Northern Michigan FruitNet 2006
Weekly Update
NW Michigan Horticultural Research Station
| Jim Nugent District Horticulturist |
Nikki Rothwell District Fruit IPM Agent |
Bill Klein Farm Mgr, NWMHRS |
| Duke Elsner Agricultural & Regional Viticulture Agent |
Jim Bardenhagen Leelanau Extension Director |
May 16, 2006
| GROWING DEGREE DAY ACCUMULATIONS as of May 15, 2006 at the NWMHRS | |||||||
|
|
|
|
|
|
|
|
|
|
|
518 |
405 |
339 |
356 |
291 |
455.0 |
372.0 |
|
|
242 |
182 |
145 |
153 |
135 |
236.0 |
172.9 |
WEATHER
The past week began fairly warm but quickly changed, with an extended period of cool, wet weather. Rain has been recorded at the NWMHRS for the past seven consecutive days, resulting in some very long wet periods.
GROWTH STAGES at NWMHRS (5/15/06 9:30 am)
Apple: Mac: 50% petal
fall, Red delicious: early petal fall
Pear: Bartlett: Late
petal fall
Sweet Cherry: Hedelfingen:
7mm
fruit, Gold: Shuck split
Tart Cherry: Montmorency:
Late petal fall; Balaton: Late petal fall
Apricot: 10 mm fruit
Plum: NY 12: Late
petal fall
Grapes: Chardonnay:
1-3" shoots
PEST REPORT
Tree Fruit Report
Apple: We had a close call for fireblight infection on 5/10 and 5/11. Some growers sprayed varieties that are especially susceptible. Temperatures then cooled too much for the rest of the week for fireblight to be of concern. Moisture and temperature conditions have been favorable for apple scab infection. No codling moth have been trapped at the NWMHRS, but two consultants each had a site in the region where codling moth were trapped this week. Sites were in areas of high populations last year or next to stored apple bins. We expect more widespread flight activity when warmer evening temperatures return. The first adult generation of spotted tentiform leaf miner is declining.
Stone fruits: Moisture and temperature conditions have been favorable for cherry leaf spot infection. Due to the rain, growers have had a hard time getting in to put on sprays. The recent extended cool, wet weather will also favor the development of European brown rot where tart cherries are still in bloom. Balaton orchards in the Northport area are of particular concern at this time, but Montmorency can also be attacked by this fungus. One lesser peach tree borer was trapped at the NWMHRS, signaling the beginning of adult flight. American plum borer adults and oriental fruit moth adults are on the rise. Plum curculio has not been active during the recent cold weather. We expect increased activity once warmer evening temperatures return. Black cherry aphid is fairly common this season on sweet cherries.
CHERRY
LEAF SPOT AND A LOT OF RAIN
Nikki Rothwell, District
Fruit IPM Educator
George Sundin, Plant Pathology
With the continuing onslaught of rain, growers are wondering about the best options for cherry leaf spot control. Because the rain has provided so few windows for fungicide applications, there have been varying amounts of fungicide applied to tart and sweet cherry blocks. As rain is expected to continue for the remainder of the week, growers need to make quick decisions about the chemistry to apply when the rain actually stops for a while and the wind dies down enough to apply a spray. The following scenarios are meant to help growers decide the best product for their orchard:
Scenario 1: Growers that applied a full cover of Bravo on Tuesday or Wednesday last week (May 9th or 10th) and had relatively good coverage can assume they were protected, but they will have to make an educated guess as to 'how protected'. There will be no way to know how long the Bravo lasted or if it is still there, but for the most part, growers with a full rate of Bravo can assume some level of comfort. If this is the case for a particular farm, a grower should go back in with another full rate of Bravo as soon as possible. This scenario assumes a good degree of protection from the cherry leaf spot (CLS) pathogen, and Bravo is the choice for continued protection into the future, up to shuck split. The one thing to keep in mind with this program is that the grower should shorten the interval between sprays if the rain continues as the material will remain on the trees for a shorter amount of time.
