Disease? Nutrient deficiency? Pest damage?

gorbelly · June 27, 2016

I have a sinking feeling that this might be bad. The plant is a melothria scabra (Mouse Melon/Mexican Sour Gherkin). My concern is that it might be a virus, however it doesn't quite resemble any photos I can find on the web.

It's affecting only a few newer leaves at the tip of one of the vines on one of my plants. There's a weird translucent quality to the lighter parts of the leaf--as though it weren't really a discoloration so much as that those parts are thinner. There doesn't seem to be deformation of leaf shape, though--although I guess I'll know that better when the two smaller leaves that are afflicted grow a bit. There have been some aphids in the garden, although I haven't noticed any on this plant. Aside from slug damage early on, the mouse melons have been basically pest-free so far.

One of my plants next to this one got some kind of wilt a couple weeks back, and I pulled it. But there were no symptoms other than catastrophic wilting--no color changes or anything.

Front of leaf (click for enlargeable photo)

Back of leaf (click for enlargeable photo)

BigVanVader · June 28, 2016

Could be angular leaf spot, I'd spray a fungicide and give it some fert.

gorbelly · June 29, 2016

It has spread to more leaves, but not in any logical manner. Still no sign of the kind of distortion that comes from viruses, although the damage to the leaves does make them look bumpier, and buds are forming normally, internode distance is normal, etc. It's also not primarily affecting new growth but seems to be spreading in a haphazard way.

It makes me think this is an atypical (or maybe typical for Melothria scabra--I wouldn't know, as I have no previous experience with this plant) presentation of one of the mildews?

I sprayed a copper fungicide on all the plants and will prune out affected leaves. I may try a dilute bleach spray in a couple of days if things continue to progress.

gorbelly · July 4, 2016

Well, it didn't respond positively to the copper fungicide, so I tried serenade. Almost all of the new growth on the vines appeared affected today, so I pulled the plant. Oddly, the plant right next to it, which had intertwined with it, remains totally unaffected. This makes me suspect it might have been CMV, which apparently does not spread easily without an insect vector, and M. scabra seems pretty uninteresting to everything except Japanese beetles.

Hoping it doesn't spread to the other mouse melon plants or to my tomatoes, squash, etc.

Although they get off to a slow start, once they get vining, they grow very quickly, so maybe there's time to plant another one and get some harvest off of that one before frost. And I suspect the slow start might not be so slow during the heat of summer vs. the cool and unpredictable weather of spring.

Thanks for your help anyway, BigVanVader.

EDITED TO ADD: It was a strange presentation, so maybe it wasn't CMV. It never managed to look like it was going to kill any of the foliage. And none of the foliage ever went significantly yellow, just mottled/dotted. Oh well. I suppose it's better to be safe than sorry.

DjonesNC · July 4, 2016

Other than a mosaic virus, I would honestly just keep an eye on the plant & possibly hit it with some neem oil. The plant seems to be fruiting and other than the leaf spots it looks relatively healthy imo.

gorbelly · July 4, 2016

Quote:

Originally Posted by DjonesNC

Other than a mosaic virus, I would honestly just keep an eye on the plant & possibly hit it with some neem oil. The plant seems to be fruiting and other than the leaf spots it looks relatively healthy imo.

Thanks. I really considered this route. I was thinking that it looked like the plant could still produce well, as whatever it is hasn't been taking down the leaves at all or affecting flowers, just discoloring leaves and changing their texture slightly.

But just in case it is a virus, I was too afraid for my other plants, which might not have the same ability to soldier on despite infection. Especially if it's CMV, then so many different plants in my garden would be susceptible, and the consequences for those species might be much more serious. So in the end, I pulled it.

It's one of the disadvantages of growing lesser known species. There are no diagnostic pictures for diseases or pests of Melothria scabra online.

clkingtx · July 4, 2016

I am growing these this year, too! I have tried to grow these in past years, but this is the first year they have done well. I don't think mine have any spots on the leaves, I will have to look tomorrow. I probably would have done the same thing, better safe than sorry. I found a website that mentions some diseases these sometimes get, probably not for your area, but will give you more information:

http://www.omafra.gov.on.ca/CropOp/e...its/mouse.html

ginger2778 · July 5, 2016

Do you have access to a microscope? Your extension office should have one. Kinda looked like spider mite damage.

gorbelly · July 6, 2016

Quote:

Originally Posted by ginger2778

Do you have access to a microscope? Your extension office should have one. Kinda looked like spider mite damage.

