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Author: kennelly

Breaking disease life cycles with good sanitation

(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.

Turf disease update

(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

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

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.

Continued root and crown woes

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:

https://blogs.k-state.edu/turf/anthracnose-crown-rot-in-putting-greens-and-the-turf-stress-behind-it/

 

Localized dry spot

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.

Turf disease update

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/

*SPECIAL ALERT* Sudden oak death pathogen reported in Kansas

Megan Kennelly, KSU Plant Pathology

The Kansas Department of Agriculture confirmed the presence of Sudden Oak Death (SOD) in Kansas. The KDA press release from today can be found here:

https://agriculture.ks.gov/news-events/news-releases/2019/06/07/plant-disease-identified-in-rhododendrons-in-kansas

SOD is a plant disease that has killed large tracts of oaks and other native species in California and Oregon. It also occurs on nursery plants including  rhododendron, azalea, camellia, viburnum, lilac, and periwinkle. Infected rhododendrons have been identified in 10 states in the Midwest, including Kansas. The infected plants that have been found in the Midwest have all been traced back to a common source.

This is a serious situation, and we ask that if you have purchased, planted, or maintained rhododendrons or other known host plants this spring please read the  information on the provided links and documents below and take action as needed.

Many details and photos are provided on the KDA website:

https://www.agriculture.ks.gov/SOD

We have provided some additional details in a pdf that you can access by clicking the link below:

KS SOD FAQs_2019

KDA, K-State, and the Kansas Forest Service are all working collaboratively to address this situation.

K-State’s press release from today is here:

https://www.ksre.k-state.edu/news/stories/2019/06/Sudden-Oak-Death-Reported-in-Kansas.html

If you have questions, you can email me at kennelly@ksu.edu (or call 785-532-1387) or Cheryl Boyer (KSU nursery crops specialist) at crboyer@ksu.edu (785-532-3504).

 

Spring turf diseases

(Megan Kennelly, KSU Plant Pathology)

As we move through spring and launch towards summer, don’t forget some key disease resources.

Fungicide info is available here:

https://entomology.ca.uky.edu/files/catmanualpdfs/ppa1.pdf

and here in a searchable online database:

https://turfpests.wisc.edu/filter.aspx?id=8-fungi

 

Large patch in zoysiagrass

Large patch has definitely been active lately with the cool, wet weather.

This is an area that was previously inoculated for a study, so it’s a high-pressure location:

In the photo below, the clear area was treated with a fungicide (tebuconazole) in early September and again in early October:

Some light N may help the turf recover. Some prior KSU work with U of Missouri (click here for info) and additional follow-up work by U of Missouri demonstrated that light N (think 0.25-0.5 lb/1000) in spring will not enhance this disease.

 

Dollar spot

 

 

The photo above is a worst-case scenario of the heaviest disease anywhere at Rocky Ford. It is an untreated area of a Cato-Crenshaw stand, which is highly susceptible. Untreated areas of less-susceptible cultivars are looking clean for now. KSU is part of a recently-published study that looked at disease susceptibility of various cultivars across several states. You can find a short preview/summary here.

What are you seeing? Let us know.

 

Root rot

We have not received samples here of Pythium root rot, but there are reports from nearby. You can read about findings of Pythium root rot in Missouri from our colleague Dr. Miller here:

https://turfpath.missouri.edu/reports/2019/05_14_19/

Cedar apple rust

(Megan Kennelly, KSU Plant Pathology)

The birds are singing, the tulips are blooming, and junipers (also called red cedars) are “blooming” in another fashion.  Cedar apple rust is here.  The pathogen (a fungus) spends part of its life cycle on a juniper tree, and the other part of its life cycle on apples, crabapples, hawthorns, or quince.  To simplify, we’ll just call them “apple hosts.”


