Please note that the next issue of this newsletter will be published April 25. – Joy N. Landis, editor.

Pollination is the crucial first step toward obtaining good yields. Most fruits grown in Michigan, including peaches, pears, apples, cherries, blueberries and cranberries, all require insect pollination to ensure good fruit set. California almond growers paid as high as $160 per colony of honey bees spring of 2006, and although we won’t be that high in Michigan, our prices for pollination will also be affected this year due to overwintering mortality. Last year (winter of 2004) the national average was 50% mortality.

To find a beekeeper nearest to you, please check the web site http://beebase.cyberbee.net where you can search beekeepers that provide pollination in Michigan. You can also register your needs for pollination so that beekeepers can find you. A website with information on bee biology, research and beekeeping is also available at MSU (http://cyberbee.msu.edu). To learn whether your fruit crop would benefit from bee pollination, please check the online pollination book at http://gears.tucson.ars.ag.gov/book/index.html.

Growers want to maximize crop production and beekeepers want to maintain their colonies healthy and productive. Sometimes there can be a conflict between the two when bees are placed in fields for pollination and spraying is needed for disease or pest control. Because bees are insects, most insecticides will have some toxicity to bees, so close cooperation among growers, pesticide applicators, and beekeepers is needed to protect bees against poisoning.

Bee poisoning can be subtle
Some pesticides cause direct kill of foragers. This happens when bees are on flowers when the pesticide application is conducted, or when the pesticide used is highly toxic to bees. The highly toxic pesticides actually leave no evidence because nearly all bees die in the field, before bees make their way home. Other types of pesticides allow bees to return home, and then die inside the hive. This type of poisoning is the easiest to diagnose, with a large pile of dead bees in front of a bee hive, usually with their tongues sticking out. Some chemicals do not directly harm adult bees, so they are brought back to the colony and cause damage to young, immature stages of bees (brood). Captan is of this type and does not kill adult bees but larvae exposed to it die or develop into malformed adults. The French beekeepers have experienced the “mad bee disease” recently, in which millions of bees simply become disoriented and not finding their way home. A suspected culprit was thought to be the chemical Gaucho (imidacloprid) applied to sunflowers to protect against parasites, but there is still much discussion about this issue. The French government in 2001 ordered a two-year extension of a ban on spraying this chemical on sunflowers, to allow more study of its impact on the nervous systems of bees. The take-home message is that diagnosis of bee poisoning can be difficult, and growers should take care with any use of pesticides during bloom, and follow the directions for bee safety.

Formulations and time of application
As a rule of thumb, if you have the same pesticide in both dust and liquid form, use the liquid form. Because hairy bee bodies maximize pollen collection, pesticides applied as dusts are more hazardous than sprays to honey bees. Micro-encapsulated pesticides are worse because bees sometimes mistake these granules as pollen and bring them home, causing long-term, chronic damage to the entire colony. ULV formulations can be more toxic to bees because of its higher concentrations, and daytime aerial application of pesticides can be bad news for bees, because many bees in flight will be hit.

Time of application can be important because many foragers will die when sprayed pesticides land on bees directly or is mixed with nectar and bees are foraging on it. Consider working with beekeepers on the spray schedule. Give him or her some options considering the chemical sprayed and the schedules of both the grower and beekeeper. For example, tell the beekeeper a spray is really necessary but you are concerned about his bees. “Should I spray tonight 7:00 to 9:00 PM, when bee activity is minimal; or do you think it is better to close the colonies tonight and I spray tomorrow morning 7:00 to 9:00 AM, and then release the bees around noon?” This type of discussion will often lead to satisfactory comprise for both sides. It does not cause any harm to bees for the colonies to be closed for a few hours. During a very hot day, overheating can be an issue, but can be worked out also, if water is provided abundantly (use soaked burlap at the hive entrance and apply water every 2 hours in July-September).

A list of pesticides of low, moderate and high toxicity, as well as considerations for both growers and beekeepers, can be found online at http://ohioline.osu.edu/hyg-fact/2000/2161.html

Honey bees continue to be plagued by a number of pests and diseases. Varroa mites (Varroa destructor) continue to be the worst pest of honeybees and cause high mortalities during fall and winter. The mites are largely resistant to Apistan (a pyrethroid), which has been used for more than a decade. They are also starting to become resistant against CheckMite+" (an organophosphate), registered as a Section 18 (emergency registration) in most states including Michigan for the last six years. Api Life Var (http://www.cdpr.ca.gov/docs/sec18/pdf/06-04.html) has become available (also Section 18) for varroa treatment since 2003. Api Life Var is composed mainly of Thymol and a few other essential oils, and its efficacy against the mites varies from 70% to over 90%, depending on weather conditions. Apiguard (http://www.vita-europe.com/products/apiguard.htm ) is very simlilar to Api Life Var, with its main ingredient as Thymol and has a federal registration (Section 3) since spring of 2006.

