The last few years certainly have been a challenge for many of us.  One unexpected consequence of the pandemic? Many who were quarantined at home decided to become gardeners.  Seed companies reported a boom in sales during the pandemic and, unlike other trends, (zoom cocktails, sourdough starters or dress shirts with pajama bottoms), it looks like gardening is here to stay.  To those new to gardening and to those more seasoned gardeners, we are here to help you every step of the way.  

We are the UConn Home and Garden Education Center, which is made up of three branches; the education center; the soil nutrient analysis laboratory; and the plant diagnostic laboratory. The education center is your first point of contact, where you will be greeted by horticultural consultants Dennis Tsui, Pamm Cooper and Marie Woodward.  Our mission is to answer your questions about anything related to home gardens and landscapes.  Our goal is to give you the best science-based response. In addition, we often rely on our other two branches for information, but that’s just the start of the services they provide. 

Dawn Pettinelli

Good gardening begins with knowing all you can about your soil, and The UConn Soil Nutrient Analysis Laboratory, headed by Dawn Pettinelli, Associate Cooperative Extension Educator, provides home gardeners a means to test the fertility of their soil and, through a comprehensive report, receive environmentally sound fertilizer and lime recommendations. 

Dr. Nick Goltz

Identifying the cause and nature of plant problems is often the key to maintaining healthy gardens and landscapes, and that’s where Dr. Nick Goltz, plant pathologist, comes in. He heads the Uconn Plant Diagnostic Laboratory and is an expert in diagnosing plant problems including diseases, insect pests and abiotic causes.  Dr. Goltz has a passion for plant health and integrated pest management, (IPM).  He especially enjoys working with homeowners to find holistic and comprehensive solutions for any plant problem they may have.

The three branches of the center are available to gardeners year-round.  To access our services, you can reach us by phone, (860-877-6271), by email, (ladybug@uconn.edu), or you can visit the center the Radcliffe Hicks Arena, 1380 Storrs Road, unit 4115, Storrs, CT. Our hours are Monday- Friday 8:30am -4:30pm.

Collecting and Submitting Samples

One of the most common questions we are asked is how to collect samples that are of good diagnostic quality.  Each laboratory website has detailed instructions on how to do so.  For the Soil Nutrient Analysis lab, there is a page with instructions on how to submit a soil sample at:

Soil Sampling Instructions

The plant diagnosis laboratory has a form with instructions on how to collect plant sample at the bottom of the submission page: 

Plant Submission Form

Samples can be mailed in or brought into our center during our office hours, (see above).

Emailing us with a question?

If you’re emailing us with a question or problem, it can be helpful, (but not necessary), to include a few photos with it.  This can help us determine our response. 

To learn more, you can visit our website: http://www.ladybug.uconn.edu/ where you will find the latest news, blogs and fact sheets about all things for your home garden.  We are ready to help make your home garden a success year after year. 

I have been asked before what my process is for identifying plant pathogens – fungi and bacteria that cause disease on plants. Although there are different techniques to identify different pathogens, often the most straightforward approach is to culture them until morphological characteristics are obvious enough to identify using keys. In other words, I grow the pathogens until they produce structures that can be identified!

You may ask, what does it mean for the pathogens to be “cultured”? While I may not be playing Beethoven’s fifth for the pathogens, I am providing them an enriching environment in the form of proper nutrition and a favorable environment. Diseased tissue can be isolated from healthy tissue, placed on a nutritious media, and allowed to grow in a warm protected environment until identifiable reproductive structures are produced.

First, diseased tissue is photographed and examined to see if identifiable signs of the pathogen are already present. An example of such would be a fungus that has grown enough on the submitted plant tissue to be actively producing reproductive spores (see fig.1 and fig. 2). For samples with minor, ambiguous, or fastidious fungal growth, some extra encouragement for growth may be necessary.

Fig. 1. Alternaria fruit rot and spot of pepper is caused by Alternaria solani, a common fungal pathogen.
Fig. 2. A magnified photo of Alternaria solani spores pulled from the pepper lesions in Fig. 1.

In instances where the identity of the pathogen is not immediately obvious, the sample is dissected. Some tissue that was surrounding the symptomatic area is excised and (usually) surface sterilized using a diluted bleach rinse. The remainder of the diseased tissue is placed in a sealed “humid chamber” to allow the pathogen to continue to grow on the submitted tissue. Humid chambers can easily be made by putting a clean, damp paper towel in a plastic deli container, placing the sample inside, then sealing and labeling the container. The sample can be checked each day to see how the pathogen is (or isn’t) developing.

The excised tissue then be placed on a substance called “agar” for the pathogen to incubate and grow. Agar is a product derived from red algae, commonly Gelidium amansii. It is a dense, jelly-like substance and is a common replacement for gelatin in vegan recipes. It is also a common ingredient in many East Asian desserts, such as boba teas. The agar is mixed with nutrients and certain chemicals to discourage non-target organisms from growing, heated and sterilized in an autoclave or pressure cooker, then poured into petri dishes to solidify (see fig. 4).

The tissue is placed on the agar using sterilized tools under a biological safety cabinet, a machine that maintains a sterile environment and protects the user from exposure to harmful agents or accidental contamination (see fig. 3). This process is often called “plating” as the tissue is being placed on petri plates. Once finished, the petri plates are labeled and may be sealed with a film to further reduce the risk of contamination. The finished plates are placed in a warm chamber, like an incubator, to allow the pathogen to grow until spores or other desired structures are produced.

Fig. 3. A biological safety cabinet with a HEPA filtration system and unidirectional airflow protects the user from contaminating samples or exposure to harmful agents.
Fig. 4. A sealed, labeled petri plate with significant fungal colonization.

Once the spores or other desired morphological characteristics have been produced, they may be photographed under a microscope and compared to references or subjected to further testing (this is usually only necessary for bacteria) for identification. When the pathogen has been identified, the used plate is securely stored until it can be sterilized via autoclave and discarded appropriately.

Until next time!

– Nick

Nick Goltz, DPM – Director of the UConn Plant Diagnostic Lab