Tag: lawn

Who’s Digging Up My Lawn!?

Lawns in the Midwest often are subject to severe injury by the larval stages (grubs) of various species of scarab beetles. Japanese beetles and May/June beetles are the predominant damaging white grub species found within home lawns. Several other white grub species including: European chafer, Asiatic garden beetle, green June beetle, masked chafer grubs, and Oriental beetle are sporadically found in lawns and may cause some damage.

GRUB DESCRIPTION:

Many white grubs look similar to each other but vary in size. Mature grubs range in size from 3/8” inch – 2″ inches. Grubs are C-shaped and have three pair of thoracic legs (ALIENS!!!). The head is dark, but the body is usually creamy white in color. White grub species identification is not necessary because the cultural control practices are similar. The arrangement of hairs and spines on the posterior end of the grub, called the raster, is a distinguishing feature between species, if identification is warranted.

DAMAGE SYMPTOMS:

lawn damage by grubs
Lawn Damage by Grubs
Damage via furries digging for grubs.
Damage via furries digging for grubs.

Grubs chew off grass roots and reduce the ability of the lawn to take up water. During the hot, dry weather of late summer, large dead patches of lawn will begin to develop. Irrigated lawns may not show the damage as quickly, because the lawn is being watered regularly. Sometimes the damage can get farther along before it is noticed in an irrigated lawn compared to a non-irrigated lawn. The sod in those dead patches can be quite easily rolled up like carpet to reveal the grubs beneath, because the grubs have chewed through all the roots. This is also the time when skunks, starlings, moles, shrews, voles and other furries start to forage for their favorite, plump snacks, which causes digging in the lawn.

GRUB FACTS:

I’ve spoken to my spray technician about what to expect this year for grub damage. She feels that the severe cold that we experienced will not make much impact on the populations of beetles this year. The grubs here can generally be put into two categories, the May/June Beetles (#1) and the Japanese beetle (#2) grubs.

The #1 grubs are generally bigger and closer to the surface. These grubs are also mostly on a 3 year cycle, living 2 years underground. Many of these beetles may not have made it, but they are also not the ones that cause a bunch of damage to the lawn as they emerge sooner, so less feeding during the summer and the lawn has had time to recover. Although, these being closer to the surface and larger makes them attractive to wildlife, who will dig feverously to get to the squishy snacks. The related thought to this, is that with the harsh winter we had, many of the furries most likely did not make it through the winter.

Regarding the severity of our winter. Yes, we did see temperatures of -16F here, but that was aboveground, air temperature. We also had a bunch of snow that does act as an insulator. Therefore, although the freeze line may have been deeper, it is still just a freeze line, no colder than freezing, just deeper.

The Japanese beetle grubs (#2) will go as deep as necessary to avoid the freeze. These emerge later in the season, thus will cause more damage as the feeding is continuing into the drier, summer months and the grass cannot keep up with lack of roots and it’s water needs.

MANAGEMENT:

  • Allowing your lawn to go dormant during the dry summer months can help by not moving the eggs of the beetles into the lawn and they will dry-out on top of the lawn where they were laid.
  • The two nematodes that are most effective against Japanese beetle grubs are Steinernema glaseri and Heterorhabditis bacteriophora. The latter is commercially available.
  • Apply Milky Spore to your lawn area only if you’ve seen grub activity in your lawn during the spring. Many experts do question it’s effectiveness, though.
  • Make your yard attractive to birds that might eat them. Starlings and robins love to get them when they are freshly hatched.
  • Attract the solitary fly (Istocheta aldrichii) and the parasitic wasp (Tiphia vernalis) that lays its eggs inside the adult beetles (fly) or the grubs (wasp). Adult wasps feed almost exclusively on the honeydew of aphids associated with the leaves of maple, cherry, and elm trees and peonies. (Hmmm, so aphids or grubs… which pest is worse!!)

small wasp

  • Unfortunately, if your lawn has been severely attacked, pesticides may be your only recourse. Responsible IPM methods can be employed to reduce the chemical impacts to the environment.

Prevention: An ounce of it…

Products containing imidacloprid, thiamethoxam or chlorantraniloprole, are preventive insecticides that work well on newly hatched grubs present in July, but do not for large grubs found from September to May. Remember, this will prevent the next generation of grubs from infecting your lawn; it has no effect on the ones that are currently maturing. There are different recommended timings for application depending on the active ingredient. Although the bag often states to apply anytime from May to Aug 15, it is highly recommended that products containing imidacloprid or thiamethoxam be applied and irrigated into the soil in June. Best to apply before a storm as it works best when watered in. Preventive products containing imidacloprid or thiamethoxam will consistently give 75%-100% reduction of grubs if they are applied in June or July.

Curative treatments:

There are two insecticides, carbaryl and trichlorfon, that are considered curative treatments. These kill all life stages of the of #2 type grubs, but do nothing to #1 type grubs. These two insecticides are the only choices available if high numbers of grubs are found in the fall after the middle of September and in the spring before early-May. They are not as effective as the preventive compounds in reducing grub numbers because they have a less active time in the soil and timing of the application is critical. Consider carefully whether it would be best to wait and apply a preventive next spring. If the need should arise to use a curative compound, make sure to keep the infested lawn watered regularly and fertilized. It is recommended to treat the area again with a preventive application the next summer or grubs will likely reoccur.

