Part 1 Quiz

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This quiz will test your knowledge of the causes of disease diagnosis in the field and in the lab.

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Question 1 of 15

1. Question
A farmer notices a problem in this part of their field that they believe is a seed or seedling disease problem. Which choice best describes the situation.
- Plants in the upper right part of the field have an oomycete disease caused by excessive water a week or so earlier.
- Plants in the lower left part of the field have an oomycete disease caused by excessive water a week or so earlier.
- The soil throughout this field was crusted so all the plants have poor emergence.
- The soil throughout this field had very low moisture levels after planting which explains the poor emergence.
Correct

Incorrect

Hint

Look at the emergence pattern in this part of the field.
Question 2 of 15

2. Question
There are four rows of soybean pictured above.. row 1 is in the lower left, row 4 in the upper right. Predict where the standing water / saturated soil line was a week earlier in this field.
- Outside of this picture
- Between row 1 and row 2
- Between row 3 and row 4
- Trick question, this part of the field shows no evidence of excessive water causing stress on the soybean plants
Correct

Incorrect

Hint

Look for between row variation
Question 3 of 15

3. Question
Why does this observation suggest there is a problem with Pythium disease in this field.
- Pythium disease is carried in the seed and the two plants to the right are healthy.
- Pythium disease is the only reason a farmer may observe poor germination.
- Pythium disease is promoted by the wet conditions and can cause both seed rot and seedling disease.
- The neucrotic (dead) and chlorotic (yellow) appearance of the cotyledons is the best way to diagnose Pythium disease.
Correct

Incorrect

Hint

These plants are in row 4 from the previous question.
Question 4 of 15

4. Question
Which part of this soybean seedling is showing damage that could have been from infection by Pythium because of direct contact with soil while the germinating seedling was still in the ground.
- The hypocotyl
- The cotyledons
- The epicotyl
- The unifolilate leaves.
Correct

Incorrect

Hint

Where is the most damaged part of this seedling?
Question 5 of 15

5. Question
What observation is the agronomist making in the image above that is consistent with pythium disease?
- The root is stunted.
- The root is difficult to cut because it no long holds moisture.
- The cortex easily scrapes from the stele.
- The excavated root grew without developing any cortex.
Correct

Incorrect

Hint

The knife assists this diagnosis.
Question 6 of 15

6. Question
Why would the agronomist want to sample these plants?
- They are the most normal plants in the field and provide a reference for the growth stage of any unhealthy plants from this same field.
- This row clearly had immergence issues.
- All the plants have a uniform level of disease progress.
- None of the above… they would not need to sample these plants.
Correct

Incorrect

Hint

The Plant disease clinician is not likely to go into the field in order to diagnose a problem and must make conclusions based on plants in the sample.
Question 7 of 15

7. Question
Why does the agronomist dig up and collect a sample that has the plant and the soil?
- The plant disease clinician will do all their analysis on the soil but need to focus on the soil next to diseased plants.
- The clinician will conduct their analysis on the roots but need to have intact root tissues so they will remove the soil.
- The agronomist must work fast and this is the fastest way to sample plants.
- Actually, for seed rot and seedling disease only the above ground part of the plant needs to be sampled.
Correct

Incorrect

Hint

Think about what will happen to this sample once it gets to the lab of the plant disease clinician.
Question 8 of 15

8. Question
What should the agronomist do next with this sample?
- Label with a sharpie how many plants, whose field and where in the field before they forget
- Throw into a cooler as quickly as possible
- Leave in the bag and if the plant health continues to decline, a better diagnosis can be made.
- Drive fast to get to their closest disease clinic lab.
Correct

Incorrect

Hint

It is difficult for the clinicians to work with samples that are confusing or poorly handled by the field biologist.
Question 9 of 15

9. Question
What is the disease diagnosis clinician doing with the plant root tissue as a first step after examining the entire plant?
- Inoculating with a microorganism
- Rinsing in acid (low pH solution) to remove the outer layer of plant cells.
- Rinsing in bleach (high pH solution) to remove microorganisms living outside of the roots but not inside.
- Simply washing away the soil so the microbes causing disease can be seen with a microscope.
Correct

Incorrect

Hint

Many kinds of microorgansisms live with plant roots.
Question 10 of 15

10. Question
What is the clinician doing at this stage of their diagnostic work?
- Extracting the DNA from the microbe causing disease
- Determining if the microbes living in the plant tissues are sensitive to an antibiotic or to a fungicide.
- Preserving the plant tissues so they can be examined under a high powered microscope.
- Providing the microbes living in the plant tissues a chance to grow in media that promotes their growth.
Correct

Incorrect

Hint

This is a petri dish with Agar
Question 11 of 15

11. Question
What is the clinician doing in the picture above in the disease diagnosis process?
- Selecting a strain of microbes that they keep in their lab to test on healthy plants to see if they can mimic the disease observed in their samples.
- Checking to see if microbes are growing on the media plates that they had inoculated days ago with the plant sample tissues sent to their lab.
- Same as above but hours ago, not days ago.
- Same as above but weeks ago, not days ago.
Correct

Incorrect

Hint

The key to diagnosis is to promote the growth of the causal organism.
Question 12 of 15

12. Question
What will the diagnostician do next if they use this kind of growth media to grow microbes from their samples.
- Compare the concentration of growth on these plates compared with the regular selective media plates.
- Compare the concentration of growth on these plates compared with the non-selective media plates.
- Look at what is growing on these plates in a few days through a microscope
- None of the above…. Nothing with grow on Water Agar.
Correct

Incorrect

Hint

Oomycetes living in water agar cannot grow for very long.
Question 13 of 15

13. Question
The clinician is examining microbes associated with disease tissue that were placed on water agar. What are they focusing their microscope examination upon?
- Any growth since only water-loving microbes have growth on this media.
- Number of spores made can be used by the clinician to identify the microbe species.
- Rate of mycelia growth induced by the nutrient rich water agar.
- Morphology of the spores induced by the low-nutrient environment
Correct

Incorrect

Hint

Techniques need to be used that induce microbes to grow structures that are visibly unique between species.
Question 14 of 15

14. Question
Why will the clinician work so hard to determine if the unhealthy plants have a disease and the disease is caused by a specific microbe?
- The farmer could be wasting money on treatments that are not effective because they target the wrong microorganism.
- The unhealthy plants may not have a disease but instead are suffering from other environmental stresses and the farmer can make management choices based on knowing this fact.
- Making the correct choice of a variety with disease resistance might be an important decision in the future for this farmer.
- All of the above are reasons why farmers can benefit from an accurate diagnosis from a plant health clinician.
Correct

Incorrect

Hint

Farmers must consider all the possible problems their plants encounter and be prepared to plan ahead to the next growing season based on what happens in the current growing season.
Question 15 of 15

15. Question
Which media provides the best information for the clinician who is trying to identify the microbe causing a disease on a plant sample?
- Selective media if there are microbes growing on this media.
- Selective media if there are NO microbes growing on this media.
- Non-selective media because of the robust growth that can be observed.
- Non-selective media when it is compared to the growth on selective media as a control
Correct

Incorrect

Hint

One microbe could be causing disease while other microbes normally grow with the healthy plant or take advantage of the dying plant.