Scenario 2: Growers that applied only a half cover of Bravo should assume they were NOT protected and need to go back into the orchard with something other than Bravo (as Bravo is only a protectant and does not have the ability to eradicate). As we have little knowledge of after-infection activity of some of our options (strobulirins and Pristine), we have to assume that these products will provide some eradication potential. First, there are no fungicides that will eradicate a spore that has germinated 5-7 days ago. Sterol inhibitors (SI's) used to provide some back action; however, those days are gone as CLS has developed resistance to these products throughout Michigan. Syllit (dodine), another product with some back action, can provide back action up to 36 hours; however, we do not know the current extent of dodine resistance in the CLS pathogen. These two products are an option if an orchard does not have SI or dodine resistance, but the likelihood of having an orchard without SI resistance is very low. Using SI's to control CLS is not recommended, and a total control failure is probable with these products. Dodine may be more efficacious against CLS, but we have no recent data to verify this assumption; if dodine is used, the flowable rate is 27 oz/acre.
The remaining products are the strobulurins and the strobulurin/boscalid compound Pristine. One tactic for growers that have applied a half side is to come in with a full rate and both sides of Pristine at 14.5 oz/acre, Flint at 4 oz/acre, or the new product Gem at 6 oz/acre (see new product write-up for more information). The full rate is essential to get the best control now and slow a possible CLS epidemic. If a grower applies one of these chemistries at a higher rate, he or she can follow up that spray with another Bravo spray at shuck split timing, about 7 days from now. This strategy does not recommend tank mixing at this time for best efficacy against CLS as well as costs. Bravo is better used as the next spray at the shuck split timing. We should also not be cutting back on the rates of the strobulurins and Pristine if orchards have gone without protection during this wet weather.
Scenario 3: Growers that have had no coverage at all in the last week should follow the recommendations for scenario 2, but bump up the rate for Gem to 8 oz/acre.
A final reminder for all growers is that we still need to keep resistance management in mind as we move through this super rainy period. Tank mixes are usually the best bet, so we should be trying to keep full rates of fungicides alone at a minimum, although dire circumstances often require dire measures.
MINIMAL
SPRAY STRATEGY FOR FROSTED APPLE TREES
Nikki Rothwell, District
Fruit IPM Educator
Amy Irish-Brown, District
Fruit IPM Educator
Jim Nugent, District Horticulturist
After the early morning frost of Saturday, May 6th, many apples in the northwest region were affected. Based on some preliminary observations, we have found most apples in 'cherry sites' fared pretty well, although some trees in those 'good fruit sites' picked up some damage. After growers determine the damage on their farms, if they find their trees suffered a lot of frost damage, they may want to opt for a minimal management program. This program is designed to keep the trees healthy for next year, but also to reduce input costs on acreage with no expected returns.
For those growers with crop insurance, the guidelines of your policy commonly state that you have to maintain the trees in a normal fashion in order to qualify for claim payments. With reduced or no crop on the tree, several insects and diseases may be ruled out of your spray programs (thankfully!).
Fire Blight - Fire blight is still an issue for a lot of the region, especially with this recent wet weather, and the big question is whether we can still become infected from fire blight with so many dead blossoms. There has been little work done on this topic, but we know that dead pistils on frosted blossoms cannot support a population of Erwinia amilavora, the causal agent of fire blight; hence, the more dead blossoms there are in the orchard, the lower the potential of fire blight infection. We are in essence reducing our fire blight inoculum in the orchard by eliminating the number of viable fire blight infection areas (flower pistils). Although most growers fear the worst, ie. 100% destruction, we cannot assume all flowers in the orchard are dead. Therefore, we must continue to monitor and potentially spray for fire blight because we may have some viable flowers still in the block. We especially cannot assume we have a total wipe out in blocks with susceptible varieties. In addition, trauma blight situations still may occur with high winds and hail, and these events can still cause devastation to orchards. Trauma blight situations should still be managed with applications of streptomycin, Mycoshield, Serenade, or copper. Streptomycin is the best material to use and will give the best management of fire blight in a post-trauma blight situation where resistance is not an issue. Mycoshield, Serenade, and copper applications should be made ahead of a trauma blight situation, and this option is not always the most economical choice as growers attempt to stay one step ahead of the weather forecast, which we all know is virtually impossible.
Apple Scab - As for all blocks, those with and without a crop, apple scab is best controlled if growers stayed ahead of primary scab. The best method to control scab blocks with little crop would be to control these initial scab lesions before growers reduce or eliminate fungicide applications from the block. If blocks have scab in them now, these blocks could defoliate early and have reduced winter hardiness and a high potential inoculum level for 2007. As we are still in primary scab, growers should not cut back on fungicides at this time. If an orchard makes it through primary scab this season without infection, we could reduce and potentially eliminate all other fungicide applications for the season.
