[Richard Tani]

I'm having a problem with a couple of plants I've never experienced before. I've got 4 garden sweet cucumbers that I planted about 4 weeks ago. Two of them, both on the same side of the bed, are going gangbusters and are about 4' up the trellis with several maturing fruit. The other two are not nearly as vigorous, but there's another issue that I've never had before. The female flowers and fruit are not developing normally. While the cucumber is still extremely small, the sepal leaves open up revealing the closed immature flower which promptly dries up. Is this a nutritional issue, or is the lack of vigor causing the plant to abort these fruit prematurely? I'm contemplating pruning off any female flowers forming in the next several weeks to promote growth, but I'm not sure if that's the correct course of action. I've only given them a heavy helping of worm castings at transplanting and fish emulsion every few weeks. Any thoughts would be greatly appreciated!

 

[Danaus29]

Are both plants getting the same amount of sun? Could there be something underground like a big rock or concrete slab that would be blocking root development?

 

[Richard Tani]

Yes, they're all getting equal sun and they're in beds with 18+ inches of a mix of 2/3 compost and 1/3 screened sand and topsoil. No rock. Drip irrigated on a timer with ~1/2" of water every three days. Mulched everything with a generous layer of straw last week. I can't figure this out. All of my other plants are doing great, but I have had a few blossoms drop on my determinate tomatoes. Just one or two, so I'm not concerned. I was thinking there might be a pocket of straight sand under them, but I very thoroughly mixed everything. If that's the case there might be a nutritional issue and may require some extra of the good stuff. I'm not sure. I do have a moderate Western flower thrip presence, but they're not doing any significant leaf damage. Weekly Neem is keeping them from exploding. I've seen a few leaf footed bug nypmhs around, but I don't know if they target cukes that haven't even had a chance to be pollinated yet.

 

[Danaus29]

Not familiar with western flower thrips. But that may be your problem. They might be more prevalent on the affected plants. According to this they can burrow into developing buds causing them to abort.
https://www.koppertus.com/challenges/thrips/western-flower-thrips/

 

[Mish]

So thrips and aphids are a huge problem in my garden (also California) with tomatoes in particular but also newly budding squash/cukes. Sounds like you're keeping up on it with the neem, but some years (and some particular plants) I just find it's a losing battle no matter what I do. Something containing Spinosad may also be marginally helpful. Annoying little suckers. (Edit - on the bad years, succession planting trying to keep ahead of them sometimes works on the fast growing stuff like cukes/squash, but also keep up on the spraying)

Another problem I have in the sandy parts of my garden are root knot nematodes. You'll see plants not developing as well, sometimes looking mangled/yellow, and when you finally pull them you'll be able to see knotted, scabby, tangled roots instead of nice healthy "hairy" root formations. I gave up on trying to deal with that because I have enough areas with good soil that I just plant the delicate stuff there, but if your whole garden is sandy you might have to look into ways to deal with your soil if nematodes seem to be the problem.

Just a random tip for the tomatoes - since we don't have a lot of the nice pollinating bugs that other more hospitable areas have, going out once or twice a day and tapping on your tomato blossoms really increases pollination (if you want to go really crazy, pressing an electric toothbrush on the bracts is a great way to go). I've been able to double my fruit set by giving the tomatoes a good shake every morning.

 

[Richard Tani]

Every time I step out in the garden I tickle my tomato flowers with a finger. Always have and it seems to work well for me. I've got a cluster of 16 on one of my lemon boy tomatoes tight now and there are three more clusters about to bloom. I prefer them small, so I never thin. Tomatoes aside, the soil in these beds is very far from sandy, I just used a bit of material that had a higher sand content. ~2 yards of compost and one yard of this stuff marketed as "planters mix" in each bed. It's a nice texture, that wicks moisture well. There is more of a thrip presence on the two plants that are blooming. I don't find any on the nearby plants except for a mulberry tree in the yard. There are ants on the cukes, but they appear to be helping me out in terms of pollination so I leave them be. I'm still lost on what's going on. There are female flowers trying to open up when the cuke is only 1/2" long. There was one night that almost dropped down into the 40s, so I'm hoping that had something to do with it. Heat is coming back in this week so I'll keep an eye on them.

 

[Mish]

Ah, OK, misread your comment about sandy soil earlier then. If you added sand nematodes probably aren't an issue, native sand and it's possible/probable.

Generally when I have ants climbing plants around here it's because they're farming aphids. Your pictures don't show any that I can see but it might be worth taking a good look at what the ants are doing. Usually they're up to nothing good around here.

Just running through the list of things that would cause those issues in my garden. Hopefully it is just the wacky weather and they'll straighten up once everything evens out.

 

[Richard Tani]

There are aphids here and there, but they're not bad at all. It looks to me like the ants are after nectar. They walk in the flower trim and svelte, and they come out so fat that their abdomens are actually transparent. The thrip problem is starting to concern me. I've never used it before, but I think I'll give spinosad a try. They're so hard to spot, that I know I'm only seeing the adults. I've had other plants, mainly peppers, sprout badly misshapen leaves every once in a while which might be a result of thrip feeding.

 

[Richard Tani]

Update: Spinosad has reduced the number of thrips and other pests to near zero throughout. With the lack of beneficials here anyhow I'm very pleased, though I hope I won't have to bring it out again. Hopefully the weekly neem will keep them down. Switched to Plantonix brand neem. Pretty cheap, but perhaps the extra cheap stuff I picked up earlier was cut with something or maybe it was past its prime. We'll see.

 

[Mish]

That's good to hear, hopefully that takes care of the problems. I did my first spinosad spray last night as well, although I've been trying to keep on top of the aphids with neem but the thrips are out of control. It's been a bad spring for bugs in general. Usually I don't have infestations like this until late June or so.

Lost my most of my first planting of pole beans and cukes to slugs/snails/grasshoppers/wet/cold weather, and now it looks like grasshoppers are intent on taking out my second planting of germinating cukes, pole beans are finally doing OK. Sluggo looks like it's doing something.

Seriously glad this isn't the old days where we'd be looking at starving with the way things have been going so far. Here's hoping!