Asked on Jul 27, 2013

Yellowing Leaves and Brown Spots on Cucumber Plants

Renee F
by Renee F
I'm sure this question has been asked before but I cannot seem to find it. I've searched the gardening sites and I'm totally confused about what this could be. The same thing happened to our cucumbers last year and I would really hate to lose this year's crop and I would most certainly like to halt this if it's in the soil. I use Garden Tone and Fish Emulsion as fertilizer. We use drip irrigation but haven't had to use It much this year with all the rain we've received. The plants are still producing beautiful cukes but really worried because last year's plants became so ugly that I ended up pulling them up. I'm stumped! Thanks in advance
  13 answers
  • Lemor Sidis Lemor Sidis on Jul 28, 2013
    One common reason for yellowing cucumber leaves is a magnesium deficiency in the soil. You may need to treat your cucumbers with an Epson salt foliar spray. About one tablespoon of Epson salt to a gallon of water, mix it up and put in a spray bottle. Until the plant starts healing its probably a good idea to spray the leaves directly. Good luck!
  • Nancy Hand Nancy Hand on Jul 28, 2013
    Downy mildew is a problem during the cool, rainy days of spring and early fall. Spray with a fungicide.
  • Douglas Hunt Douglas Hunt on Jul 28, 2013
    I'll bet your fellow Virginian @Catherine Smith will have some suggestions for you.
  • Catherine Smith Catherine Smith on Jul 28, 2013
    I would suggest you take some sample leaves to the local county extension agent (check your local phone book under government for phone number) to determine exactly what is going on there. It looks very much like downey mildew, given our weather, with the all out rains in the spring and the latest heat wave. All of which make conditions wonderful for fungal infections. I'm just not real sure that's what you're dealing with and the agent should be able to tell you more. If it is downy mildew, you may be able to help the plants by removing some of the worst damaged leaves (discard those, don't compost) Treating the area with sulphur which is an organic fungicide alternative. Please use gloves and use caution if applying that, even though it is organic it can be toxic to your eyes and lungs. Next year, look for disease resistant types and move them to another location if at all possible. If were me, I'd also experiment by using corn meal all over the ground and soil. Corn gluten is a fungus suppressant, I've used it on my roses to control black spot (yet another VA special) with great success. It certainly won't hurt and is a really "on the cheap " possibility. LOL
  • David Moffitt David Moffitt on Jul 28, 2013
    I would suggest adding a teaspoon of baking soda, to a spray bottle of water. Do not use warm water, as when mixing, the CO2 in the baking soda will blow the bottle apart when shaking. Just give it a good swirl before spraying and spray the plant directly. Baking soda is a natural fungicide, and will stop what is happening. If you smoke, wash your hands before touching the plant, as that will bring on TMV (tobacco mosaic virus).
  • Renee F Renee F on Jul 28, 2013
    Thank you everyone! I'll definitely take it to the local extension office which thank goodness is just down the street! Catherine thanks for the tip about the corn!
  • Joan Rose Joan Rose on Jul 28, 2013
    water at the bottom .it is a fungus from watering
  • Melissa Gutilla Melissa Gutilla on Jul 28, 2013
    I def. am gonna try the cornmeal! I'm in VA also and I've been battling fungus on my squash, cucumbers and black stuff on my rose plant this year.
  • Catherine Smith Catherine Smith on Jul 29, 2013
    I don't know if it will work with veggies, ladies. But I do know it works with roses. ^-^ And you have nothing to lose by giving it a try. Please post or email me your results, if you would? I'd be very interested to know the outcome.
  • Su Su on Jul 29, 2013
    I am having this problem also on cucumbers and squash...will try all the above info ..Thanks for posting this and all the advice :)
  • Sharon Sharon on Jul 29, 2013
    I can't get rhubarb to grow
  • Douglas Hunt Douglas Hunt on Jul 30, 2013
    @Sharon you will get better results if you post your question as a new question using the red "post & ask" button at the top of the page. It's likely to get lost in the discussion of cucumbers here. Tell everyone as much as possible about where you've planted the rhubarb and what you did after planting.
  • Juanita J Juanita J on Jun 15, 2015
    When water splashes up from the ground with soil in it and lands on the leaves it causes bacterial wilt to start up. If the offending leaves are not cut off, it will spread through the whole plant. After planting if you mulch well you shouldn't have this problem.