Powdery Mildew (PM) - Just as with apple scab, powdery mildew left uncontrolled can lead to reduced vigor and winter hardiness. Again, as with apple scab, most commercial blocks have had some mildewcides in their programs already this year, so mildew will not probably be a concern in most blocks with no crop. If you have a mildew problem now, treat it soon in order to reduce the inoculum potential for the 2007 season.
Plum Curculio (PC) - If there is no crop, there is no reason to spray for PC (or for other fruit feeders like apple maggot). However, growers should keep in mind that PC are good fliers, and if one block has no apples, those buggers can move from the no-apple block to an orchard with fruit in a short amount of time. Growers should be keeping an eye for PC in the orchard as well as on their neighbors' crops to determine if PC may be migrating from one orchard to another. Under light fruit load conditions, plum curculio will compete heavily for the fruit that is present. If the remaining fruit are left unprotected, these weevils can oviposit many times in one fruit, and ultimately may result in a much higher percent damage level per fruit than normal. The good news is that most of this fruit will drop, but the larvae that emerge could be the source of next year's "resident" population. Next season, growers will need to account for the difference in managing a resident population versus the predominant situation of controlling immigrants moving in from outside wild hosts. The other factor to consider is the amount of frost damage you have, and this issue remains true for other fruit insect pests: the fewer fruits per block, the less food insects will have to consume. Growers should know in the next few weeks how many fruits are left in their blocks, and this information can be considered for fruit insect pest control strategy.
Potato leafhopper (PLH) - PLH is normally controlled when broad-spectrum insecticide programs are used to control primary pests like plum curculio, codling moth, and oriental fruit moth. If growers reduce or eliminate insecticides for these key pests because of little or no crop, PLH should not be ignored. The PLH first arrives in late May with southerly-based weather fronts. Those adults lay eggs, which hatch and begin feeding on the phloem of foliage and shoot tips of actively growing terminals in mid-June. Populations vary greatly year to year. PLH often reach high populations by early July. The resulting damage appears as necrotic cupped-leaf margins and can stunt growth significantly. Apple growers should check for potato leafhopper during weekly orchard monitoring beginning in early June. Look for curled leaves and shoots that are not growing as vigorously as they should. Check the undersides of leaves for nymphs and adults. As leafhoppers are easily disturbed, and move off the leaf, it is important to do assessments in the field. Turn the leaf over slowly when monitoring to assess how many leafhoppers are on the lower leaf surface. In apples, one or two nymphs per leaf can cause leaf curling if they are allowed to feed for a prolonged period of time (four to seven days). Control will be particularly important in young blocks that still have space to fill.
Obliquebanded leafroller (OBLR) - The OBLR is largely a foliage feeder, but can do significant damage to fruit. Fruit damage from the summer generation of OBLR is often related to when terminal growth slows or buds set, forcing larvae from the preferable young foliage to fruit. Fruit damage is also common under conditions of heavy fruit set where full clusters and adjacent foliage prevent adequate penetration of targeted insecticides. Light fruit-load conditions like this year should reduce the risk of OBLR damage compared to normal years.
Codling Moth (CM) - No control is required in blocks with no fruit. If growers have a few fruits on the trees - perhaps as few as 10 or 20 fruits on a dwarf tree - codling moth will easily infest these fruits in their first generation if you eliminate cover sprays for CM. Eliminating early sprays can lead to very high CM numbers and increases the potential damage for the 2007 season. Growers should also be aware of CM moving in from an orchard with little fruit to a neighboring orchard with fruit. This movement can happen with the first generation but will be more of a concern for second generation CM. If growers have orchards with a crop, they should be conscious of any nearby orchards that may be on a reduced insecticide program because of no crop. If a neighboring block has no crop, the CM that are residents in those apple trees will most likely move to nearby blocks with fruit to lay their eggs. If a neighboring block has a few fruits and the first generation CM is not controlled, then the second generation CM will most likely move to neighboring blocks to look for more favorable egg-laying sites. Older orchards generally have higher resident populations than younger blocks.