I looked for some kind of sap-sucking pest. It's not spider mite damage. The leaves were totally, weirdly pristine when it came to pests. I looked very carefully. Also, the weather here has not been conducive at all to spider mites. In addition, spider mites would not have limited themselves to just this plant and not the one that was next to it and already intertwined with it.

Quote:

Originally Posted by clkingtx

I am growing these this year, too! I have tried to grow these in past years, but this is the first year they have done well. I don't think mine have any spots on the leaves, I will have to look tomorrow. I probably would have done the same thing, better safe than sorry. I found a website that mentions some diseases these sometimes get, probably not for your area, but will give you more information:

http://www.omafra.gov.on.ca/CropOp/e...its/mouse.html

Thanks for the link!

Most of the information I found and testimonials from other growers gave the impression that these are hardy, problem-free plants. I've found them rather disease prone. Though they are pest free. Nothing seems to want to eat them, except a Japanese beetle I found trying to chow down on a leaf.

I have a papalo plant next to these, and it's showing some signs of some problem. Yellow patches on the leaves, lighter, semi-marbled spots--although the spots are whitish and not yellow. Another not-well-known-in-the-US plant I'm growing for the first time which is hard to diagnose. *sigh* It's possible it reacted badly to getting hit by some of the fungicides I used on the mouse melons, as this plant's young leaves are very tender. I cut off a lot of the affected foliage and am waiting to see what happens. It's in the marigold family.

gorbelly · September 27, 2016

Just a report on the sanditas/mouse melons/Mexican sour gherkins for posterity and for other poor souls like me scouring the Internet for more detailed information. I pulled my plants this past weekend. I should add that the vines probably could have gone longer, but I needed the space for fall cover crop.

PLANT GROWTH: The vines were way too vigorous for the trellis I had prepared for them. Just one plant completely overran it and became a giant tangled mess and went up my papalo plant (which luckily got to be over 7 feet tall). I had planted 3, but in the end was really only left with one. That single plant became a bit of a jungle.

PRODUCTION: Good in terms of numbers of fruit. Tons and tons of these little fruits set like crazy. Not great in terms of total fruit mass, but that's expected for small little fruits. You're not going to satisfy a family's cucumber needs with this variety, but it would be a good "fun extra" if you have some space to fill.

DISEASE: Two plants died early of a sudden wilt of some kind. I couldn't identify it. Despite heavy powdery mildew on some nearby squash, the sanditas seemed to resist it well. No early pests, but when the cucumber beetles did eventually come, they did enjoy the sanditas. There were signs of bacterial wilt, but unlike the plants that died suddenly early on, the one surviving plant, which was already pretty large by then, seemed fairly resistant. Individual leaves and stretches of vine would wilt and die, but it didn't take down the entire vine. I'm wondering whether there's genetic variability in resistance--probably should have saved seed from that surviving plant, come to think of it. Oh well.

FLAVOR/CULINARY: The tart crunch is refreshing, but the skins are very thick, and the inside has no flesh to speak of--it's all seed matrix. People I shared them with oohed and aahed over them at first but didn't exactly clamor for more. Kids did enjoy them, though, for sheer cuteness. They were not my favorite, honestly. They were just OK. I did whip up a quart of refrigerator pickles with the fruit I picked off the vine when I pulled it, and I do have to say the pickles are GREAT. It would be hard to grow enough in my garden to have enough at a time to pickle, though, since they're such trellis hogs.

BOTTOM LINE: I'm going to hold on to some of my extra seed in case I want to bring them back in future, but this isn't exactly a "must-grow", IMO. Maybe a "should-try"? They are certainly fun, but not revelatory or anything.

Labradors2 · December 6, 2016

Thanks very much for the report. They look so cute, but you have saved me from wasting my time growing these. I'll stick to my Persian Green Baby Fingers F1 cukes......

Linda

gorbelly · December 9, 2016

Linda,

If you end up having a little extra space by a fence or something and want to try a plant or two, I can spare a few seeds. Just PM me.