However, anticipating a shortage of this drug, Michigan has applied also for a Section 18 for Api Life Var. Formic acid is also registered as Section 8 with the trade name "Miteaway" (http://www.miteaway.com/) from Brushy Mountain bee supply. We encourage beekeepers to rotate pesticides (CheckMite+, Api Life Var/Apiguard, Formic acid) as well as combining with other integrated pest management (IPM) tactics (such as screened bottom boards, drone brood trapping of mites, etc) to delay the onset of resistance development in mites. Using IPM will also help reduce residual chemical levels in honeybee colonies. Alternative treatments such as a fungus that attacks Varroa and the Mitezapper (http://www.mitezapper.com) are still in development. The right for exclusive production for Mitezapper is recently being considered to be purchased by a developer in Detroit, and the final agreement for purchase is expected to be signed soon. I am working closely with the developer to bring the product to the market as soon as possible (optimistic estimate: spring of 2007).

Another beekeeping concern is American Foulbrood, a bacterial disease on bee larvae that can also kill colonies. The pathogen (Paenibacillus larvae) for this disease has largely become resistant to Terramycin (Oxytetracycline) but a new drug, tylosin (trade name Tylan) is already approved for honey bee use as a Section 3 drug: http://www.fda.gov/cvm/CVM_Updates/honeybee.htm

The small hive beetle, a recently introduced pest from Africa, is also present in Michigan, but so far does not cause large damages if it is controlled in the honey houses. I have seen beetles in a few colonies in the fall of 2005, so I think this pest is now established in Michigan.

Michigan currently (2006) has 65,000 bee colonies, a large drop from the 97,000 in 1997, mainly due to more complicated management schemes to control the varroa mite. Pollination so far has not been affected because a large number of pollinating colonies come into Michigan from the southern States. In California, however, pollination price went up to $150 per hive last year due to a national average winter kill of 50%. For spring of 2006, I checked a few almond growers in the Fresno valley and the prices ranged from $130 to $160 per colony. Expect to pay anywhere from $40 to $70 per hive here in Michigan, depending on the crop and colony strength.

In 2005, the Northwest Michigan Horticultural Research Station (NWMHRS) was given a sizable donation of Osmia cornifrons, horn-face bees (HFB). Much of the initial research was conducted on Balaton ® cherry, a Hungarian variety that produces disappointing yields compared with the traditional Montmorency variety, especially in years when cool conditions persist during the bloom period. We hypothesized that fruit set would be improved if more pollen was transferred to the pistil more quickly after flower opening, thus increasing the chances for successful fertilization. Under Michigan’s variable spring conditions, we proposed using HFB to increase fruit set and ultimately help produce more cherries.

Osmia cornifrons is a pollinator that is native to Japan where they pollinate over 80 percent of Japanese apples and are considered as successful as honeybees for pollinating apples. These bees also demonstrate a distinct preference for Rosaceous plants. HFB are solitary and because they are not part of a social colony like honeybees, all females are capable of reproducing and each female must forage for its own offspring. This intensive foraging behavior is necessary to supply provisions for their larvae, and this foraging activity makes them desirable as pollinators in orchard settings; O.cornifrons visit approximately 4,050 flowers per day compared to honeybees that visit only 729 flowers in that same time. HFB adults are active for six to eight weeks, April through June, which are the peak pollinating months. These bees are easy to manage, reproduce without difficulty, and do not sting. They also do not require intensive management year-round because after pollination, the offspring develop in their nesting boxes and adults are not seen outside the colony until the following spring. There is only one generation of HFB per season.

With grower-funded support, we conducted our initial investigation into the effectiveness of HFB in Balaton ®. Preliminary observations suggest that HFB fly at cooler temperatures than honeybees. This species will also fly under slightly cloudier conditions and higher wind speeds than honeybees. Our foraging behavior study showed that HFB forage for a significantly longer amount of time per flower than honeybees, and HFB visit significantly fewer flowers per tree and for fewer flowers per minute than honeybees.

Horn-face bees have been shown to increase apple fruit set in Japan; fruit set by HFB was 82x that of honeybee fruit set. In order to quantify HFB’s pollinating capability in Michigan, nesting buckets were placed in Balaton ® orchards, two-three days before cherry bloom. Each orchard block was divided in half, and one side was stocked with HFB while the other half contained honeybees. Three orchards had significantly higher fruit set with HFB, while the remaining five orchards did not. Balaton ® yields were collected at harvest, and data suggest HFB may have the ability to pollinate as well as or better than honeybees, but only one orchard showed significantly higher yields with HFB. As most of our results are preliminary but promising, further research is warranted and needs to be expanded to other cropping systems. Determining the optimal timing to deploy HFB in orchards is the key to managing the bees and improving yields. Much of the 2005 data suggest that HFB were placed into the orchard too late to be most effective.

