Iris Leaf Spotis active and has been favored by the cool, wet weather conditions we are currently experiencing across much of Kansas. The spots are typically found on the leaves but can occur on the stalk and buds of the developing flower. The spots are dark with a reddish border and will appear water soaked followed by yellowing of the surrounding tissue.
As the disease progresses, the tips of the infected leaves will appear scorched. The disease will not kill the plant however it can reduce the plant vigor over time.
How can you protect your irises? The first step is to practice good sanitation by removing all the dead leaves prior to spring green up. The fungus that causes iris leaf spot overwinters on the dead leaves from the previous year, and removing those leaves will break the life cycle.
If you have a history of severe iris leaf spot and yearly sanitation alone is not effective, fungicides are available. Fungicides can be sprayed every 10 days for 4 to 6 weeks starting when new leaves emerge in spring. For more information on fungicide products and application for iris leaf spot go to http://www.hfrr.ksu.edu/doc1645.ashx. Be sure to follow the instructions on the fungicide label.
If you see these diseases, you may be eager to try something this spring, but the best time for fungicides is in the fall.
At KSU we’ve had good results for large patch with 1-2 fall applications. That is, fall applications have carried all the way through the following spring. Spring applications can reduce the disease but are not as effective as fall applications. There is ongoing research in the turf research community to try to optimize application timing, though, including with our colleague Dr. Lee Miller at U of Missouri.
With spring dead spot, application success has been more spotty here, but again fall has proven more effective. However, sometimes fall applications just don’t work. Cultural practices are critical, and the link above shares some great tips. Just page through to the spring dead spot section.
One very useful thing to do this spring is to take photos and map the diseased areas so that you can target those areas this fall. With large patch, I know several superintendents who only spray the known “hot spots” instead of entire fairways, with good success.
What’s going on here? First – what grass is it? This is bermudagrass, one of our warm-season grasses. When we have cold snaps, these grasses can take on a purple-red tinge. The chlorophyll is damaged and the anthocyanins become visible. If you look across a whole field, the red-purple can also have a brown-ish appearance, and that makes people wonder about diseases. But, if you look closer, you’ll see that it is purple. The turf grows out of it once temperatures are warmer.
In many parts of the state our overnight lows dropped into the 30’s last week, so the timing fits the symptoms – that is another important piece.
It’s not quite Wildcat purple. If we could do that, we’d have a nice patent on our hands and we wouldn’t have to worry about our research budgets anymore.
Here are some photos from a couple of years ago showing similar symptoms after a cold snap in early May. In the “long view” shot you can see how it can have a brownish cast, which can cause concern.
Pine tip blight is a fungal disease that can affect Austrian, Scots, ponderosa, and mugo pines. The disease is most severe on mature trees (20 years or older). Repeated infections over several years can kill large sections of trees or entire trees. Here are some Frequently-Asked-Questions about tip blight.
1) What is the pathogen?
Tip blight is caused by a fungus that has been called both Sphaeropsis and Diplodia over the years. The current name is Diplodia. Don’t let the name changes trouble you. The most important consideration is to recognize the disease, and to be able to distinguish it from other pine problems such as Dothistroma needle blight or pine wilt. To learn more how to compare/contrast those diseases, you can check out this page: http://www.ksre.ksu.edu/bookstore/pubs/l722.pdf
2) When does pine tip blight occur?
Tip blight is a spring disease. The fungus survives the winter in previously-infected tissue. Then, during spring rains, the fungal spores splash around and infect the newly developing pine shoots (candles) just as they start to grow (usually in mid-late April).
3) What are the symptoms of pine tip blight?
The symptoms become obvious in late May or early June when the infected shoots and needles are not growing right. The shoots are stunted, and the emerging needles are stunted and brown – see the photos at the top of this post. Small, sticky resin droplets often form on the infected needles. The damage usually starts in the lower branches and works its way up over several years. In trees that have been repeatedly infected for many years, damage is distributed throughout the crown.
In addition to infecting the newest growth, the fungus can invade older tissues when trees are highly stressed or if they are wounded (by hail, storm damage, etc).
