Problems With Orchids

Orchids can live in cultivation for many years - up to 100 years in established botanical gardens, for example. But for this to happen, growing conditions have to be right and any problems must be dealt with promptly. Over time, orchids progress in peaks and valleys. They advance toward a peak, producing optimum growth and flowers. Then they may regress and take some time before achieving another high performance crest. By recognizing these progressions in your orchids, you will be able to encourage them to grow and flower for years to come.

Problems with blooms

Non-flowering pseudo bulbs

Description

Plants are healthy, producing foliage from new pseudo bulbs, but no flower spikes. Affects cymbidiums and other orchids that have pseudo bulbs.

Causes

Each year, the pseudo bulbs on an orchid should become larger until the maximum size is reached. By this time, the orchid will be of flowering size and a flower spike will be produced. If the pseudo bulbs are getting smaller, the orchids will not flower. The reason for this may be that too many of the older pseudo bulbs have shed their foliage.

Cure

Repot the orchid and at the same time remove the older, leafless pseudo bulbs to restore the balance of the orchid. With fewer pseudo bulbs to support, the orchid can grow forward again. When larger pseudo bulbs are produced, flower spikes will follow.

Non-flowering, other types

Description

Orchids are healthy, producing plenty of foliage but no flower spikes.

Causes

Cool-growing orchids. These may not flower if the temperatures are too high. They will then produce lush growth and no flowers.
Warmer-growing orchids. If these are grown in conditions that are too warm, they will have dark green, limp foliage and no flowers.

Cure

Cool-growing orchids. Move orchids to cooler surroundings. In time, they should start to flower again.
Warmer-growing orchids. Phalaenopsis may need a 2-3 week period of cooler nighttime temperatures to initiate flowering. Only do this when a healthy plant has not produced the expected flower spike for several months.

Bud blast

Description

All of the buds that have been developing normally on the flowering spike turn yellow and drop off, just as they are about to open.

Causes

The causes of bud blast can include overwatering, cold and wet conditions, or, at the other extreme, surroundings that are too warm and dry. A stuffy, poorly ventilated atmosphere will also cause buds to fall off.

Cure

Try to maintain the correct growing conditions for your orchids. If the orchid is ready to flower, do not change the conditions by, for instance, bringing it indoors from a greenhouse or moving it around the room. Instead, wait until the flowers are fully open before moving the plant.

Flower-wilt

Description

Flowers wilt prematurely, even though orchid blooms can be expected to last for several weeks.

Causes

The reason for flower-wilt can often be overheating or over dryness. Flower-wilt often occurs in recently purchased orchids that have been left in their cellophane wrappers for too long before being sold.

Cure

Prevention rather than cure is the answer. Choose only healthy orchids when buying, and remove an orchid from any wrapping as soon as you get it home. Pay careful attention to the growing conditions needed for different orchids, and try to provide an environment as close as possible to the ideal.

Red lips

Description

This is most often seen on cymbidium orchids, where the flowers have either become aged or have lost their pollen. The lips turn red and the flower dies.

Causes

Pollen can be dislodged due to rough handling. On orchids outdoors, it may be eaten by mice or pecked off by small birds.  Once the pollen has been removed, the flower dies. If the pollen has already turned black, it has rotted, and the bloom will soon wither and die.

Cure

Handle orchids carefully to avoid damaging them. Outdoors, prevention is the only cure - try to make sure that the orchids are not vulnerable to raiding animals.

Spotting

Description

Blooms will often become spotted as they age, but spotting that occurs while the flowers are still fresh is caused by a fungal disease called botrytis. It is most often seen on cattleya and phalaenopsis flowers.

Causes

Cold and damp conditions or a lack of ventilation will encourage the development of the fungus. It is most common in winter when temperatures are lowest.

Cure

Destroy infected flowers and isolate any plants that are infected so that the fungus does not spread. Give the careful attention to the conditions in which your orchids are growing. Increase the air flow around the orchids and reduce humidity to help to prevent the incidence of botrytis.

