Category: Plant Healthcare

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

Who’s Camping in my Tree? Eastern Tent Caterpillars

eastern tent catipillars in webbing like tentThese guys are often confused with fall webworms, and bag worms, although all three are quite different. Eastern Tent Caterpillars (ETC) nests are active early in the season while webworms are active late season. ETC like to make their tent nests in the forks of branches, while webworm nests are located at the tips of branches. Fall webworms also enclose foliage or leaves within these nests. Tent caterpillars do not. Bag worms are single worm homes made of the foliage from the tree it has decided to call home. They mostly evergreens like junipers or arborvitae. I like to remember the difference like this… A bag can hold one, but a tent can hold many.

eastern tent catipillars in webbing like tentETC like wild cherry, other ornamental fruit trees, ash, willow and maple trees. They tend to make their tents on the eastern side of the canopy to take advantage of the early sunlight to warm them and start their digestive systems. After a about five instar, they fall from the tent, make a cocoon and after two weeks, the moth emerges. Mating occurs and the female deposits her eggs on the tree bark. Soon the eggs change into larvae, without leaving the egg and overwinter this way. In the spring, they emerge from the egg.tent catapillar netting

Other than their webs making trees appear unsightly, ETC rarely cause major problems unless their numbers become high. They are easy to control by waiting until nightfall, when they tend to go back to the tent and pruning the branch off. It can be disposed of via the garbage or campfire. If pruning is not an option, maybe these are:

  • Scrape off, discard overwintering egg masses.
  • Tear the protective tents out by hand before the larvae start to feed.
  • Control caterpillar movement and restrict access to feeding areas with Sticky Tree Bands or Tanglefoot Pest Barrier.
  • Apply Bacillus thuringiensis (Bt-k) or Monterey Garden Insect Spray (Spinosad) to the leaves to kill feeding caterpillars.
  • If necessary, spot treat with plant-derived insecticides as a last resort. Spray must penetrate silken tents for effective control.

© The Naturarain

Four Letter Words For the Four-Lined Plant Bug (Poecilocapus lineatus)

four line plant bugs eating a leafThe four-lined plant bug (Poecilocapus lineatus) removes plant’s chlorophyll via their piercing-sucking mouthparts. They also secrete a toxin in their saliva that digests the components responsible for holding the plant cells together that leaves a hole in the plant’s epidermis. This feeding produces white, dark, or translucent spots the plant’s leaves, which can run together forming large blotches. Leaves can turn brown, curl-up and ultimately fall off. If feeding occurs on new growth, wilting may result.4 lines plant bug

Damage that the four-lined plant bug inflicts can be misidentified as a fungal disease spots because of the similar appearance and timing. Many times the bug isn’t seen during scouting, as when they are disturbed, the four-lined plant bug will drop to the ground or will hide on the other side of the stem. These are the same tactics asparagus beetles employ.

How to mitigate the damage:

These bugs do like a wide variety of plants, so be aware that the damage may look just a bit different on different plants. Unless the attacked plant is very small or having the new growth chewed, most plants will pull though with some damage. Scout the damaged plant at different times of the day. Sometimes bugs don’t wake up early in the morning!

four line plant bug damage

Have a cup of soapy water ready for when you do see one. They are easy to catch, place cup below them, wave your hand near them and they will cannonball into the soap water. No squishing required. Neem oil can also be used for bad cases.

During the fall, the banana shaped eggs are placed at right angles in vertical slits along the plant’s stem. The eggs will over winter and hatch in May to late-June. Therefore, removing the dead plant material at the end of the season will lower next season’s attacks.

© The Naturarian

The Epic Battle Against the Asparagus Beetle

asparagus
Asparagus

Asparagus.

Mother Nature sure knew what she was doing when she created asparagus.

Asparagus is low in calories & sodium. It is a good source of calcium, magnesium, zinc, folic acid, protein, vitamins B, A, C, E, & K, rutin, thiamin, fiber, potassium, riboflavin, iron, phosphorus, copper, niacin, manganese and selenium, as well as chromium, a trace mineral that heightens the ability of insulin to transfer glucose from the bloodstream in cells.The amino acid asparagine derives its name from asparagus, as the asparagus plant is rich in this compound.