Interestingly, white pines are not susceptible to the tip blight phase, but they are susceptible to this “canker form” of the disease if they are wounded.
In late summer or fall, tiny black spore-producing structures (called pycnidia) are formed on the scales of 2-year-old cones — it looks like black pepper has been shaken onto the undersides of the cones.
Tip blight can be confused with winter damage or infestation by the pine tip moth. However, winter damage usually causes shoot or needle death before the new needles emerge in the spring, and it is sometimes restricted to one side of the tree (the side facing the prevailing wind). Unlike tip blight, the tip moth causes a hollowed-out area in the tip/bud area, and the larvae are sometimes present. Plus, tip moth is more common in young trees. The timing and pattern of symptoms, and the age of the tree, can help you with the diagnosis.
In extreme cases tip blight can be confused with pine wilt. To avoid confusion, look carefully at the symptoms and compare them to the descriptions and photos here and in other resources. Pines can be infected with both diseases simultaneously. If there is any doubt, bring a sample to your local K-State Research and Extension office to be forwarded to the K-State diagnostic lab.
Managing tip blight:
4) Does pruning help?
Removal of dead branches can improve the appearance of diseased trees but will not prevent infection. Many of the spores are produced on cones that remain attached to the tree. In addition, tissues that look healthy can secretly harbor the tip blight fungus. That is, there are “hidden infections” that we can’t even see. Usually, pruning for tip blight means pruning off lower branches first, since they tend to be the first to become infected. Then the pruning task moves up the tree as the disease progresses over the years. If a tree reaches a point where it is no longer pleasing or functional for the site, “one-cut pruning” (ie, tree removal) might be the best possibility.
5) What other tree care should I provide?
Trees should be adequately (not excessively!) watered to maintain tree vigor. This will help a tree fight off tip blight on its own. When a tree is drought stressed it has less energy and resources to put into defenses against pathogens.
6) Should I use a fungicide?
This is a tricky question. The trouble is, unlike smaller plants like wheat, tomatoes, or soybeans, there aren’t many studies out there to tell us about tip blight “thresholds.” As a general rule, if a tree has at least 30-50% of branches infected, the fungus is pretty well entrenched and it will be difficult for fungicides to really knock the disease down. And, if there is a lot of “canker” type infection in older wood, it is hard for fungicides to work. If a smaller portion of the canopy is affected, and it is mostly the “tip-blight” phase, fungicides are more likely to be successful over time. Finally, consider the aesthetics and site-enhancing value of the tree. In trees where the disease is caught early, and fungicides are used at the right time each year for multiple years, the disease can be managed successfully and it might be worth the investment.
7) Okay, so what is the right time for fungicides?
The critical time for fungicides is when the new shoots are expanding in the spring. If fungicides are applied at this time, new disease can be prevented. It is not a one-shot-deal, however, and not even a two-shot-deal. Fungicides will likely be needed each year to protect new annual growth. Each year, the first application should be made when new shoots start to elongate, which is usually around the third week of April. The tree should be sprayed again 10 to 14 days later, and possibly again 10 to 14 days after that if it is a wet year and the site has a history of disease. The timing should be adjusted slightly depending on host development in the spring, since every year is different. Spraying after this critical time will not be effective, because infection has already occurred and cannot be “cured.” Once you see symptoms it is too late.
8) What should I spray, and how should I spray it?
Several fungicides are labeled for pine tip blight. Thorough coverage is essential. A high-pressure sprayer may be needed to deliver the fungicide to the tops of tall trees. Homeowners should consider using a professional tree care service, especially for large trees where getting good coverage is difficult. Some fungicides (active ingredients) are listed on the last page here:
Here is a sight that no superintendent wants to find on their course.These photos are from July/August of recent years.
What is this problem? It’s hard to tell just based on photos, but after follow-up testing in the lab, we determined this is anthracnose, an important fungal disease in putting greens.
How does nitrogen (timing and amount) affect anthracnose?
Does rolling increase anthracnose? What about foot traffic?
How does irrigation impact anthracnose – should I run the turf wet or dry to prevent it?
