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View Full Version : Grubworms, grubworms........


yardmonkey
09-06-2003, 10:08 PM
What can we say about grubworms?

They say the way to recognize grubworm damage is to pull up on the grass and if it lifts up like a piece of carpet, then the brown spot is caused by grubs. This is because they have eaten the roots so there is nothing to hold the grass down. I have seen this and it seems like that is a problem worth doing something about. Of course there are all kinds of chemicals that people use for this.

There are two organic remedies I know of - milky spore disease and beneficial nematodes. The milky spore seems to be a great solution - BUT - they say it does not work on the specific species of bug we have in Oklahoma. The grubs are from June bugs and related types of bugs. I guess it could be useful to sort out those species. The beneficial nematodes may be not quite as reliable of a treatment, I don't know. But there are other problems with them. Such as you can't buy them anywhere around here - you have to order them. And they have a shelf life. And they are expensive. And there are all different kinds and it may take some research to find out what kinds would be most effective. And they don't persist in the soil from year to year, whereas the milky spore supposedly lasts a few years (or longer?)

Besides the damage that the grubs do there is the damage done by critters digging for the grubs. Not sure what all animals do this, but I have seen the damage done by armadillos - in residential neighborhoods bordering on woods.

Most books say that you don't really have a problem unless you find X amount of grubs per square foot. (easy to dig out some sod and poke around and see them) So I guess it is normal to have some grubs and if there aren't many they won't do enough damage to notice. Not sure how many there needs to be before the critters start digging, so that may be a totally separate problem.

I have read that one defense against grubs is to just have a healthy lawn, so that the grass can withstand having its roots nibbled on a bit. It makes sense that the weaker and thinner the grass, the more it will be harmed by having grubs eating the roots. And this is a seasonal thing. They go deeper in the soil in the winter and eventually fly away, so at least the grass gets to recover.

Anyway, thats about all I know on the subject. Any comments on the above could be useful.

Are there other remedies?

Preventions?

Experiences with nematodes? Milky Spore?

What I am really interested in is why the grubs are more prevalent in one lawn than another. What conditons are they looking for? I think I read somewhere that they like lots of organic matter in the soil. So I hope that improving the soil organically is not going to make the grub problem worse. But it seems like I have seen this mainly in really poor lawns. What I would like to believe is that just developing a really healthy lawn will prevent the problem, but I don't know.

If anyone knows just what species we are talking about, that would be useful, especially why are they different in Oklahoma?


Grub talk anyone?

yardmonkey
09-06-2003, 10:42 PM
Also - I just now got around to reading the lengthy thread titled "Organics" that was moved here from the Commercial Lawncare forum. VERY interesting stuff, don't know how I missed that when it was going on. Anyway, there is a little discussion of grub treatment there.

Dchall_San_Antonio
09-06-2003, 10:55 PM
All I know about milky spore is that it is a disease. It seems to be an established defense against grubs in the north but has not caught on broadly in the south. Don't know why.

Beneficial nematodes are tiny creatures that carry a disease that infects the June beetle grubs and a very few other species. There are many species of nematodes that are specific to which insects they are able to control. Armed with this information, the people who sell beneficial nematodes usually include a variety of nematode species in each batch so that more than one or two pests are controlled. So you might get a product that controls fleas, fire ants, ticks (in late winter only), termites, grubs, chiggers, and something else. This is how nematodes are able to work only on selected pests and not on the beneficials.

The nematodes eat a bacteria that happens to be deadly to their hosts. Apparently they are sloppy eaters and carry this bacteria around on their mouth parts. When the nematode hits the soil it starts looking for a host. When it finds one, it enters the body through any conveniently sized orifice. If the orifice is not conveniently sized, the nematode cannot enter. This is how the nematodes can become species specific. Once inside, the host is infected with the bacteria. The nematode lays eggs and leaves to find another host. The bacteria runs rampant killing the host in 24-48 hours usually. Once the eggs hatch, the babies (I'm not sure if nematodes have a larval stage or they may be hatched to a different sort of life cycle) start to eat the bacteria that has taken over the host's body. Then the babies exit the body to find a host for them to lay eggs in. The beneficial nematodes will die in a drought or if they run out of hosts. Ideally they will run out of hosts. After all you are applying millions to take care of a population of hundreds of pests.

As yardmonkey said, they are pricey. You might simply price them into an annual program with at least one spraying planned in the early spring and another possible later in the summer.

I would like to know why they seem to attack certain lawns, too. I never have gotten them. I never seem to have much in the way of June bugs around the lights at night, either. But my friends on the other side of the neighborhood might have as many as a thousand June bugs on their lights at night.

