It depends on what specific plants you're talking about. Some products that prevent PM from spreading can be used on some plants but not others, so to give an accurate answer, we need to know which plants have the PM problem. Once PM shows up, it is almost impossible to eradicate it, so about the best you can hope for is to keep it from spreading.

Peas, it is on my peas. Peas which are the first I've harvested, because peas don't like me. It already has small tomatoes in the bed to take over after the peas.

For the pea plants, sulfur is the answer. Again, it won't kill the PM. It just prevents it from spreading further, and I am not sure it will be able to do even that in the weather we're currently having. Sulfur for use as a fungicide is available as a dust or a spray. There are some formulations of wettable sulfur that you can mix up to make your own spray, or you can buy something like Safer Fungicide in a spray bottle.

Most years, PM arrives with the high humidity of May and the higher heat of late May and early June. When it does, I just take it as a signal that the peas are reaching the end of their productive period since they do not like heat. We really have a fairly narrow window of opportunity for peas to produce here since they are cool-season plants and often our spring cool season is fairly brief. This year, our temperatures are better for peas than normal at this time of the year, but our moisture is worse and the rainfall is simply unrelenting.

I'd watch the tomato plants carefully to ensure the PM doesn't spread to them.

Fungi, once they start growing, are hard to stop as the fungal spores can spread in the air and in water, including rainfall. It is easier to prevent fungal infections (though in a year like this, prevention would be difficult to achieve because of almost-daily rainfall) in the first place than to control it after it develops.

Thanks. D H wanted peas, but he wants regular peas, the snowpeas are going like gangbusters, snap peas and regular peas not so much. I might get one serving for him. If it weren't for the fact that the golden snow peas are so beautiful I would cross peas off the list all together.

Peas are just that way. We tend to go from too cold to too hot too fast most years. I only grew regular peas for a couple of years. It seemed like it took forever for them to set, and then after you harvest them and shell them, you throw away this big bowl of pea pods/hulls and have this small bowl of peas to cook. It irritated me to be throwing away so much and having so little left to eat. I switched to edible podded peas and have been happier with them because there is less waste. I am sure if we had a cooler climate with milder summer conditions here that raising regular peas would be more rewarding.

So is it safe to save seeds from plants with mildew or should I trash the whole thing?

I think that if you save seed from pea plants with powdery mildew, you run the risk that PM spores will survive on the seeds, so I wouldn't do it. Remember that we harvest peas in their immature stage and eat them. In order to harvest seed, you have to leave the pods on the plants until the peas are fully mature. During that time, the PM is continuing to grow and spread, making it more likely the seeds may contract PM or at least have some spores clinging to them (this could happen, for example, if the PM spores on the pea hulls transfer to the peas when you are shelling them).

Now that hot and presumably humid weather is setting in, the PM will just get worse, so I'd yank out those plants. To me, when PM shows up on peas, that is a clue from Mother Nature that we're getting too hot for them to do well here anyway. I removed and composted my plants last week. You should only compost plants with PM if you have a hot compost pile so that the heat will kill the fungal spores. If you cold compost, your pile likely will not get hot enough to kill the spores. Next year, rotate the peas to a different location. You shouldn't plant peas in any location that has had PM in the previous two years.

Interestingly, I found differing opinions on line about the mildew effecting seeds, but the plants are pulled so it is something for next year. While the bed was ideal for the brassica and greens over fall and winter, I did some things that were not good this spring. We had plastic wrapped around the bed fall and winter as a wind break. It only went up the sides a couple of feet, but it did block sun from the lower leaves and prevented airflow. I left it there this spring to keep the dogs out. Might have been better if I had taken it down. At least we got some peas to eat. Moving on to the next crop. Tomatoes in that bed now, and they look ok so far.

You can find differing opinions about anything on the internet. (grin)

I never save seeds from diseased plants. There's enough diseases that will pop up on their own without me aiding and abetting the process by carrying over disease on seeds. Some people do save seeds from diseased plants. Some save them and do a bleach soak to try to kill the disease microorganisms. Different strokes for different folks, and all that.

Yeah, but if it's on the internet it must be true, righr? When the kids were young I must have read every book on child rearing in the library. When they started contradicting each other I decided some things you just learn by tial and error. As DH says, the kids can tell their therapists about our mistakes when they grow up. The point of the contradictory article, however, was that this guy had been saving seeds (peas) for some years, and the mildew didn't show up until late season, so it wasn't likely the seeds were the cause of it. Presumably, people had no choice but to save seeds before they were available for sale. That said, I don't know if it's worth taking the chance. Or, maybe some experimenting, in isolated beds would be in order. I may be too old for that kind of experiment. I need to find a young, strong back to do the heavy work in the garden. Should have seen me trying to juggle oyster shell at Atwoods the other day. It was way heavier than I expected and refused to go in the cart.