Problems with foliage

Black marks

Description

Black or brown markings or spots form on the leaves. The tips of the leaves can also be affected. The black starts at the tip and runs down the leaf.

Causes

Sometimes spotted leaves do not indicate a problem. When they are old, leaves may develop spots before turning yellow and being discarded by the plant in the natural cycle of growth. Black tips that appear on older leaves are part of the aging process. If young leaves have black tips, this is most probably caused by overwatering or by nighttime temperatures that are too low.

Cure

Sometimes the infection can be stopped by cutting off the diseased part of the leaf. Check the roots to see whether the plant has been over watered. Repot if necessary, or increase the temperatures. If the cause is the fungal infection, an anti-fungal spray may help. To prevent the problem from recurring, be sure to collect fallen leaves and dispose of them immediately.

Sunburn

Description

Black or black-edged patches on leaves can indicate sunburn. The leaves of some of the Odontoglossum purebred hybrids can become red during the summer.

Causes

Black patches occur when the sun has shone directly on a portion of leaf for too long; it takes less than an hour for the sun to burn the leaves. A little redness in odontoglossums is acceptable, but if they receive too much sun, the leaves will suffer and be prematurely shed.

Cure

Once burned, the mark will remain. Prevent sunburn by sheltering plants from the sun. particularly in spring, when the plants are still in their winter quarters and the sun is becoming increasingly bright.

Black rot

Description

Rot that affects pseudo bulbs can be dry or wet. When an older bulb at the back of a plant shrivels and turns brown, it is drying naturally. Where root occurs in one or all of the newer pseudo bulbs, affected pseudo bulbs will turn brown and wet. This rot starts at the base of a pseudo bulb and will run through the plant. Cattleya orchids and miltoniopsis orchids are particularly susceptible.

Causes

Rot in new pseudo bulbs is caused by overwatering or by the plant remaining in a sodden state for a long time. Rot can also start in the new growth if water has lodged among the leaves and remained there for some time.

Cure

Cut away the affected pseudo bulbs to save the front part of the orchid. Do this by cutting through the rhizome, discarding the diseased part of the plant, and dipping the remaining portion in a fungicide solution. Allow the plant to dry completely before potting it in a smaller pot. Treat wet rot in leaves by dusting the affected part with powdered sulfur.

Viruses

Description

A virus infection often appears in young leaves as white streaking, either parallel to the vein or showing a defined diamond pattern along the length of the leaf. On broad-leaved orchids, such as phalaenopsis and cattleyas, a virus appears as black pitting on the leaf. As the foliage ages, the damaged areas turn completely black, the result of a secondary infection coming into the leaf to survive in the dead leaf cells. The blackened areas are often the first noticeable sign of leaf-cell damage, and within a short time the virus will spread through the whole plant.

Causes

Botanists believe that viruses are present in all plants, but only manifest themselves when a plant is weakened and not growing strongly. Orchids with a virus infection are usually unhealthy before the virus strikes, so they are under stress and less able to resist attack.

Cure

The only remedy is to discard the plant before the virus spreads to other plants.

Yellow leaves

Description

From time to time, the oldest leaves on a plant will turn yellow and drop off. This is a natural process. Where all the leaves take on a yellow shade of green, a nitrogen deficiency may be present.

Causes

Nitrogen deficiency can be the result of insufficient nutrients in the compost. It may be old and used up or have decomposed. The problem can also be caused by not feeding the plant enough while it was growing. Exposure to too much light also causes overall yellowing of the foliage. This seldom occurs indoors and is more likely to happen when orchids are grown in a greenhouse with inadequate shading. Cymbidium orchids placed outdoors for the summer can also turn yellow if they are left in too bright position.

 

Cure

Repot if new compost is necessary, and allow the orchid to establish a new root system before applying a nitrogen-based feed at regular intervals of every second or third watering. While waiting for new roots to develop, give a regular foliar feed once every two weeks, misting the foliage so that minute water droplets cover the leaves like dew. This will return the foliage to a healthy green.