I know this message is more educational than helpful. Hopefully others will have had real experience with them.

GroundKprs
09-07-2003, 03:34 AM
White grubs are the larval stage of various types of beetles. Many refer to them as Japanese beetles, but there are areas of the country not yet affected by Japanese beetles, but there are still grub problems there. There are several different types of grub species, with the specific species depending on your geographic location. Exactly identifying your pest problems will help you to manage pests now and in the future. To ID a grub, you must look at raster pattern (hairs near the grub's anus). Grab a grub and a magnifier and head for http://ohioline.osu.edu/hyg-fact/2000/2510.html. Also many other places on web and in books to help you here.

In my area, I find the most predominant species causing visible turf damage is the masked chafer beetle grub. This helps in control because the masked chafer does not feed after it pupates into winged adult. Adult function is basically just reproduction. So if you have masked chafer problems this year on a site, it's likely you will have them again next year. Jap beetles may travel a significant distance away from hatch site in search of food during it's adult stage, so their reinfestation of the same site is not as predictable.

Grubs damage turf by feeding on the roots of the grass. They work at a certain depth, just under the surface, so their action is like cutting the roots just underground. If there are enough grubs in one area, almost all the roots are cut, and turf can be lifted like fresh cut sod. You see the damage, a drying out, when the thin layer of soil above the cut dries out, and the little root that is left has no access to water. If reacted to quickly, even extensively damaged areas can be saved by irrigation. I will also give an application of starter fertilizer, high in P, to the damaged areas. The root pruning of the grubs will cause the grass to agressively grow new roots, but you have to supply extra water so the short roots left can not dry out.

Remember that grubs need a certain population density to show turf damage, roughly from 5 to 25 grubs per square foot (depending on species). People will panic if they find one or two grubs, but I just tell them, "That little guy won't eat much." My small front lawn could easily support 1000 to 3000 masked chafer grubs and never show damage, but if these were in a 100-500 ft² area they would definitely show it. Sometimes you can have extensive grub damage, but if irrigated well you do not notice it visually. Several times over the years I discovered high grub damage only when I aerated and the lawn rolled up on the aerator. I once fertilized a lawn for a buddy in mid-Sept, and only detected grubs by the give in the turf when I turned, like spinning your foot on a throw rug. Of course, these were irrigated sites.

What are likely areas to have damaging grub concentrations?

My general rule #1 - Most female beetles will lay their eggs about an inch underground. So they ignore the non-irrigated, hard-as-a-rock lawn, and go to the nice soft soil of the irrigated lawn. Eggs & newly hatched grubs also need some soil moisture to survive, and momma knows that.
Precaution #1 - If you are having a rainy spell during egg laying, you'll get grubs in non-irrigated lawns also, then these will be badly damaged later, compared to the irrigated lawns.

My general rule #2 - Warmer locations will provide a better environment for survival of newly hatched grubs. Most all insect activity in nature is enhanced by higher temps. The irrigated lawn area in full sun, slopes facing the sun (but usually not the crest of the slope, because that is drier from runoff and extra evaporation), turf areas along sunny drives and streets, and other warm spots in lawn are prime areas for high grub populations. Hardly ever find many grubs in a shaded area of a property. These are my experiences here, may vary elsewhere. For me prime areas are those very warm areas, and other potential areas are all turf in sun most of day.
Precaution #2 - Gotta watch the general temperature trends in your area. In a cooler than normal year, the above noted crest of a slope may be an ideal place for grubs, because rest of turf is relatively cool. We once had a very warm summer, and I did my Merit treatments as usual, not wasting it under large trees; I had to go back with a curative Dylox app in Sept under the trees in some places, because soil was warm enough even in heavy shade for the grubs to do well.

How do you approach grub control? History will help you the most, by knowing where a particular site has had grub problems in the past. Then you can relate the environmental conditions of this site to other locations that you manage, and know to watch there for high grub populations. I watch for grub damage in late Aug to late Sept here, and if found, apply a Dylox curative app. If these are masked chafers, I will treat the next two years in prime and potential areas with a July Merit app, then monitor in future to see if a curative is called for. If I see a nearby lawn with extensive grub damage, and the property owner lets me look at the grub species, I may use a preventative next year on my property, or more intensely monitor it for grub activity in future. If you check for grubs just after they hatch, they are harder to see, but you can then interrupt a possible damaging situation on your client's lawn. Constant application of Merit or Mach2 is a simplistic, irresponsible, money-grubbing route from my perspective.

