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Category: Environment

Declining Oaks

By Judy O’Mara

Declining Oaks...are not that easy to sort out. There is an assumption that if an oak tree is dying it must be due to a disease. That is usually NOT the case. Most of the poor growth that we see on oak trees in Kansas is generally due to a combination of site factors and environmental extremes. 2018 and 2019 provide back to back examples of weather extremes. Add in site factors like tree planting depth (too deep), construction damage, heavy soils or compacted soils that drain poorly, sandy soils that don’t hold on to water very well, and trees can develop root systems that are not as vigorous as they should be.  The result is a situation where trees are prone to declining under weather extremes – and Kansas is all about extreme weather.

A look at some weather data for Johnson County (Olathe, KS) provided by the K-State Weather Mesonet shows that the 20yr average annual precipitation is 40.04” for that location. At a glance it is easy to see that some years run wetter than average and some years are drier than average. I picked the Johnson County, KS location to highlight because we frequently get oak tree samples in the K-State Plant Disease Diagnostic Lab from the Kansas City area with questions about disease.

2018 was a dry year due to a winter drought and we saw trees decline across the state, including quite a few oaks from the Kansas City area. There was below average precipitation between November 2017 and September 2018. This weather snapshot also shows extreme weather during 2019, particularly during April and May. Saturated soils resulting in root damage and tree decline has been a common problem this year. Young trees and shrubs are particularly at risk due to smaller root systems. In many cases, damage wasn’t immediately apparent until June or July when higher temperatures put a greater demand on the root system. So bottom line, extreme weather patterns frequently play a role in the health of our landscapes.

That said (most oak problems are not due to disease), we have picked up two different oak diseases in the Kansas City area this summer that have the potential to cause tree decline, Hypoxylon canker and oak wilt.

Hypoxylon canker, also known as Biscogniauxia canker (Biscogniauxia atropunctata; B. mediterranea) is a disease common on oak trees throughout Kansas. It is considered to be a stress disease, usually associated with drought stress. Trees showing symptoms in 2019 were likely triggered by the dry growing conditions of 2018.

The initial symptoms of Hypoxylon canker are a tan or silver fungal mat on the trunk of the tree. This light colored surface layer quickly wears off and exposes a black crusty mass that looks like asphalt. Leaves turn yellow and shed and infected trees generally die within the first year. By the second year the dead oaks slough off the remainder of their bark. The best protection against Hypoxylon canker is to avoid stress. This starts with planting into well-drained sites and providing deep, regular watering during prolonged periods of dry weather. Also take care to avoid damage due to construction activities.

Oak wilt (Bretziella fagacearum) has been picked up in a couple of red oak trees in the Kansas city area (Johnson County, KS) this summer. It is an occasional problem on red oaks and pin oaks in northeast Kansas and in counties along the Missouri state line.

Oak wilt causes a partial leaf scorch (brown at the leaf tip and green at the base). Beneath the bark tissue, the disease produces dark brown streaks in the sapwood (see photos). Oak wilt on red oaks tends to start on a major limb or in a section of a tree and then progress until the tree dies, usually within a season.

 

The disease can be spread by sap feeding insects so it is important to avoid pruning oaks between April-June. Oak wilt can also spread to nearby red oak trees through roots that have fused.

There is no cure for the disease. Infected trees should be removed and destroyed. The wood should not be kept for firewood. If there are red oaks nearby, the root grafts between the trees should be severed.  Healthy red oaks nearby may benefit from a fungicide injection.

The best time to test for oak wilt is when trees are freshly wilted, generally in the spring.

More information on oak wilt can be found at the K-State Horticulture Information Center. Link is listed below:

https://hnr.k-state.edu/extension/info-center/common-pest-problems/common-pest-problem-new/oak-wilt.pdf

Common Oak Diseases in KS

  • Hypoxylon Canker
  • Bot Canker

Less common oak diseases in KS

  • Tubakia leaf spot
  • Bur oak blight
  • Oak wilt

Odd but interesting oak problems in KS

  • Oak galls
  • Obscure scale, Lecanium scale
  • Oak tatters

Hydrangea Decline + Root Rot on Coreopsis

Wet then Hot….Hydrangea shrubs crash and burn

By: Judy O’Mara

At first glance, the declining hydrangea makes you think that they were wiped out by a disease. A quick check of the very useful K-State website (http://mesonet.k-state.edu/weather/historical) for historical weather data for Morris County (where hydrangea plants were grown) shows that it got 27.83″ of rain in the first half of the year (January 1 -July 7, 2019). Of that amount, almost 23″ (22.95”) of rain was received during April 29 –July 7th with several periods of 4-6″ over that ten week period. Basically that is a lot of rain.

