Rot epidemic

[Robb]

Oh dear ! I'm so sorry for your losses.

[7george]

Eek! Maybe you just found all the plants that lost their roots over winter. They would have been sitting in damp soil since you watered, nothing to take the water away.

To be honest, a couple did not have roots; the others seemed OK. I hadn't watered the collection since late last September, I believe. But I started repotting with pumice and coir mid-to-late summer. Perhaps that was not a good idea. From now on, if I don't repot by mid-July or thereabouts I think I should let them go until the next Spring.

Sorry for the losses. But I would recommend you start re-potting (soil replacement) during the winter, dormant period. In late fall or early winter take the plants out of the old soil and store them bare-rooted until next spring. No contact with soil, easy observation. Put those into new pots before new growth begins or even shortly after that if light is enough.

BTW, what kind of insecticide did you use to treat your plants? I lost several plants because of using a spray not intended for plans but for insects, bugs. And these cacti looked about like yours pictured above. Like that spray destroyed their immune system. And some others survived so far with some ugly brown, black or gray skin scars. Just a suggestion.

[fanaticactus]

Hi, 7george...I appreciate your response with suggestions on the rot problem. I do foresee repotting most, if not all, of my remaining collection. I never thought of letting my whole collection going bare root for the winter. I think the problem traces back, as suggested by Steve Johnson, to the too early application of a systemic. I used a product for mealies containing 9.4% Acephate (O, S-dimethyl acetylphosphoramidothioate) and watered it into the soil. It was not the first drink of water the collection had and most of the cacti were showing some new growth, so I thought the roots were fully functioning. Apparently not. I am now going to experiment with a combination of pumice mixed with a small amount of natural organic Arizona soil with more sand added to loosen the binding clay effect. However, if a cactus still looks good at this point I'm thinking I'll let it stay instead of disturbing it. The whole process of soil testing and adjustment, then repotting appears daunting, though, and there are so many other aspects of my life that need attention, I'm not sure how quickly it can all be done without ignoring other aspects of what needs to be cared for around the house and property.