Fungus - Need Help

I'm now convinced that I have a fungus problem in my garden.

My plants are all tropicals.

The plants that have problems are all located in one area of the garden, and I don't think it's a coincidence.

The problem first shows as yellowing leaves, followed by brown spots on the foliage.

I bought a fungicide that contains copper (Lily Miller Kop-R-Spray). The pamphlet talks about using it as a preventative, but doesn't say much about curing a plant that's infected.

Is it too late for those plants? Does anyone have experience with this product, or with the problem I'm having?

Your input would be appreciated.

Steve

some individual pictures would be good. is that a canna leaf? we've been getting a lot of rain lately and sometimes fungus developes. i would cut off the bad leaves and spray with neem. sometimes a brown leaf spot is a lack of potassium. are they getting a good feed with micro nutrients? some plants are more prone to spots, like canna for instance. you have to be very careful with copper because it will kill ferns and bromeliads and burn other plants too.

They get plenty of micros.

I planted 3 mandevillas, and now they all look like this. I'm going to pull all of them - they're not going to make it, and they don't over-winter here, anyway.

I think it's a safe bet that I have a fungus problem. Now, I just want to treat perennials with a preventative, to keep the entire garden from getting this fungus.

Somebody told me that they've had much better luck with Spectracide than with copper, so maybe I'll pick some up.

spectracide is a potent insecticide but is not a fungicide. i would stick with the neem or even baking soda and water. i use baking soda for a variety of fungus problems.

Different plants get different fungi. If all the plants of different kinds are being affected in a bed, I would suspect a cultural problem. Such as: too much or too little water, overhead watering, too little or too much fertilizer, the use of inappropriate pesticides.
The canna leaf above looks like it has rust - the little spots. Cannas are notorious for that.
The mickey mouse ears look great in the photo, but they aren't susceptible to rust.
What plants are you talking about, and what are the symptoms for each of the different plants?
I would definitely check my watering habits. And don't use that copper spray. Many plants are damaged or killed by it. Copper is indicated in some bacterial problems, but not all.

Spectracide does make a fungicide - it's this:
http://www.spectracide.com/ProductCategories/RoseAndFlowerCare/SpectracideImmunox/

As I said in my first post, the problems first show up as a yellowing of foliage, followed by brown spots. It's happened to a canna, the 3 mandevilla, and a heliconia. They're all near each other, in the garden.

At first, I thought the yellowing might be due to a magnesium or iron deficiency. I treated a heliconia with Epsom salts, got no results, then treated with Ironite, which didn't help either.

We just had a period of about 3 weeks where it rained every day, usually heavily. The problems started during the rains.

I've used a pesticide spray on a couple of plants, but they're not showing any problems.

Fungus doesn't follow that pattern. It starts as spots and sometimes develops into yellow leaves. (There are some fungi that don't have the spots, like powdery mildew.) The yellowing of the leaves at the beginning usually indicates 1. overwatering, or 2. iron chlorosis, or 3. lack of nitrogen. Usually...

Since you have had rain for 3 weeks, I would think that may be the problem. Not only have they stayed wet, but they haven't had the sunlight they require. How is the drainage in that area? If roots stay wet, they rot, and then can't uptake nutrition or water into the plant anymore. The leaves turn yellow and will die. Since they are now compromised, fungi can easily attack. But fungi are not the cause of the yellowing. You have to deal with the yellowing. Again - drainage is critical.

Cannas can deal with a lot of water; some even grown at the edge of ponds. Not so the heliconia and mandevilla. But like I said, it looks like the canna has rust. You can spray it with a fungicide for rust on cannas, but it is difficult to control. You can also cut it to the ground and get rid of all the debris in the garbage (don't compost it) - they will grow back again. I have found it is really kind of hard to get rid of cannas. And it seems they always get rust and leafrollers. Which is the reason I have tried to get rid of them... :-)

Drainage is good in the garden - there's never standing watre, even in heavy rains.

I'm mostly concerned about the mandevilla. As you can see in the picture I posted, they're not going to recover. I'm going to replace them, and I want to prevent the problem from happening again, whatever it is.

Have you checked the amount of water the soil can hold? At the root level? It may not pool, but still be soggy down there.
Even with excellent drainage, the fact that you had so much rain, coupled with so little sun, would cause problems.
I would cut the mandevilla back, fertilize it with a liquid fertilizer, and see what happens.

I agree with ceejaytown about too much water being the problem--I've seen a lot of posts from people recently who've had a ton of rain and are having problems with their plants as a result. Even if your soil drains well, you can still get too much water--just because you don't have puddles of standing water doesn't mean that your soil a few inches down isn't wetter than the plants would like. The good news is once the rain stops and things dry out a bit, most of your plants should recover. Unless your mandevilla has gotten a lot worse than what you're showing in your picture I don't know why it couldn't recover--there are certainly no guarantees but it doesn't look that bad to me.

The plant in the photo began to yellow soon after I planted it. It never grew a tendril, and never flowered. The other 2 that I planted, right next to it, grew long tendrils, which climbed the trellis. They flowered, but then turned yellow, and now look like the plant in the picture.

I dug out the plant in the picture, to pot it. It grew a bulb underground, but it has almost no roots - the couple it has are less that an inch long. They appear to be healthy, as does the bulb, a light brown color, with no rot.