Landscape and nursery
§ Japanese beetles are on the way!
§ Scouting for weeds: Mugwort
§ Scouting for weeds: Perennial sowthistle
Turfgrass
§ Watch for billbug and chinch bug injury to home lawns in July
§ July is the best time to treat lawns for grubs
§ Heat relief for turf
Christmas trees and forestry
§ Christmas tree pest update
§ Gypsy moth spray window dates
Around the home
§ Bug news
§ Deer flies and mosquitoes are attacking
Other news
§ Too bad for cucumber growers!
§ Integrated chemical pest management
§ Weather news
Dave Smitley, Entomology
Japanese beetles are now active throughout most of southern
Feeding injury to susceptible plants is already visible now, and will continue well into August. Keep valuable trees and plants like linden trees, canna lilies, roses, raspberries, etcetera, protected with weekly sprays of Sevin or Tempo or with a homeowner product containing carbaryl or cyfluthrin.
Steve Gower
Diagnostic Services
Mugwort: Artemisia vulgaris L.
Life cycle: Clump-forming, rhizomatous perennial.
Leaves: Alternate, deeply lobed and divided leaves are dark green above and silvery white below. Leaves emit a strong, sagelike odor.
Stems: Erect, clump-forming, smooth to slightly hairy stems have lengthwise ridges and become semiwoody with age. They are up to 6 feet tall.
Flowers and fruit: Inconspicuous flowers are produced in elongated, spikelike clusters on the upper stems. The seed is enclosed in a single-seeded, brown, oblong fruit.
Reproduction: Persistent, prolific rhizomes and, rarely, seeds.
Steve Gower
Diagnostic Services
Perennial sowthistle: Sonchus arvensis L.
Life cycle: Erect, patch-forming perennial.
Leaves: Seedling leaves initially develop from a basal rosette from a deep taproot. Lower leaves are alternate, blue-green, 4 to 12 inches long with two to five lobes with prickly teeth on each side, gradually becoming smaller toward the top with a clasping base. Leaves have a thickened midvein and exude a milky sap when damaged. Leaf midvein is not prickly underneath.
Stems: Erect, herbaceous stem up to 5 feet tall that branches only near the flowers. Stems are hollow and smooth with ridges and exude a milky sap when damaged. Upper stems may have gland-tipped hairs.
Flowers and fruit: Bright yellow ray flowers are 1 to 2 inches wide and found in clustered heads. The seed is enclosed in a single-seeded, narrow, oval, reddish brown, ribbed, wind-disseminated fruit.
Reproduction: Seeds and extensive creeping roots.
Similar weeds: Annual sowthistle (S. oleraceus L.) Differs by having an annual life cycle and short taproot, less prickly leaf margins, and pale yellow, 0.5- to 1-inch-wide flower heads. Leaf midvein is not prickly underneath.
Prickly lettuce (Lactuca serriola L.) Differs by having an annual or biennial life cycle; fine prickles on leaf margins and sharp prickles on the underside of the leaf midvein; and a many branched, spreading panicle with numerous pale yellow flower heads less than 0.5 inch wide.
Spiny sowthistle [S. asper (L.) Hill] Differs by having an annual life cycle and short taproot, leaf margins with many sharp prickles, earlike lobes where the leaf attaches to the stem, and flower heads 0.5 to 1 inch wide. Leaf midvein is not prickly underneath.
Dave Smitley
Entomology
If you see dead patches in Kentucky bluegrass lawns, you can check for billbug injury by the "tug test.” Pinch a clump of grass blades in the affected area between your thumb and forefinger, and pull it out of the soil. If billbugs are responsible for the turf damage, you will see several broken-off stems filled with sawdust-like frass from the billbug. Also, look for billbug larvae, pupae and, in a few weeks, adults.
Chinch bugs are most likely to injure drought-stressed turf, especially in lawns with a mix of Kentucky bluegrass and fine fescue. Lawns with a thatch layer are also more susceptible to chinch bugs. The best place to look is in sunny parts of the lawn that appear to be turning brown from drought. Examine the soil surface for chinch bugs in dry afternoons by parting the turf and looking around the base of grass plants. You have to look close because the chinch bugs are only about a 1/8 inch-long. Twenty bugs in two minutes of searching are enough to injure turf. Spot-spraying the infested area with Sevin, Talstar, Allectus or Dylox will help prevent turf damage. Chinch bugs will keep feeding until mid August. Watering frequently helps prevent chinch bug injury.
