Downy Mildew?

It has been a while since Plants On Deck descended into the university extension wormhole. Not because there haven’t been reasons to, but because it’s a great big time suck that can usually be summarized thusly: your plants are sick. There is no cure. They will die. (Therefore, do we really want to know what those spots on the blueberry leaves are?)72714_scabbycukesBut once again, just as the Supremo, Speedy Green, and General Lee cucumbers are producing, their leaves are yellowing, spotting, and withering. It’s a good thing that a good half dozen fruits have been harvested already (testers like the Supremo best — light, citrusy, great crunch) and another dozen are on the vine, because things aren’t looking too promising.

While mildew isn’t readily apparent, POD’s plants looks suspiciously like the ones described on Clemson’s and the University of Minnesota’s extensions as having downy mildew.

They’re sick. There is no cure. They will die.

A Year Ago Today…

…POD was lamenting the aphid infestation that wiped out the cucumbers and melons. And the looper infestation, that wiped out the chard. And the whitefly infestation that wiped out the tomatoes. And, well, you get the picture.

This year, knock on the little blue deck, hasn’t been half bad, pest-wise. But now there’s this heatwave thing. And this whole lack of rain thing. And the whole taking off for a long weekend with 100+ temps in the forecast thing.

Adam F1 and White Wonder Cucumber
Poor Adam

So, enjoy those cucumbers while they last.  Remember Adam F1? There’s a seriously good chance that it’s been over-watered  or it’s got bacterial wilt. But either way, it’s wilty and yellowing.  It’s a pickle, isn’t it? One waters to protect plants from the hideous heat. Both water and heat can kill…so, to water or not?

It’s been a productive and delicious plant: 11 and counting. But POD fears its days are limited.

Mildew Voodoo

Oh, the plants on deck are happy. So happy. Sure, they get plenty of water, but nothing beats a nice, gentle soaking from Mother Nature.

Or does it? In this South Philly zone 7(ish) garden, summer showers are usually followed by a tropical heatwave. Tropical heat + cucurbits = powdery mildew.

As the ever-patient garden widower would would mumble, “Damn farmers, never happy.”

Powdery mildew  (a fungal disease that’s no fun at all) is one of the inevitable POD kill-joys. So this year, we’re giving You Grow Girl’s mildew spray (sorta’ — POD’s adding a little milk to the mix and shrinking proportions) a shot and hoping that it’ll keep those filmy white spots away from the Boothby Blonde, True Lemon, Minnesota Midget, and Mystery Melon.

POD's Powdery Mildew Spray

POD’s Powdery Mildew Spray
3/4 tsp. baking soda
3/4  tsp.  thick, non-detergent soap
2 c. water
2 c.  skim milk

Mix the ingredients together, pour it into a spray bottle. Shake. Spray the mixture all over your plants, make sure you hit the undersides of the leaves. Apply once a week and after a rainfall.

Diagnostics

scientific diagnosis
scientific diagnosis

Well, the lovely Minnesota Midget seems to have come down with a little something.

If a variety of online diagnostic tools can be trusted, it looks like Minnie may have contracted a case of ulocladium leaf spot. Which may be even more fun to say than Walla Walla, Washington. Certainly more fun alternaria leaf spot, which is another candidate.

At any rate, there’s not a whole lot than can be done at this point except treat the affected plants with a fungicide (copper sprays are recommended by some but POD’s trying out organicide) and snipping off affected leaves.

To avoid spotty leaves, gardeners should NOT:

  • water the leaves of cucumber and melon plants.
  • dash outside and run their fingers through the rain-dampened leaves.

To avoid spotty leaves, gardeners should:

  • water in the morning, before the hours of high heat.
  • water the soil directly.
  • fertilize regularly.
  • use organic fungicides regularly.
  • use clean, unaffected soil for future plants.