Sick Diospyros lotus- please help?

[Darklight]

I have about eight Diospyros lotus trees at hardened off seedling stage ( 15cm high ). Four of them were sick, two recovered, but the other two are on their last legs.

The roots seem to be rotting? Well, not rotting visibly, but on examination they seem to have lost their tips, be overly dark and underdeveloped. The sick plant is the first one, sorry, it's not in focus. The reverse of its leaf is pictured below ( or next to ) it, I can't see any obvious parasites and think the problem may be in the roots. Can anyone confirm?

The last pic os of a healthy plant, now recovered. Haven't checked the root system tho

If anyone knows what the problem is, can they also recommend something that might fix it? I know now isn't the active growing phase for anything here, but I'd really like to save them somehow

All help appreciated

[ 27. March 2005, 18:19: Message edited by: Darklight ]

[Torsten]

fungus gnats?

[Happy Cadaver]

wau, what a piece of shit!

Edited April 17, 2007 by darcy

[Amulte]

im going with both of you, watterlogged and root-rott is setting in from the looks, i couldn't see any bug nibbles. let soil dry for a day or so, but i have NOT grow these yet, jus grow alot of other plants.

[Torsten]

Originally posted by Amulte:

i couldn't see any bug nibbles. let soil dry for a day or so

Fungus gnats larvae feed on the roothairs. You would not see any damage other than that the roots rot and the plant wilts. If your organic mix is quite soggy then you have gnats. Drying the soil out for a few days won't do much cos the gnats can survive at the same moisture level needed for roots. Starving them of food by permanently keeping the soil on the dry side or by eliminating fungus with fungicide is the best option.We use gnat specific nematodes in the nursery for these painful critters. I lost half my rare species collection one winter due to them. The early cool weather would have triggered much fungus growth.

[mescalito]

"early cool weather...much fungus growth" good for some but not for you DL

[Amulte]

ahh, thanks torsten. i only know my top two mosy hated bugs, scara fly & spider mite. now its three, im sure theres more but three is enough for me. Thanks again T

[Darklight]

Thanks everyone. The plants were originally in an area that would be very cold and damp, most improved after I moved them but that one is recalcitrant.

I think I like the fungus gnats explanation, tho I can't see them now, they've been before and may well be again. I'll spray 'em with fungicide and see how it flies

[Darklight]

Torsten:

We use gnat specific nematodes in the nursery for these painful critters.  

Where did you get these? Gardening centre? Hydro shoppe? I just can't seem to get rid of the gnats, have been keeping plants drier, some are seedlings and I just can't work out what to spray them with!

[Torsten]

we dipped plants into pyrethrum solution, but many died from that. Those that survived the treatment recovered for a few weeks until the gnat population grew.

The best method to eliminate them continuously is to screen the space to exclude new gnat flies. Then put lots of yellow sticky traps at soil level (higher up is ok, but reduces the impact). The traps catch all the flies so that no eggs can be layed. The larvae eventually all pupate and turn into flies that get caught on the traps.

We also found that 'mulching' the pots with 15mm of sand will discourage the flies as there is no food for them. They will however still enter via the holes in the bottom of the pots in MUCH smaller numbers. Continuous use of sticky traps has allowed us total control over these critters even in rich and highly organic potting mixes.

The nematodes are expensive and only last a few weeks. They do appear to help with the continuous control as well, but not with outbreaks (eg when we forget to change the traps).

contact craig at ecogrow [email protected]

[Torsten]

I am also convinced that diatomaceous earth eliminates the larvae. Problem is that it needs to be worked into the soil and you need a fair amount of it. It will only last a few months, so it is really only useful for temporary pots like seedlings.

The sharp edges of the diatoms slice open the soft larval bodies. Keeps away many other grubs too, but also kills earthworms (which are not really wanted in small pots anyway).

[Rev]

So whats the attraction to Diospyros lotus NE way?

my knowledge of it is that its an obscure hardy persimmon relative from northern China and manchuria where its fruits were/are eaten as a survival food

I believ it has been used as root stock for D kaki the common persimon

I take it youre not interetsted in it for food cos of the persmmons its the one least likley to be of interest

say.. anyone know where to get seed of D americana - the true 'persimmon'?