Here are a few of the more commonly encountered orchid ailments and some suggestions on how to deal with them. These suggestions come from our own trials and tribulations over the years and are all from direct experiences dealing with the problems mentioned. The longer you grow orchids the more likely you are to come in contact with each and every one of these! When treating your orchids always remember to use clean tools, clean pots, and common sense. Good luck….
When orchids take on a droopy, wrinkly appearance this is usually a sure sign of a watering problem and in most cases a root problem. Either way, the pot has been kept overly wet and soggy (sitting in water) and has experienced root loss and therefore cannot up take water, or has been left extremely dry and has had no water to uptake. Quite ironic that leaving your orchid in a pool of water would cause it to suffer from thirst!
The first thing to do is to remove the potting media and determine the problem…brown and mushy roots= too much water, grey and shriveled roots= not enough. If the plant was under watered a 5-10 minute soak in clean, warm water would help a bit. Next remove all dead or soft roots and wash the plant under tepid water. At this point it would be recommended to treat the plant with an anti-bacteria/fungal like Phyton 27 or ground cinnamon at the least before repotting. Make sure to choose a pot that is just big enough for the remaining root system even if this means going DOWN in pot size. This is very important; sometimes you need to take one step back to take one step forward. At this point, if it has suffered from major root loss it would be helpful to stabilize the plant in its new pot by either using a rhizome clip or simply wiring the plant into the pot after repotting. Water the plant thoroughly and set it out in filtered light avoiding any extreme conditions.
The next couple of weeks will be the most important. This is when you want to encourage new root growth with a balance of higher humidity and a slight restriction of water in the pot. Do this by not watering for the next 10 days coupled with misting the leaves regularly. This should encourage new roots to break into the new potting media in search of water. After the first 10 days resume normal watering. Keep in mind the old leaves won’t recover from the droopy appearance but the new leaves that grow will be turgid and wrinkle free.
One of the most frustrating things that can happen is watching the development of new orchid buds only to have them yellow and shrivel before they ever open. The developing buds of an orchid are by far the most sensitive part of the plant. Bud blast can happen to any species of orchid but Phalaenopsis are usually the most susceptible to this issue .
Some of the more common causes for this problem are: A sudden change in environment, a plant being left too dry, over watering or sitting in water, exposure to very dry/hot air or near a heating vent or fire place, exposure to cold drafts or near an a/c vent, air pollution from any source, ethylene gas from fruits/vegetables…..to read this list it’s a wonder that any of our orchids ever bloom! Actually it’s much easier to prevent than it sounds. Just avoid any possible stress to the plant and water properly. But even sometimes when everything seems right it’s very common to see the last couple of buds drop regardless of care. Another tip; the darker the space for your blooming orchid the more fully open flowers you should have on the plant. An orchid with all buds WILL NOT open in a dark room.
Spots on Flowers (Botrytis)
Typically seen on white or light yellow/green flowers- Botrytis is caused when persistently wet, humid condition happen in cool to cold weather, most commonly in areas with poor airflow. If spotted it's best to avoid further spread by removing flowers from the plant and in effect the growing area too.
Crown and Collar Rot
Occasionally, orchids will yellow 1-2 bottom leaves with no need to worry as this is quite common and can occur from a sudden change in environment or some water resting in the folds of the lower leaves. Either let these fall off or peel them off with a downward pull on the leaf.
Spots on Leaves and or Buds
Many orchids can experience spots on the foliage which are usually of no concern. These can be caused by physical damage from the handling or shipping of plants and will not spread or become a further problem. Some Oncidiums are susceptible to fine black or brown spotting on their leaves that doesn’t seem to affect other plants and these usually do not spread or become an issue (an example of this is the famous “chocolate” orchid Oncidium Sharry Baby). Sometimes orchids can inherit a particular sensitivity to spotting that was passed down from one of its parents. Many of these hybrids have been remade with this issue in mind and the breeders have selected plants that do not show this problem.
