Dendrobium problem - Orchid Board

VickiC · #1 07-09-2010, 02:54 PM

Hello,
(photos included)
My Den has not looked healthy for a couple of weeks (maybe slightly less) and has seemed to look unhealthier basically ea. day-three or so. Fairly recently, I thought maybe it wasn't getting quite enough sun, so I moved it into a brighter area of my greenhouse gradually. Since it has looked wilty, I also kept a better check on the medium. I noticed small webs on it yesterday, as well as today. When I saw them, I thought "oh no...spider mites". I then checked the leaves, and there was absolutely no sign of the orangish-red 'powder' that would rub off onto my hand (as I understand it would). When I saw the web(s), yesterday I probably should have quarantined it from my other orchids, but I failed to. I don't know why I didn't....most likely because it was not near my other orchids. ?? Today, I did. I bought the Den a few months ago seemngly in good condition, and as I always do (whether necessary or not) I repotted it when I got home. When I unpotted it from the previous potting at the nursery, I found that the roots were fine, so I proceeded to rinse them and pot it into medium size bark and charcoal. Judging the moisture of the medium today (using a shish-ka-bob skewer), I'm guessing it's due to be watered again probably day after tomorrow (will be approx. 1 week). If it would help to know, the greenhouse airflow is very good. Ever so often, I notice small spiders (some are the little jumping kind), but I just haven't thought they were harmful to my orchids. I've never read anything about such spiders being harmly to orchids, and in fact, I thought they were probably an asset by keeping check on potential insects. Do you think it might be one of them making the webs? If so, that doesn't worry me, if you tell me that's not a problem. I thought maybe I didn't move the plant into more sun gradually enough, but I felt like I was doing it as slow as I should, so I assumed that sunburn wasn't the problem. ?? I would appreciate you experienced growers to be the judge, though. So, what do you think my problem is? I would really appreciate it if you will give me your advice.
Vicki
By the way, I realize my thoughts may be random and 'subject change' too much, but that's how my mind works sometimes.....not very organized.

I apologize.

Junebug · #2 07-09-2010, 04:05 PM

Hi Vicki,

It looks like you have a Phal. type Dendobium and in the first picture there seems to be some new growth at the base of the plant on the right side. That new growth is a sign of health and will be the part that produces new functioning roots.

I don't think spiders harmed your plant. Over time older canes will gradually wither and loose their leaves. They'll loose their roots too and this process may have been hastened when you repotted. After older canes loose their roots they will not generate new ones. These guy's are pretty famous for sulking with root loss after a repot. Can't see what size pot you used, but smaller is better...just enough for the roots and a small amount of future growth. A 4" pot would probably be the appropriate size for your plant. To keep your plant from toppling over you can seat it in a larger heavier vessel for support.

I generally increase watering during growth and flowering. You don't want the new roots from the new growth to dry out for too long, but they also should not be drenched for any extended length of time. This can be achieved by using a customized combination of potting media and a monitored watering routine. Avoid using nothing but plain bark. My media recipes vary, but if I'm growing phal type dendrobiums on a trussed screened in porch I use 1 part bark or med. sized coconut husk chips, to 1 part aerolite or pearlite, to 1 part med. charcoal chunks. This mixture is rather loose, resists rapid decay, and allows the roots to dry between waterings. I never use skewers to judge moisture. My plants are grown in a humid environment and my mix is customized so I know they can be safely watered 2 or 3 times a week. Watering is done less frequently during the rainy season because the higher humidity levels will slow the drying process. Another time to reduce watering is during cool weather.

A word of caution: In the future resist the temptation to remove older leafless shriveled canes because they serve as an important reserve of energy. They should remain with the plant until they are completely shriveled and yellowed.

VickiC · #3 07-10-2010, 02:44 AM

Hi!
Thanks for your advice!

I potted my Den in a 6" Vanda basket initially....I know what you're thinking, too big, so I repotted it into a 4" clay pot after I read your reply late this afternoon. The reason I potted it in such a large basket in the first place was because I could't get the roots in a smaller basket. I chose a basket rather than a pot initally because I could tie the canes to the basket corners for stabilzation (as you saw). When I unpotted it today, I found that the roots of the new growth were very fat and healthy, but the roots of the older canes were almost gone. I trimmed the old, dead roots away, so now that I had many fewer roots to deal with, I was able to get the Den repotted into a smaller pot, as you also advised. The reason I chose a basket rather than a pot in he beginning, was so I cold tie the canes to the corners. I tried a smaller bsdket first, but all of the roots would definitely not fit, much less have any room for future growth. I understand that Dens like to be crowded, so the smaller basket would have been my choice if only the fit would have worked out correctly. I set the new 4" pot inside a 6" one so that my new 4" one wouldn't topple over, as you advised.

