Is this Powdery Mildew?

[abellote]

Hi...

First time hop grower directly from Brazil. A friend of mine got some "UK type" hops seeds, got them to germinate and gave me some plants. At first they were slow to grow in a small planter but as soon as they hit the ground the vines are growing 2-3 inches a day. Here is a photo of the plants:



But what got my attention is the appearance of some leaves. Some are showing some white or yellowish spots. I think it may be nitrogen deficiency since some of the vines also are showing a reddish color, but I'm afraid it might be some powdery mildew.

Can you guys take a look at the pictures and give me some advice. I don't know if it's important or not but the dots don't spread or grow any bigger. Is there any way to be sure? Maybe some baking soda spray in one leaf to see if it helps?

Thank you.

 

[day_trippr]

I dunno, but I would say no, that's not mildew, Powdery or Downy or otherwise.
Probably just random sun exposure effects.

Powdery Mildew is clearly a colonizing thing and before it totally engulfs a leaf you can see the colony bounds...

Cheers!

 

[DarkCoder]

But what got my attention is the appearance of some leaves. Some are showing some white or yellowish spots. I think it may be nitrogen deficiency since some of the vines also are showing a reddish color, but I'm afraid it might be some powdery mildew.

Don't worry about reddish color of the bines, that is normal. On some variety, the bine is almost completely red and on some others, the bine can be totally green. Some have reddish stripes on the bine.

Does the white spots can be washed away from the leaves with water ? What is your wall made of ? Lime ? Is the whitish think coming off from your wall and burning the leaves ?

 

[PapaBearJay]

That is insect feeding. Actually, if you observe the second photo you can see the creepers walking on the leaves.

 

[abellote]

Thanks for the tips.

DarkCoder, yes that's lime and no, the spots are not washed away with water. I also don't think that the wall is causing this since the leaves already had those marks when I got them off the planters and to the ground. They were in a different place away from this wall.

On this post: https://www.homebrewtalk.com/f92/powdery-mildew-336685/ I found a good explanation from theredben. I think that might be my case. Just some water spots.

I think I'm just to worried. It was a hard work getting the seeds, germinate and growing it into a full plant that I don't want to lose it for some mildew.

 

[abellote]

That is insect feeding. Actually, if you observe the second photo you can see the creepers walking on the leaves.

That's another good theory. Any good way to get rid of them? Is it harmfull?

The hops already have a few spiders living in, with webs and all. I thought they would get rid of some insect. Time to find some new spiders to live there.

 

[day_trippr]

Wait - are the webs on the under-side of the leaves and so fine they're nearly invisible?

That would be spider mites. Not predatory - except on the plant vital fluids...

Cheers!

 

[PapaBearJay]

DT is right, that does actually look like mite damage. If you see fine-webs on the leaf undersides or on new growth, start spraying some insecticides as a treatment. Spider mites are not your friend.

 

[abellote]

Wait - are the webs on the under-side of the leaves and so fine they're nearly invisible?

That would be spider mites. Not predatory - except on the plant vital fluids...

Cheers!

I was actually referring to regular garden spider, but yes you're right. It is spider mites. Take a look at the photo. They are very small black mites and I can find some very very thin webbing.

Any good solutions? Yesterday I sprayed the hole plant with some soap and water solution but today I found the damn mites again. No success there. I may try a different soap,maybe regular dish soap but I read it should be a non detergent soap!??

Thanks for the help.

 

[day_trippr]

Yup, Two-Spotted Spider Mites. Ugh.

I've used Doctor Bronner's Castile Soap, roughly a tablespoon gently swirled in a quart spray bottle, then saturate the underside of the affected leaves.

The soap is non-detergent, though to be honest I don't know if that matters or not. We had a bottle of it around for washing the doggies so I gave it a try...

Cheers!

 

[abellote]

Here in Brazil it is very common to spray a tea made from dried tobacco leaves to control aphids. I was thinking on trying this. Any ideas??

 

[WayFrae]

Here in Brazil it is very common to spray a tea made from dried tobacco leaves to control aphids. I was thinking on trying this. Any ideas??

Nicotine is a natural insecticide so it should work just fine. I have used a mixture of 1 teaspoon of Dawn dish soap, 1 teaspoon of cayenne pepper, and a quart of water in a one quart spray bottle with good results. I spray the underside of the leaves and leave it for 20 minutes or so and then rinse it off with clean water. I did this every day for about 3 days before they stopped showing up.

I have heard that it is not good for the plants to use this solution in direct sunlight. It is best to do it in the early morning or late evening.

 

[HALIFAXHOPS]

I use Neem oil and it works great. 2 OZ to a gallon of water.

 

[abellote]

I sprayed a Neem Oil solution today. Let's see if it work out... Thanks for the help.

 

[day_trippr]

Whatever you try, stay on top of the mites.
If they "bloom" you'll be stunned at the carnage.

I hate spider mites. Last year was the first in four that we didn't have to deal with the li'l bastids, and it was truly a relief.
The first three years it was a hammer 'n' tong war...

Cheers!