Fungus on Leaves Activity
Fungal pathogens are a major pest of many different plant species. The fungi feed on the host plant, removing nutrients and weakening the plant. They damage plant organs such as the leaves or the roots so they do not function properly.
Plants have a range of chemical and physical defences to resist these fungal pathogens. Climate change, in particular increased CO2, may change the relationship between pathogen and plant, tipping the balance in favour of one or the other. Elevated CO2 may provide the plant with more resources to resist the parasite, or changes in the opening patterns of stomata may increase or decrease the opportunities for fungi to enter the leaves.
How do fungi infect plants?
Watch this short (5 min) video to find out
How does elevated CO2 affect tar spot infection of Sycamore trees?
Think about it:
You are going to look at some data on tar spot infections in the experimental forest.
- How do you think carbon dioxide levels in the air around the trees will affect how much the leaves are infected by tar spot fungi?
Now have a look at how scientists have investigated this and what they have discovered – and see if you need to change your ideas!
Leaf traps collect the falling leaves in both ambient and elevated CO2 rings. We can collect data on the tar spot infection rate by counting the number of spots on leaves for trees grown in both ambient and elevated CO2 . If we observe a difference we can make hypothesis that we can test with further experiment
a) Record the number of tar spots on each leaf in each photo. Remember to record the photo number next to each count.
b) Calculate the mean number of tar spots for the control ring and also for the elevated ring (to find the mean in each case, divide the total number of tar spots you have counted by the total number of leaves you have observed).
c) Plot a histogram showing the two treatments
d) What difference, if any, do you observe in the amount of fungal infection between the CO2 treatments?
e) Suggest two reasons for the effect of elevated CO2 on the rate of fungal infection you have observed
f) Post your graph and interpretation on the anonymous post it board at the bottom of this page
Ambient CO2
Elevated CO2
Results: Paste an image of your graph here and a line explaining how you might explain the data (this is anonymous)
