Signs of potato seedling stress or ....

[Stimacked]

I have 2 batches or patches of TPS seedlings growing. One batch is in a cooler and more shady spot in the backyard. These were planted out a couple of weeks back. They are generally growing well. The second batch have been planted out over the last week. They are struggling with the less pampered conditions at the allotment. scorching hot sunny weather. A few seedlings have shown leaves curled down since planting out. This is something I've noticed on a 2 or 3 few seedlings. in both patches. I pulled out two seedlings just in case its a virul infection. Has anyone else noticed curled leaves on TPS soon after planting out. I am hoping its just some form of transplant shock. The seedlings may have been left in pots for too long beforehand.

Advice please.

[Tom Wagner]

Whenever is see leaves curling I look to see if any aphids or mites are on the undersides of the leaves. I also look to see if it could be herbicide contamination. And then I look at the leaves to see if they look like a latent infection of a virus.

I am not sure if the hot weather or advanced age of the seedlings could be the problem.

If it is any solace I seem to always find a few plants that just look messed up and most of the time if they look infected/damaged...they continue to look damaged and not pull out of it. I think there are genetic factors that throw off types. Sorry, but without pictures, I am offering possibilities.

[Stimacked]

This is one of the seedlings I pulled up. It was a Magic Dragon seedling.
There could well be aphids. They are present at both my backyard and at the alotment. Plenty of ladybugs around at the alotment. Most are around my Burlap sacks of potatoes which have gone to flower. Most TPS seedlings leaves look well, while a handful of others have shown a few misshaped leaves or have a curled leaf. This was the worst one. I guess if they continue to look like this they have to be dumped in the trash like this one!

I am against the use of Pesticide and have never used it. Its not impossible there was someone else using some on another alotment plot.
What are the signs of Pesticide poisoning. Why then only one showing this sign in the whole row? I have been using Neem sprays to try and strengthen the plants and fend off some of the bugs. Peel bugs and catterpillers are helping themselves to the leaves
so they are having a tough introduction to life in Japan!!

I have tried to give the seedlings some shade today, as shown in the other snap.

Temperature went up to 30 c today. also had temps of 27-29 c on 7 of the last 10 days. Very unusual for May!

[Tom Wagner]

Looks suspiciously like a one two whammo. First an aphid infestation and then a latent virus carried by the aphids. The oldest leaf does not seem to be affected but the new leaves.....

[Redbaron]

Looks like curly top to me. A disease spread by leaf hoppers or in rare cases flea beetles. I never heard of it being spread by aphids, but I suppose it could be possible. I also never knew it was in Japan. I always thought it was mostly found here in the southwestern part of USA.

Either way, if it is curly top virus the only solution is to pull the plant before it spreads to the other healthy plants. (It spreads when an insect jumps from an infected plant to a healthy plant and starts eating)

[Stimacked]

Will continue to remove any seedling showing similar symptoms.

Big question Tom. Can TPS seeds carry the Curly leaf virus?

[Tom Wagner]

ALWAYS good to have second opinions. Host plants are everywhere it seems for a weed, cultivar, etc., to carry a virus along. I tried to find a quote online that talks about high temps, virus, transplants, weeds as key words. No proof of what I am alluding to but as a precaution....and to indicate that the TPS is not carrying the virus. I treat with TSP, chlorine and hot water before drying down the seed and that is just another safe guard for my customers.

The tomato yellow leaf curl virus and/or PLRV is not seed-borne and is not transmitted mechanically. The disease may be spread by whiteflies . Whiteflies have a wide host range. New plant growth attracts whiteflies, which feed on the lower leaf surface. It takes about 15-30 minutes for the whitefly to become infected by the virus. The incubation period is 21-24 hours, and the transmission period at least 15 min.

Factors that favor development:

• High temperatures, and low or no rainfall
• Presence of whiteflies
• Infected transplants
• Weedy fields

[Stimacked]

Thanks alot for your reply.

Have been reading around on the net a bit since last night. The hot dry conditions this year have obviously set up perfect conditions for an insect boom.
Apart from chucking any more plants that seem to have been zapped!, I Will try daily Neem spraying of my surviving TPS plants and around the alotment and also shading the ones at the alotment to see if any survive the attack! I read that aphids and leaf hoppers like the full blaring sun. If all else fails I guess I will try again with my surviving batch of mini seedlings that I planted later. Or start again in the Autumn.

Wet weather set to arrive in a week or so, so if any of the plants survive the next week, they might make it.

Are little TPS seedlings more prone to attack than fully grown potato plants which have gone to flower? Have been checking for any signs of attack on the big fellas (fully grown regular clone potatoes) and they seem O.k. so far.

[Tom Wagner]

Established leaves are most apt to be fixed in their morphology and physiology. New leaves as in transplants are quicker to be affected by a virus. One can almost tell when a virus became an issue.

[Stimacked]

So it will be more difficult to detect in potatoes grown from tuber Clones than those raised as TPS seedlings. Guess the best thing I can do is keep a close eye on the TPS and spray everything with Neem and hope one of the Ladybugs munches the culprits !!