Julie wanted to know if adding calcium fertilizer to tomato plants will prevent a disease of tomato plants called blossom-end rot. she used 10 tomato plants. she put 5 plants in a sunny part of the garden and gave each one calcium fertilizer once a week. she placed the other 5 plants in a shady part of the garden and gave them calcium fertilizer twice a week—she thought that since they were in the shade they might need more fertilizer. she then observed the 10 plants for 3 months to see if the fertilizer prevent blossom-end rot. identify and explain one weakness in julie's experimental design.