Orchid leaves turning from green to black: watch out for orchid poisoning and remedy it as soon as possible

I. Premature leaf dieback

Generally, during the growth of orchids, in order to promote the sprouting and growth of new leaves, the tips and edges of old leaves will gradually turn yellow and wither from top to bottom, thereby saving nutrients. This is the normal phenomenon of leaf dieback.

But if the new leaves are also turning yellow, scorched and withered, or even the pseudobulb is deformed and discolored, then it means the orchid leaves have died back prematurely.

What to do about premature leaf dieback?

Premature leaf dieback will cause the orchid leaves to become sparse and black, and the plant to develop slowly or even stop developing. At this time, first check the state of the root system.

1. Root damage is relatively mild

If the root damage is not great and the outer leaves wither and die back, just cut them off in time, then control water and fertilizer, do not water until dry, and water thoroughly when completely dry; in summer, apply a thin liquid fertilizer once every about 15 to 20 days.

2. Root damage is severe

If the orchid root system is severely damaged, the whole plant may die back. At this time, it must be repotted and the soil changed. After removing it from the pot, first cut off the rotten root parts, then soak the whole root in carbendazim solution for disinfection, and then repot it with planting medium, taking care to expose the pseudobulb.

II. Infection with stem rot

If you find that the orchid leaves gradually turn black from bottom to top, black spots grow on the leaf surface, and when you dig open the roots you can even see that everything from the root crown to the pseudobulb has turned black, then you should be on alert: it is very likely 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, temperatures are high, watering is frequent, and there are many pests, so orchids are prone to infection by pathogens.

Prevention first; prevention is better than cure

1. During the high-temperature period in summer, every 7 to 10 days, use diluted 500 to 1000 times fungicides such as carbendazim, chlorothalonil, or thiophanate-methyl to spray and sterilize around the plant and on the leaf surface.

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

3. Some carbofuran insecticide can be buried in the planting medium to prevent pests from infecting the pseudobulb.

How to treat it?

1. Once discovered, immediately cut off and burn the infected orchid plants and leaves;

2. Pull out the entire pot of orchids, wash them, cut off the diseased plants and rotten pseudobulbs, then place the whole remaining 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, place in a cool and ventilated place for three days of care, and every month soak the orchid pot with a 500 to 1000 times fungicide solution, and it will gradually recover and become healthy.

Note: Huahua reminds everyone that in high-temperature weather you must often loosen the soil and ventilate the orchids to ensure normal root respiration. If you find it troublesome, you can use a fan to blow on them after watering~

Alright, that is all for the introduction to orchid "heat disease,"

Flower friends, have you all learned it?