Vol. 20, No. 12, June 28, 2005

Tree fruit news

Enhancing return bloom with summer NAA

Small fruit news

David Epstein
MSU IPM Program

Apple maggots overwinter in the pupa stage and are developmentally ready to emerge as adults in early summer around 900 GDD50. Fly emergence often follows rainfall events and is typically delayed if the soils remain dry. Peak emergence generally occurs between 1400 and 1700 GDD but is highly dependent on site-specific weather conditions.

Apple maggot adults are dark flies approximately 6 mm in length. The most characteristic feature of the fly is the dark pattern on their wings. These wing-banding patterns are used to differentiate between fruit fly species. Apple maggot has four distinct black bands toward the wing tips. Further identifying characteristics for the apple maggot include a white spot on the back of the thorax and white bands across the top of the abdomen.

Upon emergence there is a seven to ten day period before female flies lay eggs. During this time they are searching for nutritional sources needed to become sexually mature. After female flies complete this pre-oviposition period and have mated, they will seek out fruit for egg laying. They lay eggs just under the skin of ripening fruit with a needlelike ovipositor. The puncture wound caused by egg laying can be difficult to distinguish from lenticels on the apple surface.

Fly larvae, called maggots, hatch from eggs within a week and begin to feed in the flesh of fruit. Maggot infestations initially appear as surface dimples, but eventually develop into deep tunnels indicated by brownish apple flesh. Maggot infestations will sometimes cause fruit to abort, but often the fruit will hang until harvest. Mature maggots drop out of fruit and enter the soil, where they pupate, starting the next generation’s life cycle.

Monitoring adult apple maggot flight is key to effective management of this pest. Adult activity can be monitored using yellow sticky boards with ammonium bait or a red sphere trap covered with an adhesive and baited with synthetic fruit volatile. The yellow trap is most useful during the pre-oviposition period when newly emerged females are actively feeding. The red sphere trap is effective throughout the season, because it mimics the ripening fruit that flies are attracted too during egg laying. Whatever traps you’re using, they should be placed on the south-facing side of trees in the perimeter rows. We place these traps in the perimeter rows because most flies are expected to be immigrating to the orchard from wild hosts outside of the orchard. Optimally, traps should be checked twice weekly starting 900 GDD base 50ºF until the first fly is captured, then once a week is sufficient.

The greater the number of traps deployed per acre (at least one trap per 2.5 acres), the greater the confidence level in basing treatment decisions on fly catch. Proper trap maintenance (keeping them clean of insects and debris and covered with adhesive) is crucial to trap effectiveness. In determining control treatment timing, on-farm fly catches should be used in conjunction with regional trapping information. Chemical control of apple maggot is focused almost entirely on the adult, with the goal of preventing egg laying. Once the egg is deposited under the apple skin, it is out of reach of most chemical insecticides. Therefore treatment decisions are based on fly captures in traps.

Applications of OPs and other contact insecticides are timed for just prior to fruit fly egg laying, which occurs seven to ten days after the first fly is captured. If a fly is trapped on-farm, and a regional trap catch is recorded prior to the on-farm fruit fly capture, the treatment should be applied seven to ten days after the earliest capture. Basing treatment decisions solely on regional information may lead to unnecessary insecticide applications. If attempting to control fruit flies with one of the newer insecticide chemistries that require ingestion of the material for effective control, these insecticides are most effective when applied immediately after the first fly has been captured in a trap. Materials that act by deterring egg laying, like kaolin clay, need to be applied before fly emergence and a thorough coverage of the tree canopy maintained as long as flies continue to be captured. Click here to see a table of results for different insectisides.

Philip Schwallier
District Horticulture Agent

Some years it is desirable to try to enhance return bloom on apple varieties that tend to be biennial. This is especially important on trees that have a heavy crop load. Most years treatments of summer NAA applied at five, seven, and nine weeks after bloom (WAFB) will increase return bloom even on varieties that have heavy crop loads and tend to have poor return bloom. This timing is after any potential thinning from NAA has pasted. Fruits are often greater than one-inch in diameter and won't respond to any NAA thinning action. Flower bud initiation has already begun but can be enhanced by NAA treatments during the next 30 days after the thinning period ends.

Summer Ethrel can also enhance return bloom by treatments of 200 to 300 ppm made at the same timing of five, seven, and nine WAFB. However, summer Ethrel can some years thin one-inch diameter fruit and later summer Ethrel can advance maturity of early maturing varieties.

