq ft per year. This can be accomplished by applying a complete fertilizer three times a year in April, June, and August. It may also be beneficial to apply potassium in September to improve cold tolerance and winter survival.  Also, remember the previous fertility recommendations are only for minimum maintenance.  For dark green, high quality Zoysia, apply 3 to 4 pounds of nitrogen per 1000 sq ft per year.

4. If properly fertilized, Zoysia will require consistent mowing kept to an optimum height of about 1 inch. This is best done by mowing once a week. If needed, cut it twice over a period of 3 days and remember that if you cut a 3rd of its height or more at once, it can cause shock. It is best to use a reel mower with Zoysia that cuts with more of a scissor action. This works better for mowing dense grass at low heights. However, a standard rotary mower will do just fine if you keep the blade sharp.

5. Thatch accumulation is one of the most common problems with Zoysia, because it can harbor insects and disease causing organisms. If thatch is allowed to accumulate to greater than 3/4 inch, it can impede oxygen and water movement and raise the turf away from the soil. Remove thatch in mid to late spring every year or two depending the amount of fertilizer used.  In addition, soil should be core aerated/plugged at least once every two years to promote a healthy root system. 

One disease to watch out for with Zoysia is large patch, a close relative of and similar to brown patch of cool season grasses. Symptoms of large patch generally present themselves in spring and fall as Zoysia enters and breaks dormancy. Rapid growth during the summer months can mask the development of disease. Symptoms initially present as small patches (less than a foot) where leaf blades show a tan orange color. Areas will expand into large, (up to 20 ft) well defined patches. The pathogen will survive locally in turf debris and is favored by increased levels of thatch. More information on large patch can be found at

(Blog written by Nick Prudhomme, U of I Plant Clinic Student)

Wednesday, May 1, 2013

U of I Tree Disease and Pest Update: May 1, 2013

Monthly Summary  

(Courtesy of Kelly Estes, State Survey Coordinator) 

Average Temperature and Precipitation

Modified Growing Degree Days (Base 50⁰ F, starting March 1

Station Location
Actual Temperature
One- Week Projection
Two-Week Projection
St. Charles
Rend Lake
Dixon Springs

Update from the U of I Plant Clinic 

(Courtesy of Stephanie Porter, Diagnostician and Outreach Coordinator and Travis Cleveland, Pesticide Safety Education Specialist)

U of I Plant Clinic Website:
U of I Plant Clinic Facebook Page:
Follow Stephanie Porter on Twitter @skporter

It has been evergreen, or should I say “ever-brown” mania at the U of I Plant Clinic, thanks in part to last year’s drought.  We have received many spruce, pine, yew, and arborvitae samples with browning attributed to abiotic problems such as drought, sunscald, winter burn, or salt injury.   Abiotic means that the browning symptoms were not caused by a disease pathogen, insect or mite. 

Stressed spruce that likely declined due to drought

Many clients and homeowners have reported that their evergreen has appeared to have died almost overnight. For most cases, it is highly unlikely that their trees died “overnight”. Clients don’t always see the early symptoms of a disease. Also, diseased evergreens may not show a sudden change like you would see with a deciduous tree. This may especially be the case for evergreen killed during fall and winter months. For example, we can cut a branch off of an evergreen to use for a wreath or winter outdoor container. Cutting the branch disrupts the physiology or the branch. Yet, many wreaths and evergreen decorations can last several months outdoors in cold to cool temperatures with minimal loss of color and appearance.  
They also question why only one tree or shrub died while others besides it remain healthy. The answer may not be simple and straight forward, and may be the result of a combination of factors. The affected tree could have been stressed for some other reason and the drought may have taken them “over the edge”, so to speak.  The trees pictured above were likely planted at the same time, yet the dead trees look shorter than the nearby living trees. That could indicate they were stressed for number of years prior to the drought. Individual plant genetics may have predisposed one tree over another. Also specific planting sites (soil, exposure, etc.) could influence the trees health.

So, why are people submitting these “ever-brown” samples to the U of I Plant Clinic?  They are ruling out disease pathogens, insects, or mites as a possibility for the observed, browning symptoms.  For more information on submitting samples to the U of I Plant Clinic, please refer to the following link:

We have received a few Blue Colorado spruces with signs of Rhizosphaera needlecast and, as most know, this is something that can be managed with a protective fungicide, at the correct timings, early in the spring.  Thanks to the drought stress, we have also been observing fungal canker diseases on trees.  In a “normal” year, we see a lot of Cytospora canker on spruce; however, now we have been finding  Eastern white pine and Douglas fir infected with canker that is suspected to be due to Cytospora.  For additional information of other secondary pests of Eastern white pine, please refer to the following ACES press release:

Fungal root and butt rots on deciduous trees are on the rise as well, due to drought stress.

Suspected Cytospora canker on Eastern White Pine

We have also received spruce with signs of spruce spider mites.  For additional information on spruce spider mites, you can refer to the following link:  Before a miticide application is made, it is important to determine that active mite stages are present and that the population is sufficiently large enough to warrant control. It is common with spruce spider mite for an infestation to suddenly disappear, probably due to predation, weather changes, or other factors. Sometimes, the mite infestation does not return for decades.” – Phil Nixon, Extension Specialist, Pesticide Safety Education Program/Ornamental Household Insects

For additional information on spruce problems, you can refer to the new Spruce Problem Factsheet:

Reports of pine wilt disease have been received as well.  Trees infected with pine wilt should have been removed by late winter. The pine sawyer beetle vector will be emerging soon and will spread the nematodes. To test a pine for the presence of pinewood nematodes, take sample branches that are 2" in diameter and about 12" long. The branches should be from an area having brown needles.   The samples can be submitted to the U of I Plant Clinic for a fee of $20.

For additional information on the stress of drought on trees or shrub, please refer to the following Home, Yard, and Garden Article:

Invasive Species News from the Illinois Cooperative Agriculture Pest Survey (CAPS) Program 

(Courtesy of Kelly Estes, State Survey Coordinator)


The CAPS program is a joint effort between several state and federal agencies that focuses on the early detection of exotic, invasive plant pests, diseases, and weeds. This year our surveys will be focusing on Thousand Cankers Disease of Walnut. Trapping for the walnut twig beetle will be beginning in May. Questions or concerns about TCD? Have a potential trapping location? Please contact Kelly Estes, State Survey Coordinator- or 217-333-1005. Other invasive species surveys across the state will be getting started as well. Gypsy moth and emerald ash borer traps will soon been seen. Remember, gypsy moth egg hatch begins around 145-200 DD and emerald ash borer adult emergence begins around 450-500 GDD.  You can keep up to date with invasive species news at the CAPS Blog.
May is Illinois Invasive Species Awareness Month! The goal of Illinois Invasive Species Awareness Month (ISAM) is to provide resources and opportunities to help stop the spread of invasive species in Illinois. There are dozens of educational events and volunteer opportunities that focus on invasives species hosted by ISAM partners – find an event in your area on the calendar