Expert: Greg Simpson - 4/21/2006

Question
i have a 5 ft tall 3 column (peruvian, san pedro type) cactus that has had mealy bug.

ive tried to control it but it has now developed top rot on the tallest column.

the rot is about 2 cm to 5cm in depth on the worst side. it is fading to light green to a depth of about 20cm.

i believe i have to amputate the rot and ive looked up the procedure, but i cant find any reference as to the faded bit.... does this have to go too.... i dont want to do that if i dont have to.

also, i dont use chemicals and am finding it very difficult to reach the inward parts to control the mealy bug. it seems to be infested where its spines are... and where the spines touch the flesh of another coulmn. any ideas?


Answer
Dear Charm,

I believe if you can eliminate the meally bug issue, you can save the part of the plant that is turning yellow. I found a website that deals with non chemical control of meally bugs, it is:

http://www.ipmofalaska.com/Files/mealybugs.html

It has links for horticultural oil, pesticides made with botanical oils, and insecticidal soap. Hopefully this will help. Make sure to read all of the instructions, as some of these remedies can injury the plant. If the plant is rotting, don't overwater. That will oly encourage the spread of the rot. Hope this helps, good luck!

Sincerely,

Greg