Oriental Fruit Moth (OFM) - OFM larvae bore into new growing terminals and cause the terminals to look ragged and flagged over. This injury is most apparent in first generation OFM, but second generation will appear as the fruit sizes and become more desirable to OFM. Populations of OFM are generally very low in NW Michigan, so reducing or eliminating spray for other pests will not likely lead to an OFM problem. However, if OFM is present, then a light fruit set will likely increase the incidence of terminal flagging during the second-generation OFM egg hatch period (July). Also, if insecticide cover sprays are eliminated from apple blocks, OFM and some other insects may build in number, likely increasing pest pressure the following year.
Apple Maggot (AM) -- As this insect pest can be found on other trees outside of commercial apple blocks, ie. hawthorns, crabapples, and abandoned blocks, they move into a block to infest fruit. If no fruit is present then thre is no need for an insecticide, in which case the adult will seek egg laying sites elsewhere. There is evidence of AM building up in orchards that remain unsprayed, so we may potentially increase AM in blocks that have some fruit but do not have insecticides. However, in a year with little fruit, there will be few oviposition sites (apples) in which AM will lay their eggs. So, if a grower plans to harvest a block with a light crop, keep in mind that the apples that do remain will be a haven for many AM larvae. Again, growers should monitor their apple crop in order to make the decision to spray for AM.
European Red Mites (ERM) and Two-spotted Spider Mites (TSSM) - Left uncontrolled, ERM's and TSSM's can reduce photosynthesis and overwintering carbohydrate reserves. These reserves provide the tree with its winter hardiness, as well as help set the next year's crop. They can cause severe bronzing, but if this occurs in a year without a crop, the damage will not be as severe, due to the lack of competition for the carbohydrates from fruits. In other words, the tree can tolerate more mites. Plus, if certain broad-spectrum insecticides are left out of an orchard system (for codling moth, for example), then mite predators will have a chance to build their populations to help curb the ERM. This season may be one to save some money by eliminating a miticide spray!
**Some growers may find they have to spray more than these general rules of thumb while other growers may not need as many applications. One important thing growers can do to reduce the number of chemical applications is to diligently monitor for insects and diseases throughout the season. This scouting could be the difference between spraying and not spraying based on the pests in the field.
Other concerns:
Benefits of Beneficials
One possible benefit of
reducing broad-spectrum insecticide sprays would be a potential increase
in biological control organisms such as beneficial insects. By eliminating
the number of insecticide applications could be helpful for the future
of an orchard system.
Return Bloom for 2007
Next year will most likely
have a tremendous return bloom. With little crop, the vegetative growth
should be at a maximum for 2006, which will lead to extra pruning for the
dormant season. A strong dormant pruning program will help regulate the
2007 crop. Apogee applications will help reduce terminal growth and could
reduce pruning costs by as much as 30%. Apogee applications are not inexpensive,
and a grower should weigh the costs of the applications against the costs
of dormant pruning. Also, Apogee is best timed when the king bloom is starting
to drop petals, so you may be out of the window for good growth control
with Apogee for this current season.
Eliminating fruit
If you have a small crop,
you might want to consider eliminating fruit completely from the trees.
You can limit the infestation from the apple insects like codling moth
and apple maggot, by eliminating the fruits on the trees. Chemical fruit
removal may be done with high labeled rates of spray thinners, such as
NAA and Sevin XLR plus a spray oil. The best program would be to make two
applications. If weather is warm (favorable for thinning), the first chemical
thinners should be applied as soon as the flower petals are 80% fallen
(not too soon in bloom or you can harm pollinators). A second application,
10 to 14 days later, may be needed to remove more fruit. Even with two
applications of chemical thinners, there may be some fruit remaining that
may need to be removed by hand. If only one application is planned, then
suggest applying when the first period of warm weather occurs after petal
fall. Suggested fruit removal program:
15-20 PPM NAA (6-8 oz. NAA in 100 gallons of water) PLUS 1 quart Sevin XLR plus 1 quart spray oil/100 gal..
Large Fruits
Fruit size will most likely
be large on trees with a light to moderate crop set. Large fruits have
some potential inherent problems such as bitter pit, water core, and cracking,
which can cause storage and marketing problems. Calcium sprays can help
and might be justified in certain higher value varieties that commonly
have problems such as bitter pit.
Scarred Fruits
There may be a lot of surface
damage on apples this year due to the cold weather during bloom. Growers
should evaluate crop quality - if it is poor, eliminating the fruit and
using a reduced spray schedule should be considered.