I’m not sure what she was thinking when she whipped up the asparagus beetle.

asperagus beetle eggs

These little guys are my bane. All in all they don’t do that much damage to my plants, but I hover over my plants like a circling vulture. I use IPM (Integrated pest management), meaning that I hunt and squish bugs! I can’t say that I am pesticide free, but most issues can be taken care of without chemicals. IMO no chemical action is need for these beetles. But, if you must, I’ve sprayed neem oil on the eggs after harvesting time, which is sometime late June (soon). There are normally 2 cycles of insects here, but there could be more.

The easiest way to catch these buggers is to have a cup of water ready. As you move towards them, they move to the other side of the stalk (quite funny to watch!) Put the cup under them & wave your hand near them. Their instinct is to drop to the ground, but instead, the cup of water will catch them. The larva and eggs aren’t as easy to remove. It’s the same method I use for typing… Hunt & peck.

spotted asperagus beetle

There are two kinds of asparagus beetle, the common asparagus beetle, Crioceris asparagi & the spotted asparagus beetle, Crioceris duodecimpunctata. Both feed on the tender young tips of the spear, but the spotted beetles larva tend to only eat the berries. How nice of them! =-)

© The Naturarian

Does My Elm Have Dutch Elm Disease?

A fungus called Ophiostoma ulmi that was introduced to the U.S. in the early 1930’s causes Dutch Elm Disease (DED). The American elm (Ulmus americana) is highly vulnerable and the disease has killed hundreds of thousands of elms across North America. All native elms are susceptible, as are European elms. However, the Asiatic elms, (U. parvifoli) and Siberian elm (U. pumila) are highly resistant to the disease.

The DED fungus is spread by two insect vectors: the native elm bark beetle (Hylurgopinus rufipes) and the European elm bark beetle (Scolytus multistriatus). The fungus is transported on the beetles from infected trees to healthy trees as they feed on twigs and upper branches. The beetles lay their eggs in the bark and wood of stressed trees along with elm firewood with the bark left on. Developing larvae form channels just under the bark and the fungus grows through the galleries until it reaches the tree’s water conducting cells, or xylem. Chemicals manufactured by the tree during its effort to fight the disease plug up the xylem, causing the tree to wilt.  In the Midwest, beetles typically have two generations per year.

DED is also transmitted through root grafts. A root graft happens when the roots of two trees intermingle and touch. Root grafts between trees are especially widespread in cramped urban street trees. Driveways and sidewalks are usually not effective in blocking root grafts, however, the disease usually does not spread in this manner beneath roads because road foundations are much deeper.

DIAGNOSIS:

elm branch showing the effects of dutch elm disease

During the early summer is when effected trees are the easiest to identify. Leaves on the upper branches will curl and turn a gray-green or yellow and finally, crunchy brown. This symptom is called “flagging”, although a flag alone is not complete assurance that the tree has DED. Another symptom is brown streaks in the sapwood beneath the bark of affected branches, which is the blocked xylem. However, only laboratory isolation and identification can positively confirm that the tree has DED. Check with your local extension or State University, usually they will perform this test for a nominal fee. Most arborists find these two symptoms are enough evidence to treat or remove an elm.

There are two other diseases that may look like DED, Elm Yellows and Bacterial Leaf Scorch. Below is a symptom checker:

Dutch Elm Disease Bacterial Leaf Scorch Elm Yellows
Caused by fungus Caused by bacteria Caused by phytoplasma
Affects individual branches first. Affects lower crown nearest root graft. Damage initially observed on single branches, and spreads to entire crown; oldest leaves affected first. Affects the entire crown at the same time.
Leaves wilt and turn yellow, then brown. Leaves brown along margin, with a yellow halo. Leaves turn yellow and may drop prematurely.
Symptoms often observed in early summer, however, could be anytime during the season. Symptoms appear in summer and early fall. Symptoms visible from July to September.
Brown streaking in sapwood. No discoloration in sapwood. No discoloration in sapwood.
No discoloration in inner bark. No discoloration of inner bark. Tan discoloration of inner bark.
No wintergreen odor. No wintergreen odor. Wintergreen odor in inner bark.