Michigan State University Cooperative Extension and International Plant Management, Inc. have combined to sponsor a Sweet Cherry Variety Showcase for commercial growers at Clarksville Horticultural Experiment Station on July 7.

The new high tunnel over producing Sweetheart and Rainier cherries will be a special feature of the showcase. This structure was installed this spring and will be used to study the feasibility of high tunnels in sweet cherry production in the Midwest.

Speakers include Dr. Greg Lang, Phil Schwallier, and Dr. Bill Shane of Michigan State University and Wallace Heuser of International Plant Management, Inc. The variety displays will feature selections from Southwestern, Northern and Central Michigan, Ontario, Washington, Oregon and New York. Also featured will be a video presentation of the new sweet cherry series from The University of Bologna in Bologna, Italy and some views of sweet cherry production and processing in Turkey.

The program will begin at 1:00 PM. Refreshments will be available after the session. Clarksville Experiment Station is 15 miles east of Grand Rapids on I-96. Take exit 59 toward Saranac/Clarksville and turn right on Portland Road. For more information call International Plant Management, Inc at 1-800-424-2765.

Rufus Isaacs, Luis Tiexera, and John Wise
Entomology

Last week’s Fruit CAT Alert (June 21) contained an article on how to monitor for blueberry maggot. Since then, the first of these flies have been trapped in southwest Michigan at non-commercial blueberry fields. Commercial growers should be monitoring for this pest and making management decisions as the harvest season approaches, to prevent infestation of fruit (see photo).

The blueberry maggot is a key pest of blueberries, because infestation of fruit by the larvae of blueberry maggot makes it unmarketable. Although spray programs for other insect pests, particularly Japanese beetle, can make blueberry maggot seem of lower importance late in the season, monitoring for this pest is advisable. Weekly checking of yellow sticky traps can be used to identify when adult blueberry maggot flies are active, and action should be taken soon thereafter to prevent infestation of the fruit. Flies often immigrate into fields from surrounding wild habitats, but infestations can also become established in fields if appropriate controls are not used. Maintaining harvested fruit free of blueberry maggot is essential to prevent this pest from building within a field. This article reviews the currently-available insecticide options for fruit protection against blueberry maggot infestation.

Note that Guthion is limited to two applications per season in blueberry, and that Lannate cannot be used once a U-Pick planting is open to the public.

SpinTor is a Dow AgroSciences product with activity on fruit flies that has performed well in recent trials on commercial blueberry farms, providing over 90 percent reduction in infestation compared to untreated plots. This product works by contact activity and ingestion, so it is important to apply immediately after the first fly is trapped. It is also worth noting that SpinTor requires reapplication after significant rain. A baited formulation of SpinTor, called GF-120, is also registered for blueberry. This product is designed to be applied in large droplets spread across the foliage, and flies come to the droplets to feed and eat a toxic dose of insecticide. This product provided 98 percent fruit fly control in plot trials, but it has had little commercial testing in Michigan due to the lack of activity on Japanese beetle.

Evergreen (MGK) is a pyrethrum insecticide with fast initial knockdown activity against blueberry maggot, though with not more than 1 day of residual activity.

Many neem-containing insecticides such as Ecozin, Azadirect, and AgroNeem are certified for use in organic blueberry production. These products disrupt insect development and reproduction and may also act as antifeedants. Some formulations may affect fruit finish on ripe fruit, so spraying a test patch is advisable before widespread use. In recent trials in New Jersey, AgroNeem provided slightly less control of blueberry maggot than either Entrust, GF-120 or Pyganic.

Pyganic (MGK) is an organic option for fruit fly control. It is a pyrethrum insecticide that has very short activity, but provides high knockdown and control of adult flies. This product has a short PHI and broad activity.

Surround WP (Engelhard) has demonstrated efficacy against blueberry maggot in multiple research trials in recent years. This refined kaolin clay formulation produces a fine white coating over the bush that may operate to prevent egglaying by irritation of the fly as it searches in the plant canopy. A coating of Surround must be maintained for adequate performance, and reapplication after heavy rain will likely be required. Because this product can leave a residue on the fruit at harvest, it is more suitable for processing berries than for the fresh market.

Annemiek Schilder
Plant Pathology

The warm, dry weather this season has some benefits; we are seeing a lot fewer disease symptoms than in wet years. Since most fungal and bacterial plant pathogens need moisture, dry conditions discourage their development. Does this mean that growers can put the sprayer away or stretch spray intervals? Fewer sprays mean money saved and less environmental pesticide exposure. The answer to the question is: in some cases, yes, but let’s discuss a few considerations before you do so.