Dave Smitley
Entomology
If you had grub damage to your lawn last fall or this spring
you may want to consider using an insecticide to prevent grub damage this coming
fall. The most effective homeowner products contain imidacloprid or
halofenozide. They must be applied to lawns in July to be effective. Professional
turf managers can also use Merit,
Kevin Frank
Crop & Soil Sciences
The recent round of thunderstorms that swept across many
areas of the
Many irrigation systems have not been checked to ensure uniformity of coverage. I’ve driven by many landscape turf areas that have green and brown circles that are obviously from poor irrigation coverage. It seems like until we have a dry period everyone thinks their irrigation system is functioning perfectly.
Soil differences across an area can result in visual differences in turfgrass very similar to those seen with poorly functioning irrigation systems. Although, we would all like to think we have a very uniform soil type to grown, our turf and landscape plants in, that is often not the case.
Some golf course grasses that are considered weeds in a home lawn (i.e. creeping bentgrass and Poa annua) took a hit in the heat, while other weeds such as crabgrass (a warm season annual) securely anchored their roots and spread vigorously during the recent heat.
Heat tracks have been everywhere from home lawns to golf courses. Anytime you put traffic from a cart, mower or fertilizer spreader on turf that is nearing the wilting point or has already wilted, you will likely see a track in the following days or week. If you’re not familiar with what I’m calling heat tracks see the Landscape CAT Alert from May 25, 2007.
Jill O’Donnell
Christmas Tree ICM educator
The second generation of crawlers should be hatching pretty
soon, probably within the next several weeks or so. If you are in the southern
half of
Even though the gypsy moth spray window is closed in some areas and coming to a close in others, growers need to be walking their fencerows and scouting their plantations (especially spruce) for signs of gypsy moth. This is the time of year we are particularly concerned with the large larvae that have nearly completed their feeding and begin to crawl around, looking for a dark protected place to pupate.
When the female moths emerge from the cocoons, they cannot fly. That means that there is a real good chance that they will lay their eggs right on the tree. Taking the time now to scout your fields may mean you avoid having the plantation restricted this fall.
If you grow Scotch pine and had high populations of pine
tortoise scale last year, you should be scouting your trees for the crawlers.
Particularly check trees that had black sooty mold last year. If you have trees
that are within two years of harvest, you don't want to let pine tortoise scale
build up to high levels. These scales secrete huge amounts of sugary honeydew.
Black sooty mold grows on the honeydew and can make the trees unacceptable to
sell when scale populations are very high. If you had some "black
scale" last summer and need to apply a horticultural oil or insecticide
spray, you should time the spray to coincide with this crawler stage. The
crawlers are pinkish-red and can easily be seen moving about on the shoots and
needles. Be sure to get good coverage.
Mike Bryan
Michigan Dept. of Agriculture
Growers should note the closing date for Zone 5 – all other compounds has been set as July 5. The chart below shows all open/close dates for the 2007 season as they pertain to application of the two groups of pesticides used for regulatory treatment of gypsy moth in nursery stock and Christmas trees. Degree day accumulations have been well ahead of normal this season. MDA will be mailing packets to growers shortly for identifying those fields that need to be inspected for gypsy moth certification.
|
Zone |
Open – Dimilin (150 DD*) |
Open – all other compounds
(200 DD) |
Close – Dimilin (700 DD) |
Close
– all other compounds (800 DD) |
|
1 |
April 23 |
May 4 |
June 5 |
June 11 |
|
2 |
April 30 |
May 7 |
June 5 |
June 17 |
|
3 |
May 3 |
May 15 |
June 15 |
June 24 |
|
4 |
May 15 |
May 21 |
June 24 |
June 29 |
|
5 |
May 18 |
May 27 |
June 29 |
July 5 |
* DD = Degree Days
at base 50 degrees F.
