help with disease ID

[Orchid Whisperer]

The more I look at the first photo, the more I think it is Phyllosticta (given the unfortunate name "Thai crud" by some growers). Check the following for information on this disease: http://www.staugorchidsociety.org/PD...t-ThaiCrud.pdf

Generally, you should not let the leaves stay wet. Humid air yes, spraying roots yes, but minimize the water on the leaves. In addition to the fungicide, make sure you are providing all your plants with some supplemental calcium, which is beneficial and seems to help ward off some diseases.

Another good resource for learning about which fungicides treat specific diseases: http://www.staugorchidsociety.org/PD...ySueBottom.pdf Not all fungicides treat all problems.

And this link for information on diseases in general: Orchid Diseases


The St. Augustine Orchid Society's website is a good one to bookmark. Lots of good information.

[Selmo]

Looking at the pictures and info you have given, you have had this problem for some time on both plants. It is probably guignardia/phyllosticta (both are the same, just different times In the life cycle), but you have other things going on too. The two dark spots surrounded by the yellowish circles is something else. I believe you have two different, at least, things happening. One is bacterial, the spots with rings and some of the dark patches that look water soaked, bacterial infection. If it just showed up, you may not have much time. Erwinia, brown rot, shows up fast and moves fast. If it has been there for awhile and has not moved much and has a clear edge, it could puedomonas, or it could be both. Use hydrogen peroxide or Physan to control the sprend of both of these. You also have fungal problem, guignardia, this probably happen awhile back. You will have to use a fungside for this. Since you have muiltiple things going on here, this will not be simple. It should live, but it will look ugly for while. The scars will be there until the leaves drop. Both the bacterial and fungi gal problems are caused by warm and wet condions. Usually, by the leaves staying wet to long. Water early in the morning and dunk only the pot into water, try to keep leaves dry. Increase air movment, and increase amount of light (if possible). In the last picture of the cattleya, this could also be guignardia. It could be scale also. Take your fingernail and try to scratch it off. If it scratchs off like wax, it is scale, use a systemic insecticide. If it does not scratch off, and is hard and feels ruff, like sandpaper, then it is guignardia. This shows how the same dieseses can look completely different on different types of orchids or at different times in the life cycle of the fungus. If all your plants are in the same area then it is likely that most of your plants have this, with or without symptoms. You can start a funguside spray program, where you spray every few weeks, or you change your watering practices. No over head watering and increase air movment. These pathogens move by water splashing so isolate infected plants. Start by trying to eliminate one problem at a time. Them on to the next problem. This will have a happy end, it will be awhile.

[hanzy08]

Thank you for your help. I will be very cautious now. I can easily throw the neostylis out that has a lot of problems but i am up for the challenge and in the end there will be lessons learned and knowledge acquired and when the plant gets through it, i can always look at it and smile.