This looks like an infestation from Bulb Scale Mites Steneotarsonemus laticeps and opportunistic Super Infection from Fungus Stagonospora curtisii to me. If you just crossed some ordinary Hippeastrums then discard your crop. If you rather deem it worthwhile to actually rescue them then and only then, prepare a dilution of 5 mL per L water, of one of the common Dimethoate preparations (400g/L in Cyclohexanone) like Roxion or Bi-58, take your pots to a closed room not frequented by other Persons neither Pets, and spray thoroughly between the leaves and also on the substrate. If you spray outdoors, you must be sure it is ABSOLUTELY wind calm. Yet you might face problems from your neigbors due to the obnoxious smell. After spraying, let the surfaces dry until the smell will vanish. Move your crop to a place where you can raise the substrate temperature to 23 up to 26°Celsius permanently. Repeat the treatment after 2 weeks, and only use freshly prepared dilutions of Dimethoate. Note that you will never eradicate the pest - there will always remain a reservoir population in the substrate; and NO, adding Dimethoate to the water supply will accomplish nothing in this respect. Kind regards from GERMANY and good luck.

Thank you so much Hans for the details instruction. It's surprised me if this is mites attack as i put 6 bulbs with mites problem just next to my seedlings last months. All seedling don't have this red lesion before. It's might be the mites problem as you said. I will try insecticide first.

Nititii

Thank you Hans for sharing this information. Is this only spread by mites?

I think (so that is a mere assertion) that the Fungus is "everywhere" (at least ON the bulb) like Bacteria are on our bodies. They will thrive when the bulb is injured (and BEING injured continually after infestation from Mites respectively) particularly at low temperatures, which weakens the bulb more than the fungus, so the bulb cannot fight back - and be it merely by out-growing the damage. Big damage can occurr after bulbs had been handled inappropriately, namely been dropped down, which can transform the affected sides of the bulbs into pulp and will require extended peeling in order to rescue them.

I tear off a yellow leaf and found some white dust.

That looks like mold...like what you can see on old bread. Have you had a really wet season?

Mealybugs?

Hey Salpal!! Where have you been?

I think you are right....mealy bugs leave a webby mess! UGH...Nititii....you have compound problems!!