If the spots do spread or become larger or are soft and watery, then it’s most likely a bacteria/fungal problem and should be treated as such. Segregate the plant from any others and remove or cut away any effected tissue making sure to cut around and not through rotting tissue with a sharp, sterile tool (such as a disposable razor blade). Treat the plant with a bactericide/fungicide made for use ON plants (such as Phyton 27, Captan, Thyomil, etc) or sprinkle cinnamon over the area. This will usually solve any issues and after a week or so the plant could be put back with your other orchids.
Always avoid letting standing water sit on horizontally held foliage and try to water earlier in the day to ensure your plants dry off by night fall. Constant air movement is a must and should be maintained at all times.
Leaf tip die-back
Leaf tip die back can happen for several reasons but is usually caused by a case of severe over-fertilization or using extremely bad quality water. Another cause can be otherwise docile water and fertilizer impurities building up over time in the potting media. If it’s been many years since you’ve repotted this would probably be the case. This can be avoided by proper leaching of the potting media each time you water making sure to flush the pot thoroughly. At the next opportunity re-pot the orchid with fresh media and a clean pot.
In some cases particular orchids can be more susceptible to leaf tip die-back because of their needs for high quality water (Phragmipediums are one such example). It’s best to use Reverse Osmosis/Deionized or Distilled water if available making sure to use the appropriate pure water fertilizer when feeding.
Another cause can be severe under watering of your plants. In this situation the leaf tips dies from the lack of water reaching this area of the leaf. Water and leach your pots thoroughly when needed to avoid this problem.
Sometimes older back bulbs on sympodial orchids will turn brown in appearance and become mushy and decayed. If it is on the very end bulbs and not towards the center of the pot, you can sometimes cut through the rhizome and pull out the affected bulbs without repotting. If it doesn’t seem to want to come out easily or the bad bulbs are in the center, repotting will be the only option. Make sure to cut out any bad tissue (including any areas of the rhizome that may be affected) and treat with a bactericide/fungicide or dust with cinnamon. This can be a very common occurrence in Cymbidiums that have not been repotted for years.
“Accordion Pleating” Look To Foliage
This is almost always caused by very low humidity or inconsistent watering while new growth is developing. This usually occurs in orchids with thin foliage and can affect a large number of different species. Some of the more common orchids you see this in are Miltoniopsis and their hybrids. Try to raise the humidity around your orchids or make sure to be more diligent about watering while your plants are in active growth. In my experience this is more of a cosmetic issue than anything. The plants can flower just fine and by solving the watering or humidity problem the new growths will develop normally. Just be careful that newly developing flower spikes don’t get caught in the pleated foliage causing a deformed inflorescence.
Orchids are only affected by a handful of pests. But all of the most common “house plant” or tropical plant pests can become problems with your plants. Anyone who has grown orchids for any significant amount of time has dealt with bugs. And any orchid grower who makes the claim that their plants don’t, can’t, or won’t get bugs is either lying to him or herself or is extremely naive. If you suspect that any of your orchids have insects, the first thing to do is to isolate them from the other plants in your collection. Most pests are relatively slow moving but by the time you notice, they more than likely have spread to others. The number one piece of advice that I can offer is to be diligent no matter how small the problem may seem. A small problem today can turn into a big headache in 2 weeks. And when using any insecticides, ALWAYS use the appropriate safety precautions. Also make sure to complete a full cycle of treatments since these pests have different stages in their life cycle and each stage may be affected differently by the same insecticide. Think as if your doctor has prescribed you a round of penicillin, partial treatments only serve to help the insects build resistance, while 3- 4 treatments 7-10 days apart can do wonders.
Mealy bug appears as a white cottony mass on the underside of leaves, at the base of buds and even on the flowers themselves. If not controlled they can cause leaf and flower deformities and yellowing of the foliage. In warmer weather they will quickly form colonies in the crevices between leaves and can have a special taste for Phalaenopsis and Paphiopedilums. Spot treat with straight Rubbing Alcohol on a cotton ball/q–tip or directly from a sprayer diluted at 50% with a good squirt of mild soap (note: I have never seen RA negatively affect any orchids before but use good judgment and do not spray in warm weather or direct sun and not into the pot. After spraying RA I will usually wait 5 minutes then rinse off the plant). Safers Soap , Neem Oil or Horticultural Oil could be useful if you are in the home since they are relatively benign (except for the smell)…the only problem is that at times it seems they are benign to the bugs also! These can be good non-toxic approaches if only a small number of plants are affected but don’t expect to control them in a medium/large group. They are best controlled with a systemic insecticide.
