Lower leaf drop in orchids is a physiological disease

Lower leaf drop is usually related to root diseases, leaf diseases and damage by scale insects; excessive age can also cause the shedding of lower leaves. Other non-pathogenic factors related to lower leaf drop are impropercultivationpractices and water stress. For orchids planted in the groundorchids, impropercultivationand water stress are the most common causes of leaf drop. When the soil has not been properly treated and the roots of newly planted seedlings are not well covered by soil or ground cover, they cannot absorb enough water, resulting in water stress. The lower leaves then turn yellow, dry out and drop off. During hot weather, rapid transpiration from the leaves and high-intensity evaporation from the soil mean that if the plant does not absorb sufficient water, water stress occurs. Sustained water stress leads to lower leaf drop and inhibited growth, especially in newly planted plants. Prevention: The seedbed for orchids planted in the groundorchidsshould be carefully prepared, and newly collected plants should be carefully planted according to the correct method. Lower leaf drop can also be prevented by mulching between the rows and regular watering to avoid water stress. If replanting is carried out during the rainy season, water stress in the newly planted plants can also be avoided. (Liu Zhongjian)