Howard Russell
Diagnostic Services
Japanese beetles emerged last week and are busy devouring
our favorite trees and shrubs. Some of those who have called the lab have asked
about the need to spray their yards to prevent Japanese beetle damage. I think
not, but some may need to protect their trees and shrubs, particularly roses,
linden and ornamental fruit trees. Cyfluthrin is still the product of choice
for Japanese beetle and it is available to homeowners.
Fireflies are out and about
Fireflies are providing quite the light show in fields and woodlots
around the
Howard Russell
Diagnostic Services
Several people have called complaining about deer flies and mosquitoes this past week. I don’t have anything new to tell them about warding off their attacks. DEET-based repellents still work for mosquitoes, but deer flies are a different matter. The ones that are chasing me around at home belong to the genus Chrysops, the true deer flies (see photos). The following is a rerun of an article I wrote a few years back.
Deer flies and related horse flies belong to the family Tabanidae.
There are about 350 species of tabanids in the
Those of us who are plagued by deer flies have probably noticed that mosquito repellents don’t seem to work against deer flies. The main reason for this failure is that tabanids do not use scent to find their hosts. They use their keen vision and key in on anything that moves. They are among the fastest fliers in the insect world, so somebody who is walking in their yard or jogging down the road, or running full speed for that matter is really no match for a swarm of hungry and determined deer flies. Wearing a hat helps, they seem to be attracted to hair.
If you live in a deer fly kind of a world and wish do to
something about it, then traps and sticky patches are likely your only hope. I
found a couple of suppliers of small 3X6 inch patches with sticky “goopage” on
one side that are attached to the back of your baseball cap. When flies zoom
in, they get stuck in the goopage, and it’s all over for that fly. Somebody
down in
If you’re interested in trying them, these patches can be purchased through the following web sites: http://www.gemplers.com/a/shop/product.asp?T1=RDF4&src=21SM001 and
http://www.tucker-usa.com/users/stieg/deerfly.htm.
Another approach to controlling deer flies is to catch them in a trap that uses something other than us for bait. There are commercially available deer fly traps that use motion to attract the flies. One such trap is called the HORSE PAL® fly trap. The following is from the manufacturer. “The HORSE PAL® biting fly trap is constantly on duty, attracting the biting flies in the area and capturing them. The trap is environmentally sound. It requires no smelly or messy baits. The only care required is occasionally removing the capture bottle and dumping out dead flies.”
Dumping out bottles filled with dead deer flies must be pretty satisfying if the thing works.
You can read about these traps at: http://bitingflies.com/. If you decide to buy one, let me know how it works. You can email me at bugman@msu.edu.
More general information on tabanids can be read at the
http://ohioline.osu.edu/hyg-fact/2000/2115.html
Jennie Stanger
MSU Extension Educator
Late on June 25, Paul Marks and Jennie Stanger visited a
home gardener who felt his cucumbers were showing the same symptoms as last
year when an unprecedented outbreak of downy mildew swept across the county in
midsummer, killing nearly all home garden cucumber plants and many farm field
plantings within several days. Unfortunately, he was correct and this may be
the first confirmed outbreak in
Commercial growers were already taking preventive measures
because the disease had been reported this month in
Paul Marks’ three photos show the yellowish spots first visible on the topside of leaves, the dirty look at the bottom side of those spots from all the tiny black spores forming, and the declining health of an infested plant.
The reason growers must spray often is that the cucumber
plants are quickly forming new leaves, and the reason for rotating chemicals is
that the disease would otherwise develop resistance to one product used all the
time. Furthermore, this disease is so different from the “normal” cucumber
diseases like common powdery mildew, that at least two different fungicides
must be used. It is not economical nor convenient for home gardeners to attempt
chemical control. In fact, it is expensive and difficult for commercial growers
as well. This one disease has potential to ruin the entire pickle industry in
Last year some people blamed the first farm in the county
where the disease was found, thinking that because the cucumber plants on that
farm were early and large due to plastic and row covers, that perhaps the
disease had been brought to that farm on plants from the south. However, this
year, after learning of downy mildew reports from year-round cucumber
production greenhouses in
Home gardeners around
Willie Kirk
Plant Pathology
Reliance solely on fungicides, bactericides or viricides for control of pathogens often results in unforeseen problems such as build up of chemical-tolerant or resistant races of the pathogen and displacement of one pathogen by another. Often expectations for the efficacy of chemicals are too high. Chemicals should therefore be used with caution and lowered expectations. Once a disease has appeared on a plant it is difficult to eradicate. To get the best from chemicals, they should be applied as part of an integrated disease management strategy. Routine spray programs should only be used when for example seed or propagation materials are known to be infected. Areas that are historically at risk should also be routinely protected rather than utilizing a non-planned emergency program after the appearance of symptoms of an expected disease. It is easier to prevent disease than to cure disease on plants. To help predict when diseases infect, it is useful to have prior knowledge of the conditions that enhance infection periods.
