Yellowing Phrags & Paphs

[eOrchids]

Hey all,
Several of my Paphs & Phrags are turning yellow then brown. For my Paphs, they usually occured on the old growths. My Phrags, it follows the same scenario, but the Phrags are seedlings and should not occur this rapidly.

I fertilize my plants weekly 3/4 per gallon of water.

High: 85'F (60% humidity)
Low: 70'F (60% humidity)

What's causing these problems? Too much fertilizer? Water? Sun? Natural die back? Lack of fertilizer? Too much sun? Stress?

Thanks for the input.

 

[likespaphs]

it isn't stinky, is it?

 

[SlipperFan]

How are the roots?

 

[Shiva]

Looks like heat stress to me. Last week was very hot in the North-East with temps going up to near 100F. Some of my phrags are also showing heat stress. Old growths with fewer good roots and seedlings with few roots are particularily vulnerable.

 

[eOrchids]

it isn't stinky, is it?

Nope.

How are the roots?

I just unpotted one of them; strong and healthy! They are all still growing.

Looks like heat stress to me. Last week was very hot in the North-East with temps going up to near 100F. Some of my phrags are also showing heat stress. Old growths with fewer good roots and seedlings with few roots are particularily vulnerable.

I'm thinking the same thing too, Shiva! I'm in the northeast as well (NJ).

I have used Superthrive to counter the stress of the plants. Let's see what happens next...

Have you done anything to counter this?

Thanks!

 

[swamprad]

I'm experiencing the same thing, this is the first summer in my greenhouse, highs in mid 90's and lots of sun. I think it is heat stress but not sure.

 

[NYEric]

I bet it was hotter than 85! Looks like heat.

 

[Shiva]

I'm thinking the same thing too, Shiva! I'm in the northeast as well (NJ).

Have you done anything to counter this?

There's nothing to be done for the affected leaves and growths. You can only hope that they will survive and send new growths, and make sure they're located in a cooler spot next time a heat wave hits. :sob:

 

[eOrchids]

Well thank you all for your input.

 

[goldenrose]

I'm thinking the same thing too, Shiva! I'm in the northeast as well (NJ).

Have you done anything to counter this?

There's nothing to be done for the affected leaves and growths. You can only hope that they will survive and send new growths, and make sure they're located in a cooler spot next time a heat wave hits. :sob:

This brings up a good question ...
If you have a GH, how do you counter this? When mother nature is throwing unusually high temps across the country, what options does one have? Add more shade, if possible? increase air movement? wet the floor? Plants more susceptible to rots/fungus, use fungicide as prevetative? back off fertilizer?

 

[Shiva]

This brings up a good question ...
If you have a GH, how do you counter this? When mother nature is throwing unusually high temps across the country, what options does one have? Add more shade, if possible? increase air movement? wet the floor? Plants more susceptible to rots/fungus, use fungicide as prevetative? back off fertilizer?

Well, this heat wave thought me a lesson: Don't grow your phrags under HID lamps in summer. I've got several days of high heat in my growing room, up to 36C one afternoon. Still most of the plants went through without trouble. But those that get clubbed are always some of your most precious ones. Meanwhile, I left the masdevallias and draculas outside under shade and I sprayed freely with cold water and, so far, everything's ok. Now if I had put the phrags in there as well, I'm sure they'd all come through with no trouble.

As for my greenhouse, I keep it empty for the summer and let the temperature rise as much as it wants. That helps get rid of the bugs and weeds. I don't think it's cost effective to put in all kind of cooling systems in, considering that summer here lasts about a month, and that's in a good year. So every spring, the plants starts coming out and under a shade house. And when the cold sets in again, they return gradually to a clean greenhouse. I have about 500 plants to move in and out.

When you think of it, plants are made to grow outside anyway and it takes much less effort to keep them healthy when the heat goes up. My phals are still under light. These guys love heat anyway.

 

[NYEric]

More fans and spray lightly to have a cooling evaporative cover!