Sap on the underside of phal leaves?

counselor4444(6A NJ)October 25, 2008

On one leaf on one of my phals I suddenly noticed the underside to be heavily blotched with sticky clear bubbles of sap. I promptly used hydrogen peroxide to clean all of it off but want to know if this is a sign of something else. Is this the sign of an insect? What should I be looking for? and how? TIA!

Debbie

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howard_a(z6 NYC)

Sap on the underside of a phal leaf would definitely put me on the alert for mealybugs, aphids or scale. I would use rubbing alcohol vs peroxide to wipe down the leaves. Phal leaves are usually a bit too tough for sucking pests to get really excited over but they can bring down softer leaved species fairly quickly in warm weather. Temps at this time of year actually work in your favor, even indoors just those few degrees cooler slows their reproduction and vigor. What to look for, hmmm... I'll leave that to others but get out a bright light to aid you if you aren't seeing anything in regular room light. You won't see juveniles but if there is sap and it is in fact caused by sucking pests you will see them eventually.

H

    Bookmark   October 25, 2008 at 3:35PM
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xmpraedicta(3b Saskatoon)

Sometimes they just release sap when they're happy. If you don't see insects and no other damage is visible, I don't think you have anything to worry about.

    Bookmark   October 25, 2008 at 4:08PM
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mehitabel(z6 MO)

I've never seen sap under a phal leaf without finding culprits, tho sometimes you have to look and look til you find them, and they are excellent hiders.

The question is where to look, and the answer is look everywhere one of the little buggers can hide.

Aphids usually go for tender new growth and wouldn't be on the relatively tough underside of a phal leaf. So look for mealies (white cottony blobs) or scale (bumps that slide off-- ie clearly are not dings).

They are hiding somewhere pretty successfully, or you would have seen them already. So look under the leaves, and especially in the junction where the leaf attaches to the stem.

It's astonishing the places they can find to hide. I have found them in the leaf junction of a tiny old seedling leaf still hanging on to the stem of a fairly biggish phal, but hidden away below now big newer leaves. Bend the leaf back as far as you dare without breaking it to look inside.

I have even found them nestled in the center of a tiny new leaf, the devils. They also hide out in the nodules on a flower stem. I once had a recurring infestation of mealies on a spike of a Doritis hybrid. Those spikes last and last, and the infestation kept coming back, always on the flowers (they *love* flowers). Finally, I cut the flower stem and peeled the covering off the nodules on it. Sure enough, every undeveloped nodule had mealies tucked inside ready to get on the flower when it developed.

So check every flower all over with an eagle eye.

However, usually sap under the leaf means there is a pest somewhere nearby on that or a nearby leaf.

If you use a systemic you are more likely to get them, since they can spread all over, even below the medium. Be sure to spray a lot of stuff in the leaf junction as they can get in there pretty far and you can't always bend the leaf far enough back to see them.

Think of it as a safari. :)

    Bookmark   October 25, 2008 at 5:57PM
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counselor4444(6A NJ)

What would I do without this forum? LOL You guys are the best. I learn so much here.

Hmmm... I don't know how I would have gotten one of these pests... I've had a gnat problem but I haven't introduced any new plants to my collection for the last 7 weeks... so would they just suddenly appear? where would they come from?

I'll keep a lookout for bugs.... what should I use to kill them and any eggs? Is insecticidal soap enough? or do I need something else? TIA!

Debbie

    Bookmark   October 26, 2008 at 11:36AM
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cnslr81

Aphids are tricky suckers (I've had them several times on my peace lily at work). If you find those, wipe them off with alcohol and then use and insecticidal soap. Also, if you have aphids, check every few weeks, b/c they often return. I would use the same treatment if you have mealy bugs.

Sarah

    Bookmark   October 26, 2008 at 1:49PM
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cnslr81

Oops! I meant scale above, not aphids, esp. as far as returning.

Sarah

    Bookmark   October 26, 2008 at 1:53PM
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sweetcicely(S7 USDA9 No.CA)

Hi Debbie,

Both of my mature phals have produced beads of sap on leaf edges without the presence of any insects. These appeared at different times and on one leaf, only, in each instance. In one case the beads appeared around the edge of a fairly new leaf. They were so evenly arranged at the upper surface leaf margin that I assumed the sap was coming from some very tiny stomatic cells.

In the other case the sap appeared near the edge of the underside of a very large leaf and over a length of about 3 or 4 inches. These beads were less orderly in their arrangement than the ones on the other phal, but there were no bugs present in either case.

I have also seen each of these phals make beads of sap at the bases of flower buds that were within 24 hours of opening.

In all of these cases, I've done scrupulous searches for critters over periods of a week or more, and have found none.

Rather than abuse the plants with unnecessary cures for problems I didn't see, I opted for gently wiping the sap with paper toweling dampened with lukewarm water and patting dry. In both cases with the leaves I had to repeat the warm water wiping 2 or 3 times. I removed the sticky stuff only to avoid attracting any unwanted critters or fungi.

I hope your orchids are just happy, as Calvin says, exuding sweet beads of joy.

Sweetcicely

    Bookmark   October 27, 2008 at 3:54AM
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orchid126(z6, NJ)

You might also check at night with a flashlight.

Some people suggest wiping a clean cotton ball over the underside of the leaf. If you see any specks, you've got trouble in River City.

    Bookmark   October 27, 2008 at 4:06PM
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