what causes sap production

hi, x-posted -- what causes sap production (there are sap drops at the leaves' bases (where the stem (?) attaches to the leaf)) this has been occurring since summer 2004 these are indoor plants (tropical hibiscus) (no relation to h2o, food, light, humidity, soil, no pests, etc...) plants eventually lose all leaves and die:( so would like to know what stimulates sap production to troubleshoot tia
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You probably have aphids or mealybugs, both are very common on tropical hibiscus. What you are seeing is probably not sap, but insect poop. On another note, sap production is a function of staying alive, the only thing that would affect its production is temperature.
Toad
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Tanya might also be describing the result of extrafloral nectar that some plants produce. It is generally used by the plant to feed ants that would otherwise farm aphids on them. Extrafloral nectar is generally produced in pit-like glands at the base of leaves, ends of petioles, or other parts of the plant.
In addition to extrafloral nectar, some plants will produce fluid under certain conditions. I refer to a process called 'guttation', which usually occurs under very high humidity. This fluid is nearly pure water.
Sean
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thank you very much for the response! [...below...]
Sean Houtman wrote:

these are in the house (no ants) and i have thoroughly inspected them for pests... (some had spider mites in the past (several years ago) but i cannot see any now) also i've tried safer's insecticidal soap (which made them worse)

this is the location if the sap -- at the leaf bases (where it attaches to the leaf stem(?) (i'm defining the leaf stem as the part that attaches to the branch -- not certain about the term) appears as a drop of fluid but is really sticky
this is in regards to tropical hibiscus (hibiscus rosa-sinensis) housePlants most of which i rooted from cuttings; (since 2001)

this problem started during the summer... (2004) with higher humidity (however it has continued through the winter (zone 5))

i don't think that it is guttation (which afaik feels like water) -- would you know the name of the glands at the leaf base? is there any other cause of gland activity apart from being used by ants? thanks very much again! sincerely Tanya the end result of this is leaf loss and the plant dies...
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The gland would be called an extrafloral nectary. Don't count on my thoughts about the cause of the glands suddenly turning on. It is possible that stress could cause a plant to produce more than normal, and that stress could be leading to the loss of leaves, etc.
Sean
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Sean Houtman wrote:

thank you, Sean, i'll look into the extrafloral nectary (as you mention, they may be under some sort of stress -- all of them (regardless of where they are etc.) have this feature... thanks! sincerely Tanya
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hi and thanks for the reply! [...below...]
" snipped-for-privacy@comcast.net" wrote:

no pests i have been over them with magnifying glasses (plus some have those yellow insect *traps* - sticky) and there are no pests...

no it is very sticky and is *only* at the leaf base

this began during the summer (2004) (i live in zone 5 -- these are housePlants) and it continues now (and through the winter) (the house temp fluctuates slightly summer <-> winter) thanks

sincerely Tanya
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Tanya Wrote:

guttation caused by overwatering maybe
-- Eyebright
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Eyebright wrote:

hi and thanks for replying! i thought guttation is similar to water? the *sap* - like liquid is very sticky... (also there's no correlation between watering and this) sincerely Tanya
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