When there are too many fruits on the trees, those remaining ones on the tree fall naturally to the ground.
ご質問ありがとうございます。
"When there are too many fruits on the trees,"＝「果樹に実がなりすぎると」
"those remaining ones on the tree"＝「木の上に残っている実は」
"fall naturally to the ground."＝「自然に地面に落下する。」
Sentence in context: "The remaining fruits fell naturally to the ground, making it easier for us to collect them."
ご参考になると良いです！
アメリカ合衆国 