Do you have any experience with gherkins? I would love to grow something for making cornichons but I don't have much experience with those varieties. Wondering if you have any recs.

oakley · December 10, 2016

I made the same mistake 2015. I'm sticking with the thin skinned lemon cukes. And the PersianBabyFingers like Linda. Trying a few new varieties that are small but not tiny. I get a good
harvest with the small varieties and thin-skinned. Small seed mass, firm, not too wet. Great for fresh
eating as no peelings loss. Great for 24hr fresh fridge pickles.

June 27, 2016	#1
gorbelly Tomatovillian™ Join Date: Jul 2015 Location: Southeastern Pennsylvania Posts: 1,069	Disease? Nutrient deficiency? Pest damage? I have a sinking feeling that this might be bad. The plant is a melothria scabra (Mouse Melon/Mexican Sour Gherkin). My concern is that it might be a virus, however it doesn't quite resemble any photos I can find on the web. It's affecting only a few newer leaves at the tip of one of the vines on one of my plants. There's a weird translucent quality to the lighter parts of the leaf--as though it weren't really a discoloration so much as that those parts are thinner. There doesn't seem to be deformation of leaf shape, though--although I guess I'll know that better when the two smaller leaves that are afflicted grow a bit. There have been some aphids in the garden, although I haven't noticed any on this plant. Aside from slug damage early on, the mouse melons have been basically pest-free so far. One of my plants next to this one got some kind of wilt a couple weeks back, and I pulled it. But there were no symptoms other than catastrophic wilting--no color changes or anything. Front of leaf (click for enlargeable photo) Back of leaf (click for enlargeable photo)

July 4, 2016	#4
gorbelly Tomatovillian™ Join Date: Jul 2015 Location: Southeastern Pennsylvania Posts: 1,069	Well, it didn't respond positively to the copper fungicide, so I tried serenade. Almost all of the new growth on the vines appeared affected today, so I pulled the plant. Oddly, the plant right next to it, which had intertwined with it, remains totally unaffected. This makes me suspect it might have been CMV, which apparently does not spread easily without an insect vector, and M. scabra seems pretty uninteresting to everything except Japanese beetles. Hoping it doesn't spread to the other mouse melon plants or to my tomatoes, squash, etc. Although they get off to a slow start, once they get vining, they grow very quickly, so maybe there's time to plant another one and get some harvest off of that one before frost. And I suspect the slow start might not be so slow during the heat of summer vs. the cool and unpredictable weather of spring. Thanks for your help anyway, BigVanVader. EDITED TO ADD: It was a strange presentation, so maybe it wasn't CMV. It never managed to look like it was going to kill any of the foliage. And none of the foliage ever went significantly yellow, just mottled/dotted. Oh well. I suppose it's better to be safe than sorry. Last edited by gorbelly; July 4, 2016 at 01:59 PM.

July 4, 2016	#7
clkingtx Tomatovillian™ Join Date: Apr 2008 Location: Wichita Falls Texas Posts: 446	I am growing these this year, too! I have tried to grow these in past years, but this is the first year they have done well. I don't think mine have any spots on the leaves, I will have to look tomorrow. I probably would have done the same thing, better safe than sorry. I found a website that mentions some diseases these sometimes get, probably not for your area, but will give you more information: http://www.omafra.gov.on.ca/CropOp/e...its/mouse.html __________________ Carrie

