Question

cactus fungus   ok this plant has been hanging over my sofa for about 4 years now.  the basket has several types of hanging cactus in it. in the summer i water once a week and in the winter every two weeks if dry.  i noticed a white powdery substance on the plant recently that feels moist.  the stems that have this on it are drying and dying off.  the bottom of the plant is mint condition.  no leaves (pads) on the bottom  part are dying.  this plants gets some direct sun but mostly bright full light.  space prevents me from moving it to full all day sun. what did i do wrong and how can i fix it please.  thank you for your help.  i live in maine and the house is around 60-64 degrees days and  mostly 60 degrees nights but can go to 57 some colder nights if that helps.

Answer
Mary,

Your picture is a little fuzzy. The bright white spots may be mealy bugs if they look like little bits of cotton balls on the plant they are mealy bugs and you should spray them with rubbing alcohol in a spray bottle every three days for a month. Make sure you get the fronts and backs of all areas that have mealy bugs. You have to spray consistently every 3 days for a month to kill any that hatch from eggs.

I also see signs of overwatering. Especially in the cool temperatures you are growing in you do not need to water more often than once a month until after April 1st. Many of my cacti I do not water at all during the winter unless they start to shrivel then I only give them a half cup of water. Yours may be shriveling because you have watered too much and the delicate roots have rotted so they can no longer take up any water and are shriveling as though they are too dry. Keep them dryer by not watering more than once a month and the roots will slowly grow back.

Cacti need as much direct sun as possible. Or you can substitute a florescent light bulb shining directly on the plant for 14 hours a day. As long as it is a florescent light it will not raise your electric bill significantly. Good luck with your cactus.

Darlene