If you have seasonal or perennial allergies and experience itching in your mouth, throat, or ears when eating certain foods, your symptoms may have oral allergy syndrome. This is caused because the food and pollen to which you are reacting containing proteins that are similar enough that your body recognizes and reacts to them as if they are the same. So, if you have strong allergic symptoms to birch pollen, you may consider avoiding intake of the associated foods during the spring, as symptoms may be worse during allergy season.
Common sense note: if you have any unusual or strong symptoms after eating specific foods, consult a physician for full evaluation, as your symptoms could be due to a more serious form of allergy.
See the chart below (Source: UpToDate®) for foods that may cause oral allergy syndrome, listed by allergy causing pollen: