Landscape and nursery
§ Japanese beetles are now out in full force
§ Fall webworms beginning to appear
§ New publication on organic growing of ornamentals
§ Scouting for weeds: prostrate knotweed, prostrate pigweed, prostrate spurge and common purslane
Turfgrass
§ Heat tracks on lawns
Christmas trees and forestry
§ Christmas trees and forestry disease update
§ Christmas trees and forestry insect update
Around the home
§ Armyworms marching across the northwest Lower Peninsula
§ Northern black widow outbreak?
§ Cicada killers starting nest construction
§ European chafer confirmed in Mackinaw County
Other news
§ Weather news
Next issue August 8
Dave Smitley, Entomology
Japanese beetles are beginning to defoliate some types of
trees, shrubs and flowers in southern
In order to protect susceptible types of trees, shrubs and flowers from Japanese beetle, spray them with Sevin (carbaryl) or Bayer Multi-Insect Killer (cyfluthrin) as soon as they start stripping leaves. Spray again every week to two weeks, until late August, if necessary. The Japanese beetle traps are a great way to find out if you have Japanese beetle, but do little to prevent plant damage.
Dave Smitley, Entomology
In the last two to three years, webworms have been abundant
throughout southern
New publication on organic growing
of ornamentals
Janna L. Beckerman
Dept. of Botany and Plant Pathology
Purdue University
Editor’s note: MSU
plant pathologist Willie Kirk advises that he likes this publication for the
way it promotes integrated pest management (IPM) and clearly states the limits
of the products. Thanks to Purdue for its development.
Disease control on ornamentals is a significant problem for the homeowner, nursery and greenhouse grower, and the landscape professional. By definition, these plants are to be “ornamental,” however, diseases often mar the beauty of these plants, and growers are often puzzled by the many different chemicals, and how to use them.
To address this use, we published a new brief in the Disease Management Strategies Series titled, “Using Organic Fungicides.” This brief is available online at: http://www.extension.purdue.edu/extmedia/BP/BP-69-W.pdf. This publication offers strategies for properly using organic fungicides and describes a number of organic fungicides growers can use to prevent plant diseases.
Steven Gower
MSU Diagnostic Services
Landscape professionals and homeowners may encounter some common weeds in landscape beds, gardens and driveways with a prostrate, mat-forming growth. Four of the most common low-growing, summer annual weeds include prostrate knotweed, prostrate pigweed, prostrate spurge and common purslane. While similar in habit, these plants have specific characteristics that aid in their identification (see below). Just as with any other pest, correct weed identification is the first step to creating an integrated weed management program.
Editor’s note: The identification information is from the field guide An IPM Pocket Guide for Weed Identification in Nurseries and Landscapes. For ordering information, call 517-353-6740 or visit: http://www.ipm.msu.edu/pdf/pocketGuidesLandsc07.pdf
Life cycle: Prostrate, mat-forming summer annual.
Leaves: Alternate, narrow oval to oblong leaves with pointed tips, smooth margins and short petioles.
Stems: Prostrate, tough, wiry stems with distinct nodes are highly branched and mat-forming. Plants perform well in compacted areas. A membranous sheath (ocrea) surrounds the stem at the base of each petiole
Flowers and fruit: Small, inconspicuous flowers are white to pinkish and clustered in the leaf axils. The seed is enclosed in a single-seeded, dark reddish brown, three-sided fruit.
Reproduction: Seeds.
Life cycle: Prostrate, mat-forming summer annual.
Leaves: Alternate and pale green to shiny, dark green leaves are oblong, oval to egg-shaped with pointed, rounded to slightly indented leaf tips. Leaf margins are smooth and usually whitish. Leaves are numerous at the stem ends.
Stems: Prostrate and nearly smooth, light green to red-dish stems form thick, circular mats. Stems may be 1 to 3 feet long and mostly erect at the tip.
Flowers and fruit: Small, greenish flowers are found in dense clusters in the leaf axils. Flowers have bracts as long as the sepals and yield small, round, shiny black seeds.
Reproduction: Seeds.
Life cycle: Prostrate summer annual.
Leaves: Cotyledons are oval with maroon undersides and short petioles. Opposite, pale green, egg-shaped leaves with rounded tips have small, irregular teeth along the margins and short petioles. The upper leaf surface often has a maroon watermark.
Stems: Prostrate, densely hairy stems are highly branched from the base, forming circular mats up to 16 inches in diameter. Stems may root at the lower nodes and exude a milky sap when damaged.
Flowers and fruit: Inconspicuous flowers are formed in the leaf axils. Fruit are hairy, three-lobed capsules that contain three wrinkled, three-sided, pale brown seeds.
Reproduction: Seeds.
Similar weeds: Spotted spurge [Chamaesyce maculata (L.) Small] Differs by having stems that do not root at the nodes, narrow oval to oblong leaves, and ridged, not wrinkled, seeds.
