Leaves dying on a giant pumpkin plant after a hot summer

Downy Mildew? Probably.

I Changed my Mind

I mentioned in a previous post that my plant was stuffed. And in a video or a post to social media, I said that I thought the cause was because of the sun.

Giant pumpkin next to a garden gnome

I’ve changed my mind.

Yes, the heat and UV from the sun take its toll. But it looks like something else.

I’ve been going through a bunch of files to help organise it better and have all the information on hand when I need it.

In one pumpkin diseases PDF I had, they talked about Downy Mildew. The leaves in those photos look almost similar to my plant.

So I’m now leaning towards that.

Downy but Not Powdery

I’m pretty sure my plant got downy mildew.

There seems to be different information out there on what and how it affects plants. But from what I’ve read, here’s the basics.

  • It can affect pumpkin plants
  • It spreads through the plant fast
  • It can look different, as there are different strains of it so not the easiest to identify 100%.

Whatever this thing is, if it isn’t exactly downy mildew, then it’s some sort of bacterial wilt. And that’s not good for the plant.

The aim is to keep the plant as healthy as possible and keep it alive for as long as possible.

What’s the Difference?

Powdery mildew looks like a white powder that spreads across the leaves on the plant. This usually happens near the end of the growing season for most people.

But it can happen earlier.

Humid damp conditions help this mildew form.

I’ve been lucky with the location of the tiny patch and having a lot of airflow.

Now downy mildew is a bit different.

It can cause tiny orange – yellow spots on the leaves. These can then turn into angular yellow to brown lesions on top of the leaves. Leaf veins restrict these lesions. Well, according to one source I read.

Sorta looks like the plant is dying. Just like how my plant looked.

What Causes It?

Fungal spores are the culprit.

The downy growth which is actually masses of pathogen spores call sporangia can be seen with a 20x handheld lens, apparently. According to this website, https://cuccap.org/disease-management/squash/downy-mildew/

Downy mildew is not as destructive on giant pumpkins as it is on other cucurbit crop types. The leaves aren’t killed as rapidly.

Which is great to know. But still sucks.

These spores could have come from anywhere. I’m wondering if growing in a small area with lots of neighbours around increases the chances.

How I Should Have Handled It

I should have done preventative spraying early on.

This would have helped control or slow down any fungus type growth that could happen on the plant.

Combined with removing any leaves as soon as any changes were seen. This would have prolonged the vine and plants life. Which should have allowed the pumpkin to grow more.

It’s something you need to catch fast. Treat it and see if that slows it down. If not, try another product.

Here’s a couple of products I saw the other day at Mitre 10

There are a few out there that can help with fungus or blights on plants. Which one is the best? Not sure. But moving forward, I will make sure I have 2 different types on hand.

Ready to deal with this problem.

To Wrap Up

There are always things to learn when growing things.

So if you’re not happy with the results, make notes about the different areas of growing and improvement next year.

I’ll have my end-of-year wrap up post coming out in the future and I’ll cover my season. What worked and what I should have improved upon.

Let me know what you wish you’d done this season.


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