The impact here is that lots of rain can keep soils wet and soggy, which in turn damages the root system. Plants with damaged roots may not have expressed symptoms during May or June because temperatures during that period were fairly moderate. More recently temps jumped into the 90s and damaged root system were unable to support the tops of the plant. Affected Hydrangeas crashed and burned. Mulch is generally a useful tool to help suppress weeds and keeps soils moist. Too much mulch over heavy clay soils can aggravate the problem by keeping soils too wet.  It can be very hard to regrow damaged root systems so, recovery potential for these plants isn’t very good.

Rhizoctonia Root Rot on Coreopsis

Many plants with poor growth this summer have been suffering due to saturated soils and high temperatures. However, sometimes plant decline is due to a disease. This Coreopsis bed sustained damage from a fungal disease called Rhizoctonia crown and root rot. The disease can survive in the soil for long periods and is triggered by high temperatures and moist soils. Long-term the best management option is to start over with new Coreopsis plants in a new location.

Spring Leaf Drop – Sycamore Anthracnose

by Judy O’Mara

I walk past a big beautiful Sycamore tree on my way into work every day. I recently noticed leaves dropping to the ground. A close look at the defoliated leaves showed the characteristic symptoms for a fungal disease called sycamore anthracnose – brown lesions along the veins and on the petiole. Once the water conducting tissue in the veins is damaged, the leaf gets knocked off the tree. Also visible in the tree were also small, blighted shoots.

Sycamore anthracnose is a spring disease, meaning it is favored by cool (60-73F), wet conditions. With a prolonged spring weather pattern, the disease can sometimes look dramatic. In Kansas, chemical control of this disease isn’t necessary. With the move into warmer summer weather, sycamore anthracnose ceases activity and the tree pushes out a new flush of growth.

K-State Radio Network “Plantorama” – Oversoaked Homelawn Management

(By Jared Hoyle, KSU Turfgrass Research and Extension)

Home lawns have been soaked to the point of oversaturation.  Even if it’s not outright flooding, K-State turfgrass specialist Jared Hoyle says these conditions can be detrimental to that lawn grass, so a little extra care in lawn management may be in order.

Click the link below for K-State Research and Extension Agriculture Today Radio Program “Plantorama” hosted by Eric Atkinson.

Check out the KSRE bookstore more more information on all things turf! – https://www.bookstore.ksre.ksu.edu/Category.aspx?id=528&catId=545

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.***

Don’t forget to follow me on twitter @KSUTurf.

Also, visit our facebook page www.facebook.com/KSUTurf

Paying Attention to Pine Diseases

Now is a really good time to check for Dothistroma Needle Blight on Austrian, Ponderosa and Mugo pine trees. Several pine samples from northeast Kansas have the K-State Plant Disease Diagnostic Lab with classic symptoms. This disease tends to show up in crowded, mature pine plantings. The key is crowded plantings that lead to poor air circulation. Wet weather and poor air circulation lead to increased disease severity.

    

If you are trying to sort out winter damage from Dothistroma needle blight, the first thing to do is to look into the bottom of the tree. Dothistroma causes needle shedding and tends to be more severe in the bottom of the tree. Essentially when you look into the bottom of the tree, the interior needles are gone and all of the lower limbs tend to be bare. Needle loss tends to be particularly severe in crowded windbreaks where air circulation is poor.

Next take a look at the foliage. The needles will have scattered spotting and a half needle scorch. The outer needle tip will be brown and the inner portion of the needle will be green. Each needle will be affected in a different location.

You can contrast this with winter burn which can also produce a half needle scorch but will always burn all of the needles back in exactly the same location. Plus the damage tends to be in the outermost foliage.

The last thing to look for is raised black fruiting bodies (acervuli) on the affected needles. This is diagnostic sign for the disease. You may need a magnifying glass or 10X hand lens to see them, although when they are fully mature they are visible with the naked eye. The fungal fruiting bodies don’t start developing until late December or January, but now is a good time to look for them. If you don’t initially see them you can put the suspect needles in a Ziploc bag with a wet paper towel for couple of days. The high humidity will help the fruiting bodies pop out.

Dothistroma needle blight and winter damage can look very similar. If you are going to spend money to treat for the Dothistroma needle blight disease then it is a good idea to confirm that the disease is present. Samples can also be sent to the K-State Plant Disease Diagnostic Lab at the address listed at the bottom of this post. Dothistroma needle blight can be managed with fungicides.

