Although there are no strict rules, some of the names of fruits are commonly written in katakana.

Click link to hear the pronunciation.

vegetables
yasai
??

spinach
hourensou
?????

potato
jagaimo
?????

pumpkin
kabocha
????

mushroom
kinoko
???

cabbage
kyabetsu
????

cucumber
kyuuri
????

beans
mame
?

bean sprouts
moyashi
???

eggplant
nasu
??

green onion
negi
??

carrot
ninjin
????

garlic
ninniku
????

parsley
paseri
???

green pepper
piiman
????

lettuce
retasu
???

sweet potato
satsumaimo
?????

celery
serori
???

bamboo shoot
takenoko
????

onion
tamanegi
????

tomato
tomato
???