Over the past few years, a team of turfgrass researchers has been conducting experiments to answer these questions. The have developed a science-based list of best management practices (BMPs) for turfgrass anthracnose. Various researchers studied the effects of nitrogen, potassium, mowing, rolling, plant growth regulators (PGRs), irrigation, topdressing, aerification, foot traffic, and fungicides. Based on that work, they developed a set of recommendations.
Rather than copy all the text into this page, I’ll provide the link below to their BMPs (it’s 2.5 pages – detailed, but concise and easy to understand), then add a few comments and photos.
Here in Kansas, the samples of anthracnose that I have seen were usually associated with the “risk factors” identified in the BMP list – low mowing, keeping N low to keep things “lean and mean” before a tournament, poor drainage at the site, etc.
Okay – anthracnose is more likely during summer stress. Why am I talking about this NOW?
It’s important to keep the BMPs in mind all season long, not just when you are already into a stressful time of year. Managing the turf holistically, all-season long, will help reduce your risk of this disease. As you’ll see in the BMP’s, it’s mostly a set of good agronomic practices, too. There’s nothing on that list that is out-of-bounds with routine good agronomy. And, you don’t necessarily have to do EVERYTHING on the list but I’m sure you will find some practices that fit with you and your site and budget.
(By Jared Hoyle, KSU Turfgrass Research and Extension)
Last year I wrote a post about some of the things I have learned while I have been in KS. One thing was how hard it is to grow turfgrass in the north-western part of the transition zone. And because it is hard to grow turfgrass here it is also hard to diagnose problems when they occur in our turfgrass systems.
So before we start talking about diagnosing turfgrass problems lets talk about how we are diagnosed when we are sick. So one day you wake up and you don’t feel good. You know your throat hurts, you have a fever so you go to the doctor. While at the doctor’s office the doctor asks you questions like what hurts?, when did you start feeling bad?, have you taken any medicine?, etc. So the doctor asks you questions to figure out what is wrong, Right? So you don’t just show up, sit down, and then say fix me. It is a process that you have to go through.
But after all the questions the doctor will prescribe you something to help you feel better. Maybe drink more fluids, get some rest, take some medicine, or all sorts of other remedies. So you go home and start doing what the doctor tells you. In about three days you still feel bad. So you go back to the doctor and start it all over again. And again you get your marching orders on how to feel better. This time it worked and you are better.
That’s how we have to approach issues when they occur in turfgrass. So many times I get a fuzzy picture and the question, “Why is my grass dead? Fix it!” This is just like showing up at the doctor and saying “Fix me”. So to properly diagnose a turfgrass issue some basic information is needed.
What type of turfgrass do you have?
What type of soil do you have?
Is it a weed, disease, insect, or other issue?
When did you first see what was going on? What time of year? How long has it been going on?
Do you or someone else take care of the turfgrass? If someone else what do they do to the turf?
What chemical or cultural practices have recently been conducted?
What type of pattern is the damage? (uniform or random)
Any other information?
I would recommend to have as much of the information as possible if you are really trying to figure out what is going on. This way you can diagnose the issue quicker instead of having to go back and forth to finally get all the information for a proper diagnosis. That’s like having to go back to the doctor because the first diagnosis was incorrect because the doctor didn’t know all of the information.
Lastly, many times when you are gathering all this information, you end up solving the problem yourself!
***Mention of trade names or commercial products in this article is solely for identification purposes and does not imply recommendation or endorsement, nor is criticism implied of similar products not mentioned by Kansas State University.***
(By Jared Hoyle, KSU Turfgrass Extension Specialist)
Pre-emergent (PRE) herbicides prevent summer annual weed (For Example, crabgrass, goosegrass, annual sedges, and spurge) seeds from developing into mature plants. The reason we use PRE herbicides for summer annual weed control is because these summer annuals come back every year from seeds. So if we can stop the seed from growing then we don’t have to deal with the weeds later in the season.
For all that don’t know how a PRE herbicide works here is a very short explanation. They do not keep the seed from germinating but kill the young germinating plant. With few exceptions they have no effect on existing plants, so they must be applied before germination.
