An Introduction to NCSU Plant Disease and Insect Clinic

by Andrea Laine, EMGV

You know you’re a serious gardener when you get excited about preparing a sample for the NCSU Plant Disease and Insect Clinic. I just wish I had engaged this problem-solving staff sooner and I hope you will learn from my experience.

Over the last three or four years, the mature evergreen azaleas in my landscape – of which there were many – began to succumb to a sudden dieback. Where there was once dark green glossy leaves and abundant flowering, seemingly overnight a swath of vertical branches would turn brown and die. I was alarmed, but knew not what to do. So, I did next to nothing: I trimmed out the crispy parts and hoped for the best.

I am ashamed to admit this experience was after my master gardener training. In training we certainly learned about the services provided by the Plant Disease and Insect Clinic, but either I didn’t think my plant problem was important enough to bother someone at NC State, or I was too lazy to prepare a sample. Probably a little of both.

Inspired to act

Fast forward to this summer when two things happened that inspired me to act. First, the mysterious dieback attacked a stand of azaleas that are a key structural element in the design of my landscape (see photos above). And secondly, I noticed the exact symptoms on a few azaleas in a Durham neighborhood far from my own. The problem no longer belonged just to me; I resolved to seek a diagnosis on behalf of all of us.

My first step was to collect a soil sample from the vicinity of the azalea with the most recent dieback. The results showed that the soil pH was too high – 6.2 – where azaleas prefer a number between 4.7 and 5.3. Phosphorus was high and potassium was a little low. While all that is not a great situation for these acid-loving plants, it did not explain the sudden dieback. I needed to delve deeper.

I decided to access the NCSU Plant Disease and Insect Clinic. (You’ll find a direct link to it on the right side of this blog’s homepage as well as in the list of resources below.) I dug up a smaller azalea that had browned out a year or so earlier, left a good bit of the roots and soil intact and plunked it into a double plastic bag. Back indoors, I downloaded a submission form from the Clinic’s website, filled it out to the best of my ability and brought it and the sample to the master gardener office where I enlisted the help of our County Ag Agent Dr. Ashley Troth. Ashley submitted the sample on my behalf and we included digital images of the affected plants in my landscape. The more information a client can provide, the better will be the diagnosis and recommendations.

I had decided to remove these small, scraggly azaleas from the landscape anyway. So, I used half of one as my sample to the Plant Disease and Insect Clinic. Photo by A. Laine.

A diagnosis

A week later the diagnosis was in:  Symptoms are typical of Phomopsis dieback, a fungus disease. “The disease can be very serious if the fungus moves into larger branches and the base of the plant. This dieback was found down into the base of the plant submitted,” wrote Shawn Butler, an ornamentals diagnostician. “Presence of this disease,” he continued,  “often is an indicator of stressed or injured plants. Photos show that there is probably a problem in the root zones of these plants.  No root rot pathogens were isolated from these roots.  If the plants have been water-stressed in the past, then that might be the primary problem.” 

He also sent a root sample out to check for presence of damaging nematode populations. Some parasitic nematodes were found but populations were not high enough to cause damage.

A new pledge

I will take away at least two lessons from this experience (and I hope you do, too). The first is to seek help sooner, and the second is to not ignore long-established shrubbery. (These azaleas were planted at least 20 years ago.) The plants I inherited with my landscape deserve tender-loving-care equal to that which I provide to the plants I personally select for the landscape. 

Yet another azalea is affected. Removing it would leave a hole in the bush to the right as they have grown together over the decades. Photo by A. Laine.

Resources & Further Reading

How to submit a sample to the clinic: https://projects.ncsu.edu/cals/plantpath/extension/clinic/submit-sample.html

Meet the staff
https://projects.ncsu.edu/cals/plantpath/extension/clinic/about.html

Fees for the Clinic’s diagnostic services: https://projects.ncsu.edu/cals/plantpath/extension/clinic/services.html

Azalea care – a factsheet from Clemson University
https://hgic.clemson.edu/factsheet/azalea-care/

A comment about old azaleas from Louisiana State University
https://www.lsuagcenter.com/portals/blogs/southerngarden/problems-with-old-azaleas

Learn With Us, week of October 20

Composting – Sarah P. Duke Gardens
Thursday, October 24⋅7:00 – 9:00pm

Sarah P. Duke Gardens
420 Anderson St, Durham, NC 27708
Composting by Georgeanne Sebastian and Darcey Martin

Discover the basics of successful composting and vermicomposting. Learn how to transform food scraps, leaves, and other organic materials into a nutrient-rich soil conditioner that will benefit your lawn and gardens.