Nutrition
Trees with little to no
crop do not need as much nitrogen. If a split application was planned,
the second application should be reduced or eliminated. If no apples will
be harvested, apply only foliar nutrients where a known deficiency exists.
For example, if N was applied to the soil prior to the freeze, then there
should be no need for foliar N this season. As noted above, if a light
crop will be harvested, then foliar calcium will be especially important
on bitter pit susceptible varieties.
In Conclusion
Be sure of your crop situation
before you decide to eliminate cover sprays entirely from an apple block.
Apple fruit set can fool the eye sometimes, especially now that the foliage
if growing so rapidly. One week may look like a total loss and the next
week, the fruit will start to show up more readily. Also, if you have crop
insurance, be sure to check with your insurance representative of the details
that they may require of your pest management program so that you are not
disqualified in any way.
A
LONG LOOK AT FIRE BLIGHT
Dr. Nikki Rothwell, District
Fruit IPM Educator
As we are entering bloom in apples, growers need to be concerned about fire blight. This disease is particularly hard to control because of a variety of reasons: 1) unlike apple scab, the fire blight bacteria are dispersed several weeks prior to 1st infection, 2) Erwinia amylovora (the FB bacterium) is a complete epiphyte, which means it grows and relies on the apple blossom for support only, 3) the doubling time of the pathogen is about 20-30 minutes when temperatures are between 65-75 F, 4) infection can occur in minutes, so almost any wetting event is a potential infection period, 5) new infections produce many new bacteria which are efficiently transmitted by insects, wind, and rain, 6) trauma events (rain, hail, or wind) put every orchard at risk, and lastly 7) overwintering cankers are often difficult to find and remove, so they are likely to be present in spring in time for warm wet weather.
Fire blight bacteria growth is favored with temperatures over 65 F. Degree hours using a base of 65 F (DH65) is used to estimate bacterial population growth, with 198 degree hours (base 65 F) from first bloom needed to build the population to a potentially dangerous level. According to current research, fire blight bacteria build up on the tip of the flower pistil (the stigmata, which receives pollen grains). Once the population has built up on the stigmata, a rain or heavy dew can wash the bacteria deep inside the flower where infection can take place.
The fire blight model is based on the EIP value (Epiphytic Infection Potential), which is a way to express this heat unit accumulation on a 0 to 100 scale. ("Epiphytic" = plant surface). The EIP is calculated by dividing the current DH65 accumulation by 195 and then multiplying this by 100. If the DH65 reaches 195 (which also means that the EIP is 100), then a rain or heavy dew at this time will wash the bacterial down into the infection site at the base of the pistil.
The blossom blight model reduces the EIP value under cooler weather conditions by figuring in blossom life. In addition, the model reduces the EIP if the maximum temperature for a day is not above 64 F, because the fire blight bacteria require warm temperatures to grow. The EIP value is reduced by 1/3 by one "cool" day, another third by a second consecutive cool day, and to zero with a third. A day with freezing temperatures reduces the EIP to zero. However, once the EIP reaches 200, cool weather no longer reduces the accumulation.
The fire blight model is very different from our other pest models in that it is based on degree 'hours' rather than degree 'days'. Since the threshold temperature for fire blight is 65 F, we often go above that temperature for many hours in one day, so it takes a lot less time to collect degree hours above the threshold compared to collecting 'daily' temperatures that average above 65 F. Growers must be particularly diligent about checking for fire blight infection because the temperatures can change drastically in one day, and slight changes can cause the EIP to raise quickly and warrant a fire flight spray.
Therefore, at this time of the year, we need to be on the look out for weather conditions that favor fire blight, especially in susceptible varieties (See list of susceptible varieties below). Infection can occur with a small amount of rain or immediately following a warm period that allows bacterial populations to reach critical levels. The Enviroweather website has a reliable chart growers can use to determine if an antibiotic spray is needed. Click on www.enviroweather.msu.edu, go to the weather station closest to you, then to Fruit, then to 'Fire Blight of Apple Blossoms'. Locate the biofix date (the date bloom first opened OR the date a spray was applied to control fire blight) on the top row. Follow that column down to determine Epiphytic Infection Potential (EIP) for that block on each date in the left column. If this number is greater than 100, and the average temperature is greater than or equal to 60 F, this area will be shaded and rain or trauma (high winds or hail) is all that is needed for infection.