But like in everything in life there is an exception. Dithiopyr can kill crabgrass as long as it is young (two- to three-leaf stage, see photo below of three leaf crabgrass) and still have some residual for continued PRE activity. It doesn’t last as long as some of the other PRE herbicides but there is flexibility if you miss your window of opportunity to apply.
So when do I put out the PRE application for summer annual weed control? Well, it depends on many things. What summer annuals you have? Where are you located in Kansas? Many times turfgrass managers center their PRE applications around crabgrass germination. Crabgrass typically begins to germinate around May 1 or a little later in KS. April 15 is a good target date for applying a PRE because it gives active ingredients time to evenly disperse in the soil before crabgrass germination starts. The April 15 target works well for most of the state, but for southeast Kansas April 1 is more appropriate, and for northwest Kansas May 1 is best. Additionally, weather varies from one spring to the next, and with it the timing of crabgrass germination. Some turfgrass managers base their PRE application around the bloom of the Redbuds but other ways can be used as well. Crabgrass germinates when the soil at approximately 1 cm deep reaches 55° F. So watch your soil temperatures to see when the soil consistently reaches 55° F. Here is a great website that will give you soil temperatures for your area.
PRE herbicides do not last forever once applied to the soil. Microorganisms and natural processes begin to gradually break them down soon after they are applied. If some products are applied too early, they may have lost much of their strength by the time they are needed. Additionally, PRE herbicides have different half-life, Koc, water solubility, and vapor pressure. This can determine how fast microbial, chemical and physical decay occurs along with infiltration, volatilization, leaching, and run-off.
Therefore, not all PRE herbicides are created equal. Here is a list of PRE herbicides, the weeds they target and some concerns that you might want to know before applying.
On golf courses: Can be used on cool- and warm-season. Other turf areas: Warm-season only.
siduron
crabgrass, bermudagrass (suppression)
Does not control goosegrass or annual bluegrass.
Information in this table was acquired from “Turfgrass Weed Control for Professionals” by A. Patton and D. Weisenberger, Purdue University.For more information about purchasing this publication ($12.00) for complete information see;
***There are many combination PRE herbicides that combine these active ingredients with each other and with other POST-emergent herbicides***
Always remember to READ THE LABEL for the correct rate, turfgrass tolerance, and specific instructions before application!!!
***Mention of trade names or commercial products in this article is solely for identification purposes and does not imply recommendation or endorsement, nor is criticism implied of similar products not mentioned by Kansas State University.***
(By Jared Hoyle; KSU Turfgrass Research and Extension)
We would like to congratulate KSU Turfgrass Graduate Students, Jake Reeves and Evan Alderman for placing 2nd and 3rd in the K-State Graduate Research Forum Competition. Jake Reeves placed 2nd in the Agriculture Poster Session and Evan Alderman placed 3rd in the Agriculture Oral Session.
Yesterday KSU Turfgrass Graduate Students, Ross Braun, Jake Reeves and Evan Alderman participate in the the 2015 K-State Research Forum. Sponsored by The Graduate Student Council, KSU Graduate School, Offices of the President and Provost and Sigma Xi, the K-State Research Forum allows all graduate students across the university to compete in oral and poster presentation competitions about research they are conducting during their graduate career. The titles listed below represented the turfgrass graduate students that participated in the forum.
ENHANCING WINTER AESTHETICS OF ZOYSIAGRASS WITH COLORANTS Ross Braun, Jack Fry, Megan Kennelly, Dale Bremer, and Jason Griffin
BERMUDAGRASS CONTROL WITH GLYPHOSATE, FLUAZIFOP, AND MESOTRIONE FOR SPRING RENOVATION Jacob A. Reeves, Jared A. Hoyle, and Cole S. Thompson
INFLUENCE OF NITROGEN FERTILIZER SOURCE AND RATE ON BUFFALOGRASS DIVOT RECOVERY Evan J. Alderman, Jared A. Hoyle, Jack D. Fry, and Steve J. Keeley
Job well done to all the participants in the K-State Graduate Research Forum!