Durham Master Gardener Program News

Public Events
Is your community planning a feast, fair or festival? Add to the excitement by inviting the Master Gardeners to staff a table at which your guests can have their gardening questions answered. Our “Ask an Expert” program travels all over Durham County to provide this service. Call 919-560-0528 to make a request or learn more.   


Soil Sampling
Statewide, the soil sampling kits and associated paperwork are now available in Spanish and English! Locally, you may pick them up at 721 Foster Street in Durham from the Durham County Master Gardener office.

The season for free soil samples is coming to a close next month. The last day that samples will be collected at 721 Foster Street is November 25, 2019. From December 1, 2019 through March 31, 2020 residents will be responsible for delivery of their soil samples to the NC Department of Agriculture and Consumer Sciences in Raleigh and paying for their soil to be tested ($4.00 per box).  Extension will resume accepting soil samples on March 19, 2020. There is much to gain by testing your soil! Learn more.

New Partnership with HUB Farm
Durham County Master Gardeners now serve The Hub Farm, a 30-acre farm, forest, and aquatic educational center in Durham whose mission is to improve the academic achievement and well-being of students in Durham Public Schools through experiential outdoor learning. Hub Farm engages students, teachers, and the greater Durham community in environmental stewardship, health and nutrition, and career development. The farm is a program of Durham Public Schools Career-Technical Education Department and is guided by a small staff and advisory board. It is located at 117 Milton Road. Learn more about Hub Farm.

Edible Plants Sale in April
The addition of a greenhouse at Briggs Avenue Community Garden has enabled on-site seed-starting to flourish. The gardeners hope to share their bounty of seedlings of edible plants at an Earth Day event in Durham in 2020. Stay tuned for more information!

NC Extension Gardener Plant Toolbox
Though still a work in progress, the North Carolina Extension Gardener Plant Toolbox is a great resource. It contains detailed descriptions and photographs of 3,311 plants that grow in and around North Carolina. You can search for a plant by its common name or its scientific name. Use the “Find a Plant” feature to select a plant for a specific location, or  try “Identify a Plant” to determine the name of a plant based on its flower and leaf characteristics.

The primary goal of the plant database is to help consumers select plants that will bring them joy, provide a valuable function in their landscape, and thrive where planted. Users are encouraged to consider year-round functionality and potential disease and insect problems as part of their selection process. Access the database at https://plants.ces.ncsu.edu/ now and in the future. It will only get better!

— A. Laine

Learn With Us, week of October 13

Why We Study Soil – Durham Garden Forum
Tuesday, October 15⋅7:00 – 8:30pm

Sarah P. Duke Gardens
420 Anderson St, Durham, NC 27708
With Dr. David Crouse, Professor & Undergraduate Teaching Coordinator of Crop and Soil Science at North Carolina State University Soil is the basis of all garden success. Dr. David Crouse will outline some of the basic ecoservices provided by soil to give you the big picture of how soil impacts your garden and some specifics about how you can work to improve your soil.

The Durham Garden Forum is an informal group that meets once a month to enrich our gardening knowledge and skill, on Tuesdays, 7:00- 8:30 pm at Sarah P. Duke Gardens. Lectures free for members, $10 general public.
No pre-registration necessary.

Our Straw Bale Gardening Experiment

by Marty Fisher, EMGV

After three painful years of crop-destroying diseases on our beloved heirloom tomatoes, my husband and I decided to give straw bale gardening a try.

I had tried grafting—attaching an heirloom scion onto a hardy root stock—for two years with some success, but it was a long, painstaking process, and we still weren’t getting the yields we enjoyed in the days before the dreaded fungal, viral, and bacterial diseases took over in our garden. We also tried disease-resistant tomatoes like Early Girl, Better Boy, Celebrity, Sweet 100, etc., but we missed the complexity of flavors and variety of colors of our favorite heirlooms like Carbon, Amana Orange, Green Zebra, Pineapple, Lucky Tiger, and more. We also tried removing the lower branches of our plants to keep them away from disease spores in the soil as well as spraying with copper sulfate—it all seemed a lot of work for a limited return on investment!

