Orchid tip burn is closely tied to root health

Judging orchid roots from tip burn http://www.dfac.cc/showtopic-18-135183-0-0-1.htmJudging orchid roots from tip burn

Some orchid growers find tip burn a headache, and its causes are complex: it may be brought on by too dry conditions, too wet conditions or fertilizing, or by bruising and infection, and it may also occur when the roots have rotted. Once tip burn appears, it cannot be undone. The usual methods are to cut the leaf (down to the green part), pry it open, pierce it through and so on to keep it in check. Interested growers might as well try the folding method: fold the leaf at the green area just below the burned tip to block the water supply and hold back the spread of the burn. When you fold it, you can sometimes hear a snapping sound, which shows the tip burn was caused by excessive dryness. If there is no sound and moisture comes out at the fold, it may be caused by excessive wetness or fertilizer burn (fertilizer burn first looks as if it has been cooked, then infection spreads). By checking with the fold, you can spot the problem and treat it accordingly. This is much more fun than simply cutting it off.

In addition, treating the burned tip by folding also serves as a diagnostic tool: observe how the tip burn and disease spots develop above and below the fold. Generally within 3-5 days you can find that the part above the fold line dries up, turning from dark brown to yellowish brown and then white, while no new symptoms appear below the fold line. This shows the tip burn was caused by fungal infection after physical injury, and blocking the water supply is enough to control its spread; at this point you can simply cut off the whitened part. If lesions continue to appear below the fold line, and after folding again further down dark brown disease spots still appear below the fold, then you should suspect that pathogens have invaded the roots and been transported to the wound at the fold line, which shows as an expanding condition. In this case it is advisable to check the roots, all the way to repotting and replanting!

To prevent tip burn, the main thing is to control the moisture level of the growing medium, and the medium formula must emphasize air permeability. Be sure never to fertilize too strongly: at least one part per thousand, or even weaker. At the same time, keep the orchid area ventilated and maintain a certain level of environmental humidity. If tip burn or disease spots occur, you can deal with them using the methods above. Everyone can give it a try!