Orchid leaves turning from green to black: is it poisoning? Treat quickly to avoid the plant dying

1. Premature leaf dieback

Normally, during the growth of an orchid, in order to promote the sprouting and growth of new leaves, the tips and edges of the old leaves gradually turn yellow and die back from top to bottom, thereby saving nutrients. This is the normal phenomenon of leaf dieback.

But if the new leaves are also turning yellow and scorching, or even the pseudobulbs are deforming and changing color, then the orchid leaves are dying back prematurely.

What to do about premature leaf dieback?

Premature leaf dieback causes the orchid leaves to become sparse and turn black, and the plant to develop slowly or even stop developing. At this point, you should first check the state of the root system.

1. Roots only lightly damaged

If the roots are not badly damaged and only the outer leaves are dying back, just trim them off promptly, then control water and fertilizer: do not water until dry, and water thoroughly once completely dry; in summer, apply a dilute liquid fertilizer about once every 15 to 20 days.

2. Roots severely damaged

If the orchid's root system is severely damaged, the whole plant may die back. In this case, you must repot it and change the soil. After taking it out of the pot, first cut off the rotten roots, then soak the entire root system in a carbendazim solution to disinfect it. Then repot it with fresh growing medium, taking care to leave the pseudobulb exposed.

2. Infection with stem rot

If you find the orchid leaves gradually turning black from the bottom upward, black spots growing on the leaves, and when you dig around the roots you can even see that everything from the root collar to the pseudobulb has turned black, then you should be on alert: it has very likely been infected with stem rot!

How to prevent and treat stem rot?

The peak period for stem rot is from June to September. During this period, with high temperatures, frequent watering and many pests, orchids are prone to infection by pathogens.

Prevention first: preventing is better than curing

1. During the hot summer period, every 7 to 10 days, use carbendazim, chlorothalonil or thiophanate-methyl and other antibacterial agents diluted 500 to 1000 times to spray and sterilize around the plant and on the leaf surfaces.

2. Treat wounds promptly, especially after division, immediately apply a wound healing agent to prevent infection and disease;

3. You can bury some carbofuran insecticide in the growing medium to prevent pests from infecting the pseudobulbs.

How to treat it?

1. As soon as it is discovered, immediately cut off and burn the infected orchid plants and leaves;

2. Pull out the whole pot of orchids, wash them clean, cut away the diseased plants and rotten pseudobulbs, then place the remaining whole orchid in a difenoconazole solution slightly stronger than 500 times and soak for 1 full day.

3. After drying, change the soil and repot. Do not water, and keep it in a cool, ventilated place for three days. Soak the orchid pot with a 500 to 1000 times fungicide solution once a month, and it will gradually recover to health.

Note: Huahua reminds everyone that in hot weather you must frequently loosen the soil and ventilate your orchids to ensure the roots breathe normally. If you find that too troublesome, you can use a fan to blow on them after watering~

Alright, that is all for the introduction to orchids' "heat sickness."

Fellow flower growers, have you all learned it?