Hello,
it's a typical question for many citrus growers, and first:
Don't get sorrow about the plant, everything is fine!
But, you may have small bugs on the plant -> scales!
j-ust look at the twigs and young stems, on the underside of the leaves along the midvein... You will find ovale, yellow-green to dark brown knuckels... they are soft and can be rubberd away, thicker ones will 'loose' a yellowish sap if squeezed to death
This are scale insects, and there are many types. Usually the brown soft scale will be found....
Use a soap-ethylic-alcohol-water mixture, to get rid of and wash away the sticky scale 'pooh'. The 'pooh' of scales is sticky, because it's simply sugar, so it's harmless and if someone whant's to be sure: Taste...
Bees collect it, and form a special kind of honey of it, with usually a darker color. So it's realy nothing to get in panic or sorrow, even if a baby sucks on it....
The soap-alcoholic-water mixture will attack the wax protection of the scale and soap will give the water the possibility to enter the insects breath opening and kill it.
If this doesn't work, or seem to work, severaly spray oils are useable, but: The oil film should to be removed indoors after three days, because it will form in the absence of rain, wind, dew and sunlight a sticky surface, plugging the plants stomatal openings, and prevent photosynthesis. The cause is severe leaf drop.
So ensure to crack the oil film indoors by my mentioned 'salad dressign' made of soap, water and ethylic alcohol, just to get rid of the oil film indoors, and also wash off the death insect mummies.
If oil seems to be not the chioce, use systemic insecticides, but be aware: No bees and other benefical insects should have contact to the plants and do not eat the fruits....
