Western Kansas experienced an extremely sharp drop in temperature recently. Temperatures in some areas of northwest Kansas were near 80 on Wednesday and dropped to near 20 or lower Friday morning. Unfortunately, trees were not hardened off before this happened. In other words, they were not ready for these cold temperatures.
What does this mean? You can read the whole article here in the Horticulture News. Go to this page and scroll down partway:
(Megan Kennelly, KSU Plant Pathology)
As I write this on Thursday we are looking into a weekend with forecast lows deep down into the 30’s. This comes after a September with multiple days in the 90’s and even more in the upper 80’s. Depending on how the weather shakes out after this weekend our warm-season turf may start showing signs of dormancy. Right now it is all still quite green.
In our cool season turf I’ve not seen much dollar spot lately, and it should be simmering down. I have heard a few reports of rust,
and my first suggestion in those cases is to review the fertility regime and make sure it’s not too low on N.
We are seeing and hearing reports of large patch across the region. Here is one example from today at our research facility in Manhattan:
Spring dead spot happens in … spring. But fall is a time to think about it. I’ll point you to an excellent summary of fall disease info from Dr. Miller next door in Missouri, with details about large patch, spring dead spot and other diseases:
https://turfpath.missouri.edu/reports/2019/10_09_19/
Is it okay to prune trees and shrubs in now? It depends on the situation. This article from the KSU Horticulture News will help you sort through the details:
KSU Entomology has been getting reports of Green June beetle larvae being noticed crawling around right now.
You can read more about it here:
http://blogs.k-state.edu/kansasbugs/2019/10/10/green-june-beetle-larvae/
June beetles are described in more detail in this publication:
https://www.bookstore.ksre.ksu.edu/pubs/mf2901.pdf
As stated in that publication, “Although Phyllophaga grubs can be recovered from most turf venues, populations rarely are sufficient to cause visible damage.”
(Megan Kennelly, KSU Plant Pathology)
In my neighborhood, and many communities across Kansas, we had an outbreak of oak leaf itch mites with a peak a couple of years ago. If you have itch mites in your area this year, you’ve had them before, or you simply have oak trees around, here is a new information sheet from KSU Entomology about this topic:
https://www.bookstore.ksre.ksu.edu/pubs/MF2806.pdf
With raking season upon us, take extra care if you do have them active in your area this year.
Curled leaf symptoms:
Unhappy person with itch mite bites during windy raking season a few years ago:
(Megan Kennelly, KSU Plant Pathology)
My family did a campfire and cooked our first pot of chili in awhile – it’s really feeling like fall! We have a few weeks remaining in October, and between now and Halloween is still a great time to plant trees and shrubs. Here are some articles with tricks of the trade before you trick-or-treat:
Nice summary from Johnson County:
Excellent nuts and bolts of tree planting:
https://www.bookstore.ksre.ksu.edu/pubs/MF3313.pdf
A few more details on methods:
https://www.bookstore.ksre.ksu.edu/pubs/mf402.pdf
Watering new trees and shrubs:
https://www.bookstore.ksre.ksu.edu/pubs/MF2800.pdf
Now, with all that, truly your most important FIRST step is deciding on what to plant. If you have not yet done your research on that question, here are some more resources on tree and shrub selection.
Trees and shrubs for difficult sites:
https://www.bookstore.ksre.ksu.edu/pubs/MF2205.PDF
Trees for Northeast Kansas:
https://www.kansasforests.org/community_forestry/community_docs/NE%20Kansas%20Preferred%20Trees.pdf
Trees for Northwest Kansas:
https://www.kansasforests.org/community_forestry/community_docs/NW%20Preferred%20Trees122016.pdf
Trees for Southwest Kansas:
https://www.kansasforests.org/community_forestry/community_docs/Pref%20Trees%20SW.pdf
Water-wise plants for south central Kansas:
https://www.sedgwick.k-state.edu/gardening-lawn-care/documents/Water%20Wise%20Plants%202015.pdf
(Megan Kennelly, KSU Plant Pathology)
KSU continues its work with the turf breeding team at Texas A&M and colleagues at Purdue. We recently inoculated some breeding lines with the large patch pathogen. We grow the fungus on sterilized oats then bury it just under the thatch layer. Sometimes we see symptoms in fall, but often we do not see them until spring. Scientific research takes a lot of patience :). In the meantime, we are keeping the plots moist to foster fungal growth.
In the meantime, large patch is active especially in wet areas:
Take note of these areas. It’s too late to fertilize zoysia now, but when spring comes around a bump of slow-release N may prompt recovery. In the meantime there may be actions you can take to improve drainage.
(Megan Kennelly, KSU Plant Pathology)
Many plant pathogens like to survive the winter in infected crop debris. One example is iris leaf spot.