Has new plant tissue emerged or have treated leaves or fruit expanded substantially since the last application? If so, these new tissues are probably not well protected since redistribution to fungicides is limited, particularly in dry weather. In addition, young tissues may be more susceptible to some diseases and therefore would need extra protection. Make sure to apply a fungicide if rain or heavy dews are in the forecast and pathogens are still active.

Is residue still visible on plant surfaces? Depending on rainfall and the period of time since the last application, fungicide residues may remain visible on plant surfaces. The question is whether these residues are still active. Fungicides on exposed plant surfaces may not be present in high enough concentrations to be effective after two to three weeks, even in the absence of rain. Most fungicides are subject to natural breakdown, either by ultraviolet (UV) light or by microbes. Ziram, for instance, is known to be degraded by UV light as are many other fungicides and insecticides. Since sunlight has been intense in the last few weeks, fungicide residues on exposed plant surfaces may have degraded relatively quickly. What you see on the surface of the plant may be just the carrier, while the active ingredient has broken down. Some spray adjuvants may slow UV degradation of pesticides.

Is powdery mildew a potential problem? Hot, humid weather is ideal for powdery mildew and no rain is needed for infection. The conditions right now are ideal for powdery mildew development, and the disease has already been sighted on blueberries and cherries. So keep up the spray program for powdery mildew in crops where this disease can be damaging. Remember not to spray sulfur at temperatures of 85ºF or higher as crop injury is possible at these temperatures.

Is there rain in the forecast or are you applying overhead irrigation? Stretching fungicide spray intervals is okay as long as long as it is dry. However, if rain is in the forecast, you will probably have better results with fungicides applied ahead of the rain as most fungicides act as protectants. You can apply soon after a rain event if you use fungicides with post-infection activity. However, this is usually discouraged later in the season when pathogen populations are larger. First of all, it is more difficult to get full control if there are many infective spores present, and secondly, it could increase the chances of fungicide resistance development. Overhead irrigation can provide good infection conditions in the absence of rain and also contribute to fungicide wash-off. If you overhead irrigate frequently, regular fungicide applications may be needed for disease control.

One last thing to consider when applying fungicides close to harvest; in continued dry weather, some fungicides leave visible residues on fruit surfaces, which can affect appearance and salability and may increase the risk of exposure of consumers to fungicides.

Regional reports

1 – Southwest

Mark Longstroth
Bill Shane
Al Gaus

Weather
Last week was hot with highs around 90. No rain fell in most of the region. A strong thunderstorm moved across parts of Van Buren County on Monday (June 27). Areas close to the lake are very dry. We are seeing drought stress symptoms of wilting and leaf loss in many areas. Soil temperatures are about 75. This week’s forecast is for continued weather with highs near 90.

Early apricot varieties are ripening and harvest will begin soon.

Peach pits are hardening. The second flight of Oriental fruit moth has started. We are at peak emergence for the second generation and peak egg laying should occur at about 1500 GDD45. Oriental fruit moth trap catches were down in many areas, probably because of the heat. We are catching peach tree borer adults, and growers should be thinking about trunk sprays. Green peach aphids numbers are increasing.

Sweet cherry harvest is underway, and tart cherry harvest should begin in the middle of the week. Cherry growers should be protecting against brown rot. Cherry fruit flies are being trapped in abandoned cherry plantings. No symptoms of cherry leaf spot have been found. There is very little leaf yellowing of any kind from Ethrel, sour cherry yellows or cherry leaf spot. All the yellow leaves are on weak trees that are shedding their leaves.

In plums, brown rot has shown up on fruit damaged by insects.

In apples, fire blight is still spreading and is becoming severe in some orchards. Jonathon is the most severely affected variety. Green apple aphids are becoming common and can spread the infection to healthy trees. Growers are treating for aphids in their cover sprays for codling moth. Codling moth trap catches are still high. We biofixed for codling moth on May 20 at 334 GDD50. We are now at 995 GDDs, about 660 GDD past biofix. Activity for the first generation of codling moth should end at about 1000 GDD after biofix, so we are only about halfway though the first generation. Obliquebanded leafroller biofix was June 6 at 935 GDD. We are at 1578 GDD and egg hatch began last week. See the article on summer leafroller control in the June 21, 2005 Fruit CAT Alert. We are finding leafroller larvae in abandoned orchards. The second generation of Oriental fruit moth is laying eggs. European red mite numbers are increasing, and this hot weather may make them explode. The treatment threshold for European red mite from mid-June to mid-July is five mites per leaf. Spotted tentiform leafminer mines are easier to find.