Life cycle: Prostrate, mat-forming summer annual.
Leaves: Cotyledons are oblong, hairless and succulent. Cotyledons and young leaves are maroon-tinted on the undersides. Thick, fleshy, succulent leaves are hairless, spatula-shaped and about 1 inch long or less. Leaves are alternate but appear opposite and are often crowded near the stem tips.
Stems: Prostrate, purplish red or green stems have multiple branches that form circular mats. Stems are thick, fleshy, succulent and hairless and up to 20 inches long.
Flowers and fruit: Small, yellow, star-shaped flowers with five petals are produced in the leaf axils, opening only on sunny mornings. Fruit are egg-shaped capsules that split around the middle, scattering many tiny, black, shiny seeds.
Reproduction: Seeds.
Jackie Smith
MSU Diagnostic Services
Woody ornamental vascular wilt diseases such as Verticillium wilt, Dutch elm disease and oak wilt can be frustrating, not only for our clients but also for lab staff. They can be challenging to diagnose and downright impossible without a quality sample. The accuracy of results relies heavily on the sample itself. Improperly collected, stored, or shipped samples decrease the chances of isolating a pathogen. Following the procedures outlined below will help to ensure sample quality and increase the likelihood of an accurate diagnosis.
1) Select branches that are partially wilted, with symptomatic leaves progressing from the tip of branches inward to the trunk. Be sure that branches are not totally wilted, dry or dead. Check sapwood for discoloration by removing a small section of bark. Discoloration appears as gray to green streaks. Discoloration is not present in all species of trees; however its presence greatly increases the chances of isolating the fungus.
2) Select samples from up to three symptomatic branches per single tree. It is critical that the sapwood is moist to the touch. Avoid collecting samples from the extreme tips of branches: this tissue wilts first and is often too dry for successful isolation.
3) Branch samples should be at least one inch in diameter (when possible), cut into six to eight inch lengths, and placed in large resealable plastic bags. Do not add moisture to the bag. Smaller diameter branch samples are acceptable only if the sapwood is moist, and samples have been kept cool.
4) Keep samples cool during sampling, shipping, and storage, but do not freeze. Never leave samples un-refrigerated or exposed to direct sunlight.
5) Ship samples by overnight mail or deliver in person to the laboratory. And, as always, do not ship samples on Friday.
You may not be able to follow all of the guidelines for every sample. The most important guideline to remember is to collect samples from live, symptomatic branches. If the sample would make good kindling, it probably isn’t going to be acceptable for vascular wilt testing. If you’re not sure what kind of sample to submit, feel free to contact the lab at (517) 432-0988.
Kevin Frank
Crop and Soil Sciences
I call them heat tracks, but apparently I’m about the only one. If you’re like me and you’re looking for quick information, I naturally go to Google. However when I Google heat tracks the results are some music or Nascar references. Add heat tracks in turf and the results are some of my previous Landscape Alert articles.
Recently, we received some pictures of heat track damage
from
The challenge for large commercial mowing operations is knowing when to avoid mowing jobs to reduce the risk of heat track damage. If the lawn is starting to look bluish or you notice foot printing on the turf, you can be guaranteed that equipment will really do a number on the turf. The best advice is to mow during the cooler times of the day and keep an eye on foot printing.
Jill O’Donnell and Dennis Fulbright
Christmas Tree ICM educator
Spruce needle rust is showing up now in Christmas tree
fields and blue spruce in the landscape in the Cadillac area. Needles have
yellow bands with small yellow-orange pustules on them. Spruce needle rust
overwinters on
Management of Lophodermia needlecast disease of Scotch and red pine, caused by the fungal pathogen Lophodermium seditiosum, is slightly different than the needlecast diseases found on Douglas fir and spruce that I have written about in other reports. This disease can kill red pine seedlings, and causes browning and massive amounts of needle loss on Scotch pines. Scotch pines infected with this disease have needles with brown spots surrounded by yellow margins, yellow needles or brown needles, especially at the bottom of the tree.
Lophodermium is a severe needlecast of Scotch pine, which in some cases can cause the entire tree to brown in the spring. Even though we see the symptoms of Lophodermium in the spring, the most important time to protect trees is from the end of July through September. This is when needles are infected from spores being released by the small, shiny, football-shaped, black fruiting bodies that form on the fallen needles. The dead needles currently falling off the trees this summer (June, July, and August) will be providing the inoculum (spores) that will spread throughout the trees in your plantation or nursery. These spores will infect this year's crop of needles from August to October. And, even though you won't see the result of those infection events until next year, 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. To break this disease cycle, the time to manage this disease is in late July and throughout August, even into Fall, if it stays warm and moist.