Learn all you can about the real biology of the grub species possible in your area. Then observe the simple things that happen over time. Remember that nature is very simple, and we can easily overlook a simple solution by trying to solve a particular problem with our great technological knowledge. How do you control the turf torn up by raccoons digging? CHARGE - slay the grubs! But the coons will still eat the dead grubs, and coons instinctively know that there is all types of life in the soil. I just trap the coon. LOL

And the use of parasitic, parasitoid, or predator organism is not a new idea in organics. It is actually called biological control, and has been around in this country for at least 115 years. Predator insect species can be ordered from several insectories, located around the country.

The new classes of grub control are not like the older ones. Merit is systemic in many plants, remains in the plant circulatory system for several months. When certain insects feed on the plant, they ingest the Merit, but are not killed by it. Merit is (I forget, it is or it causes production of) an insect hormone that tells the insect it is full, and the insect sits there happily full and starves to death. Mach2 is a hormone that tells the insect it's time to molt, and the molting too soon causes mortality. And some people call these poisons? Nicotene, table salt, and (if I remember right) peanut butter are more poisonous than these two.

Now on the nema idea, there ought to be concerns there. Only about 10K out of an estimated 1/2Mil species of nema have been identified by man. Are they just like fungi and bacteria, in which a simple imbalance can cause a bloom of some undesireable species? Don't think anyone knows yet. But we have learned in the last 100 years, and especially in the last 50, how meddling in one level of life can disrupt all levels of life above that level. And there's a lot of life forms above nematodes. Might it not be a little cavalier to dump a few million or billion of anything in your yard and expect there will only be good consequences? That's how they thought about DDT in the 40s. Of course, some things are recommended by researchers today, but time has a way of shafting a lot of human ideas, LOL.

As the original question here reveals, people are still thinking bass ackwards. He needs to learn more about grubs. You need to learn all you can about a problem, and grubs have been dealt with extensively in research. Lots of good info out there on grubs. Look for info at Ohio State (Dr. David Shetlar's work), or at your own state extension service. Only when you understand the problem thoroughly can you really begin to discuss & understand control of the problem. Join state and local green industry associations, go to trade shows and seminars, subscribe to trade periodicals. Like most other trades, what you learned 5 years ago has sometimes been enhanced 4 fold since then. In the last 15 years, I can't remember one year in which grubs were not discussed in at least one seminar, and usually I heard about them 2-4 times a year, with new info at least half the time. In 4 years here on LawnSite I never learned anything new about grubs. Oops, one thing: turfdog21 taught me how to read the grub raster without having to be a buttwiper.

dan deutekom
09-07-2003, 10:32 AM
Thankyou Jim. Excellent post with a great take on biologicals and synthetics.:D Also a great refresher on grubs. I never had much problem with them because my lawns are well irrigated.

Dchall_San_Antonio
09-07-2003, 06:39 PM
So, bringing the drift of the discussion back to the Organic Forum, for practical use on organic managed turf, the current state of the art in grub control remains milky spore and beneficial nematodes - not Merit, Grub-Ex, or any other synthetic insecticides.

You cannot trump an organic solution by playing the DDT card. The evolution of synthetic pesticides moved from DDT to imidacloprid, not from DDT to beneficial nematodes.

Enjoy Life Ronnie
09-07-2003, 06:53 PM
I also us Merit now that Lorsban has been removed from my L&O program. And I see no reason to go completely organic. I'm just not sure total organic will enable me to take care of many of my customers needs. If they get termites they want results... not excuses.
However, I do intend to give cornmeal a shot and see if it really is as good on lawns and greens as I've been told.

GroundKprs
09-08-2003, 11:27 AM
Sorry, Dave, didn't mean to mess up your forum with synthetics. Just copied something I've written before, and added a little about biologicals. Needed to emphasize, especially for someone expecting to control pests for hire, that you need to learn the details of your problems, and keep learning.

And how about a definition of "organic" as to be used here? Put it in a sticky and lock it at top. Is the insect control discussed in this thread defined as organic or biological? Or does organics include biologicals? Organics can't be anything not manufactured, because corn meal is manufactured corn.

Is tricking the insect with his own hormones a foul ball in organics? Exactly what are the rules? Or is there no concensus on rules?

The EPA registration of imidacloprid was delayed for many months because the EPA, in response to anti-chemical vocalism, had decided that all new insecticides would carry a "Danger" label. The developer held out because they felt it ridiculous to label something that way when it is less toxic than most things under the kitchen sink.

yardmonkey
09-08-2003, 11:41 AM
I think it is useful and interesting to hear about chemical and non-chemical options just to have the whole story. If someone is against using chemicals they should know what those chemicals are and what problems there may be with them. Also many people are not going to be strictly totally organic and it is useful to know what chemicals are more harmful than others, maybe it is appropriate to use some type of chemical in some situation. And maybe there are some things that we might think of as chemicals that aren't in any way poisonous.