In pears, pear psylla numbers are building and many growers have recently treated for this pest.

Bob Tritten

Weather
Hot weather over the past week has continued to push along our season in terms of both degree days and growth stages. Our season is now running back to “normal” in terms of degree days. One odd note concerning our season is that at a few farms that grow all of the following fruit crops, they are all currently being harvested at the same time. The crops are strawberries, sweet cherries, tart cherries and a few early summer red raspberries. The lack of precipitation is the most noted weather event over the last week. Most areas of southeast Michigan remain dry with a few isolated pockets in Lenawee and Monroe County have not had significant rain events since early May. The effects on fruit size are beginning to be noted in unirrigated blocks of peaches and che

GDD totals for March 1, to June 28

The only new pest seen this week is early signs of cedar apple rust. Most apple blocks continue to have problems with green apple aphids and we are starting to see mite populations build. As was reported last week, our green apple aphid populations have seemed to explode. I have seen a good number of predators feeding on those aphid populations in the terminals, however at most farms the aphids have moved on to the fruit. I am concerned about these aphids populations feeding on the fruit. If this is the case at your farm, then I would consider an application of pesticide to control them. European red mite populations are building. A few limbs or entire trees are beginning to bronze from mite feeding. This is an early indication that with the amount of heat and the lack of rainfall that mite populations are potentially a pest to be concerned about over the next two weeks. Thorough scouting needs to take place at this time to check for European red mite populations. Codling moth trap catches remain low in most conventional blocks and are almost nonexistent in mating disruption blocks. We are currently between generations of codling moth flight. I expect to see the beginning of flight for the second generation of codling moth any day now. Remember to double check codling moth articles in early CAT Alerts to review biofix and control options. Oriental fruit moth populations also remain low. While I am continuing to see flagging of terminals, it also appears that we are between generations of Oriental fruit moth. I am continuing to see a few wooly apple aphid scattered amongst the interior of trees, however their populations are low. Potato leafhopper populations are generally under control, however they need to be monitored fairly quickly. These generally low levels are causing some minor curling on the inside middles on a few varieties of trees, however their populations are low enough that I am not concerned about them. White apple leafhopper populations remain low, as do obliquebanded leafroller. I am continuing to find dogwood borer adults flying at low levels, as well as tarnished plant bug. Other mite problems include low levels of apple rust mites and slowly increasing numbers of twospotted spider mites on apples and other tree fruits. There continues to be a great abundance of predators over the last few weeks. These encouraging levels of predators include: big-eyed bug, syrphid fly, ladybird beetles in all stages, Stethorus punctum, minute pirate bug, solider bug and six spotted thrips. I am also beginning to see higher populations of velvet mites and Amblyseius fallacies.

Apple scab continues to show up on both fruit and foliage. While it is not a serious problem at most farms, it appears that we can find scab at just about every farm. It is a bit unusual to find it on certain varieties and not others. I am also finding it in some plantings only on fruit and not foliage. While fire blight shoot strikes continue to be seen more prominently then they have in the last week, I am seeing few if any new strikes. This is an encouraging sign as fire blight may have run its course for the year. As mentioned earlier, cedar apple rust is starting to show up. Frogeye leafspot continues to be seen in several apple blocks.

Pears continue to size with most being around 1.25 to 1.5 inches in diameter. I have found that while most people have pear psylla under control, there are still a few blocks where pear psylla populations seem to be high this year despite other control measures. I’m not seeing any fire blight show up yet. I am seeing aphids in a few blocks as well as twospotted spider mites.

Peaches continue to size with most being around 1.5 to 1.75 inches in diameter. Twospotted spider mites continue to be seen on peaches at low levels. X disease is in more blocks of peaches this year than I’ve seen over the last 10 to 15 years. Bacterial spot infected leaves continue to appear with severely infected leaves continuing to drop. There is no new infection from bacterial spot. Oriental fruit moth flagging from the first generation continues. I am also starting to see higher populations of green peach aphids in the top centers of trees.

Sweet cherry harvest continues. Most people started harvest mid- to late last week. Sweet cherries have sized very well this year with no cracking. We do have a bit of an uneven ripening in sweet cherries due to the extended bloom period. Birds continue to be a serious problem. I have seen high bird populations also damage strawberries and are starting to move into tart cherries. Due to the high bird population, many farms may be finishing harvest early this year. The only other pest problem to report is twospotted spider mites, however they are at relatively low levels.