In orchids the most common types you encounter are: brown scale, soft scale, and Boisduval scale and none of them are fun to deal with. Scale can be very pervasive and if not handled swiftly can take years to eradicate. A lot of our “experienced” orchid friends have seen scale become a major problem in their collections as they get older in life and have less energy to keep up with the maintenance of their plants. Most times scale will be introduced through another orchid that already has it or other tropical house plants (older Ficus, Scheffelara and Palms are notorious for having scale). But ants can be a major carrier of scale. They have a somewhat interesting relationship. The ants carry the scale to the host and once established the scale secrete excrement as they feed on the plant and the ants harvest the sugary secretion! So…many times if you notice ants on or around your orchids (or your Ficus) you will see a sticky residue on the ground or furniture in the area (if in the home). This is sometimes the first thing to bring your attention to the scale.
A decent way to attack scale is with an old (or new) toothbrush dipped in Rubbing Alcohol. Wear rubber gloves and scrub the scale off of the pseudo-bulbs with the RA wetted toothbrush. This could be done at anytime but is easiest when repotting. This can be a very effective way to deal with scale infested Cattleyas, Dendrobiums or other sympodial orchids, just make sure to peel away the dry sheaths along the pseudo-bulbs since this is a favorite hiding place. Another first approach technique (or a spot-killing trick) is to spray the affected area with leaf shine. We use Design Master but other brands such as Pokon Leaf Shine works as well. They work by suffocating the scale on the spot. Just spray and the next day wipe off the scale with a towel.
Keep in mind that the 2 above tricks only work on small scale (no pun intended) applications and a long term approach involving a full cycle of systemic insecticides is the best choice. The above techniques coupled with other less toxic choices like Safers Soap, Neem Oil, or Horticultural Oil could be the best choice in the home though.
Aphids are small soft bodied insects that tend to cluster around areas of soft growth (developing leaves or flower spikes or buds) and produce a honeydew type substance that can also attract ants and be a growth medium for sooty mold. Most outdoor gardeners are very familiar with aphids since they also love rose bushes. In fact, those rose bushes could be the reason you have them on your orchid! Aphids tend to appear in the home or greenhouse in the spring but could show up at anytime of the year. The only good thing is that they usually disappear as fast as they appeared and for minor infestations can be washed off the plant quite easily with mild soapy water. Ladybugs are a natural predator of aphids and in the spring you can usually find them for sale at a local garden center, but this only works in enclosed spaces and for just as long as there are aphids…then the Ladybugs disappear too.
The best approach is to treat the same as Mealy Bug.
Severely thrip-damaged Cattleya flower
Thrips aren’t as common in orchids as the above mentioned pests but if they are present they are the most menacing. They have a way of staying unnoticed to the human eye until the flowers have opened and the ever present chewed-away outer edge of your favorite orchid flowers appear. Against a light colored flower they can be easy to spot, they are brown/black/yellow and have a thin and long appearance.
Thrips tend to come in (the home or greenhouse) during warmer weather and usually come from outside flowering plants. In the home treat with Safers Soap/Horticultural Oil but the best approach is still a systemic insecticide applied for a full cycle and possibly used in conjunction with a growth regulator.
Yet another garden pest that also has a taste for exotic fare…slugs and snails can be a very frustrating problem in the greenhouse. Since they tend to like wet and damp areas you usually don’t see them in the home. So if you grow in the house consider yourself lucky, because there is nothing more disappointing than waiting for flowers to open only to have a slug eat his way across the petals the first night its open! If you catch them, discard as you see fit. But its best to bait with any of the dozens of products marketed for the garden. Just be sure to keep them away from pets or little ones.