Set by Phil Taylor (CABI).
This month’s quiz is on the chemicals that are used to prevent microbial pathogen. The world is reliant on chemicals to protect our crops and there is increasing concern over their safety and environmental damage they cause, and many have been withdrawn or are becoming prohibited. Test yourself to see what you know of crop protection chemicals. The photos are not of much relevance to the question so don’t spend too long looking at the photo.
#1. Fungicides (and insecticides) are often described as systemic. What does systemic mean?
The correct answer is:
Moves into the plant will relocate within the plant.
Systemic chemicals enter the plant and will be moved around to new areas. They generally move up and seldom get into the roots.
#2. When considering a fungicide container, what information does the trade name (the big name on the front) provide?
The correct answer is:
It provides no information whatsoever with regard the contents.
The names of agrochemicals are invented by those marketing the product, It may be a corruption of the active ingredients but often is not. It is a marketing name and it tells you nothing about the contents.
#3. Once a fungal pathogen population has become resistant to an active ingredient, to what extent will this spread to other fungi?
The correct answer is:
Resistance will not spread to other fungal species.
Unlike bacterial species which readily share resistance genes the same is not the case for fungi. A single fungal species may have become resistant to a chemical but that has little bearing on other fungi (other than you have created conditions for resistance to occur).
#4. There are relatively few fungal pathogens of humans but they are on the rise. How is resistance to fungicides in human medicine related to agricultural fungicide use?
The correct answer is:
There are some examples of resistance spreading from agriculture into medically important pathogens.
Resistance to the triazole group of fungicides has spread from agriculture to human pathogens.
#5. The “mode of action” of a fungicide is determined by which aspect of a product?
The correct answer is:
The active ingredient of the product:
The mode of action (how the chemical kills the fungus) is due to the active ingredient(s). The remainder of the canister is important but are unrelated to mode of action.
#6. Oomycetes (watermoulds) look like fungi and are often considered as fungi (Phytophthora and the downy mildew pathogens). To what extent do chemicals sold as fungicides control these oomycete diseases?
The correct answer is:
Some fungicides will control oomycetes:
Oomycides or watermouldicides don’t often enter into our language. People talk of fungicides controlling the oomycetes, however although many fungicides have activity against oomycetes many do not (Metalaxyl as a good example).
#7. Classifying fungicides into resistance categories is relevant to whom?
The correct answer is:
All those who make, recommend, or use fungicides.
It is essential that all those working with fungicides under the concept of resistance and which resistance group various fungi are in.
#8. When is it important to blend fungicide products in the spray tank?
The correct answer is:
If the product being used contains only one active ingredient.
If the commercial product purchased from the ag chem store contains only one active ingredient it is important to mix the fungicide with another product. Repeated use of a single active ingredient will lead to resistance.
#9. Spraying fungicides at below their recommended rate will have what effect on the resistance in the fungal population?
The correct answer is:
Reduced doses are helpful in reducing selection pressure and delaying the emergence of resistance.
Possibly counter intuitively most examples in the literature suggest that reduced doses are helpful in reducing selection pressure and delaying the emergence of resistance. What you must not do (with regard resistance) to in increase the dose in an attempt to overcome the resistance developing in a population. That will really ramp up the resistance.
#10. Resistance can develop to any fungicide but what kind of fungicide is resistance most likely to develop
The correct answer is:
Single site systemic.
Fungicides with a single mode of action are more likely to have resistance developed against them as are systemic fungicides. Multisite contact fungicides like Chlorothalonil or Macozeb have been used for years without resistance developing whereas resistance developed quickly to Azoxystrobin; single site with systemic action.
Results
We hope you enjoyed the quiz and learned something!
See how your score matches up…
1-3: You need to do a few more of these quizzes to become a field diagnostics expert.
3-5: You have made a start in your field diagnostics but there is some way to go…
5-7: You are getting more right than wrong so keep on learning!
7-9: Impressive you are getting pretty experienced in your field diagnostics!
10: Well done! But make sure you do the quiz again next month.
We hope you enjoyed the quiz and learned something!
See how your score matches up…
1-3: You need to do a few more of these quizzes to become a field diagnostics expert.
3-5: You have made a start in your field diagnostics but there is some way to go…
5-7: You are getting more right than wrong so keep on learning!
7-9: Impressive you are getting pretty experienced in your field diagnostics!
10: Well done! But make sure you do the quiz again next month.