Tart cherries are continuing to size well with most being about 20 to 22 mm in size. Several farms are reporting that they will begin harvest of tart cherries in a few days. Their color has changed a great deal over the last week. We have a light crop of tart cherries.

Plum drop seems to be finished with only a light to moderate crop of plums. Most are currently about 1 to 1.25 inches in diameter.

Raspberry fruit is changing color very quickly. A few farms are starting harvest today, but I expect to see most beginning harvest in the next five to seven days. Despite winter injury we apparently have a good crop of red raspberries coming along. Fall red raspberries continue to grow quite nicely with most being around 2 feet or so in height. I’m not seeing any crown or cane borer injury in red raspberries, this is a bit unusual.

Blueberries are mostly at 11 to 13 mm in range with berries beginning to color. Light amounts of blueberry aphids continue to be seen with predators mostly keeping them under control.

Grapes are currently at about 24 inches in length with buckshot size fruit. I continue to see grape berry moth.

Phil Schwallier
Amy Irish Brown
Carlos Garcia-Salazar

Powdery mildew in apple and other fruit crops is starting to spread.

Plum curculio activity has been light this season and should be over for the year. Codling moth trap numbers have continued to decline over the last week and we should be very near the end of first generation adult flight. Obliquebanded leafroller are flying in normal numbers in most blocks with some blocks reporting very high numbers. Green apple aphids continue to be very high in numbers in some blocks – there are pretty good numbers of predators in colonies that are helping control populations.

Some growers are reluctant to remove pruned wood out of the field because it requires intensive use of labor, it is much easer to shred and incorporate it into the soil. However, this practice only augments the chances for re-infection of the field because the inoculum remains alive in the dead wood and splashing rain or sprinkle irrigation water will bring it back onto the plant.

Regarding insect pest, blueberry maggot has started its emergence in Allegan but in Ottawa County we have not seen it yet. There is a need for a correct identification of fruit flies found in yellow sticky traps to not confuse the blueberry maggot with other maggots, particularly the cherry fruit fly. So far, at least in one case, cherry fruit fly adults found in yellow sticky traps triggered an insecticide application against blueberry maggot. As a reminder, the difference between both flies is presented in the pictures provided.

Mira Danilovich

Insect pests are quite active. Codling moth numbers have significantly dropped since last week averaging 2.5 per trap. We have accumulated 575 GDD50 since regional biofix, which indicates that we are more than 50 percent through the egg hatch cycle. Block coverage still needs to be in place to prevent fruit injury. Obliquebanded leafroller flight is underway. We are catching them in high numbers indicating that there is a real threat of a serious problem in those blocks. We are 319 GDD42 post biofix of June 14 (898 GDD42₎. The egg hatch starts at 400-450 GDD post biofix. Given the current temperature trend the egg hatching starts today. Treatment should go on within the next couple of days. Spotted tentiform leafminer second generation flight has started. Scouts are reporting finding European red mite adults and their eggs in a few more blocks. Aphids have been spotted in orchards throughout the area. There is increased number of predatory insects. Scouts are finding various stages of ladybugs, lacewings, syrphid flies and various predatory mites.

Scouts are reporting increased numbers of pear psylla. The weather conditions have favored their development facilitating buildup in their pressure. Some blister mite injury is showing.

Peaches have not gained much in size since last week. Crop looks very good.

Sweet cherry harvest started last Thursday (June 23). Fruit is looking good. The weather forecast is predicting rain for the next three days (starting tonight) so it will be very important to keep an eye on the fruit brown rot (Monilinia fructicola, G.Wint.) development. Depending on the amount of rain and its frequency we may or may not see some cherry splitting. These cherries will be subject to brown rot infection. Humid, warm weather will facilitate disease development. Uses of SI’s (Elite) or strobilurines (Flint) are some of the options at this time.

Tart cherry harvest is not that far off. July 7 to 10 is mentioned as a potential start date. Not much ethrel has been applied yet. There is some hesitation due to the extreme temperatures. Forecast is predicting slight drop in temperatures towards the end of the week so this is the likely window when the ethrel applications will start. Cherries are looking surprisingly good given the droughty conditions. They have a very good size and color. Crop outlook is very good. The official processor/grower and USDA guesstimate for our region (WC) is 62 million pounds. It looks like there is more than that, but time will tell.