 

MANAGEMENT:

Elm tree with dutch elm disease

  • Branches infected with DED should be removed the same year the infection started. All infected branches should be pruned at least 5 feet, preferably 10 feet, below the last sign of streaking in the sapwood. Dip pruners often (best after each cut) in a solution of 10% bleach to prevent spreading the disease. Be sure to remove infected branches before the disease has moved into the main stem of the tree.
  • Trees with many branches infected with DED should be removed. There is no cure. The best thing to do to stop the spread of the disease is to promptly remove the tree.
  • Wood from DED infected elm trees need to be buried, burned, debarked, or chipped. When chipping and composting, temperatures must attain at least 120F. Cut logs from diseased trees should not be stored for firewood unless it has been debarked and there is no evidence of beetles.
  • Neighboring elm roots need to be severed with a vibratory plow or trencher before the infected tree is removed in order to prevent the movement through root graphs.
  • Choose cultivars that are resistant to Dutch elm disease. ‘Frontier’, ‘Homestead’, and ‘Valley Forge’ are a few that are offered in my area, but there are many more.
  • Healthy elms can be treated with a preventative fungicide injection to protect trees from infection by beetle feeding. Although, fungicide injections are not effective in averting infection through root grafts. Injections can only be done by a trained arborist and depending on the chosen fungicide, must be repeated on a 1-3 year cycle.
  • The consensus on treating the beetles with insecticide is not to. Contact insecticides require repeated applications during the growing season that may kill beneficial or harmless insects. Sanitation is by far the best way to control beetle populations.

Sadly, this is a prime example of what happens when we plant a monoculture of trees. Diversity is where it’s at!!

© The Naturarian

Time to Look for Oak Wilt Signs

oak wilt cycleIf your in the Midwest and your oak (Quercus) leaves are now looking like the above photo, it more than likely has oak wilt.

Oak wilt is a disease caused by the fungus Ceratocystis fagacearum, that is either spread by beetles of the nitidulid family (commonly known as sap bugs) or by roots touching underground. The disease clogs the vascular system of the tree causing wilting.

This disease kills red oaks including; red, black, pin, and scarlet varieties. White oaks including; white, bur, and swamp white oaks tend to pull through, although it takes many injectable fungicide treatments and a lot of care must be given.

signs of oak wilt in oak tree

The symptoms on red and white oaks are different also. Red oaks develop wilting leaves, bronzing, and shedding of the leaves near the top of the tree. Bronzing starts on the edges of the leaves, moving inward to the midrib, along with wilting. Both green and bronzed leaves fall to the ground. Spore mats grow on dead trees in early summer on the sapwood, directly under the bark. There is enough pressure exerted to pop the bark off. The fungus extrudes a fruity odor that attracts the sap beetles for its dispersion.

White oaks develop symptoms within the top of the tree also, but only on a few branches, and not so severe. Streaking of the sapwood is more pronounced on the white oak than the red, and there are no spore mats.

Oak wilt is confused with other problems such as drought, construction stress, borers, and root problems.

These symptoms would include:

  • More noticeable during late summer
  • Regular size leaves, little wilting
  • Leaves browning evenly
  • Leaves remain on the tree after discoloring
  • Dying trees scattered throughout stand
  • More common on stressed sites
  • Signs of borers or root disease

Oak Wilt symptoms:

  • More noticeable during early summer
  • Small leaves, thin crown, wilting
  • Edges and tips of leaves bronzing first
  • Leaves drop soon after discoloring
  • Dying trees found in groups (root grafts)
  • Streaking and discoloration of vascular tissues
Firewood

There is no cure for oak wilt, only management of the disease, which consists of preventing the spread of it.

Other considerations to remember:

  • Avoid pruning oaks from April through August as that is the time the spore mats mature and the beetles can infect recently wounded trees
  • If a red oak is infected with other non-infected trees around it, sever roots via trenching to 3-4 feet deep to prevent root grafts to healthy trees
  • An injectable, systemic fungicide (Alamo) is available from a licensed arborist for white oaks.
  • Unfortunately, there is no cure for red oaks, which should be removed and properly disposed of.

© The Naturarian

How to Get Rid of Euonymus Scale

euonymus scale

Edward L. Manigault, Clemson University Donated Collection, Bugwood.org – See more at: http://www.forestryimages.org/browse/detail.cfm?imgnum=1225115#sthash.fE97Hbiu.dpuf
Edwar

Euonymus scale (Unaspis euonymi) is a pest that is around all year, especially on groundcover euonymus. Treatment should be done when the crawlers emerge, which is around the early part of June, although it may be a bit later this year. Male adult scales are white, and females are dark brown and are shaped like an oyster shell. Euonymus scale overwinters as a mated (pregnant) female on the plant stems. Eggs develop beneath the scale and hatch during late spring.

