The leaf tips of Cymbidium are yellowing.

There are leaf spots on the outer leaves of a green leaf, except for the normal growth physiological law of yellow leaves, that is, the general leaves survive on the plant for about 3 years, while the old leaves turn yellow and age and fall off naturally, which has no side effects on the plant. it is a natural process of normal growth and metabolism of Cymbidium.

The appearance of leaf spots and yellow leaves in new and immature leaves is an abnormal phenomenon.

The main symptom of leaf spot disease is that yellow or brown dots appear on the leaf surface, and then the color of the spot deepens gradually, and the festering area of the spot gradually expands, so that the leaf or the whole plant rots away.

The main causes of leaf spot disease are:

1 apply fertilizer that is not fully fermented. Causes bacteria to multiply in large numbers in the basin soil to produce a large amount of heat.

(2) the pot soil has not been changed for a long time, and there are pathogenic bacteria in the old soil.

(3) the new soil was not fermented fully. Second fermentation in a basin.

(4) the imbalance of nitrogen, phosphorus and potassium in fertilizer, especially due to the direct contact of fertilizer with make-up in the case of low potassium fertilizer or fertilization.

According to the above specific reasons, different methods should be taken to prevent and cure them. The fertilizer used must be fully fermented, the concentration of fertilizer should be small, nitrogen, phosphorus and potassium should be balanced, and the fully fermented nutrient soil should be changed twice a year in spring and autumn without raw soil. In this way, leaf spots can be prevented.

The main symptoms of leaf yellow disease are:

1 one leaf turned yellow locally, and the yellow leaf was irregular.

(2) the leaf tip first yellowed and gradually spread to the pseudobulb.

(3) the false bulb first yellowed and gradually spread to the end of the leaf.

4 the whole leaf turns yellow from the bottom to the end at the same time.

The first situation is caused by sunburn on the leaf surface, cold wind, local spread of germs bitten by pests such as slugs and snails, or enlarged wounds after trauma. The leaf tip yellowed at first mainly because the rotten root interrupted the nutrient supply of the leaf, and began to turn yellow from the leaf tip to the pseudobulb. Or caused by the use of raw soil or poor soil quality. The reason for the third situation may be that insect pests bite the leaves of the pseudobulb and make it gradually expand to the tip or stagnant water at the pseudobulb in summer, and bacteria breed local yellow leaves and spread gradually.

It is more common for the whole leaf to turn yellow at the same time, and the cause is also more complicated, mainly due to improper management. Such as poor ventilation in summer, excessive fertilization, root problems and so on may make the leaves turn yellow as a whole. The preventive measures are, first of all, to prevent the rotten roots of the plant, so that the leaves can get adequate nutrition, and then to put an end to trauma and prevent the wound from spreading, the amount of fertilizer applied must be well controlled, and hypertrophy must be avoided. Adult flowers in summer should not water the false bulbs, and should pay attention to ventilation, cooling and strengthening management. Regular spraying of carbendazim, chlorothalonil, methyl tobu, agricultural streptomycin and other sterilization drugs for prevention and control. That is, it can reduce and put an end to the occurrence of abnormal yellow leaves.