As one of the Four Gentlemen, how do you prevent and control pests and diseases in orchids? Why do they lose their fragrance? How much does one plant cost?

Orchids are herbaceous plants, symbolizing detachment and elegance. When orchids are cultivated artificially, the differences in temperature, humidity, light and air, together with unclean ambient air, make them prone to pests and diseases. So do you know how to prevent and control pests and diseases in orchids? Why do they lose their fragrance? How much does one plant cost? From the orchid trading market we learned about orchid prices: prices vary with the variety, and the price gap between different varieties is enormous. For example, a cheap one can be bought for just a few yuan per plant, while an expensive one costs tens of thousands of yuan or even over a hundred thousand yuan, and some sell for several million yuan.

I. How to prevent and control pests and diseases in orchids

Orchids are most prone to leaf diseases such as anthracnose, black spot, banded sclerotial blight and rust spot. For the prevention and control of orchid leaf diseases, the following 3 control methods are adopted:

1. Foliar spraying method. You can use thiophanate-methyl at 1000 times dilution, or carbendazim at 800 times dilution, sprayed to sterilize and prevent disease. Dimethoate at 1000 times dilution can be mixed in to kill insects, but thiophanate-methyl and carbendazim must not be mixed together for use, because mixing these two chemicals produces resistance and loses the control effect. In hot and humid seasons, applying once every 10 or 15 days at the proportional dilution gives even better results.

2. Root-drenching sterilization method. For diseased plants with severe black spot, anthracnose, etc., root-drenching sterilization and disinfection measures can be adopted. Specifically, you can drench the potting soil with carbendazim at 1000 times dilution or soak the pot, and at the same time spray the leaves with the solution to sterilize them; doing this once every 1 week gives very good results.

3. Injection method for disease removal. For diseased leaves of orchid plants that have severe black spot or anthracnose, the usual method is to cut them off. If a rare variegated orchid is affected, cutting off the leaves is truly a pity, so following the principles of medicine, you can give the diseased orchid leaves an injection to remove the disease, with especially good results.

Specific method: draw 18 ml of the pre-prepared thiophanate-methyl at 800 times dilution into a disposable 20 ml syringe, insert the needle into the diseased spots on the orchid leaf surface and inject the solution at the same time. Give 1 injection at each diseased spot for an obvious effect. When injecting, use a piece of sterilized foam plastic as a backing to prevent the needle from pricking your hand.

II. Why orchids lose their fragrance

1. Insufficient light

Orchids like a semi-shaded environment, which often makes people think that orchid growth does not need sunlight, so they keep them indoors long-term or even in shaded places. In this way the orchids cannot get enough sunlight for photosynthesis; even if there is occasional scattered light, the nutrients produced are negligible and simply cannot create fragrance.

There is a solution for this: keep adjusting the light. In winter and spring they can be grown in full sun, while in summer and autumn place them in a semi-shaded spot. Try not to move them outdoors; you can periodically move them to a windowsill with morning or evening sun.

2: Variety degeneration

Changes in the living environment, or transplanting and cultivating them together with other plants, can affect the orchid's genes to some extent. When flowering, interference from the pollen of other plants may prevent the orchid from giving off the fragrant nectar.

To avoid variety degeneration in orchids, do not place them together with non-fragrant varieties or other orchids that bloom in the same period, so as to prevent natural cross-pollination and degeneration.

3. Temperature too low

For orchids that bloom in winter and spring, such as Cymbidium kanran, Cymbidium sinense, Cymbidium goeringii and Cymbidium ensifolium, the nectar in the orchid's body is affected because the temperature is relatively low. When the temperature drops below 0°C, the nectar freezes and the fragrance will not be released. When the temperature rises again or after temperature adjustment, the fragrance can still be released.

Adjust the indoor temperature. When orchids bloom in winter, keep the temperature above 5°C, or higher.

4. Lack of fertilizer

Although orchids have little demand for fertilizer, if fertilizing is neglected and the orchid lacks nutrients, it easily causes yellow leaves and even flower and bud drop, affecting the orchid's growth and development, so its nectaries naturally have no way to produce fragrance-rich nectar.

Apply more phosphorus and potassium fertilizer. During the growth period and flower bud differentiation period, topdress in time around the Autumn Equinox.