Set by Dr Phil Taylor.
It is the time of year in the UK when people are planting their potatoes. This month’s quiz is all about potatoes.
#1. What is wrong with saving potatoes from the previous harvest to be planted as a seed crop the following year?
The correct answer is:
They may carry over diseases from the previous crop.
The tubers may carry diseases which will reduce the yield of the following crop.
#2. Chitting is a process whereby the potatoes are grown in trays initially. What does this achieve?
The correct answer is:
An earlier crop.
The main reason people will chit the potatoes is so that they are off to a flying start when they are planted. Commercial growers are often unable to do this as the mechanical planters will knock off the developing roots and shoots.
#3. Leaf distortion due to mineral deficiency is very unusual, but the lack of which nutrient is causing distortion in this potato leaf?
The correct answer is:
Zinc.
It is very unusual to see a deficiency in a nutrient causing in leaf distortion, but it does happen occasionally. Zinc deficiency can be manifest in many different ways depending on the crop. In this case the leaves of the potato are folded and narrow due to a shortage of zinc however in other crops the symptoms of zinc deficiency are very different
#4. Why are viral pathogens such a threat to a potato crop? Note the distortion due to PVY infection on the leaves on the right.
The correct answer is:
The vegetative propagation of potatoes allows them to build up:.
Plant viruses are seldom “seed borne”. As potatoes are propagated vegetatively, in the form of tubers, they will accumulate viruses year on year.
#5. What has caused these symptoms in the tip of this potato plant?
#6. These swellings are often referred to as aerial tubers. What is the cause of this phenomenon?
The correct answer is:
Phytoplasma complaint.
When the phloem is blocked, tubers can begin to develop in the axial buds. These symptoms can be due to Rhizoctonia (fungal) infection or phytoplasma infection.
Photo credit Shalik Ram Adhikari, Ministry of Agriculture; Nepal
#7. Phytophthora infestans famously caused the great famine in Ireland, in 1845. Potatoes had been grown in Ireland for at least 200 years before that, but when was late blight first seen in Ireland?
The correct answer is:
1845.
Until 1845, Phytophthora infestans was unknown in Ireland, it was accidentally introduced at this time and immediately caused a huge famine.
#8. During the winter months, when there is no actively growing potato crop, where does Phytophthora infestans survive in the UK?
The correct answer is:
Potato dumps.
In many countries (UK included) there are not both mating types present and so the pathogen cannot make the thick-walled resting spores (oospores) that are commonly produced by Phytophthoras. The pathogen will survive on volunteer potatoes and on those which have been discarded.
#9. This symptom is known as “spraing” but what is the cause?
The correct answer is:
Two viruses can cause this symptom of crescents/rings of necrosis within the tubers. Tobacco Rattle virus and Potato mop top can cause this symptom.
Photo credit: Owusu Domfeh – https://www.ag.ndsu.edu/pubs/plantsci/crops/a1777.pdf, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=45352737
#10. Killing the potato tops mechanically, or chemically, prior to lifting the potatoes, is good for disease control but there is another aspect of potato production that requires the tops to be killed prior to lifting. Why are the above-ground potato plants killed before harvest?
The correct answer is:
The skin of the potato “sets” i.e. matures.
All the time the tops are green, the tubers will be expanding, and the skin of the potato will be stretching. Once the tops are dead the potato skin will mature and seal the potato tuber.
Photo credit: Farmers Guardian
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.
