We may be talking apples and oranges here because to me, the water permeable weed fabric is not plastic; it's also light permeable and needs a good layer of mulch on top to keep the weeds down. But first, what is your purpose? Do you intend to plant transplants through the fabric? Will you plant seeds through the fabric? I may be missing the point but regardless of the answer, the fabric I have seen has no problem with water getting through and you will not need any irrigation. A more likely problem might be light penetration and weeds growing underneath.

Agree it's the wrong forum but personally I wouldn't use it unless you have a very active hot cooking compost pile. Then again if that is what you really had your soil is already contaminated anyway. Suggest you do some research into the disease and learn how it thrives and survives and then decide. Dave Here is a link that might be useful: Composting forum

Most likely if the temperatures of your compost pile get into the 135 to 145 degree F range that should be sufficient to kill those disease pathogens. If the temperatures do not reach those levels then time will also work, although several years would not be necesary. You may want to consider being careful where that compost is put and what you plant there, the precautionary principle.

Composting is not rocket science as much as some purists would like the un-enlightened to believe. In my experience, it's extremely hard to do it wrong and my experience has been that one would have to work hard to cause ill effects. (Though if you believe that the natural way of disposing of used motor oil is to compost it along with your kitchen scraps and then spread it around your lettuce or if your boy friend is prone to dumping paint thinner anywhere he thinks the EPA won't find it, then you may be heading towards complications in your compost, your garden and your health.) Like life, composting is not a race and if it doesn't get super-hot, the material will still rot in time and be of as much use. I read endless posts here from those who worry far too much about "doing it wrong." Should I compost my coffee filters? Should I run my kitchen scraps through the blender? Oh, no, my compost has cooled down! I think my carbon/nitrogen ratio is off and how can I face my family after such a failure? Should I measure all woody material with a micrometer after chopping it up with surgical instruments? How do I measure the volume of air relative to the solid matter in my compost? And on and on and on (as Kurt Vonnegut was fond of saying.) If you only think that you may have introduced a few, and only possibly diseased plants into your compost, you probably have extremely little to worry about (as opposed to those who have had acre upon acre of crops wiped out by disease and then said, what the Hell? Let's throw all those disease-ridden plants into a pile, turn it once or twice and see if we can get lucky by spreading it around our new seedlings.) Nature constantly spreads a little disease all around our gardens and all around our bodies. For the most part, our gardens and our bodies build up natural immunities to all sorts of things that we would naturally be horrified to know about in detail and I'm sure there are websites where horror-stricken people write about all the god-awful things that put their lives in jeopardy: "Just today, on the bus ride home from work, there was a guy with a runny nose, and I'm sure that he sneezed in my direction. I've heard that there may be a new flu strain from Asia and this guy had a foreign look to him. In fact, I verified it with his seat mate when he left that he did, in fact, sneeze. Now I'm very prone to colds and I'm sure that...." And on and on and on. Not that I'm trying to belittle your concerns. Just that some here would have us believe that this esoteric, mystical art of composting is so much more than just piling up organic matter, adding a little moisture and mixing it now and then. Ma Nature, as far as I almost know, never calculates carbon/nitrogen ratios when composting leaves and brush on the forest floor, nor does she dispair when she doesn't achieve a "hot pile" with internal temps of 140 degrees or more, since everyone knows that a hot pile is critical to to the very survival of the species, yet she seems to have a pretty fair rate of success, at least since the last Ice Age. My advice: Don't worry; make compost. Wayne