Placement of bees in 1-acre blocks: HFB nesting buckets should be hung in a visible location as observational data suggests these bees use visual cues to locate their nesting sites. At the NWMHRS, we are placing the buckets into apple boxes tipped on their sides, such that the buckets can be hung from the side slats of the wooden apple box. Last year, we wired buckets to the tops of the tipped up apple box with standard wire at the most horizontal angle possible. HFB in the wild use old beetle holes in trees for nesting, and because of the nests position in the wild, horizontal nesting sites are conducive for bee entrance. We want to mimic the wild system, so buckets placed horizontally will work better than buckets placed at an angle. However, make sure the bucket tilts slightly downward to prevent rain from collecting in the bucket. Also, make sure to tie the buckets tight so they do not swing in the wind.

We recommend placing one bucket in the middle row if you do not have many bees. If you have enough bees, I would recommend splitting the 70 full tubes into two buckets, 35 full tubes per bucket, with the remaining tubes with no bees. Buckets should be placed a third of the distance into the orchards from both ends, either north or south or east or west. These bees do not forage as far as honeybees in terms of distance, approximately 200 m, so placing the 250 females (70 full tubes) in the middle of the 1-acre block may be beneficial. Splitting those full tubes into two buckets to try to spread the bees out through the orchard may be even more advantageous.

Timing of placement into orchard: Based on 2005 data and more recent literature, we recommend placing HFB into the orchards 1.5 to 2 weeks prior to bloom. Last year, we recommended putting them into the orchard three to four days before bloom, but we think this timing was much too late for optimal foraging activity (aka. pollination). The literature suggested that they needed a food source or they would “take off.” We did not see this behavior last year as their “homing” behavior was much stronger than their desire to depart to look for a food source. The major behavior we all noticed last year was their need to mate before major foraging activity. Males chew through the mud first, as they are laid toward the opening of the tubes. The males feed a bit, but they are more concerned with emerging females. Emerging and mating took longer than anticipated last spring.

Although the following information will vary based on temperature, males usually emerge within three days of placement into the orchard (as long as temperature is above 55°F), and females will emerge by day 6. Again, they will need a few days to mate and feed. Females must collect pollen and nectar for their offspring, and these females will forage excessively for their brood; hence, the majority of pollinating potential comes from these egg-laying females. In order for females to reach the rigorous foraging stage, they must emerge, find a mate, mate, feed and then she will begin to look for food. This timing is not well known for Michigan orchards, but our current recommendations based on last year’s results are to place the buckets into the orchard 1.5 to 2 weeks before bloom. Again this timing will be dependent on temperature as they emerge based on temperature—the warmer the day, the faster they will emerge and vice versa. Additionally, these bees do not live long, approximately 35 days, so we want to time emergence close to fruit bloom in order for these bees to use fruit pollen for a food source rather than other pollen from other blooming plants.

The need for mud: HFB females use mud to separate the cells of their nest (tube). Therefore, somewhere near the hive, a mud source is needed, especially in a dry year. The recommended mud source is a 1 to 1.5 ft deep trench, approximately 20 yards from the nesting sites; this trench provides bees with a low angle to approach the nest. The soil in the trench should be kept moist, but there should be no standing water. The bees are capable of locating their own source of mud, but in the event of a droughty season, a mud trench is a good idea.

Propagation/new nesting: The only thing needed to propagate more O. cornifrons is a 6- to 8-inch depth hole with a 5/16 inch diameter. There are many methods of creating these “nesting sites:” drilling holes into wooden blocks of wood, pvc pipes, cardboard tubes and potentially many more. However, the key point to remember is that these bees will need enough empty holes to increase the size of the colony, and each female is capable of producing two to four nests each year. Therefore, if we put out 250 females per acre, a minimum of 750 empty nesting tubes are needed.

Another observation from 2005 is that the emerging bees prefer to reestablish the tubes from which they emerged. They will not start creating nests in an empty bucket of tubes unless the “used” bucket is completely full. Therefore, we are recommended setting up your buckets with the minimum number of occupied tubes (about 70 tubes with 250 females) and the remainder of the tubes should be empty. We have used old square “cherry” buckets with wide screens to hold the tubes in the bucket, but any bucket would probably work.

All of the tree and small fruit crops grown in northwest Michigan (except grapes, which are wind pollinated) require insects for pollination. That’s right – wind plays virtually no role in pollination; the job is done by bees! Native wild solitary bees are present and populations likely vary a great deal from site to site, but their numbers alone are generally not adequate to provide the necessary pollination to achieve good yields. Feral (wild) honey bees used to be plentiful and greatly aided pollination, but today no feral honey bees survive the winter due to the introduced mite parasites. This all means that providing additional bees is a necessity to achieve desired yields, particularly in those years when weather conditions are unfavorable for pollination.

