Pruning should not be performed in late summer or early spring, however any other time of the year is fine.

修剪不能在早春或夏末进行，在一年中的其它时间都可以。

youdao

Summer pruning devitalises the tree on an extent and consequently reduces excessive vigour.

夏剪能在一定程度上减弱植株的生命力，从而削弱过分的生长势。

youdao

The major part of summer pruning is the upper half of crowns of apple trees.

夏季修剪的主要部位是树冠的上半部。

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The researchers advise growers to investigate the effects of thinning or pruning to reduce the number of fruit in early summer of the on-crop year.

VOA: special.2009.11.10