Scouts are reporting finding very few cherry leaf spot lesions (Blumeriella japii, Rehm. Arx). There are a few more incidences of powdery mildew (Podosphaera clandestine, Wallr.:Fr.). Bacterial canker (Pseudomonas syringae) symptoms have been found on the leaves, stems and the fruit of a few Balaton blocks (see photo).

Green peach aphids are present in relatively high numbers. Lesser peachtree borer numbers have increased significantly since last week. There is a report of a first catch of a greater peachtree borer. Cherry fruit fly trap numbers have gone up since last week, though they are still on a low side. I would expect significantly higher activity this week after the rainfall. There has been higher mite activity. Scouts are finding European red mites and twospotted mites.

Jim Nugent
Jim Bardenhagen
Duke Elsner
Nikki Rothwell

Although most of northwest Michigan has been very dry in the last month, Benzie County received a quarter inch of rain on Friday night, which resulted in cherry leaf spot infection. However, overall we have detected very few cherry leaf spot lesions this season. Powdery mildew has been reported in most scouted cherry blocks. Plum curculio larvae are now in second or third instars, and infested fruit will begin to drop from the tree in the next week. The plum curculio egg laying period is finished in most areas. American plum borer and lesser peachtree borer numbers are still low this week. Twospotted spider mites have been found in relatively high numbers on older, inner spur leaves. Cherry fruit fly numbers have increased dramatically this week; we captured one fly last week, and this week the average number of flies per trap is 49 in an unsprayed block at the NWMHRS.

Most grape varieties are done with bloom, and fruit set looks very good. Foliar disease pressure is still light, despite a long period of time with weather favoring powdery mildew. Canopies are getting dense quickly, so powdery mildew on clusters is a major threat. Potato leafhopper is the most serious insect concern at this time. Hornworm larvae are starting to gain size and should soon become more noticeable. Rose chafer activity is declining.

Jeff Andresen
Agricultural Meteorology
Geography

An upper air ridge across much of the Midwest has brought hot, humid summer-like weather to Michigan for much of the past week. Even though high levels of low-level moisture (the “raw material” of precipitation) have been in place recently with dew point temperatures in the mid and upper 60s to low 70s, there has been a pronounced lack of any atmospheric focusing mechanisms to generate large scale/widespread convection. As a result, the showers and thunderstorms that have developed have been widely scattered with only limited aereal coverage. Looking at the season as a whole thus far, precipitation deficits from the beginning of April now have reached as high as seven inches in some sections of western Lower Michigan with normal rainfall only on the order of 8.0 to 8.5 inches. NOAA Palmer Drought Index values calculated late last week now characterize all but the east central Lower Peninsula in either “moderate” or “severe” drought conditions.

There are prospects for some relief from the dryness and heat in the new few days. A weak cool frontal boundary will make its way into Michigan during the next 24 hours, likely leading to areas of showers and thunderstorms over most areas of the state during the afternoon and evening hours on Tuesday. Rainfall amounts of 0.25 to 0.50 inches are possible where rain occurs. Showers and thunderstorms will be possible once again Wednesday, but coverage will likely be only scattered at best. By late Wednesday, a second and stronger front will approach from the west, bringing a better chance for more thunderstorms. The timing of the frontal passage will be important: if it passes through the state during the cooler, more stable early morning hours, precipitation is likely to remain scattered. If it passes through during the day on Thursday, especially after some daytime heating, more widespread rainfall is likely, including the chance for severe thunderstorms with high winds being the primary threat. Much cooler and drier air will move into the state overnight Thursday and set the stage for a fair and cool early weekend.

Warmer weather with the chance for showers and thunderstorms is on tap for early next week, as yet another frontal boundary moves into the region. Temperatures will remain at much above normal levels with daytime highs near 80 in northern lakeshore areas to the upper 80s to the low 90s south both Wednesday and Thursdays before falling back to the 70s Friday and Saturday. Low temperatures will fall back from the 60s to low 70s Wednesday morning to the 50s by Friday.

Medium range forecast guidance calls for a broad upper air ridge to cover much of the central and eastern United States with southwesterly flow aloft across the Great Lakes region. The NOAA Climate Prediction Center 6-10 day (for July 3-7) and 8-14 day (covering July 5-11) outlooks both call for above normal temperatures state- and region-wide. Precipitation totals during the 6-10 day time frame are forecast to range from below normal levels across the southern two tiers of counties in the Lower Peninsula to above normal over the northern one half of the state. Below normal precipitation totals are forecast statewide during the 8-14 day period.