I plan to keep in mind what you advised about watering, also. I have one more question for you (or anyone) if you don't mind: I've been using skewers to judge moisture for quite sometime since I haven't mastered judging the moisture level by the lightness and heaviness if the pot. I'm wondering why you don't use the skewer method ?? Maybe you can give me a helpful tip?? The only thing that has made me leary of this method is in case I were to stab a root with a skewer, I assume I would get an erroneous reading, since the root would always stay moist. Am I correct?? By the way, it's way past my bedtime and my fingers and my mind are sleepy, so please overlook typos.

Thanks again,
Vicki

Quote:

Originally Posted by Junebug

Hi Vicki,

It looks like you have a Phal. type Dendobium and in the first picture there seems to be some new growth at the base of the plant on the right side. That new growth is a sign of health and will be the part that produces new functioning roots.

I don't think spiders harmed your plant. Over time older canes will gradually wither and loose their leaves. They'll loose their roots too and this process may have been hastened when you repotted. After older canes loose their roots they will not generate new ones. These guy's are pretty famous for sulking with root loss after a repot. Can't see what size pot you used, but smaller is better...just enough for the roots and a small amount of future growth. A 4" pot would probably be the appropriate size for your plant. To keep your plant from toppling over you can seat it in a larger heavier vessel for support.

I generally increase watering during growth and flowering. You don't want the new roots from the new growth to dry out for too long, but they also should not be drenched for any extended length of time. This can be achieved by using a customized combination of potting media and a monitored watering routine. Avoid using nothing but plain bark. My media recipes vary, but if I'm growing phal type dendrobiums on a trussed screened in porch I use 1 part bark or med. sized coconut husk chips, to 1 part aerolite or pearlite, to 1 part med. charcoal chunks. This mixture is rather loose, resists rapid decay, and allows the roots to dry between waterings. I never use skewers to judge moisture. My plants are grown in a humid environment and my mix is customized so I know they can be safely watered 2 or 3 times a week. Watering is done less frequently during the rainy season because the higher humidity levels will slow the drying process. Another time to reduce watering is during cool weather.

A word of caution: In the future resist the temptation to remove older leafless shriveled canes because they serve as an important reserve of energy. They should remain with the plant until they are completely shriveled and yellowed.

Junebug · #4 07-10-2010, 05:20 AM

Quote:

Originally Posted by VickiC

Hi!
Thanks for your advice!

I potted my Den in a 6" Vanda basket initially....I know what you're thinking, too big, so I repotted it into a 4" clay pot after I read your reply late this afternoon. The reason I potted it in such a large basket in the first place was because I could't get the roots in a smaller basket. I chose a basket rather than a pot initally because I could tie the canes to the basket corners for stabilzation (as you saw). When I unpotted it today, I found that the roots of the new growth were very fat and healthy, but the roots of the older canes were almost gone. I trimmed the old, dead roots away, so now that I had many fewer roots to deal with, I was able to get the Den repotted into a smaller pot, as you also advised. The reason I chose a basket rather than a pot in he beginning, was so I cold tie the canes to the corners. I tried a smaller bsdket first, but all of the roots would definitely not fit, much less have any room for future growth. I understand that Dens like to be crowded, so the smaller basket would have been my choice if only the fit would have worked out correctly. I set the new 4" pot inside a 6" one so that my new 4" one wouldn't topple over, as you advised.

I plan to keep in mind what you advised about watering, also. I have one more question for you (or anyone) if you don't mind: I've been using skewers to judge moisture for quite sometime since I haven't mastered judging the moisture level by the lightness and heaviness if the pot. I'm wondering why you don't use the skewer method ?? Maybe you can give me a helpful tip?? The only thing that has made me leary of this method is in case I were to stab a root with a skewer, I assume I would get an erroneous reading, since the root would always stay moist. Am I correct?? By the way, it's way past my bedtime and my fingers and my mind are sleepy, so please overlook typos.

