Tropical Fruit > Tropical Fruit Discussion

safe to spray lychee trees with all season horticultural oil

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lycheeluva:
so i just spent an hour squashing scale on my producing sweetheart lychee tree. i must have removed about 75 scale. this is not the stick shaped scale i posted of yesterday- this is the tan oval shaped scale that attaches itself to the branches and twigs of the tree, especially in or near the cervices of branches.  its insane how well coumaflaged they are. they are the exact color of the branches and they curve exactly with the branch. only by very carefully looking at the twig, can you see a slight extra layer indicating a scale. i spent an hour going over the tree and each time i fingered through the branches id find another few id missed the first 20-30 checks. im sure i didnt get them all, though i must surely have gotten at least 75%. this my fruiting sweetheart tree and given how sensitive lychee trees are to chemicals, im thinking to not spray the tree with horticultural oil in case it damages or weakens the tree and causes it to drop the fruit.

so im thinking dont spray till the fruit are harvested and then revisit the issue if the tree still has scale. your thoughts everyone?

bsbullie:

--- Quote from: lycheeluva on March 09, 2012, 10:53:14 PM ---so i just spent an hour squashing scale on my producing sweetheart lychee tree. i must have removed about 75 scale. this is not the stick shaped scale i posted of yesterday- this is the tan oval shaped scale that attaches itself to the branches and twigs of the tree, especially in or near the cervices of branches.  its insane how well coumaflaged they are. they are the exact color of the branches and they curve exactly with the branch. only by very carefully looking at the twig, can you see a slight extra layer indicating a scale. i spent an hour going over the tree and each time i fingered through the branches id find another few id missed the first 20-30 checks. im sure i didnt get them all, though i must surely have gotten at least 75%. this my fruiting sweetheart tree and given how sensitive lychee trees are to chemicals, im thinking to not spray the tree with horticultural oil in case it damages or weakens the tree and causes it to drop the fruit.

so im thinking dont spray till the fruit are harvested and then revisit the issue if the tree still has scale. your thoughts everyone?

--- End quote ---
You might want to take a close look on your mangoes, as well as any other of your tropical fruit trees in your "greenhouse".  Scale are not usually particular to just one plant, especially in a confined area.

As far as using oils, I am not sure what the reaction would be under your grow lights.  Oils used under a summer sun will tend to burn the plant/leaves.

lycheeluva:
wow, this scale is a real ****.
just spent another hour removing another 75% of the scale. so im upto 150% of the scale removed, and no i doubt when i go take a fresh look tomorrow, i will find another 75%. never seen a bug that is so hard to spot, and pretty tricky to remove too.

CoPlantNut:
I'm growing under lights in similar conditions, and have never had a problem as long as I use a good-quality refined paraffin oil (I've used SunSpray for years).  If any of your plants are starting to show stress from being too close to the light, you might want to move them away from the lights for 4-5 days after spraying, as the oil will make leaf scorching more likely.

However, I've sprayed oil on things more delicate than lychees and never had a problem under a 1000W light before.

Just like picking the scale off, when you're sure you've sprayed every leaf surface and you're done, I would recommend spraying again.  And then again.  You want to make sure you smother them all.  If you repeat this in another two weeks, you probably won't see scale again until next fall (they always seem to discover the plants outdoors over the summer again).

And I would also recommend spraying every plant you have, whether you see scale or not.  Any refuge will lead to re-population.

   Kevin

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