Leaf physiological disorders should not be ignored; identify and prevent them early

Leaf symptoms: 1. Leaf color turns yellow-green, while all other parts remain normal. Cause: Sunlight is too strong. 2. Leaves turn yellow, new shoots grow slowly and small, but do not shrivel. Cause: Insufficient nitrogen fertilizer. 3. Except for the new leaves, which remain normal, the other stems and leaves turn yellow, and the pseudobulbs shrink and become wrinkled. Cause: Overwatering, improper repotting, or root damage. 4. Leaves appear purplish-red, especially noticeable on new leaves. Cause: Caused by low-temperature injury or phosphorus deficiency. 5. Old leaves yellow and drop off. Cause: Normal aging or caused by repotting and transplanting. 6. The tips of new leaves look scorched, and in severe cases the scorching extends toward the base until the tissue dies, and roots at the potting surface die, but there is no infection. Cause: Fertilizer burn caused by excessive or improper fertilization; too much salt accumulates in the growing medium. Fertilizing should be stopped and the growing medium should be flushed. 7. Leaves are scorched, showing dark brown patches surrounded by yellow halos. Cause: Sunscald caused by too much light; it occurs more easily when ventilation is poor. 8. Leaves shrivel rapidly and turn grayish-green, and the pseudobulbs also gradually shrivel. Cause: Overwatering or poor drainage damages the roots; air humidity should be increased. 9. Leaves shrivel slowly, old leaves gradually turn yellow-green and in severe cases drop off, and old pseudobulbs shrivel. Cause: The growing medium is too dense or poorly aerated, or there is a lack of nitrogen fertilizer or the pot is too large. (Xue Congxian)