Depending on where you live
Adeniums have only 2 seasons > wet - and - dry
wet = the active growing season (summer months in the northern hemisphere) water adeniums like a tropical
dry = the dormant season (winter months in the northern hemisphere) treat adeniums like a cacti
Adeniums will not live through a freeze - and must be brought indoors
Adeniums also seem to take forever to go through phases or changes ....so give everything you do extra time
Many of the outside edges of leaves on my adeniums have that same crimson red color .....sometimes see that crimson red on new growth throughout the year ....no idea what causes it - or if it is detrimental to the plant - but the plants appear to be healthy & thriving
But the red specks on the interior surfaces of leaves may be something else entirely - fungal perhaps ... resembles rust fungus .... rust is often found under moist conditions, or prolonged high levels of humidity - but having treated the plant for spider mites is contradictory ...since spider mites prefer dry conditions
the red specks also resembles over-spray from a weed / grass / brush killer - if I spray a certain common weed killer on Asiatic Jasmine (Trachelospermum asiaticum) - the leaves turn brilliant red - and it stays that way for weeks if not months ...
has anyone in the neighborhood sprayed weed or brush killer recently ?
Have used alcohol (both Isopropyl & ethanol) with excellent & immediate results - especially on aphids and scale - But have stopped using alcohol because no matter how weak I mix the alcohol it will damage the leaves - (it brings back a science class memory of extracting chlorophyll from leaves - by putting a leaf in a jar, then filling the jar with alcohol - in just a few minutes the alcohol turns green) - alcohol leaf damage appears as a spot or blotch that is pale green turning near colorless .... and eventually the leaf wants to fall off the plant but sometimes dangles there at the end of the stem ....
For insects - consider using *insecticidal soap* that contains fatty acids (warning > never apply insecticidal soap on a hot day and always wash it off once it dries)
The yellow on the leaves could mean a couple of things ...sometimes over-watering - and - sometimes the lack of watering .... this time of year (in the northern hemisphere) leaves turning yellow could signal that the dormant season has began .... and leaves fall off the plant .... (sometimes during the dormant season, adeniums keep leaves) in either case its normal
As others have suggested - stop fertilizing (until next spring) and stop watering -
Don't water again for 3 months - mark the date on a calendar ...when the day comes up for watering.... only water 1/4 to 1/2 *less* than the total size of the pot - you want to water just enough that it only dampens the potting media ... then repeat the 3 month no water cycle .....
Plants may shrivel a little (or alot) ...but resist the temptation to water - over-watering or plants sitting in water during the dormant season - will kill adeniums ....
