I'm not an expert gardener, but would say get rid of the ants and figure out what the "fungus" is. If the fungus is causing damage to your plants, figure out how to treat it without killing the ladybugs if possible. I wouldn't allow the ants to continue to farm aphids since they are spreading disease among your plants.

But now please wait for the experienced gardener's responses. :-)

Good luck.

OK, not an expert either, but what I have been doing is planting epazote around the base of plants that seem affected by ants and aphids they farm. One example for me: artichokes. Ants hate epazote, but it can get a little aggressive. Not a problem for me, I just cut it down. When I have too much, I use it as mulch for other plants that I want to keep ant (and aphid) free.

I also plant a lot of cilantro, it seems to attract lady bugs.

First - ants. With the exception of fire ants, I find them to be beneficial in the garden. I have watched them chew through a spinach leaf and remove a leaf miner. In California, once they started doing that I didn't have leaf miner damage (here in PA the paperwasps do the same thing - no more leaf miners). I have a large black ant (not carpenter) patrolling my squash. I haven't figured out for sure if they are hunting, but they are not doing damage. Ants will farm aphids (and, boy, has it been a year for them), which can be annoying. But if you have a huge ladybug population, I would just leave it. My ladybug larvae ate all my aphids in short order.

While it is possible that the fungus is spread by the aphids (and therefore, moved by the ants), I'd guess it is unrelated. Can you get a picture of the fungus? It would be easier to diagnosis. If you can, get a picture of both the beans and the melons. Could be two different things. Google pictures of powdery mildew. If it is that, the aphids and ants have nothing to do with it.

Bellatrix

I had ant farming aphids on my blackeyed peas, I was going crazy washing the aphids off the plants with water, and from what I hear the ants will put the aphids back on the plants. so I smashed the aphids and washed them off so the ants could not put them back on. That worked somewhat, so I decided to get those ant traps (tarro) I think it's called and I put them all around. It's the traps that the ants carry back to the nests and poision the the queen and other ants. That is working, I have few ants left. Now I go back and smash the aphids and wash them off, I have very few of both left!! the aphids were sucking all the juices from the plants and they were starting to turn yellow.

The only place I have ants is all over my sunflowers. I kept wondering if I should remove the ants, but the sunflowers are growing very tall and the ants don't seem to be harming it. I also noticed a lot candy striped leaf miners on my sunflower for awhile. Once the ants showed up, the candy striped buggers have been harder and harder to find.

Thanks for the advice everyone. I haven't taken pics of my melons yet, but I pulled the beans because they were just too far gone. I will try to get a pic of it the next time I'm out there.

I also had ants on my sunflowers one year. The ants farmed the aphids on them the same way they are doing the beans and melons this year. I later learned that aphids LOVE sunflowers. So much so that people plant them as a trap crop. And the ants love the aphids, so that's why they were there. My sunflower leaves were literally black from all the activity. Anyway, that's neither here nor there. Still trying to decide what to do.

Ants don't harm plants. The worst they do (other than the fire ants) is protect aphids which are usually easy enough to just spray off plants or they make mounds too close the the roots of a plant and it dies.

Other than that they are beneficials.

Your fungus is likely powdery mildew. You can try to treat it, but like most fungi, it's better dealt with by trying to prevent it. If it is powdery mildew, blast it with water to try to keep it in check. It's one of the few plant eating fungi that don't thrive on wet leaves.

In summary: blast both the aphids and the powdery mildew (if you confirm that is what it is) with as forceful a water spray as the plants can withstand. Leave the ants alone.

Another vote here one the side of the ants. Our native ants have been hit hard by competition with fire ants, and I hate to kill them if I can possibly avoid it.

Also, the average person doesn't seem to know that there are lots of different kinds of ants with all sorts of different lifestyles. I've heard people talk like all ants are fire ants, which they're not, or like all ants farm aphids, which isn't true either (though it sounds like you've got the kind that do). So not only do native ants get killed by fire ants, but also by people who think they're fire ants or think they're harming their gardens when they're not.

I must admit, the whole thing about the aphid farming seems really cool to me. I know it must be annoying if you've got an infestation, but still you gotta admit that's pretty amazing.