To initiate control, you must begin now. Look for needle spots and brown foliage on the lower branches of 50 or more trees scattered throughout the plantation. If ten percent of the trees are infected, consider treating the entire plantation by the first week of August. To reduce Lophodermium needlecast, remove the branches of pine from cut stumps where spores are likely to be produced. Apply a registered, preventative fungicide three or four times, once every two to three weeks from late July through October. Make sure all the older pines have been removed from windbreaks near nurseries or plantations. These pines can serve as sources of fungal spores.
Jill O’Donnell and Dennis Fulbright
Christmas Tree ICM educator
Douglas fir growers should be actively scouting the trees near harvest age for Cooley spruce gall adelgid. Check for white, cottony balls dotting the undersides of needles on Douglas-fir. If you look under the cottony material, you will find pale peach-colored eggs or possibly the first emerging nymphs. Eggs will hatch about 1500 - 1600 degree days base 50. In most years, this has been the last part of July. Insecticide can be applied once these eggs hatch to control nymphs that will overwinter.
On spruce, we are beginning to see the first nymphs emerging from galls. These nymphs will either continue their life cycles on blue spruce or fly to Douglas-fir to lay eggs. So if you are planning to cut off and destroy galls, you will need to do that quickly before they open and a new generation of adelgids emerges.
The second generation of crawlers should be hatching in northern
lower Michigan and the
We are still finding crawlers active under the reddish-brown, roundish scales of pine tortoise scales. So if you have had problems with this scale you will want to keep checking your fields. What makes this even more of a problem is that it excretes amazing amounts of sugary honeydew and black sooty mold, then grows on the honeydew that coats the needles and branches. Trees can look pretty awful if the scale population builds up to even moderate levels, making the trees unsalable.
The new generation of pine shoot beetle can be found feeding in tunnels in the center of new or one year old shoots on various pine species. They will spend the rest of the summer feeding in the shoots. Look for broken branches, needles on the tips of branches turning brown and a round hole seen on the outside of the shoot which is often surrounded by pitch. Some shoots will have only one tunnel while others may have several short tunnels.
We are finding the first adult weevils of white pine weevil. These adults emerge from late July to late August. Adults feed on the bark of small branches before dropping to the litter to over-winter. If you are having problems with white pine weevil an insecticide application between mid-August and September may help to control the newly emerged adults.
Howard Russell and Christina DiFonzo
MSU Diagnostic Services, Entomology
Hungry hordes of armyworms are eating their way through corn and alfalfa
fields in the northwest
Armyworm, Mythimna (= Pseudaletia) puncta (Lepidoptera: Noctuidae) is a grass loving caterpillar whose
numbers can wildly fluctuate from one year to the next. One year it’s difficult
to find any of them and then the next year they are seen in the millions
marching from one field to another eating all the grass that lie in their path.
Steve Gower described this year’s outbreak as “biblical” in proportion.
Howard Russell
MSU Diagnostic Services
That’s the question that two reporters from the northern
The northern black widow spider,
Latrodectus variolus (Araneae: Theridiidae), is found throughout the
eastern
Surprisingly, as
common as this spider is, black widow bites are infrequent because the spider
is actually very timid and prefers fleeing when disturbed. That’s a good thing
because the venom of a widow spider is 15 times more toxic than that of
rattlesnakes. However, due to the small amount of the venom injected into the
bite, widow bites are far less serious. There is less than one percent
mortality (mostly children) of persons bitten by black widows. The toxin
affects the central nervous system and the severity of the bite depends on many
factors including the age, size and sensitivity of the victim, location and
depth of the bite, and when the spider last used her venom. Pain is felt almost
immediately after the bite, and increases for one to three hours, but may last
for 24 hours. In severe cases, large muscles become rigid with spasms, there is
a rise in body temperature, blood pressure, profuse perspiration, and a
tendency to be nauseous. If a person has been bitten by a widow spider, keep
the bite victim calm and under observation. Immediately take the victim to a
doctor or emergency room. If the spider can be safely captured, take it to the
doctor for verification of the type of bite. The bite victim may need to be
hospitalized. Fatalities are uncommon and healthy victims usually recover
quickly.
See photos of a northern black widow at http://bugguide.net/node/view/184137/bgimage.
Howard Russell
MSU Diagnostic Services
A gentleman from
Read more than you will ever care to know about cicada killers at:
http://ww2.lafayette.edu/~hollidac/cicadakillerhome.html
Howard Russell
MSU Diagnostic Services
For those keeping track, the first European chafers from
Jeff
Andresen
Agricultural Meteorology
Geography
A large area of high pressure over the eastern
High temperatures Friday and Saturday should range from the upper 70s far north to the mid-80s south with lows from the upper 50s into the mid-60s. Slightly cooler temperatures are expected by the end of the weekend and early next week, with highs from the low 70s north to the low 80s south and lows from the mid-50 south to low 60s far south. High pressure is forecast to dominate weather across the region early next week with fair and dry conditions expected. Rainfall should be possible again by the middle of next week.
In the medium range period, forecast guidance suggests upper
air troughs across northwestern and northeastern sections of the