First off a warning. DO NOT try and kill bindweed with tillage especially rototillers! You chop it in little pieces and under the right conditions every little piece regrows into its own plant. You can go from 1 or 2 plants per square foot to something like 100 plants per square foot in a single quick go round. This lesson was learned the hard way. Now I noticed in the loose fluffy soil where I had not walked or caused compaction that I could run my fingers through it and easily rake these young plants out of the soil and this lead to another plan. I raked everything I could out and tilled again being careful to leave no compaction areas this time. The stress of regular tillage combined with raking all the plants out would kill it was the plan After 2 cycles of this I had more plants below the tillage layer than I started with. This was NOT working. Ended up covering it with plywood and every time a plant poked its head up beyond a sheet I flipped that sheet up and pulled everything. This technique will get it eventually if you can do a big enough area. Be aware the kill in from the edges for about 2 to 3 feet is poorer. Water for best growth but keep it away from light so you are always pulling up white plants. Be aware you are probably going to need 3 years with the ground covered mimimum. Notice there is a lot of
mouse and earthworm activity under the sheets. The mice are cat or dog food and fun. Late fall before the sheets are covered in snow and early spring after the snow has melted just take your pets with you. You will scare them the first couple times while flipping sheets but eventually they will get where they are standing at the edge of the sheet waiting for you to flip it. Now you say I can't afford plywood. Here is how you might. Places that get
pallets of heavy bags in will often have 1/4 thick roughly 4 foot squares of plywood or hardboard like masonite that was used as a pallet topper. Or you can make your own by gathering a bunch of the smaller scrapes from what a construction company puts in the dumpster and gluing them in over lapping layers into bigger sheets.(be sure to use a waterproof wood glue)
Given what I have learned in the last few years here is how I would try this if I tried again. I would start by covering the ground. Weaken the plants first. Then pull and rake all the plants out I could from the first growth cycle under the sheets. Then I would till. The thinking being that the plants are already weakened by being starved for light and now when I tilled the little pieces should be weak and they won't have light to restart so when they try and regrow they should mostly die off. This will hopefully leave the just deep root and
seed bed layers as the weed source. While I am tilling I would work large quantities of organic material in and a nitrogen source to help it decay. Do a mixture of long life like wood chips and fast decay stuff like grass clippings. The thinking here is that I may as well be building the soil for future use while at the same time I am trying to create optimal growth conditions for my lightless plants. I want them to waste all the energy possible trying to grow. By adding decaying matter I am adding nutrients, concentrated
CO2, worm food and raising the moisture holding capability of the ground optimizing for growth but without light. Any time I have it uncovered to deal with plants poking up around the edges water for good growth and sprinkle some more leaves or grass clippings on the surface of the ground for best worm food. Worms love this protected habitat with no care. That much is obvious from the tracks when a sheet is lifted. So if they are getting good food on a regular basis they should breed like crazy. Now I might uncover the area for a bit in the spring and maybe late fall with the goal of sprouting any seeds that would sprout. The minute I saw any kind of green growth recover it so no plant builds energy. At the end of this I should have ground that has been undisturbed for at least 2 years(and likely more) for good decay fungal growth , with good organic content, lots of worm activity and the surface seeds mostly germinated to death. This should be about as close as possible to the ideal place to start new bed when finished. That leaves one question that I think I would try both ways. In the past I have always removed the plants once they poked up around an edge. The thinking was that I was taking all of that energy out of the system and the plant would have to start over from scratch. But I wonder if maybe instead I should be coiling the bindweed back to the middle. The thinking this way is the more plant it has to support the faster it should starve to death. So if I can get 20 or 50 feet of bind weed curled in a circle in the middle under the sheet the roots have to maintain all that plant which should drain them faster. The little spurts of energy of getting around the edge of the sheet will go to more and more plant till it bleeds itself dry. Since it mostly only grows from the tip taking the tips back to the middle is giving basicallythe same distance that must be grown that pulling it does minus the bit of root pulled. Maybe off center the plant tip so it is pointed east but closer to the west edge of the sheet so it actually will likely grow farther than from the middle to escape? I think I would try this last two both ways to see which got better results.
The only other permies compatible method that I know works is pigs. Pigs will kill nearly anything short of
trees if kept in concentrated pen with it long enough. Keep the ground watered so they can root around. Pen pigs over the patch for a couple years and you can kill it. Any root that pokes its head up they will kill and dig out down a bit besides. You will end up with basically dead soil but you get rid of the bindweed in the process. We had big patches of bindweed in a corn field that we put pigs on for a single summer. They reduced the size of the patch by about half for the next year and even where it grew, it was thinner.
Finally a possible method to try from something strange I have noticed in the garden over the last few years. Because of various family health problems the garden has been way under utilized the last few years. So figuring I was building organic I have been
watering weeds and mowing to limit seed production. The first year there were a bunch of small clumps of lawn grass from using seedy grass the year before as mulch in the garden. Figuring I could transplant those back out I mowed around most of those the first few years till they got big enough to go to seed and them mowed them to scatter the seed. That means over about 5 years I have covered about 1/3 of the garden in lawn grass by doing nothing but mowing and watering.(my garden is way better lawn than my bit of real lawn) Now it happens to be the third where I had bind weed problems the worst and along to nanking cherry rows where I had really bad bindweed problems. The lawn grass mixed with a bit of brome and a bit of a something similar to sword grass that isn't a bunch grass has crawled out under the nanking cherries. As this grass has spread the bindweed has disappeared. At first I thought it was simply hiding down in the grass but I looked for it this last summer and it is gone. So my question is: Will lawn grass push out bindweed over time?? Easy enough to try. Take a shovel full of established turf and plant it close to where you want to take the bindweed out and encourage it to spread.
Bindweed and morning glory are different plants. Bindweed is harder to kill because it does more tiers of root layers in the ground but morning glory spreads faster from seed.
While you may be able to burn it down with lime I can tell you that my unmodified soil pH is 8.7-8.8 with high salt content and heavy clay and bindweed grows fine in it so low boosts in soil pH will not work.