What’s wrong with my plant?
Thank you for contacting the Toronto Master Gardeners.
A Meyer lemon tree is a cross between a true lemon and either a mandarin or regular orange, resulting a delicious fruit.
Good cultural practices are the first step to maintaining and healthy tree and providing it with the strength to fight of pests and diseases
Your photo indicates that your plant is growing indoors, hopefully with 6 hours of sunlight every day.
Lemons should be planted in a large pot with good drainage. Watering should be consistent, ensuring the soil remains damp, not wet. Never let the pot sit in water. Between April and September your tree should be regularly fertilized with special citrus specific fertilizer. This should be stopped over the winter.
In spite of the above care, your plant can be susceptible to problems. Yellowing leaves are usually caused by over watering or over fertilizing. Meyer lemon trees can also be affected by spider mites, aphids and mealy bugs. Please check your leaves, both on the top and underside as well as the stems for any of these pests. If you do find any pests, you may try to spray your tree with insecticidal soap.
Good luck with your harvest.