Thanks for the question.

It is easy in early spring to think that if the yard is brown then everything died. However in your picture there are many large areas of just dirt. This is not winter kill but, as you surmised, the effects of Japanese Beetle grubs. During the latter part of summer 2020 these grubs ate grass roots that led to the bare spots this spring. The grubs are still in the ground but unlikely to do much further damage. They are now down into the soil and, most likely, quite large. At this stage any grub control insecticide is ineffective. They will emerge from the soil as adults within the next month or so depending upon the weather. These adults will start eating, mate, and lay eggs. These events will take place during June and into July. The eggs will hatch and become grubs in July and August. These grubs are very susceptible to chemical control at that time and then you should apply one or more treatments of grub control. In short, you want to kill these new grubs before they can damage your yard in late summer.

With respect to your current situation, here are a few suggestions:

1). Let your yard dry out for the next couple of weeks. When dry, rake it to remove all dead grass and to loosen up the bare areas.

2). Then seed all the bare areas. Grass seed germinates once the soil temperature is 50 degrees and above. To achieve this requires at least a week or more during which the daytime temperature needs to get to 60 degrees or higher. This will probably occur in late April to early May.

3). Apply your grass seed at that time. It will be important that you use the right mixture of seed. After seeding, water well.  It may be wise to cover the seeded areas with a slight layer of straw (NOT hay).  This will help the soil to retain moisture and to prevent the seed from blowing away.  Just leave this straw on your yard.  The grass will grow through it.  Also the straw will add organic material to your soil.

The following should give you further information on these and other points:

https://extension.umn.edu/yard-and-garden-insects/japanese-beetles

http://cues.cfans.umn.edu/old/extpubs/7664japanese/DG7664.html

https://www.bachmans.com/information/care-advice/japanese-beetles

https://turf.umn.edu/news/finding-right-grass-seed

https://extension.umn.edu/lawn-care/renovating-lawn-quality-and-sustainability

Good luck and please get back to us if you have any further questions.

Hi Lynn, thanks for getting back to us.

The presence of grubs in your yard indicates that they are Japanese Beetles. The fact that you have not seen a large number of adult beetles in your yard, given the type of plants you have, doesn’t surprise me. Adult beetles can fly significant distances to deposit their eggs. I suspect that the grubs that are now visiting you came from adults last summer in adjacent properties. Also on this same note, the grubs currently in your yard will mature into adult beetles that may fly elsewhere.

There is no good insecticide that will now kill the grubs currently in your yard. Often birds and skunks will be attracted to them and take care of them. Treating your yard in late June to early July with a grub killer, perhaps at both times would be fine. Hopefully this will forestall damage to your yard this fall.  Waiting until September for the second treatment might be too late.

If you have not already done so, planting grass at this time, or certainly within the next two weeks, would be fine. Covering with burlap would be preferable. There are two issues with using pine needles. Firstly, it takes them a long time to decompose and this process may increase the acidity level of the turf and deplete soil nitrogen. Secondly, once your new grass starts to germinate, removal of the pine needles is difficult to do without uprooting the grass seedlings.

The decision to use the services of a profession gardening service is, of course, up to you. I do not envision that they would be able to provide more information from what we have suggested. Of course going this route would save you time and effort. The following may help you:

https://extension.umn.edu/yard-and-garden - lawns

Good luck and please feel free to get back to us with any additional questions.