Organic lawncare may mean different things to different people and for many heading that way it may be a gradual process.

Dchall_San_Antonio
09-08-2003, 12:22 PM
I agree, organic gardening is as hard to pin down as is vegetarianism. There are vegetarians at one end of the spectrum who eat cheese eggs, drink milk, and even eat poultry and fish; and there are others who won't eat any animal products, wear leather shoes or belts, or use any product that has been tested on animals or requires animal labor to process. Organic gardeners are the same. I'll have to define my terms. When I do I'll try to cover some of the bridge products, or what I consider to be bridge products.

There will times when a certain protein or even a chemical gets distilled from an organic source and is given a chemical sounding name. I apologize in advance for not being on top of the industry enough to know all of those. So if I refer to something that sounds to be chemical and you know is really organic, please help me out without making me look too stupid :)

I would love to post stickies/announcements to the top of the forum however I have not been granted that power yet. The Lawnsite gurus think I'm all up and running, but I can't figure out how to do the stickies given what I have. I'm asking for help and am sure they will get back to me.

GroundKprs
09-08-2003, 10:43 PM
The hangup in registering imidacloprid was over registering it as a "restricted use" pesticide. In that category it would have only been available to fully licensed turf applicators.

The Lawn Boy Pro
09-09-2003, 01:48 PM
Answer: (They love grubs!)

edger
10-12-2003, 01:01 PM
I'm at a loss here with the pic attached. I have dug up a few slices of turf in my front yard and have found not one thing. Just nice clean soil. These pictures are of my own front yard. You can see in the picture that there are more then one mound of what I think are grubs pushing the soil up? I'm in need of help here cause I lost. I've done all i can do with out putting anything down on the truf as of yet. From what I've read in this thread and many other things on the net. This is the time of year for me to handle this in my area.

Chris

edger
10-12-2003, 01:04 PM
This picture is that of one of the mounds of soil. Long story short bout this yard. When we moved in it had nothing in it. I mean nothing. That was 4 years ago. The last 2 years I haven't put anything down on it. As this season get close to the end i will put something down the help the truf get back to being heathy.

Chris

SWD
10-13-2003, 07:46 AM
Where in NC are you? Those isolated mounds look like mole crickets. A good, non poisonous way to sample really any type of soil of insects is easy. Simply add two to three tablespoons of lemon scented Joy dish washing soap to one gallon of water in a bucket. Pour this solution slowly (to avoid run off) into an area about three square feet and watch the critters (if there are any) come up to the surface. I use half quart mason jars with rubbing alcohol in them as a capture vessel to gas the critters. Once they are dead and not moving, particularly with grubs, it makes ID'ing much easier. By the way, this process will work with mole crickets too.

edger
10-13-2003, 08:38 PM
SWD,

I'm located just outside of Fayetteville, NC. In the sandhills of NC.

I tried lemon scented Joy today in three spots in the yard. I'm posting pics of what i got to come out.

I also went to my extention office here in town and had them look at what I had gotten. The one person that would have been able to help me was off today. Just my luck!! The Master gardners in there think that it could be yellow jackets doing it. But they were not sure. So i'll try again there later this week when i drop off some more soil samples.

edger
10-13-2003, 08:39 PM
here the underside of this cridder ;)

Chris

SWD
10-14-2003, 10:35 AM
When you say you have put nothing down, do you mean insecticides?
The May beetle has a larva life cycle of up to 3 years in the soil before they emerge as an adult.
From looking at the pictures, obviously it is a type of beetle, from your discreption of the environment, it could be a May beetle.
Call NCSU, or try and see if you can get into the entomology department.
The foremost southern entomologist is a Dr Rick Brandenburg - he is noted for his tawny and southern mole cricket work.
I am not as familiar with eastern, southern insect pressure in your habitat.
If you do have May beetle pressure, pheneological timing is critical to control. The NCSU entomological department should have advisories on timing.

YardMeister
10-29-2003, 01:57 PM
Edger,

I have the same things in my yard here in Fayetteville NC. I had one of those " professional " pesticide folks tell me that those little mounds were the work of termites working on a piece of wood or root under the surface. Those things seen are the tubules that they make. I have my doubts, but I don't have anything else to weigh against it either.

edger
10-29-2003, 03:43 PM
Steve, I've email the Agro Center and they are talking to NC State to see what they come up with. Was over there the other day talking and they have no idea what it is yet

chris