Thanks again,
Vicki

Hi Vicki,

It sounds like you did a good job! Your canes still look nice and plump. Expect to loose a few leaves from dehydration. The lost leaves will not be replaced by new ones. This is normal so don't fret. Your baby cane should grow rather quickly and you will probably see another emerging cane as the baby one matures. A few pebbles could be added to the larger pot to increase weight and stability.

Skewers have potential with sphagnum because it's soft, but IMO it risks injuring the roots and I've never been able to justify root injury for the purpose of checking moisture.

The truth is everyone must develop their own method of watering. My growing zone is 9b in Central Florida and it's rather hot and humid down here. For this reason I choose orchids that are compatible with my climate and grow them outdoors. Some grow under the roof of a screened porch and others are grown in a shade house, pocket garden, or suspended from trees. Outdoor growers must do things differently than indoor growers. The plants exposed to elements must have very good drainage because there are certain times of the year when we can expect daily afternoon thunderstorms. Daily drenchings pose a high risk for root rot unless the medium is adjusted. I've been altering my ingredients since late last year when my shade house was built and have begun using a lot more sponge rock, charcoal, and lava rock and lesser amounts of bark and coconut husk chunks. Skewers just won't work in all that chunky stuff. Some of my chids are mounted and their roots are completely exposed.

My porch plants are grown in a larger ratio of bark and CHC. Skewers won't work in that mixture either unless it's become degraded and when the medium degrades it's time for a repot. If I could poke a skewer in my orchid pots without resistance it would indicate to me that my bark is rotten and needs to be changed.

If you don't use rocks in your medium then the weight system works pretty well for determining moisture. After a while you'll get accustomed to the wet vs. dry weight of your potted plants. Dehydration or shriveling of leaves, bulbs, and canes is a good indication that the plant is not taking in enough water. The condition can be caused by either a lack of sufficient watering or, in most instances, too much water resulting in a rotted root system.

There are various methods of watering too. Examples include dunking, soaking, misting and pouring. It's all about the requirements of the particular plant and/or personal choice. I pour or mist and occassionaly dunk, but your choice of watering techniques might differ from mine. The health of your plant will be your best determining factor.

VickiC · #5 07-12-2010, 12:06 AM

Thanks again for all of your great advice! You've helped me a lot! I appreciate you taking time to help me!
Vicki

Quote:

Originally Posted by Junebug

Hi Vicki,

It sounds like you did a good job! Your canes still look nice and plump. Expect to loose a few leaves from dehydration. The lost leaves will not be replaced by new ones. This is normal so don't fret. Your baby cane should grow rather quickly and you will probably see another emerging cane as the baby one matures. A few pebbles could be added to the larger pot to increase weight and stability.

Skewers have potential with sphagnum because it's soft, but IMO it risks injuring the roots and I've never been able to justify root injury for the purpose of checking moisture.

The truth is everyone must develop their own method of watering. My growing zone is 9b in Central Florida and it's rather hot and humid down here. For this reason I choose orchids that are compatible with my climate and grow them outdoors. Some grow under the roof of a screened porch and others are grown in a shade house, pocket garden, or suspended from trees. Outdoor growers must do things differently than indoor growers. The plants exposed to elements must have very good drainage because there are certain times of the year when we can expect daily afternoon thunderstorms. Daily drenchings pose a high risk for root rot unless the medium is adjusted. I've been altering my ingredients since late last year when my shade house was built and have begun using a lot more sponge rock, charcoal, and lava rock and lesser amounts of bark and coconut husk chunks. Skewers just won't work in all that chunky stuff. Some of my chids are mounted and their roots are completely exposed.

My porch plants are grown in a larger ratio of bark and CHC. Skewers won't work in that mixture either unless it's become degraded and when the medium degrades it's time for a repot. If I could poke a skewer in my orchid pots without resistance it would indicate to me that my bark is rotten and needs to be changed.

If you don't use rocks in your medium then the weight system works pretty well for determining moisture. After a while you'll get accustomed to the wet vs. dry weight of your potted plants. Dehydration or shriveling of leaves, bulbs, and canes is a good indication that the plant is not taking in enough water. The condition can be caused by either a lack of sufficient watering or, in most instances, too much water resulting in a rotted root system.

There are various methods of watering too. Examples include dunking, soaking, misting and pouring. It's all about the requirements of the particular plant and/or personal choice. I pour or mist and occassionaly dunk, but your choice of watering techniques might differ from mine. The health of your plant will be your best determining factor.