Hatch times coincide with the blooming of:

  • Chionanthus virginicus – White Fringe Tree
  • Crataegus crusgalli –  Cockspur Hawthorn
  • Cornus alternifolia – Alternateleaf Dogwood
  • Syringa vilrosa – Lilac
  • Catalpa speciosa

Management: Pesticides won’t help until the crawlers emerge, but if the population is heavy now, prune out the infested branches to reduce the number of scales. Then, when it is time to use an insecticide it will be more effective. Since there has been a lot of winter damage on ground cover euonymus, pruning will be required to remove the dead branches and take care of two problems at the same time.

Horticulture soap* or oil will work to kill the crawlers.

*Please remember that you can’t make horticulture soap out of today’s dish soaps. Yes, back in the day, when soap was manufactured out of fats, it could be done. However, now they are all detergents, lacking the fat factor necessary to kill the insect.

© The Naturarian

How to Spot Rose Sawfly on Your Roses

 

lightly damaged rose leaves by sawfly

A friend of mine has some roses that I noticed looked a bit brown. Upon closer inspection, the leaves looked skeletonized, like the damage a Japanese beetle does, but this was sucked dry, but not chewed through. It’s also a bit too early for Japanese beetle. Keep looking…

The rose sawfly has one generation a year, with larvae appearing in mid to late spring.

sawfly larvae on rose leaf

The larvae fall from the plants and tunnel into the soil by mid-June, but it’s a bit earlier this year.  They remain dormant underground until next spring, when the adults emerge and lay eggs on the new rose foliage to begin the cycle over again.

saw rose fly larvae

Larvae can be effectively controlled with a neem oil product or an insecticidal soap. Spray only the leaves (both sides), in the morning as neem oil can possibility hurt pollinators (More research needs to go into that). The strategy is to find larvae while they are still small and before damage becomes severe, like my friend’s roses! There is no need for control after the larvae have finished eating and left the plants, give or take mid-July.

One last note, these are not caterpillars, they are actually primitive wasps, so Bt or Bacillus thuringiensis will not work.

© The Naturarian

Why Bulbs Aren’t Happy Looking Up Annuals Butts…

orange tulipsI was asked by a client the other day if we could plant her annual flowers right over her tulips, with the intent to allow the bulbs to ‘multiply’. I had to pass on bad news. Bulbs and annuals don’t play nicey-nice together. At least not with the selection we have here in the Midwest…

  • Bulbs should be planted at the correct depth for the bulb. If a bulb is planted too deep, to make room for the annual above, it may not grow.
  • Tulip foliage must be allowed to die-back naturally and will make an annual display look a bit messy until the foliage has died back and been removed. If you must prune the leaves back, there’s very little chance you’ll see tulips next Spring.
  • Bulbs, tulips in particular, do not multiply*, rather they disintegrate over time in the ground unless removed after the foliage has died back naturally, are stored properly and replanted in the fall. (Side note: Tulips give 3 years of service, in my opinion.)
  • Annuals planted over bulbs will remove all the nutrients from the surrounding soil leaving the bulb starved.
  • Bulbs need dry conditions, if annuals are planted above bulbs they will rot from the added water annual flowers require.

*Daffodils do multiply, however all the rest of the conditions would not be good for daffodil bulbs either.

 

© The Naturarian

Four-Spotted Sap Beetle ~ Glischrochilus quadrisignatus

Happy Memorial Day Weekend!! If you’re enjoying your libations during the weekend and notice you’re not drinking alone anymore… This guy may be your buddy!

Four-Spotted Sap Beetle (or picnic beetles, picnic bugs, or beer bugs) feed on sap from injured trees, decaying vegetables or fungal matter. They love ripened fruit, as well as beer, wine, fruit juice and fermented beverages. The beetles like to party in large numbers wblack sap beetlehen these beverages are present, often drowning while enjoying their libation. Then I get to enjoy protein in my wine =-P

They can be a nuisance to farmers, however they don’t generally bother crops until something else causes the crop to be damaged in some way. Once damage is done, like Japanese beetles nibbling on tomatoes do they come from miles around. They aren’t strong fliers, however scientists have tested marked beetles by placing a basket of rotten tomatoes 200 yards away, and the beetles found the prize in less than two hours.

Researchers have also found that their favorite food is beer mixed with bananas. Hmmm, I do peanut butter and bananas.. However, I wouldn’t think to down my meal with beer, yuk.

© The Naturarian