Although maples are winter hardy, late spring frosts and cold winds can scorch the emerging foliage. This turns brown, particularly around the margins, then curls and shrivels especially at the tips.
Occasionally premature leaf fall occurs, but a second flush
of growth normally appears. In dry soil conditions moisture
lost from the leaves is not easily replaced and leaf scorch
will occur. Sometimes, however, scorch can be caused by strong
sunlight striking the leaves and in this case the symptoms
may not be seen until later in the season.
Golden-leaved or variegated plants are particularly susceptible because their foliage is inclined to be weaker than those with dark green leaves.
Prevention
- Maples do best in sheltered sites avoiding strong wind
and sun.
- Avoid sites that are too wet by improving drainage before
planting.
- Avoid stress from dry conditions, by watering before
the soil completely dries out. Mulching each spring with
shredded bark or leafmould helps keep the roots cool and
conserves moisture.
- Leaf scorch is likely to occur on plants lacking in vigour. Feed weak plants in spring with a general-purpose fertiliser but avoid overfeeding which may damage the roots and cause further leaf scorch. Badly affected plants with some premature defoliation may benefit from an application of a foliar feed. This may promote vigour and encourage the development of new roots.
Maples in containers should be positioned carefully to avoid strong sun and wind. The compost should drain freely in winter and close attention paid to watering in summer. Grow in a John Innes No.3 compost to which some composted bark and grit is added or use composted bark mixed with some grit. Water-retaining granules may be added to improve summer moisture levels.