Vol. 20, No. 13, July 29, 2005

Dave Smitley, Entomology

In some places, linden trees, pin oaks, purple leaf plum, roses, grapes, raspberries and many other trees, shrubs and flowers have been stripped from Japanese beetle feeding, leaving lace-like leaves with just the veins intact.

This is a good year for Japanese beetle because last July and August we had frequent rain that kept lawns green. This means the grubs survived real well last year. Japanese beetle grubs do not survive well if lawns are droughty in July and August. But because last summer lawns were moist, we had excellent survival and a bumper crop of beetles emerging now.

For plants susceptible to defoliation, like linden and roses, you can spray them with Sevin, Tempo or Discus to prevent more feeding damage. In heavily infested areas, you may have to spray once every week or two. Homeowners can use Sevin or Bayer Multi Insect Killer. Expect the beetles to remain active until early September this year.

Dave Smitley, Entomology

Watch for webs to appear on the branch tips of walnuts, crabapples and a few other types of trees that fall webworms love. Remove the webs by pruning whenever possible, or spray the branches around the webs with an insecticide to kill the caterpillars before the webs become larger.

Fall webworms don’t usually cause enough defoliation to hurt the trees, but the webbing can be unsightly. Bacillus thuringiensis products provide a good alternative to conventional insecticides for fall webworm and other caterpillars.

Bert Cregg,
Horticulture and Forestry

In evaluating landscape problems around the mid-Michigan region, inadequate soil drainage is one of the most common issues I encounter. I recently received a call from a site manager in southwest Lansing who reported that a large proportion of the boxwoods planted in his landscape last fall were dead or dying. Before visiting the site, I suggested that the manager dig a few of the plants to inspect the roots to see if the plants were showing signs of becoming established. When I visited the site the next week, the problem was obvious. All of the holes where the plants were dug were filled with water to within three inches of the soil surface. Clearly, the drainage on the site was inadequate for anything but the most flood-tolerant plants. Unfortunately, the most realistic solution – installing drain tile – will be more difficult and expensive then if it had been installed before the irrigation system and landscape plants were established.

Lack of surface drainage. This refers to the inability of run-off water to leave the site. Surface grading may eliminate the problem. As a general rule a slope of at least 2% (2’ drop per 100’ of length) should be provided to ensure runoff.

Impervious layers. Even though the soil near the surface may be coarse and permit infiltration, clay layers or hard pans may limit drainage into the subsoil. The remedy may be to break up the plow pan by sub-soiling, which breaks up the plow pan. However, sub-surface hard pans can re-form over time and drain tiles may still be the best long-term solution.

High water table. In some cases, saturated soils cannot be avoided due to the response of a high water table rather than inadequate surface drainage. Sub-surface drainage can eliminate the problem, but another long-term solution is to select wetland plants adapted to wet conditions.

For more information visit:
http://grounds-mag.com/ar/grounds_maintenance_drainage_solutions/

Bert Cregg
Horticulture and Forestry

Pneumonics are a great device for memorizing information. In fact, sometimes it’s amazing how well they work. Over 25 years ago, I learned the essential elements for plant growth in Mr. Rackowicz’s Intro Botany class at Centralia College with pneumonic “See Hopkins café, managed by my cousin Mocl (C H O P K N S Ca Fe Mg B Mn Cu Zn Mo Cl).” Those 16 elements have been locked in my brain ever since.

As with most things in science, however, some of the views we learned growing up don’t tell the whole story anymore. I remember learning in grade school that Jupiter has 12 moons. I think the latest count is 40-something. Recent advances are also changing our view of plant nutrition. The list of 16 elements deemed to be essential was based on research that showed plants could not complete their life cycle without them. Researchers are learning, however, that some elements, nickel and silicon, are beneficial for plant growth.

Nickel, in particular, has received attention recently. USDA scientists report that Ni deficiency results in a condition known as “mouse ear” (curling of leaf margins) in pecan orchards. Moreover, the researchers at the Southeastern Fruit and Tree Nut Research laboratory found that the deficiency could be corrected with foliar application of Ni fertilizer. As with most micronutrients, Ni is not usually considered limiting in normal field growing conditions. However, Ni deficiency may occur in soils with adequate Ni due to competitive uptake of other metal elements such as magnesium, iron, copper and zinc. The researchers observed that Ni deficiency was often induced by excessive accumulation of other metals due to long-term fertilization. Ni deficiency is also referred to as “little leaf disease” and may occur in river birch, plum, peach, walnut and grapes. If you suspect a Ni problem with your crop, the usual rules for diagnoses still apply: note visible symptoms, consider other causes (stress, insects, pathogens), get a soil test, run a foliar analysis. Since we don’t have a lot of comparative data on Ni levels in ornamentals, the most useful analysis is to collect separate soil and foliar samples from “good” and “bad” samples. Then these results can be compared side by side to gain insights into the cause of the nutrient imbalance.

Dave Smitley,
Entomology

Chinch bug damage will appear as drought damage to the sunniest areas of the lawn. Examine the thatch and soil surface carefully for the tiny 1/8 inch long black chinch bugs with white markings on the wings.

More than 15 bugs in two minutes of searching means you have enough to cause some turf injury. Spot-spray infested parts of lawn with Talstar, Tempo, DeltaGard, Scimitar or Sevin.

Homeowners can use the Multi-Insect Killer.

For billbugs grab a pinch of turf from around a damaged area and pull it up. Examine the base for hollow stems and sawdust-like frass. The 3/8 inch long legless grubs may also be present. Spot-treat infested areas with Sevin at the grub rate.