© The Naturarian

Ring Around the Lawn – Fairy Rings

fairy ring fungus in lawn a ring of darker colored grassFairy Ring fungi are in the soil to break down old tree stumps, roots, logs and other larger pieces of organic material in the soil below the lawn. The uniform outward growth of the fungus results in the development of rings. Once the material is exhausted, the fairy ring will disappear. This may take many years. Several fairy rings may appear close together, especially in lawns that were previously wooded areas.

When these fungi digest the organic material, they expel nitrogen. This is why the grass looks seemingly happy in the fairy ring. However, sometimes the opposite effect can happen, which depletes soil nutrients and produces toxic levels of hydrogen cyanide.

Fairy ring with mushrooms bloomingApproximately 50 species of fungi in the Basidiomycetes family are known to cause fairy rings in turf; however, there are only three outcomes:

  • Variety A: The most inconspicuous type of fairy ring. The dark ring of grass is absent. Only parts of the ring will show fruiting bodies (mushrooms) at different times of the year, mostly during wet springs.
    • Remove the mushrooms to help retard the spread in the area. Don’t over-water.
  • Variety B: It’s the dark green rings, with or without mushrooms, which identify these varieties of fairy rings. At worst, this type of ring can appear unsightly with its lush growth, accompanied with mushrooms.
    • Remove any mushrooms and use a balanced fertilizer to green up the rest of the lawn so the ring is not as obvious.
  • Variety C: This variety of fairy ring is the most destructive and damaging as it produces a ring of dead grass. The dead area can contain fruiting bodies. If a soil profile is pulled from the dead area, white thread-like structures called mycelia will be visible in the soil. Mycelium is hydrophobic. Because of this property, it causes water to move away from the circle, thus drying out the grass.

There are really no fast cures for fairy rings that aren’t extreme. Digging up the area to remove the organic matter the fungi is feeding on, along with all of the adjacent soil is one method. It’s been said that fairy rings do not cross. Some have said that digging up soil from one fairy ring and exchanging it for another has worked. Spraying fungicides are ineffective and a waste of money.

It is best to just be proactive in how you maintain the lawn. Do not over-water or over-fertilize, and be sure to aerate in the spring.

dancing fairiesThere’s another theory about how fairy rings are created…

Fairies create the circles by dancing within them.

Some cultures believe these circles to be dangerous to humans. Those violating fairy perimeters become invisible to those outside and may be unable leave the circle. The fairies then force the intruder to dance till exhausted, dead or in the throes of madness.

The only safe way to investigate a fairy ring is to run around it nine times. Doing this permits the runner to hear the fairies dancing underground. This must be done under a full moon and in the direction the sun travels.

Other cultures still believe in fairy activity and that fairy rings are omens of good fortune. Some legends see fairy circles as places of fertility and fortune. The Welsh believe that mountain sheep eating the grass from a fairy ring flourish and crops sown around tend to grow better. European folklore believe fairy rings are gateways into elfin kingdoms.

© The Naturarian

Don’t Let Crabgrass Get You Crabby!

Crabgrass (Digitaria sp.) is one of the most widespread grassy weeds found in Midwestern lawns. Crabgrass flourishes in full sunlight, high temperatures and can easily out compete common cool-season grasses, like our Kentucky Bluegrass. Crabgrass is a summer annual, which germinates in the spring, grows through the summer and dies with the first hard frost. They produce a tremendous amount of seeds in the mid to late summer when the days start to shorten. These seeds not only ensure next year’s crop of weeds, they can also remain dormant in the soil for many years before germinating. Generally, if you have crabgrass in your lawn, it will be there next year, also. Horticulturists say, “One year’s seed equals seven years weeding.” Gasp!!!

forsythia blooming yellow
Forsythia

The easiest way to take care of crabrass is to take care of it during the spring season, rather than take care of it later on in the season. A well-timed application of a ‘pre-emergent’ is what you’ll need. Just as the name states, a pre-emergent prevents seeds from germination. Killing it before it emerges. Be aware that you can’t use this type of herbicide if you are planning to or have just recently seeded your lawn, as it will kill those seeds also. Timing is critical, as the herbicide does not last long and must coincide with the seed wanting to germinate.

Crabgrass seed will not germinate until the soil temperatures are 55F degrees at the one-inch level. The Illinois State Water Survey reports soil temperature at the four-inch depth at St. Charles reporting station was 47.5F degrees on April 16. The soil temperature at one-inch will be slightly higher. This suggests Northern Illinois is approaching the right conditions for application. Next week the weathermen say it will be warm and that will help the soil temperatures progress. North Americans can go to this site for application timing. Or the indicator plant that can be used for application timing is ‘forsythia is in bloom’. Late April (now) into early May will most likely be our target for 2019.

© The Naturarian