For example, if leaf wetness is persistent or there are
extended periods (14-24 hours) of relative humidity greater than 90 percent, it
would be prudent to apply a protectant fungicide to known susceptible species.
During extensive dry and low humidity periods it would not be necessary to
apply protectant chemicals frequently; however in
The farm or nursery should be well mapped to document plant locations. Susceptible species should be highlighted on maps and inspected regularly. A record of symptoms should be kept and correlated with weather records to determine if the appearance of irregularities is associated with abiotic conditions. Specific pest problems should be identified to determine appropriate control options. Determine if there are action thresholds based on acceptable levels of disease to decide when to treat. Not all diseases are lethal and some may cause only temporary blemishes which may be tolerable. If it is decided that chemical control is warranted always use the appropriate chemical for the species and disease and always read the label and always use chemicals in compliance with the safety recommendations. Consider using biopesticides or softer pesticides that are less toxic to the environment, e.g., horticultural oils or soaps. However, be careful with methylated oils as they can cause cuticle disruptions and allow further infections to occur.
When conditions are less conducive for disease development, reliance on chemical control may be reduced. These conditions can be manipulated and their impact minimized by reducing plant exposure to high risk environments e.g. avoiding early planting into cool wet soil, avoiding late fall harvest when plants are again exposed to a cool wet climate, avoiding inappropriate irrigation which can increase soil moisture, extend duration of leaf wetness and canopy humidity.
In summary:
§ Start with clean seed/stock and appropriate rotation.
§ Plan a preventative spray program.
§ Initiate a timely program with the use of seed treatments where appropriate.
§ Spray programs with a mixtures of fungicides with different modes of action.
§ Scout fields for pest occurrence.
§ Follow guidelines on maximum usage of high resistance risk fungicides.
§ Minimize exposure to high risk environments, e.g., early planting, late fall harvest, unnecessary or over/under irrigation.
Jeff
Andresen
Agricultural Meteorology
Geography
A slow-moving cool front brought much-needed moisture to some sections of the state this past Wednesday, June 27 (mainly southern sections of Lower Michigan), but unfortunately many areas were also missed and remain unfavorably dry. During the weekend, dry weather is likely to continue statewide as Canadian-origin high pressure covers the region. Temperatures will remain at near to below normal levels Saturday, with highs ranging from the upper 60's or low 70's far north to the upper 70's south and low temperatures from the upper 30's north to low 60's south through Sunday. Warmer temperatures are likely by early next week.Highs will move back into the low and mid 80's and lows returning to the upper 50's to low 60's.
One positive aspect of the forecast for those missed by Wednesday=s rainfall is that the cooler temperatures in the near term should lead to at least a temporary reduction in evapotranspiration rates, water demand and moisture stress relative to recent levels. A weather system is forecast to approach the state from the west by Monday, bringing the next chance for significant precipitation across northern sections of the state Monday and statewide on Tuesday. Another round of rainfall is possible in the late Wednesday/Thursday time frame as well. Cooler than normal weather is expected to return by late next week and may remain with us for the next week or two.
As mentioned here last week, medium range forecast guidance
is suggesting the formation of an upper air trough across the eastern
Earlier this year, sea surface temperatures in the equatorial Pacific region were falling, and the development of an El Niño event looked possible. That surface temperature trend unexpectedly stabilized during the spring season and has remained steady since, reducing the chance of an El Niño anytime soon. ENSO factors thus play little if any role in the new series of NOAA long lead outlooks for the upcoming months.
For the month of July, the outlooks are directionless for