Orange Spots on Leaves, is it Rust?

[therevverend]

Recently a plant developed orange necrotic type spots on some of it's leaves.

It's near a neglected hops plant, haven't been feeding or watering it properly this year. I don't know anyone who brews at the moment so I figured it's a waste of fertilizer. The hops has developed a rusty orange on some of it's leaves. I'm wondering if the ailment hopped onto my ganja.

Some of the ganja leaves look a bit rusty too. Check out this one.

Doesn't look the same but they're different plants and the ganja is much healthier then the hops. Any ideas what it could be? Any treatment recommended? It hasn't shown any deficiencies, every leaf on it and it's neighbors is healthy green.

 

[DrLongbottom]

I'll take calcium deficiency for $500 alex!

 

[therevverend]

That's a good call, looks very similar to calcium deficiency. I'm pretty sure that's not it. I added lime, epsom salts, manure, very well fed. It's the only plant showing the spots. It's not as big as other, healthier plants. The new growth is green and healthy, the entire plant is green and healthy, except a few of the leaves which have the spots. There haven't been any new spots in the last week.

The orange color has changed to yellow and no new spots. A few of he leaves have the orange tinge the hops has. Earlier in the season a couple of my other plants had a bit of PM. When it rained the PM disappeared, replaced by yellow spots. I'm still thinking fungal.

 

[Muarco]

Definitely not a calcium deficiency. Looks like pollen or some dusty material being transported by the air. Just my 2 cents.

 

[ramse]

from the book "What's Wrong with My Marijuana Plant?"

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could it be?

 

[OG_NoMan]

I am guessing some kinda bug/mite. To me it looks like the rust color spreads out from the dots that look like a bite from some kinda leaf sucking critter. I hope you solve your problem. Good luck!

 

[therevverend]

To rule out calcium deficiency I gave my plant a shot of lime along with a dose of kelp meal high in calcium. It's still producing the orange spots.

I'm certain it's rust. Definitely not a bug, I've inspected the plant carefully. The spots only appear on the oldest leaves. I have a pear nearby which develops rust at this time every year. It doesn't harm the tree, just makes orange rust spots on the leaves.

It's strange that only the one plant is effected. I've seen this with cannabis diseases, a plant is genetically susceptible to the disease or deficiency. It doesn't seem to harm the plant, it's still vigorously growing it's flowers. I've removed most of the rusty leaves but it was so many you wouldn't notice they're missing. They're the older shade leaves anyway, I don't like to remove them but it may be letting more light into the center of the plant.

I'll keep an eye on it, do some more research, let everyone know how it goes.

 

[therevverend]

It's harvest time and the plant is still showing the effects of the disease. Check out this sick leaf.

You can see the healthy leaves and flowers below but you can tell there's something wrong with the older leaves. If you look close you can see the orange spots and the necrosis starting at the tips. Still only the one plant has it, must be genetically susceptible. I'm sure it's fungal blight, brown or black blight. Something to watch for next season.

 

[Teddybrae]

So ... "older leaves". Does this mean the sickness is caused by mobile elements? Like all the goodies have gone to the small leaves and flowers?