September 27, 2016	#10
gorbelly Tomatovillian™ Join Date: Jul 2015 Location: Southeastern Pennsylvania Posts: 1,069	Sandita/mouse melon/Melothria scabra end of season report Just a report on the sanditas/mouse melons/Mexican sour gherkins for posterity and for other poor souls like me scouring the Internet for more detailed information. I pulled my plants this past weekend. I should add that the vines probably could have gone longer, but I needed the space for fall cover crop. PLANT GROWTH: The vines were way too vigorous for the trellis I had prepared for them. Just one plant completely overran it and became a giant tangled mess and went up my papalo plant (which luckily got to be over 7 feet tall). I had planted 3, but in the end was really only left with one. That single plant became a bit of a jungle. PRODUCTION: Good in terms of numbers of fruit. Tons and tons of these little fruits set like crazy. Not great in terms of total fruit mass, but that's expected for small little fruits. You're not going to satisfy a family's cucumber needs with this variety, but it would be a good "fun extra" if you have some space to fill. DISEASE: Two plants died early of a sudden wilt of some kind. I couldn't identify it. Despite heavy powdery mildew on some nearby squash, the sanditas seemed to resist it well. No early pests, but when the cucumber beetles did eventually come, they did enjoy the sanditas. There were signs of bacterial wilt, but unlike the plants that died suddenly early on, the one surviving plant, which was already pretty large by then, seemed fairly resistant. Individual leaves and stretches of vine would wilt and die, but it didn't take down the entire vine. I'm wondering whether there's genetic variability in resistance--probably should have saved seed from that surviving plant, come to think of it. Oh well. FLAVOR/CULINARY: The tart crunch is refreshing, but the skins are very thick, and the inside has no flesh to speak of--it's all seed matrix. People I shared them with oohed and aahed over them at first but didn't exactly clamor for more. Kids did enjoy them, though, for sheer cuteness. They were not my favorite, honestly. They were just OK. I did whip up a quart of refrigerator pickles with the fruit I picked off the vine when I pulled it, and I do have to say the pickles are GREAT. It would be hard to grow enough in my garden to have enough at a time to pickle, though, since they're such trellis hogs. BOTTOM LINE: I'm going to hold on to some of my extra seed in case I want to bring them back in future, but this isn't exactly a "must-grow", IMO. Maybe a "should-try"? They are certainly fun, but not revelatory or anything. Last edited by gorbelly; September 27, 2016 at 11:44 PM. Reason: added new title

June 28, 2016	#2
BigVanVader Tomatovillian™ Join Date: Mar 2014 Location: Greenville, South Carolina Posts: 3,099	Could be angular leaf spot, I'd spray a fungicide and give it some fert.

June 29, 2016	#3
gorbelly Tomatovillian™ Join Date: Jul 2015 Location: Southeastern Pennsylvania Posts: 1,069	It has spread to more leaves, but not in any logical manner. Still no sign of the kind of distortion that comes from viruses, although the damage to the leaves does make them look bumpier, and buds are forming normally, internode distance is normal, etc. It's also not primarily affecting new growth but seems to be spreading in a haphazard way. It makes me think this is an atypical (or maybe typical for Melothria scabra--I wouldn't know, as I have no previous experience with this plant) presentation of one of the mildews? I sprayed a copper fungicide on all the plants and will prune out affected leaves. I may try a dilute bleach spray in a couple of days if things continue to progress.

July 4, 2016	#5
DjonesNC Tomatovillian™ Join Date: May 2016 Location: Charlotte, NC Posts: 31	Other than a mosaic virus, I would honestly just keep an eye on the plant & possibly hit it with some neem oil. The plant seems to be fruiting and other than the leaf spots it looks relatively healthy imo.

July 5, 2016	#8
ginger2778 Tomatovillian™ Join Date: Aug 2011 Location: Plantation, Florida zone 10 Posts: 9,283	Do you have access to a microscope? Your extension office should have one. Kinda looked like spider mite damage.

December 6, 2016	#11
Labradors2 Tomatovillian™ Join Date: Jul 2013 Location: Ontario Posts: 3,895	Thanks very much for the report. They look so cute, but you have saved me from wasting my time growing these. I'll stick to my Persian Green Baby Fingers F1 cukes...... Linda

December 9, 2016	#12
gorbelly Tomatovillian™ Join Date: Jul 2015 Location: Southeastern Pennsylvania Posts: 1,069	Linda, If you end up having a little extra space by a fence or something and want to try a plant or two, I can spare a few seeds. Just PM me. Do you have any experience with gherkins? I would love to grow something for making cornichons but I don't have much experience with those varieties. Wondering if you have any recs.

December 10, 2016	#13
oakley Tomatovillian™ Join Date: Jun 2015 Location: NewYork 5a Posts: 2,303	I made the same mistake 2015. I'm sticking with the thin skinned lemon cukes. And the PersianBabyFingers like Linda. Trying a few new varieties that are small but not tiny. I get a good harvest with the small varieties and thin-skinned. Small seed mass, firm, not too wet. Great for fresh eating as no peelings loss. Great for 24hr fresh fridge pickles.