Several of you have written to ask me what's wrong with your cucumber and squash vines. They have a white cast to them and you're worried it's a sign of a disease. Actually, many plants in the squash family have a natural white shading on the leaves from the fuzzy, scratchy hairs. If it's been there most of the season and the plants look healthy and happy, don't worry about it.
If the white is blotchy, powdery and spreading, like the spots on the squash leaf here, it could easily be powdery mildew. Some varieties of squash and cucs are resistant, but a lot of the old favorites still succumb in humid weather. Powdery mildew doesn't kill the plant, but it does weaken it and it makes it difficult for the plant to photosynthesize and make food. Once powdery mildew takes hold, it's hard to stop it by organic means, but the old stand-by baking soda recipe can help to keep it from spreading.
Photo: © Marie Iannotti
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Even my resistant Divas seem to eventually succumb to PM about this point every summer. Following the advice I saw on a gardening discussion board, I planted “backup” cucumber plants at the beginning of the summer (Salad Bush). They are up and almost ready to produce, just as the earlier ones are fading.
I wish my cucumbers’ problem was as simple! But no, we’ve been hit with Bacterial Cucumber Wilt, which apparently is often fatal to the entire plant! Stupid striped cucumber beetles! They nibble on the plant, which introduces the bacteria, leading to the plant’s inability to move fluids. When I read some descriptions of the wilt, it kind of seemed like a plant-version of P.A.D., or a stroke.
Even after planting a few extra cuke plants, I think we have but ONE plant left, a small one, with 3 or 4 blossoms
That really does stink. Wilts and viruses are so quick and disappointing and they always seem to pop up in my garden, just when it’s too late to replant.
I thought I had mosaic virus earlier this month, but it turned out to be a bad case of powdery mildew. So I’m crossing my fingers that I eek out a few more squash and cucs, before the vines give out
Lynn, that was very wise of you. I usually try to re-seed cukes and zucs in June, for the same reason.
I have had problems in the past with powdery mildew and mosiac. But no more! I only plant cukes on trellises now, they get plenty of air and breezes blow on the leaves keeping them dry. And, you only have to hand water with a wand, sprinkler, etc., at the base of the plant thereby keeping leaves dry and decreasing the chance of the dreaded PM. As for mosiac, certain brands are almost totally resistant to mosiac. I have had bountiful cuke crops the last 2 years via cukes on a trellis.
i havent had much problems with my cucumbers. this is the second year in a row i have planted them and being in centeral florida i thought i would have a major mildew problem from all of the hot muggy weather. all of the rain dose make good juicy cucumbers though. i feel bad for all of you who dont get much rain and have to water your garden every day! once a week is all i have to do!
i planted my cucumbers on a trellas. thus not letting the plant touch the ground so mildew isn’t a huge problem. i also live in central florida and if that is what courtney is doing then that is why she dosent have a mildew problem probably.
help! is there any such thing as too much sun for squash plants? they start off beautifully every year then they fade and look all shriveled and pathetic – the biggest spaghetti squash i’ve ever gotten was only 5 inches long! i noticed that my friends squash gets shaded for part of the day and therefore the vines are NEVER exposed to harsh sunlight (unlike mine). and she has mountains and mountains of huge beautiful squash. my vines never produce more than 1 or 2 fruits – hers have anywhere from 5 – 10! my squash or in full sun from sun-up to sun-down… any advice would be hugely appreciated!
cheers!
Growing cucumbers on a trellis is a good idea. It helps with air flow and the dangling cukes grow nice and straight. It also makes it harder for animals to get to them.
But some of us have so much humidity, even a trellis isn’t going to stop mildew. Even the gourd arching over my arbor, was affected this year. You just have to catch it early.
Kat, sun should only help your squash. If they are starting to grow and then shrivel, it could be a pollination problem. Plants in the squash family need to be pollinated multiple times, to produce a viable fruit and each flower is only open for one day, to the window of opportunity is small. If a female flower isn’t sufficiently pollinated, the fruit will start to grow and then shrivel and turn black, starting at the blossom end.
To avoid this, you need lots of flowers, which means multiple plants. And you need to attract bees and other pollinating insects. Or you can take matters into your own hand and dust the female flowers with the male flowers, yourself.
thanks! i was wondering if pollination was part of the problem… unfortunately, one of the not-local logging companies clearcut their property next door to us and proceeded (despite my objections) to carry out a brushing treatment using glyphosate, which is very toxic to – get this – bees & fish!!!! i live on the west coast (bc, canada) and it has been super dry this summer but powdery mildew is back for the 4th year in a row… have moved my squash around every year and still it gets me…. i water from below, etc…. everyone says squash is easy to grow but not for me! planted it in tires filled with composted manure… about 5 plants per tire… am an organic gardener so no chemmies…. i should take a picture tomorrow and send it to you?
thanks!
Kat, I’d love to see your tire planters.
hi – i emailed the pics to you
Glyphosate is a herbicide AKA Roundup. It does not kill Bees, Birds, Bugs or Humans. It does not cause PM nor does it make the environment more susceptible to PM. Show us any study that says differently.
BC is a rainforest. Dry is relative. The moisture, watering at night, and growing plants too close together all contribute to the problem. Try different varieties, grow on trellis systems, etc.
So Chuck, how do you feel about RoundUp?
You are absolutely right, Roundup does not cause powdery mildew. I think kat’s point was that the environment around her yard had been altered by the clear cutting.
Kat said Roundup is extremely toxic to bees and fish which is just not true.
As far as Roundup it is one of the safer herbicides. It does not have residual effects and is translocated only through green growing plant tissue.
Lots of not so good and bad herbicides are out there that potentially cause problems. I worry much more about insecticides, which can be extremely harmful to the animal kingdom.
You’re right, Roundup is supposed to have little residual or unintended effects, if used correctly. The label does say not to spray on humans, pets or in bodies of water – which should be common sense. But very few people read the labels and even fewer follow them.
I know other organizations have done tests that show potential harm by Roundup, but I’m skeptical enough not to trust any study. There’s either a marketing angle, an agenda or an ego behind the vast majority of them. I wish I could take what “they” say as fact, but the facts just seem to keep changing,
And I agree about insecticides. Even the botanical ones can linger and do a lot of harm. Point well taken. Besides, you could consider all sprays as harmful in some way. Even a strong blast of water can kill some insects.