Those jelly-like orange masses on the junipers produce spores that infect the apple hosts.  Once infection occurs, leaf spots on apple leaves develop in 1-3 weeks.  Eventually, fungal spores are produced in these leaf spots on the apple tissues.  The spores are spread by wind and rain back to junipers starting in about July.  Without both hosts, the fungus can’t complete its life cycle.
The disease looks dramatic on junipers, but it does not cause any harm.  The rusts can cause problems in the apple host, however.  If infection is severe, many leaves drop off early and the tree is weakened due to reduced photosynthesis.   If your tree only gets a small amount of rust each year, it probably won’t be an issue for long term tree health.
Management options (for apple hosts):
1) Resistance:  For new plantings of fruiting or flowering apples, consider planting a rust-resistant variety.  Information on crabapple cultivars is available at:
http://www.midway.k-state.edu/lawn-garden/docs/flowering%20crabapples.pdf
2) Tree care:  For any apple tree, proper pruning will allow air movement through the canopy. This practice reduces the leaf wetness that promotes disease.  Maintaining overall tree health will also help prevent the disease.
3) Fungicides:  Homeowners with a bad history of this disease (severe defoliation), might consider preventative fungicide sprays on the apple hosts when leaves are out and the orange galls are active.  For best control, applications should continue through May or as long as the orange galls are active. Products with the active ingredients myclobutanil or propiconazole are examples of materials labeled for cedar apple rust management in flowering crabapples and non-fruiting apples.  Make sure you check the label carefully. For example, if you are talking about fruiting apples instead of flowering crabapples, some products are not allowed.

Commercial fruit growers should consult the Midwest Fruit Pest Management guide: https://ag.purdue.edu/hla/hort/documents/id-465.pdf

There is also a video on rust diseases at: https://www.youtube.com/watch?v=yQdwSPtvhH8  The video is 15 minutes long and describes the life cycle and biology of these fascinating fungi!

Cut and destroy those pine wilt infected trees ASAP

(Megan Kennelly, KSU Plant Pathology)

Pine wilt has been killing our pines for decades. It is caused by a nematode (microscopic worm) that is spread by a beetle. The nematodes and beetles spend the winter in dead and dying trees. The beetles, loaded up with nematodes, start emerging in late April or early May and spread to new trees. Got pine wilt? Get that tree outta there! Chop it down, and burn or chip the wood, making sure not to leave stumps. Get this done in early April to stop disease spread.

If you have a dead pine in the eastern 2/3 of Kansas it could very well be pine wilt. Sure, it could be something else, like drought, but if it’s dead anyway you might as well assume it is pine wilt, and get it out and destroyed. You can send a sample in to KSU for testing if you want to know.

And, if you suspect pine wilt in the western part of the state, contact your local county K-State Research and Extension agent for help. Not only do we want it destroyed, we want to know where it is so we can understand where disease is spreading. (Find your agent here: https://www.ksre.k-state.edu/about/stateandareamaps.html)

 

Entirely dead tree? Cut it down and destroy the wood by chipping or burning.

 

 

 

Pines have multiple problems though, such as tip blight and Dothistroma needle blight. If you have any doubt you can work with your KSRE Extension agent to ship a sample up to KSU. For more information on pine diseases, and how to tell them apart, check out our publication about Pine Diseases in Kansas

Turf conference innovation showcase booth – share your favorite turf and landscape hacks!

Share your tips and tricks!

Do you have any special tips or tricks to managing turfgrass? Have you come up with your own method, style, or piece of equipment?

Do you have any unique methods for motivating employees, or working with difficult customers?

If so – email me at kennelly@ksu.edu and we’ll post them at the Kansas Turf Conference. Send me a description of your method, or perhaps a photo. We’ll display them and have a vote to determine the best innovation! Winner will get a prize 🙂

 

 

 

 

Large patch in research plots

Before the snow hit I was able to view some large patch symptoms in our breeding plots with our PhD student Manoj Chhetri.

Strong large patch symptoms:

Not much symptoms here:

Definitely some differences in % green after the recent cold snaps, but before the snow and this weeks extreme cold temps:

Odd weather patterns lead to odd disease patterns

 

I saw some brown patch recently – in late September/early October!

In the meantime, our warm-season grasses are slowing down, and all the cool, cloudy, rainy weather this week may trigger some large patch in zoysiagrass.

Pathogens will take advantage of conducive conditions whenever they occur. Here are some great updates from my excellent turf pathology colleague Dr. Lee Miller, next door in Missouri:

https://turfpath.missouri.edu/reports/2018/update10_05_18.cfm