Here is a zoom – the black spots are structures where the fungus produces spores:
Here are some other flower diseases that carry over on debris:
Rose black spot lesions, close-up of lesions, and microscopic view showing abundant spores:
Cercospora leaf spot on hosta:
For many of these common flower-garden leaf spots, removing diseases and dead leaves can help reduce the amount of the fungi lurking over winter to cause disease next year. If composting, don’t put the compost back in the spot where you took the leaves.
(Megan Kennelly, KSU Plant Pathology)
Around this time every year we all look forward to early September. Often Labor Day weekend marks the end of “summer diseases” and the beginning of fall repair and renovation to our cool-season grasses.
Moisture and humidity continue to trigger turf diseases. Here are a few recent photos:
Brown patch in tall fescue, with mycelium present on a wet, humid morning. The first photo shows the characteristic lesions. As I write this on Friday Aug 16 there is a stretch of hot days and very warm nights ahead, so this disease may continue. But September is not far away…
Dollar spot in an untreated bentgrass area:
The photo above is a worse-case scenario, with a susceptible cultivar untreated. If you are having breakthroughs, review your fungicide regime and maybe your N regime, as low N can make this one worse (but too much is a problem, too!). Check your calibration and coverage. If you’ve never read it, read the dollar spot section starting on page 14 here:
http://www2.ca.uky.edu/agcomm/pubs/ppa/ppa1/ppa1.pdf
Unlike brown patch, dollar spot loves the more moderate temps of September, so this one does not fade away after Labor Day. So don’t let your guard down yet.
Another issue I’ve been seeing lately is continued problems with saturated roots, and there were more heavy rains this week. The wet soils deprive the roots of oxygen plus they hold heat, so turf does not have any “chill out time” overnight. Organic matter in the profile makes it worse. On top of the physiological issues, those wet soils can trigger Pythium root rot and sometimes anthracnose crown rot comes in on top of that.
For more details, you can check out the report this week from our great neighbor Dr. Miller here:
https://turfpath.missouri.edu/reports/2019/08_15_19/
Or here:
Finally, another issue I’d like to mention is hydrophobic soils. Despite all the rain, hydrophobic soils/localized dry spot can still occur.
Here is what localized dry spot can look like, and it can come on fast.
Keep an eye on your soil profile so you can stop this damage before it starts. When you get damage to the extent shown in those two photos above it is a long road to recovery.
To check for localized dry spot, pull up some cores and use the “droplet test” by putting drops of water on the plug. If the drops just sit there, not wicking in, you have a problem. The soil is water-repellent.
Sometimes there is a defined hydrophobic layer with normal soil above and/or below, so check at different depths, all the way down the rootzone:
You might also notice water beading up on the surface and not wicking in.
You don’t want this to sneak up on you. Keep an eye on your soil profile, especially locations with a history of problems. Aerification and use of wetting agents can help get moisture where it needs to go.
Megan Kennelly, KSU Plant Pathology
Moisture and humidity are causing continued disease activity in both ornamentals and turf.
Below is some dollar spot activity in untreated controls in a fungicide study. As you can sort of tell from the photo, the disease has gotten to the point where the infection centers are not just off color but are also sunken/pitted.
If you are struggling with dollar spot control, consider your fertility regime. Low N can make the turf more susceptible, but high N comes with its own issues. Check your nozzles and spray equipment to ensure good coverage. Be sure to rotate among different modes of action. For more details check the dollar spot section starting on page 14 of THIS DOCUMENT.
We are getting some heat and humidity, and brown patch is becoming more active. Typically we think about brown patch as affecting tall fescue, perennial ryegrass, and our putting greens. However, this disease can affect bluegrass, too. This photo shows a sample from a Kentucky bluegrass fairway. You can see the fungal mycelium. With all the moisture, foliar Pythium also came to mind as a possibility, but in the microscope it was clearly the brown patch pathogen.
In the photo below, you can also discern that this is a heavy clay soil – see how shiny and glossy it looks. And, there is a thatch layer starting to build up, which can lead to its own set of problems. This site already has an aerification plan in place for fall.
The final disease I want to mention is Pythium root rot in putting greens.
Saturated soils alone can cause major decline in root systems. Unfortunately those same conditions can trigger Pythium root rot. The photos below illustrate typical symptoms I’ve seen recently, including several already this week:
When you pull up a turf core, the root system does not cling together well, and the whole core kind of lacks structure. If you wash them off, they are brown and mushy.
Canopy is thinned out and yellowing:
In the microscope the roots are dark, sloughing outer tissues, lacking root hairs, and have Pythium oospores present. (The physiological decline from wet soils alone can also cause browning, lack of root hairs, etc)
Here are a couple of resources about this disease:
https://turfpath.missouri.edu/profile/pythium_root_rot/index.cfm
and:
https://www.turffiles.ncsu.edu/diseases-in-turf/pythium-root-rot-in-turf/
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