Sunburn is a common problem in greenhouse or
shade house grown plants. It is also problematic in plants grown in open beds
or filtered sunlight in nurseries when these plants are transplanted into open
Those parts of the plant that have not been
acclimated to direct sun will burn easily.
Sunburned plants turn yellow. As the damage
progresses, the epidermis turns straw yellow and dies. Barrel cacti and
columnar cacti are verysusceptible to this kind of damage.The
entire plant usually does not die, but it is permanently scarred. Similar
damage occurs on
Y. aloifolia, Y. gloriosa,and Y. recurvifolia,
especially during summer months. The apex of the leaf or the area where the
leaf naturally curves will become yellow. In severe cases leaves may die, but
if damage is not severe, they may recover at cooler temperatures.
Sunburn can be minimized in nursery-grown
plants by placing the plant in the same direction as it had been previously
growing. Many nurseries will mark one side of the plant so it can be
transplanted in the same orientation. Placing shade cloth (30%) or cheese cloth
over newly-acquired plants reduces sunburn. If possible, purchase locally grown
plants that have been grown in full sun or partial sun (depending on
the species) and acclimated to sunlight.
sunburn. Application of a mulch about two to
four inches (5 - 10 cm) deep will help retain soil moisture and reduce
reflected light and heat, but be sure the mulch does not cover the base of the
plant and create a moist environment for rot organisms.
Many species will benefit from partial or
dappled shade. By planting near a deciduous tree or shrub, the plant will be
protected from the summer sun and winter freezes.