Extreme conditions prove too much for preemergence herbicides

Ronald Calhoun,
Crop & Soil Sciences

Make a space on the trophy shelf – 2005 will go down as a banner crabgrass year. In what is shaping up to be one of the hottest summers in 100 years, the weeds are “making hay while the sun shines.” Calls coming in from all over the state are reporting very heavy crabgrass infestations. Lawncare operators who are accustomed to Michigan’s usually low-to-moderate crabgrass pressure are pulling out whatever hair they have left as their preemergence applications continue to break.

In May only the moisture requirement was not met. As a result, the crabgrass did not germinate in mid- to late May, as it sometimes will, and the turf ended the month in a significantly stressed state. In addition, the above normal temperatures combined with the heavy, sporadic rainfall events of June and July have been a boon for weed development (Figure 2). Think of this year as the 100-year flood event, only for weeds. Large and smooth crabgrass, white clover, chicory, buckhorn plantain and wild carrot are out in record numbers. Most new establishments from this spring are completely overrun with weeds (photos). If the weeds haven’t suffocated those tender new turf stands, diseases such as pythium and brown patch probably have.

It is impossible to predict a late germinating crabgrass year. Even applicators that properly timed their preemergence applications based on soil temperatures are likely to have breaks this year due to the lack of moisture and thin turf that occurred in May. The result is that many (properly timed) preemergence applications did not prove effective. Crabgrass and customer callbacks abound and postemergence products are flying off the shelves. See MSU Extension bulletin E-0002 TURF “Crabgrass Control in Home Lawns”(available in pdf) for specific management and herbicide recommendations.

Jill O’Donnell,
Christmas Tree ICM Agent

Pictures of the Douglas fir needle midge can be found in the September 5, 2003, Landscape Alert.

Dennis Fulbright,
Plant Pathology

Management of this needlecast disease of Scotch and red pine is slightly different than the needlecast diseases found on Douglas fir and spruce we have written about in other issues. This disease can kill red pine seedlings and causes browning on Scotch pines in the spring. Scotch pines with needles showing brown spots with yellow margins, yellow needles or brown needles, especially at the bottom of the tree are probably infected with Lophodermium seditiosum.

The dead needles will fall off the trees in June, July and August, and these dead needles will continue to support fungal reproduction by allowing the fruiting bodies to develop and the spores to disseminate throughout the trees. Trees look as if they are making a comeback since the new buds break with a green flush; however, these new needles will become infected from August to October from the spores issuing from the fruiting bodies on the dead needles. The fungus will stay in those healthy looking needles all winter until spring, when, again, those needles will begin the process of yellowing, browning and dropping off.

Even though we see the symptoms of Lophodermium in the spring, the most important time to protect trees is in late July throughout the summer and fall especially if these months are warm and moist. Apply a registered, preventative fungicide three or four times, once every two to three weeks from late July through October. Plant long-needle Scotch pines, which are more resistant such as those from Germany, Belgian, Poland and Czechoslovakia. Make sure all the older pines have been removed from windbreaks near nurseries or plantations. These pines can serve as sources of fungal spores.

Howard Russell,
Diagnostic Services

We are getting lots of calls and samples of springtails this summer from people who are finding large numbers of them in their homes. Springtails are minute, primitive insects that can occur in enormous numbers (50,000 per cubic foot) in forest litter and organic soils (photos). Springtails can be found outdoors in any moist situation, usually feeding on algae, fungi and decaying vegetation. We think this invasive behavior is the result of our hot, dry summer.

Springtails (Order Collembola) are extremely sensitive to moisture. If their normal environment becomes dry, they will actively seek moisture, sometimes invading homes and similar structures. They are most commonly found in walk-out basements, kitchens and bathrooms. These harmless insects are not known to bite or cause damage to stored food, wood or fabrics. Springtails can persist indoors if adequate moisture is found and if fungi, mildew or decaying vegetable matter exist in sufficient quantities, but in general, they are only occasional or incidental visitors in structures.

If springtails persist indoors, the best control is to decrease the humidity and remove anything found to be moldy or in a state of decay. Household aerosol insecticides or persistent insecticides can be used indoors to control them. Treating the exterior walls and foundations with a persistent insecticide registered for this use may aid in preventing their entry.

There are nearly 700 species of springtails in the US and Canada.

Howard Russell,
Diagnostic Services

Lots of people have been calling us and sending in specimens of another odd-looking insect they are finding in large groups on the bark of their shade trees. These strange bugs are known as giant barklice (Order Psocoptera) or more aptly as bark cattle because they form large congregations or herds and move en masse across the tree bark (photos).

These bark lice are among the biggest of their kind in Michigan. They are usually about 1/8 to just under 1/4 of an inch in length. Their yellow-striped abdomens make them quite conspicuous as they move in their herds on the trunks of trees and shrubs. They may be noticed with or without wings. All psocids are characterized by a swollen bump on their faces and have chewing mouthparts and relatively large heads.

Bark cattle feed on molds, fungi, pollen, fragments of dead insects and other detritus. None of the barklice is capable of injuring plants. Since they do not harm the tree, no control measures are needed.

Howard Russell
Diagnostic Services

It looks to be another great summer for the European paper wasp. We are finding numerous nests around our yards, and the nests are getting bigger with 30 or more workers tending a single nest. They are getting less and less tolerant to anyone who disturbs them. All this mean is that it is time to start carrying a can of wasp killer (the kind that shoots a stream of juice 15 feet or so) whenever we venture out into our yards.

This wasp will build a nest practically anywhere that offers the slightest protection from the rain. Common nesting sites include bird feeders and nest boxes, under “in-use” covers on outdoor electrical outlets, beneath mailboxes, beneath steps and deck.

Get them now before they get you. Shoot fast and shoot straight, Tex. (Photos)