This time of year is particularly difficult to gauge fire blight as we often have warm and rainy weather, but we don't want to 'waste' an antibiotic spray if it is not truly necessary. If the fire blight model's EIP is not at 100, but kind of close to call, there are a few rules of thumb to determine if an antibiotic application is warranted: 1) a block with a history of fire blight, 2) susceptible varieties, and/or 3) visible cankers are all pretty good reasons to go into a rainy period with a strep spray.
Susceptible Varieties
Gala, Fuji, Jonathan, Rome, Ida Red, Ginger Gold, Mutsu (Crispin), Rhode Island Greening, Paulared
EXAMPLE: Interpreting the Enviroweather Chart
First pick the column that best corresponds to the first day blossoms opened in your orchard (see figure). The numbers in the squares gives the EIP (Epiphytic Infection Potential) for these blossoms. Bacterial populations (larger EIP) build on days with temperatures over 65 F. When the EIP reaches 100, a rain or trauma event (strong wind or hail) will initiate a blossom infection. The higher the EIP, the greater is the risk of infection with rain or trauma.
QUICK LOOK AT EUROPEAN
BROWN ROT FOR THE NORTHPORT AREA
Nikki Rothwell, District
Fruit IPM Educator, MSU Extension
This cool, wet weather and open bloom is the combination for European brown rot to invade tart cherries. Although this pathogen (Monilinia laxa) rarely infects Montmorency, it can be a problem in years under the right conditions. Montmorency trees infected with European brown rot are found in low areas of the orchard or along hedgerows, locations that do not dry off quickly. This pathogen is a major disease in other cultivars like Meteor, English Morello, and Balaton.
European brown rot infects and kills blossoms and spurs when wetting events last for a day or more (we have had plenty of those days lately!). The infected blossoms turn brown, and the leaves are also killed by the pathogen. Eventually, the pathogen moves into the spur and causes a systemic infection. Cankers form at the end of the infected spurs, which can infect the tree again in the following season.
To control this disease, two fungicide sprays should be applied; the first spray is at the popcorn stage, followed by a second spray seven days later. Indar at the 2 oz rate is the most efficacious fungicide for controlling European brown rot. Pruning the infected spurs during dormant months will reduce inoculum for the following season.
NEW PRODUCTS
Nikki Rothwell, District
Fruit IPM Educator
Gem
A new strobulirin fungicide
labeled for stone fruit. The active ingredient is trifloxystrobin, the
same ingredient as in the product Flint. This product provides control
of cherry leaf spot (Blumeriella jaapii), powdery mildew (Podosphaera
spp. and Sphaerotheca pannosa), and scab (Cladosporium carpophilum)
at 4-8 oz/acre. Gem also controls shot hole (Wilsonomyces carpophilus)
at 6-8oz/acre and shows some disease suppression of blossom blight (Monilinia
spp.) at 4-6 oz/acre. Growers cannot apply more than 32 oz of Gem per acre
per season, and this product cannot be applied within one day of harvest.
For resistance management, growers should not make more than two sequential
application of Gem or apply more than four applications per season.
Proclaim
A new insecticide is now
become available for pome fruit: Proclaim. The active ingredient in this
product is emamectin benzoate. Proclaim is labeled for Lepidopteran pests,
such as OBLR, RBLR, codling moth, lesser apple worm, and OFM, and it is
also effective on pear psylla, leafminers, and two-spotted spider mites.
The product works best if it is applied to small larvae, just after hatch.
The product needs good coverage with sufficient water when applying. The
recommended rates are 3.2 oz/acre for low to moderate infestations and
4.8 oz/acre for high infestations. The PHI on Proclaim is 14 days, and
the maximum amount is 14.4 oz/acre for the season. Proper resistance management
strategies are recommended for this product.
This issue and past issues of the weekly FruitNet report are posted on our website at: http://www.maes.msu.edu/nwmihort/faxnet.htm
ACTUAL
AND PREDICTED DEGREE-DAY
ACCUMULATIONS
SINCE MARCH 1, 2006
Please send any comments or suggestions
regarding this site to:
Bill Klein, kleinw@msu.edu
Last Revised: 5-17-06
Northwest Michigan Horticultural Research Station
6686 S. Center Hwy • Traverse City, Michigan 49684
Tel: 231/946-1510 Fax: 231/946-1404