Anyway, I would say you should treat the fungus and leave in insects alone. See if the ladybugs take care of the aphids for you. I would be afraid that any pesticides you put on to kill the aphids and ants would get the ladybugs too, and there's no denying that ladybugs are beneficial.

update: no more ants nor aphids :), I do have ants in my zucs across the other side of the garden but they are not farming aphids so I leave them alone, I even think they are helping with pollination

Ok, for better or worse, this morning I hosed down the melons. I'm pretty sure that there is no fungus. It doesn't look like the powdery mildew that justaguy spoke of. I think it's just the aphids that are killing the leaves. Here is a picture of what the bad leaves look like after their bath this morning.

{{gwi:88519}}

Here is the other side of the patch with good leaves.

{{gwi:88520}}And just for fun, here is one of my melons. :)

{{gwi:88521}}

genghis_bunny

I've actually heard the exact opposite advice from what justaguy2 said for powdery mildew. The recommendation that I know is to NOT water from above and not get the leaves wet. Spraying with milk (1:3, 1:4) does help (at least in my garden). But, your pictures don't look like powdery mildew.

When I look at the pictures, I'm vaguely remembering a nutritional problem that I had in my squash in California. The leaves turned yellow, but the veins of the leaves stayed green. If I remember correctly, it was iron deficiency caused by high pH soils (often in dry regions of California). Have you had your soil tested?

But I think squash mosaic virus also causes green-veined yellow leaves. It is spread by cucumber beetles, not aphids.

Hope this helps,
Bellatrix

I've actually heard the exact opposite advice from what justaguy2 said for powdery mildew. The recommendation that I know is to NOT water from above and not get the leaves wet. Spraying with milk (1:3, 1:4) does help (at least in my garden). But, your pictures don't look like powdery mildew.

I agree that there doesn't appear to be any PM going on. However, the advice to not wet leaves is true of virtual all fungi pests in the garden except PM. PM is one of the few that doesn't thrive in wet conditions and as a result water blasts can be used to remove much of it.

Not to hijack, but in regards to the PM, does spraying it with water spread the spores? When I had it on my peas, I tried really hard not to wet them with anything but a milk solution because I was afraid I'd be washing it into the soil to rear its ugly head again. But then, I don't really know much about PM, aside from the milk spray remedy, in terms of how it's spread or whether or not it stays in soil.

Well I changed my mind about the ants (at least the ones in my garden) The aphids are destroying my black eyed peas, the suck the juices from the blossom so they peas grow a little then just dry up. Then I found aphids in the zucs. So now it's ON, a war on ants and aphids. Ant traps around the whole garden and instant grits and organic pestcide for the aphids!

I've heard that the sweet stuff aphids produce for the ants to eat (which is why they "farm" them) works like a culture for fungus to grow on. I have no idea what type of fungus it is, however.

I ran into the same problem - altho on a particular clump of perennials I had. They were virtually covered with aphids - as a matter of fact, at first I thought they were thorns, but I knew this plant didn't have thorns, that's how heavily each stem was covered with aphids. I did have some lady bug larvae around and every time I found one, I'd carry it across the yard and place it on this plant! I didn't want to spray anything to kill the aphids because I didn't want to kill the lady bugs - anyone know if inscecticidal soap kills lady bugs too? Anyway, I just washed the aphids off as best I could with the hose, but I notice they're back like nothing happened. The plant seems to be doing fine other than looking like it's covered with red thorns! Hopefully, it's working like a trap crop so I don't suddenly find "thorns" all over my veggies!

Lisa

No love for the Argentine ants here in my SoCal yard. They spread the aphids, seem to do the same with scale on my citrus, and when I water, they swarm up my legs and make me look like an idiot as I'm trying to brush them off before they are into my crotch. A few weeks back I spaced out for a few minutes, then ended up having to put my jeans straight in the washer and go take a shower because they were everywhere on me.

That said, I've failed to slow their spread down (much less eradicate them) using organic, chemical or strange Chinese methods. So I mainly focus on killing the aphids and scale. Insecticidal soap will kill the lady bugs and their larvae on contact, but doesn't present a threat once it has dried.