Sentence:  But, because the <WSD>first flush</WSD> of growth is from a preformed bud and subsequent flushes are from buds developed during the current growing season, chilling directly affects only the <WSD>first flush</WSD>. 
Meaning of the word marked with <WSD> tags:  (horticulture) The first growth of buds, flowers, seeds, or whatever is harvested from a plant.