Hello, we bought a house in Las Vegas w/ many existing plants. The former owner told us that these cacti have rotted like this b/c of frost last year. I am not sure what to do. Should we trim them below the rot? Or are they a lost cause and we should just dig them up? Also, our landscape co. said that it's too hot to trim them now, we have to wait until fall. Is this correct? Because if not, I'll go trim them. Just not sure how to proceed. Thanks!
Thank you. So it's ok to trim the tops of the column-shaped ones leaving an open hole there at the top? Just wanted to make sure, don't want to cause more damage.
I wonder if it is frost that has affected the plants. I would expect it to hit more of the plants. It seems to have affected only some of the plants in a group, or only parts of one and more of another. But then, I cannot say it is not due to frost. If it were me, I would investigate other possible causes. I would check the roots. Perhaps they have been overwatered, maybe insects (root or elsewhere). Good luck.
looks like frost to me, damaged tips, healthy pupping. this suggests healthy roots, but accute damage to meristem. this CAN be caused by insects, but insects also force dormancy, there wouldn't be pups. root damage would cause the plant to shrivel, root rot would cause rotting from the base, not the tip. plus there was a strong arctic flow last winter that hit the west, alot of this type of damage has been going around. i'd say just slice off the ugly bits low and at an angle (angle away from plant-center) to keep water from pooling on callous. offer weekly feedings in peak growth months (possibly untill mid-oct in your area) stop watering when lows start going below 10c regularly by the end of next year the Cereus peruvianus should look quite nice and thick. those establshed roots should produce a stocky plant that can grow quite tall. if frost is an issue, many people cover cacti with a burlap blanket, or for smaller frosts, styrofoam cups on top can protect the tips. the Pachycereus marginatus will take longer to look nice, be careful not to remove pups while cutting.
Another way to prevent rot in fresh cuts is to apply agricultural sulphur on them, it will prevent rot and is a mitecide as well.. Thats will bounce back wonderfully,,, Cheers Charliewood