The missing shade

Original non-fiction-style practice text.

The young trees beside the nursery fence began to lose their leaves in July. Their neighbours, planted in the same soil only a few metres away, remained healthy. A delivery driver suggested insects, but technician Salma found no bite marks. She checked the watering log next. Both rows had received the same measured amount each evening, and a probe showed damp earth beneath each tree.

The difference appeared when Salma stayed after lunch. A storage building shaded the healthy row throughout the hottest part of the afternoon. The fence row stood in direct sunlight until evening. Its leaves felt noticeably hotter, although the air temperature was the same on either side of the path. Salma placed a temporary screen above half the affected trees. She left the other half uncovered, and kept the watering routine unchanged.

During the following fortnight, the screened trees produced healthy new leaves. Those without protection continued to shed theirs. Salma did not announce that every tree in the nursery needed a screen. She recommended moving this particular row before the next summer and testing a different position with a small group first. The nursery manager had wanted an immediate answer. What she received was a modest conclusion supported by a comparison that someone else could repeat.

Give two details from the first paragraph which suggest that a shortage of water was not causing the damage.