Wednesday, May 4, 2011

PLANT: CSI (How Plant Problem Investigation Works at the U of I Plant Clinic)

When I first started, I have a couple of tough, plant samples that I was working on.  Now, my definition of a "tough, plant problem" can mean one of following:
A.  It's not a disease (I am a plant pathologist) Suzanne Bissonnette is a plant pathologist too; however she plays the role of an entomologist on TV! Ha ha!
B.  The plant is exhibiting symptoms that could be attributed to a variety of problems (we just have to rule of some of these problems out).
C.  The plant has a variety of problems that is contributing to the symptoms that are exhibited.
D.  I don't know what the "heck" is going on!

I was helping to consult with Richard Hentschel, Extension Educator Horticulture, on a difficult plant issue (that could be an entirely different blog in itself), and in the flurry of emails back and forth between myself and his client, he mentioned that this whole process of plant diagnosis was much like, "Plant CSI".  I liked that analogy and Richard, you inspired me to write this blog : )

Plant Crime Scence Evidence: Dead or yellowing plant parts/not normal plant symptoms <invision yellow crime scence tape placed around the plant sample>

Unfortunately, we are unable to come to the "plant scene", but alot of times, we want you to send us pictures of the "plant scene".  Then, we recommend that you send the "Plant Crime Scene Evidence" to the lab: U of I Plant Clinic

First, we do an "initial walk-through" to get an overall feel for the injured plant scene.  Luckily, we don't have to worry about touching things!  Now, we can make some theories of diagnosis based on visual plant symptoms.

Here we don't swab or collect fingerprints, hair, or dried blood (that is why I am a plant doctor, not a medical doctor).  We look for signs of fungal diseases, nematodes, chemical injury, environmental injury, or insects.

We do try to document all of this "evidence".  And, of course, we are very careful to preserve this plant evidence in it's current form by using refridgeration or even watering (if we have an entire plant).  Sometimes, we even document the "plant crime scene" by taking pictures, sketches, but no video walk throughs are necessary.

Next, we take the plant sample to the scopes (dissecting scope and microscope) to collect potential evidence.  We don't use a swab, but we do use tweezers, as well as other tools such as pruners, knives, and razor blades.  Here are some things we may find on the plant sample in question:  fungal structures, fungal spores, bacterial oozing, nematodes, insect exoskeletons, insect frass, insect webbing, insect feeding, or even nematodes.   Depending on the plant symptoms, we could also use assays or quick strip tests involving ELISA or PCR!  Then, I guess you could say we tag, log, and package it!

If we can't find any of these things above (signs of disease or insect), now that is when it can get tricky!  It could be an environmental, nutrient, or pesticide injury situation.

In this case, we may need to rely on documents such as soil tests, water analysis, or pesticide application log.

Don't forget, once we have a plant sample in hand, we reserve the right to call or email a grower, and perform a full interrogation!  No, we don't ask them were the plant was on the night in question, but we may ask them questions such as:
When was it planted?
What pesticides have been applied?
When were the pesticides applied?
Have you had a soil test?
What fertilizer has been applied?
What was the rate of fertilzer applied?
What has the weather been like?
How long have you had this problem?
In what kind of site is this plant growing?
Was it planted correctly?
What is planted in this area before?
What is the soil type?
What is the condition of the nearby plants?
How old is the plant?
What is the pattern of the affected plants?
What is the name of the plant species?
Are you a homeowner or a commercial grower?
Just to name a few.................................................

When all of the evidence is collected and research has been done (books and internet), it goes straight to the lead detective or in our case, the head diagnostician (that's me).  If I need too, I can also consult with experts.  Now, I don't deal with experts in blood pattern spatter, trajectory determination, serology (blood and bodily fluides), but rather deal with campus specialists that can help me in more specific areas such as crop, fruit, and vegetable pathology or entomology. 

Some Plant CSI's only work in the field - these are Extension Educators or Consultants.  They help to collect the evidence and they pass it to our forensic lab - The U of I Plant Clinic!

Based on these procedures, we can hopefully, MAKE A PLANT DIAGNOSIS!

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