I grew a lot of plants this Spring that ended up dying, for a variety of reasons - no doubt contributing to it was mealy bug infestation. Because I'm cheap and very into efficient gardening, I was wondering if it was safe to re-use the soil I potted these plants with (amending it, obviously). Would there be a risk of the soil harboring mealy bug eggs? Is there a period of time I should wait before this danger will have passed? (Presumably they can't live long in soil without a plant to feed on). Any thoughts? Thanks.

Jesse

i would as mealy bugs etc.,. don't exist in the soil as such, they are sap suckers and would be found on the roots of plants, and plants that are so badly affected do generally die.

len

"..... no apparent reason." Hmmm. Rather than worry about reusing the soil, perhaps you should take a closer look at it. In my experience, most of the difficulties you encounter in container culture stem from an inadequate soil. Poor soils stress plants. Stress leads to strain, which if uncorrected always leads to the death of the organism. Death usually comes by way of biotic pathogens or as a result of insect infestation, which, had the plant been growing robustly it could have fought off.

Plants mount a number of genetically encoded responses to (insect) wounding, ALL of which require energy allocation. In plant cells, there are genes that control proteins functioning in defense, sending defense signals, altering metabolism, controlling cellular maintenance, and regulating photosynthesis, as well as many genes of unknown function. In short, plant energy reallocation is prioritized in the plant's own defense, & other things, like every day metabolism and photosynthesis are put on the back burner.

When wounding occurs (insect attack) there is a "wound response" that occurs both at the site of injury as well as distally (in other plant parts). Plants can even differentiate between the wounds of a pin and those of insects and react in different fashion to the "attack". Without getting more technical, the plant produces various anti-feedants, anti-metabolites, and toxins that make the insects feel pretty unwelcome - as long as the plant is in good vitality, which means growing strongly, or has high energy reserves. In other words, as long as the plant is in good health. Stressed or strained plants cannot quickly or efficiently respond and ward off insect/disease attack.

The speed with which the response occurs, and the effectiveness of the defense response are also both energy driven, so it should be no surprise that plants grown under constant stress are highly susceptible to insect marauders. If you want to keep the bugs away - keep your plants growing with as much vitality as possible, which is almost always culturally dependent and very often originates with soil choice.

Al

Thanks for the thoughts. Small correction, though: I said my plants died for a "variety of reasons", which include raccoons, deer, bugs, powdery mildew and (I'm guessing) inadequate container sizes. I don't think soil quality was an issue - I used a good organic Uni-Gro potting mix and amended it with compost and other things as needed; I watered them a good amount and they got a ton of sun. It does remain a mystery why some did so much better than others, so your point about stress is a good one.

In any case, my concern wasn't so much with why my plants were dying as it was with whether mealy bugs might somehow survive in the soil after I've uprooted the dead plants. I'm fairly certain they never got to the roots (is it a different kind of mealy bug entirely that gets to the roots, or can they simply travel downward?). Still now sure what the verdict is...

But thanks for all the info about plant defenses - very interesting anyway!

It might have been helpful if you'd mentioned the deer & coons. Amending what you feel is a good soil with compost & 'other things as needed' doesn't necessarily mean you've improved the soil. Adding water-retentive compost to a soil that is already likely rather water-retentive from the bag, would not, in my mind, be an improvement. Had you said that you mixed your 'good soil' 50/50 with pine bark fines and some perlite (instead of compost .... care to share what else you felt was needed to amend what you started with?) to ensure there would be a minimal amount of soggy soil at the container's bottom, and to ensure that the soil would have adequate aeration for the expected life of the planting, I would agree that there probably is no issue.

I think you've discounted the probability, even the possibility of it being a soil issue in the end w/o seriously considering it from a perspective other than your own, but it's your decision, of course. Good luck.

Al

It might have been a soil issue, but again, that's not what my post was about. You sure like to argue!

It's nothing to me how your plants fare, I was simply trying to help by pointing out that a very high % of problems in container culture originate with the soil. Since you reject that possibility in your case, and are clearly looking for a blame other than grower malfeasance, I'll happily move along.

Good growing.

Al

Retract your claws, buddy. Life is good!