For more information on managing this problem see the pine disease factsheet at the following web link (O’Mara):

https://www.bookstore.ksre.ksu.edu/pubs/l722.pdf

K-State Plant Disease Diagnostic Lab
4032 Throckmorton, PCS
1712 Claflin Rd
Manhattan, KS 66503
Send Questions to: jomara@ksu.edu
Testing for Needle Blight: $10 Extension/$13.50 Non-Extension

Weed Control Update

(By Jared Hoyle, KSU Turfgrass Research and Extension)

As I look back through blog posts from Spring time in previous years, I notice a repeated theme – Crabgrass, Knotweed and Wild Garlic.

So instead of “reinventing the wheel this year” and writing a new blog post I am going to post previous years posts for these weeds.  There is lots of great information about these weeds and how to control them. (Links to information below the photograph.)

This way I can focus on adding a weed to this list that is become more and more persistent in Kansas. (Stay tuned!)

Crabgrass

https://blogs.k-state.edu/turf/more-than-you-ever-want-to-know-about-preemergent-herbicides/

Photo credit – Auburn University Turfgrass – http://cses.auburn.edu/turfgrass-management/weed-identification/wild-garlic/

Wild Garlic

https://blogs.k-state.edu/turf/stinks-dont-it-wild-garlic-control-in-turfgrass/

Knotweed

https://blogs.k-state.edu/turf/not-your-fathers-knotweed/ 

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.***

Don’t forget to follow me on twitter @KSUTurf.

Also, visit our facebook page www.facebook.com/KSUTurf

Weekend Warrior Turfgrass Lawn Care

(By Jared Hoyle, KSU Turfgrass Research and Extension)

Finally I think we have turned the corner into Spring.  With that, I see more and more of my neighbors, and myself, working in the yard.  I get excited when the turf starts to turn green.  But before I get too carried away I want to get out on the right foot and planning is everything.  To help help you plan out your lawncare program below are monthly calendars for tall fescue, Kentucky bluegrass, buffalograss, bermudagrass and zoysiagrass.

Bermudagrass and Zoysiagrass Lawns

https://blogs.k-state.edu/turf/a-homeowner-step-by-step-guide-to-bermudagrass-and-zoysiagrass-lawns/

Buffalograss Lawns

https://blogs.k-state.edu/turf/a-homeowner-step-by-step-buffalograss-lawn-guide/

Tall Fescue and Kentucky Bluegrass Lawns

https://blogs.k-state.edu/turf/a-homeowner-step-by-step-tall-fescue-and-kentucky-bluegrass-lawn-guide/

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.***

Don’t forget to follow me on twitter @KSUTurf.

Also, visit our facebook page www.facebook.com/KSUTurf

K-State Radio Network “Plantorama” – Home Lawn Winterkill

(By Jared Hoyle, KSU Turfgrass Research and Extension)

HOME LAWN WINTERKILL– It was a fairly harsh winter in this region.  And that has homeowners wondering if their lawn grasses were adversely affected by the extended cold and wet conditions. K-State turfgrass specialist Jared Hoyle says while the likelihood of outright turfgrass winterkill is relatively low, some limited damage may have occurred.

Click the link below for K-State Research and Extension Agriculture Today Radio Program “Plantorama” hosted by Eric Atkinson.

Check out the KSRE bookstore more more information on all things turf! – https://www.bookstore.ksre.ksu.edu/Category.aspx?id=528&catId=545

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.***

Don’t forget to follow me on twitter @KSUTurf.

Also, visit our facebook page www.facebook.com/KSUTurf

NEW – Turfgrass Weed Control for Professionals – 2019

(By Jared Hoyle, KSU Turfgrass Research and Extension)

With new herbicides entering the market, new techniques for controlling weeds, and with more and more difficult to control weeds the “Turfgrass Weed Control for Professionals” manual has been updated to address many of these issues.  Check out the 2019 edition!  It is a must have for every turfgrass manager!

To get your copy click here – https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=545&pubId=20239

 

First 2019 Disease Report from Mizzou

Only of our good friends to the east, Dr. Lee Miller, posted his first disease report of 2019.  In this update he covers what we have been through over the past winter and what to look for in the weather to come.  Check it out!  This is some great information, especially if you are on the east side of Kansas.

https://turfpath.missouri.edu/reports/2019/update03_21_19.cfm?fbclid=IwAR2-mfRuh5r_-pnd8LbpHYEPEsZn4z2-pOwpE77hr6ozxUS4aVW1MHblfso

(Figured I would add a picture in here that shows some green turf! – Jared Hoyle)