Many people become spooked by the white flies or moth looking critters in the lawn. By and large those are harmless. Web worms form a web in the grass for protection from birds. If you don't see webs, then you have some other issue. If you do have webs, then there is a biological control called BT Worm Killer. It contains bacillus thurengiensis. BT is a disease in caterpillars. In my experience it kills them on contact but that is supposedly not the mechanism. One small bottle is a life time supply and it lasts for 20 years on the shelf. If you mix a little molasses in with the spray for the BT, it seems to dramatically improve the longevity of the spray. Grubs that live in the soil can be killed with the Guardian nematodes. This is a good time of year to spray for fleas and ticks. If you are concerned about lawn grubs, wait until May or June. If you see a lot of beetles swarming your porch lights, that is the time to spray. Those beetles (either June bugs or Japanese beetle) are the buggers that get to your grass from underneath. 90/10 is the mix of fescue to Kentucky bluegrass. That is measured by weight. Due to the weight differences between the two seeds, it provides about a 50/50 coverage. I have not heard of keeping the lawn wet to kill grubs. Interesting approach if it works. One thing that will happen by keeping the lawn wet is all the weed seed in the soil will sprout.

You could spend the money to buy those nematodes and they would find other ways to survive, but since there are no grubs to be found, why? For grubs to damage a lawn there needs to be a fairtly large population, 10 per square foot. Also, in May any grubs that might be in the soil will be pupating, preparing to morph into adults to emerge as those adults in June. A better time to apply nematodes, or the Milky Spore Disease, or any other means of contol of grubs, is early to mid August or about when the grubs hatch from eggs and are small enough for environmentally safer products would be more effective at control.

My soil in Long Beach had nematodes. I planted every year, using sturdy transplants from 4 inch pots. I always made certain the kind of tomato I chose had nematode resistance -- when you look at labels, certain capital letters will follow the tomato's name. If they're all present, you would see VFFNT -- You need a kind with the N. Even though nothing is 100% resistant, you can get a good crop. Other keys to success are these: 1. Mix in at least 2 inches of compost every time you plant the tomatoes. 2. Be certain you keep up with adequate water; if not, the impaired roots won't be able to keep up with the tops. 3. at the end up the season, dig up the rootball, immediately wrap and trash it. Don't drag it to the trash can because you'll leave a trail of contaminated soil behind you. And that's a very bad thing. Oh yes, always work in your infested bed the last thing, then clean your tools thoroughly before putting them away. Or perhaps reserve a 2nd set of tools to use only for the contaminated bed. Yes, solarization has been tried. But that effect goes only so deep, not enough to protect a vigorous root system of a tomato. I don't have any experience w/nematodes. But I doubt the effect is 100%. Nothing is.

I know you are a regular here, but where do you live? In the south you can use BN for fleas and ticks in about February. You can use them anywhere in July for grubs, chinch bugs, and anything else. Yes they do need a host and a lot of water to move around from host to host. The best time to apply them is Day 3 of a 4-day rainstorm. When they have a host they will multiply crazy fast, but as soon as the hosts are gone, so are the nematodes. I get mine locally, but he gets them from here.