I started researching straw bale gardening in January, thinking it offered the advantage of a sterile environment for the tomato plants as well as the effect of a raised be d. I found a book written by the man who pioneered the concept, Joel Karsten. He came up with the idea after observing healthy, vigorous weeds sprouting in old straw bales on his family farm. He began experimenting with vegetables, and over decades, developed the techniques for gardening with straw bales. Since then, he has published two editions of his book, Straw Bale Gardens, and has spoken all over the world about what is touted on the book jacket as “the hottest new method of veggie growing.” The book contains a wealth of useful information, plans, diagrams, and more.

Our first task was to find straw bales—they must be wheat straw bales, not hay. They are not cheap, especially given the size of our garden. The best price we found was about $6 a bale. We inquired about delivery and were told by several farm supply stores that they sell the bales at a loss or break-even and were not interested in delivering them. So, several pick-up truck trips later, we had lots of bales on our garden site. 

The next step was placing and conditioning the bales, a process that takes 10-12 days. Conditioning should be started two weeks before the average last frost date. 

Although I had reservations about the fertilizer recipe given in the book, we decided to just follow the instructions and evaluate the results. Over the conditioning period, fertilizer and water are applied to the bales according to a day-by-day schedule. My reservation concerned the recommendation of nitrogen-rich “traditional refined lawn fertilizer.” Instructions are also given for organic nitrogen sources, but this seemed more complex, and we followed the conventional method. Fertilizer is sprinkled over the top of each bale, and water carries it deep into the bale, starting the bacterial process of breaking down the bales to release nitrogen.

On Day 10, the instructions call for one cup per bale of 10-10-10 general garden fertilizer, watered in. 

Planting can begin on Day 12. A little sterile potting soil can be used to anchor the plant in the straw bale, but all the nutrients and growing medium the plants will need are contained within the conditioned bales. Adding garden soil or compost could introduce fungal spores to the sterile bales.

Results  

Our concerns about using lawn fertilizer were confirmed over the spring and early summer: TOO MUCH NITROGEN! Our plants quickly became enormous, with fewer blooms than normal. They also began to shade out the eggplants and herbs that we had planted beside the tomato plants. We added a phosphorous- and potassium-rich fertilizer and gradually the plants started to have more blossoms and bear fruit. We also noticed that plants growing in straw bales require more diligent watering. Karsten recommends placing soaker hoses on top of the bales, controlled by a timer. 

In researching this article, I found an N.C. Cooperative Extension Service article (see “Hay” Bale Gardening link below) that recommends a different conditioning method. It calls for simply watering the bales for three days. On Day 4, you add 2 cups of dolomitic limestone and a half cup of ammonium sulfate, and water it in. On Days 5-9, you add more ammonium sulfate, followed by a cup of 10-10-10 or 8-8-8 on Day 10. Planting commences on Day 11.

This year we did lose a few plants to “the *%#* fungus,” our common term for fungal, viral, and bacterial diseases including early blight, late blight, fusarium wilt, tomato spotted wilt, various cankers—you name it. My husband also sprayed the plants with copper sulfate as a preventative. 

Overall, we deemed the straw bale gardening experiment a success. We canned, made salsa, roasted, sliced, and froze plenty of colorful tomatoes to get us through the winter. We plan to try it again next year using the Extension Service-recommended fertilizer recipe.

I also plan to graft tomatoes again next year after taking this year off. And, I’ll give some of the newer disease-resistant varieties a try. Some I’m particularly interested in include Iron Lady, described as “super resistant,” and Mountain Magic, which was developed by Dr. Randy Gardiner, professor emeritus at North Carolina State University. Apparently, some breeders are also developing disease-resistant heirlooms, including two old favorites of mine, Lemon Drop and Mr. Stripey.

This was our first harvest this year–it got better after we adjusted the fertilizer.
Good old fashioned canned tomatoes! Heirlooms make the jars so colorful.
Tomatoes growing in straw bales in our garden. In addition to diseases, we also battle squirrels, hence the large cage under construction.

All photos taken by Marty Fisher.

Sources

Straw Bale Gardens Complete, by Joel Karsten

Understanding Tomato Varieties:
https://lee.ces.ncsu.edu/2019/05/understanding-tomato-varieties/

How to Grow Better Tomatoes
https://forsyth.ces.ncsu.edu/2018/05/how-to-grow-better-tomatoes/

Grafting for Disease Resistance
https://content.ces.ncsu.edu/grafting-for-disease-resistance-in-heirloom-tomatoes

Blight Resistant Tomato Varieties Worth Growing
https://www.growveg.com/guides/blight-resistant-tomato-varieties-worth-growing/

“Hay” Bale Gardening
https://pamlico.ces.ncsu.edu/2013/05/hay-bale-gardening/