Part 3 Quiz

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This quiz will test your knowledge of the causes of seed treatments.

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Question 1 of 15

1. Question
What situation would most motivate a farmer to pay for a fungicide seed treatment on their soybean seed?
- When they rarely grow soybean as a crop because they use other crops in their rotations.
- When they have well-drained soils.
- When seed costs are high.
- When seed costs are low.
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Question 2 of 15

2. Question
Why does the price of seed have an influence on the farmer’s decision to pay for a seed treatment
- Farmers who can pay more for seed should be able to justify the cost of the seed treatment.
- A farmer could decide to lower their seeding rate and spend less money on seed but use the seed treatment to increase the chance of a better stand throughout their field.
- Prices of soybean seed continue to remain low so farmers can now afford to spend money on seed treatments.
- Trick question. The price of soybean seed does not influence the decision to use seed treatment.
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Question 3 of 15

3. Question
Which statement best describes the choices farmers have with the active ingredients in fungicide seed treatments
- There are 15-20 active ingredient choices in fungicides and the fungicides effectiveness on a specific soybean disease varies.
- There are 15-20 active ingredients in fungicide seed treatment choices but each of the active ingredients is effectiveness on all of the soybean seed and seedling diseases.
- There are only 3-4 active ingredient choices in fungicides, one for each of the major soybean seed or seedling pathogens.
- There are only 3-4 active ingredients, but each works well on ALL the major soybean seed or seedling pathogens.
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Question 4 of 15

4. Question
The EC50 for a fungicide is…
- the rate that will prevent mycelia growth in 50% of the plates in an experiment.
- The rate that will reduce mycelia diameter by 50% on average in an experiment.
- The rate that will slow mycelia growth rate in 50% of the isolates from a particular soil sample.
- The rate that delays mycelia growth to require 50% more time to completely cover a petri dish in an experiment.
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Question 5 of 15

5. Question
If the control is represented by the petri plate image on the far left of the picture above, which plate would contain a fungicide rate that is closest to the EC₅₀ ?
- The plate on the far right.
- The plate next to the control.
- The plate that is second to the right from the control.
- The plate that is the third to the right from the control.
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Question 6 of 15

6. Question
The blue circle drawn on the plates above shows the area of mycelia growth. Which is the best description of the “poison plate” experiment conducted on the impact of Ethaboxam on the growth of Pythium aphanidermatum and Phytophthora sansomeana?
- The EC50 is about the same for both Pythium aphanidermatum and Phytophthora sansomeana
- The EC50 is higher for Phythium aphanidermatum than for Phytophthora sansomeana
- The EC50 is lower for Pythium aphanidermatum than for Phytophthora sansomeana
- Neither Pythium aphanidermatuk nor Phytophthora sansomeana had their growth effected by this fungicide.
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Question 7 of 15

7. Question
The best estimate the EC₅₀ for Ethaboxam on the growth of Pythium aphanidermatum from the image above is….
- 0.1 ug / ml
- 1 ug/ml
- 10 ug/ml
- 100 ug/ml
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Question 8 of 15

8. Question
Which isolate has the LOWEST EC₅₀ based on the picture above?
- 107
- 108
- 109
- 110
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Question 9 of 15

9. Question
Assume that this Poison Plate experiment was conducted on isolates of oomycetes to determine if a new fungicide should be developed for use as a seed treatment. Which would be a ‘good’ result that would encourage a company to continue testing this seed treatment chemical?
- If every isolate tested looked like isolate 109 did in this experiment.
- If every isolate tested gave the result observed for isolate 110 in this experiment.
- If the experiment had a similar result, the effectiveness varied among the isolates.
- If every isolate showed NO growth meaning this chemical was highly toxic to every oomycete and might be toxic to many other soil microbes.
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Question 10 of 15

10. Question
What is different about this microtiter plate method for determining the EC50 of a fungicide compared with the Poison Plate method?
- The growth of mycelia from different isolates is not measured, instead the concentration of molecules extracted from mycelia from each isolate is measured.
- Different concentrations of the fungicide are not tested.
- The data is obtained in just a few minutes after all the microtiter plates are set up.
- The method requires less time and expense than it takes to pour agar plates and then take visual readings from the plates a few days later.
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Question 11 of 15

11. Question
What advantage would the microtiter 96 well plate assay have over the Poison Plate method?
- You do not need to keep isolates alive that need to be tested.
- You can test new fungicides on more isolates with less expense with time and materials.
- You can test new fungicides at just one standard concentration instead of a range of concentrations.
- This can be done in the field instead of the lab.
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Question 12 of 15

12. Question
Result A Result B

Assume that a fungicide is tested on several isolates using both the Poison Plate method (X axis) and the Optical density reading obtained from the microtiter plant method. Which result supports the hypothesis that the Optical density reading could replace the Poison Plate method?
- Result A
- Result B
- Both Results
- Neither result
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Question 13 of 15

13. Question
Which statement below is supported by the data shown in the figure above?
- All 9 species have their growth effected by Ethaboxam in the same way.
- The Optical Density experiment and the Poison Plate experiment give similar results.
- The Optical Density method is more accurate than the Poison plant method.
- The Optical Density method is more accurate than the Poison plant method when the EC50 is low.
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Question 14 of 15

14. Question
Assume the Optical Density method continues to be improved. What impact would this have for farmers who are deciding on seed treatment options.
- They will have access to better information on how a seed treatment might work on the oomycete species in their field.
- They will have more choices of seed treatment chemicals with different active ingredients.
- Both of the above would be positive impacts of fungicide testing methods that are easier to conduct and cost less money but provide accurate results.
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Question 15 of 15

15. Question
Which of these active ingredients appears to be the best seed treatment choice to reduce the impact of seed rots caused by Phythium sp?
- Ethaboxam
- Mefenoxam
- Both would be good choices.
- Neither appears to be effective based on the EC50 readings.
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