More strange leaves

[Doll]

Here is a ph chart I found online showing how different nutrients are affected by ph.

[roadrunner]

Thanks John but this is looking more like a viral problem. I've been growing these hibiscus since 2004 and the new problems have started recently only in about 15 percent of my 100 plant collection. Most of my plants are thriving and all receive the same nutrients, water, and are growing in the same potting mix.  I occasionally see iron chlorosis which is quickly corrected with HVH's iron chelate.  This also does not respond to Fulmag magnesium.  This is something different.

I've lost several plants following last summer's major spider mite attack before I got them on Kontos.  Some hibiscus just never recover from a major mite attack and it appears this possible virus is something that was transmitted by the mites.  Several of my plants have struggled and lingered and are finally starting to die from it.  The peculiar thing is that many of the mite attacked plants have recovered nicely.  Some survive it, some just don't. Incredibly frustrating and annoying. 

dave

[Cindy]

As I'm studying the post-spider-mite problem, it's looking less and less like a viral infection to me. The more I read about viruses, the more it seems that they're spread mostly by flying insects. Thrips and whiteflies are the two main hibiscus culprits. Spider mites don't move very far in their lifetimes. In fact, most of their movement from one plant to another comes from either plants directly touching each other, or humans or pets picking them up and carrying them from one plant to another. Spider mites are slow walkers who can't jump across gaps, so simple isolation is the first line of defense against spreading them. The second line of defense is our own body awareness, and being careful not to pick them up on sleeves, hands, gloves, watering tools, pruners, etc. The only way spider mites can spread a virus is if you already have a plant that has a virus, and you allow the spider mites to spread to other plants in your collection. But viruses would not spread rampantly through a collection - they would move only from one plant to an adjacent plant that's touching it. The virus must be picked up from the sap of one plant, and then walked over to another plant that the same spider mite chews on. It's rare for one spider mite to make big moves like this. So the virus theory is look less and less credible as I study more and more. I haven't found a virus that infects hibiscus that is spread through water or from mother to child through DNA or RNA. These viruses don't actually infect the spider mite - they are simply carried by the spider mite's mouth from one leaf to another. Spider mites have such a short lifespan and travel such short distances that this really is not very feasible. A spider mite can live an entire lifetime on a single leaf!

But after lots of reading, observing, and studying the post-spider-mite syndrome, it's looking more and more like a root problem to me, whether mechanical or microbial. My guess is that it's a mechanical problem, due to the diminished capacity of damaged leaves to suck water through the plant. This problem slowly grows worse as water uptake is diminished, and water builds up in the soil since it's not being drawn up into the plant, which starts to drown the most delicate root ends. Then we start to see the leaves wilt a bit more and slowly die from even more lack of water, diminishing water transport even more, leaving more water to sit in the soil and drown more roots... even more diminished water transport... even more standing water in soil... even more of the leaf drop.... a kind of self-perpetuating syndrome where leaves seem to slowly die of thirst and roots seem to slowly die of drowning. If it goes on long enough, you can dig up the root ball and see that it is about 20-30% the size it should be! A root-bound pot will have turned into a tiny little root ball with dark colored roots instead of healthy white roots.

Giving the hibiscus more sunlight to try to force the water transport to work better sometimes helps in the very early stages. But too often it makes the problem worse. Leaves that aren't getting enough water just can't take extra sunlight, and they drop off even more quickly and speed up the vicious circle.

Giving the plant bright shade and extra humidity, with daily misting of the leaves to provide extra moisture, seems to work much better and more consistently. Misting with a solution of Wake Up Spray (1/8-1/4 strength) and Super Nova (full strength) has worked best of all for me, by helping the leaves start growing, and sucking water through the plant a bit more quickly again. If this is started immediately after a spider mite attack, the prognosis is really good - close to 100% recovery. If the plant is almost completely defoliated from spider mites, the prognosis is not as good and recovery takes much longer, but it's still the best thing I've found to try.

It's not just spider-mited hibiscus that this has worked on for me either! I've used it on overwatered African Violets, heat stress and transplant shocked roses, and other garden plants and houseplants that have had severe stress (like puppy attacks!).

Cindy

[roadrunner]

Since spider mites are not the virus vector then the culprit must have been the white flies I had for a good portion of 2010 and 2011 before I started the Kontos treatments. Cindy and I have exchanged emails discussing the loss of leaves and roots and the pots retaining water too long in a revolving downward spiral with the end result the loss of root mass and eventual death of the plant.  I've seen it in my own collection several times and currently have 8 plants in the last stages before their demise which I expect within a few days.  Unfortunately I believe most of these are only infrequently offered in the store and will be difficult to replace.

dave