Newer, higher density apple plantings, with a single cultivar interplanted with a few pollenizers, require more bees per acre than the older, multi-variety traditional plantings. Likewise, use higher bees rates in sweets where one non-selffertile variety represents 76% or more of the planting.

Hive placement. Pallets of bees should be spread out to minimize flight distance to flowers, with a maximum of 300 yards between colonies. Place in a sunny location if possible.

Place bees in orchards prior to the first blossom opening. The first blooms to open in apple (king blooms) generally produce the largest fruit. The first blossoms to open in cherry have a higher percent fruit set.

Control dandelion to reduce competition for bees.

The study of pollen tube viability and growth had been conducted on sweet and tart cherry varieties under the variable conditions. The samples were placed into the chambers at 15 0, 20 0, 25 0 and 30 0C. Pollen tube growth was observed under the fluorescent microscope 4 hours after the pollination and than every 24 hours thereafter over the 120-hour period. Pollen tube growth in the outside field conditions were used as control. Montmorency and MC-15 were used as female varieties in all the combinations.

Very slow tube elongation and growth were observed in all self- and cross-pollinations where Montmorency was a pollen donor. The best results were obtained in combinations Montmorency X Vladimir and Montmorency X Montmore. Pollen tube penetration was completed two days after the pollination took place. Cultivars Late Duke, NY 5261 and 4X showed no germination at all. In combinations with MC-15 as a female, the following could be inferred: MC-15 self-pollinated had many vital pollen tubes traversed the style 48-72 hours after the pollination. In all cross-pollinations, there was a great variability in pollen tube elongation and behavior. They could be classified in five distinct groups.

In the first group, pollen tubes reached the ovary within the first 4 hours followed the pollination than regression appeared (Viva, NY 1625, Hedelfingen). The second group could be characterized with good pollen grain germination and tube elongation within 4 hours following the pollination and with scores of viable pollen tubes near ovary ( Ulster). In the third group, there was good germination at the beginning with a slow-down requiring 48 hours for pollen tube to reach the vicinity of the ovary (Black Tartarian, Noble). For the fourth group, the pollen tube growth progressed slowly in the first hours following the pollination, requiring 72 hours for tubes to penetrate down to the ovary (Windsor, Chinook). In the fifth group, there was extremely fast germination, growth and penetration. Within the first 4 hours of pollination, multitude of pollen tubes traversed throughout the styles with no regressing observed over the duration (120 hrs) of the experiment (Gold).

Ambiance temperature highly effected pollen tube growth. At 15 0 C in self-pollinated Montmorency, pollen tubes grew at a slower rate. Optimum growth and penetration occurred at 25 0C reaching the ovary within 24 hours following pollination. Increases in temperature caused acceleration of the pollen tube elongation rate but at the same time that was the main reason for decreased pollen tube viability. The same was true for the other varieties in the trial. The experiment revealed different but variety-specific optimum temperatures for the pollen tube growth.

Different varieties respond differently to the ambiance temperatures and have specific requirements when it comes to optimum temperatures for pollen tube growth, penetration and fruit set. Such response to the meteorological conditions during the bloom time and fruit set will result in the fact that certain varieties show strong self-fruitfulness under optimum conditions for pollination and pollen tube growth, whereas those same varieties will fail to set fruit under less favorable circumstances showing self-sterile behavior (such as the case in MC-15).

Our findings are in concurrence with the findings reported by the other authors (Chang, N.W., Struckmeyer, B. E., Nyeky, J., R., D. E. Kester and M.V. Bradley).

A longer, more complete version of this article will be available on the Internet by April 13 at:
http://www.ipm.msu.edu/catfruit/pollination.htm

Using bees for pollination of small fruit crops
Rufus Isaacs and Zachary Huang
Entomology

Value of pollination
According to calculations by Calderone and Morse (2000), the value of honey bee pollination to agriculture in the United States is as high as $US 14.6 billion per year. In Michigan alone the total value to the main fruit and vegetable crops dependent on honey bee pollination is about $300 million per year. Bee pollination of small fruit crops provides the essential cross-fertilization of plants that promotes larger, earlier berries and increased percentage of fruit set.

Use the “late” strategy for small fruit crops
In general, flowers of small fruit crops are less attractive to honeybees than other flowers due to the shape and the relatively low “reward,” so a different strategy is required than you might use for apples, which need bees early. You want to have your crop starting to bloom before bringing bees in so that bees tend to forage more on your crop. If brought in too early, bees will learn to forage elsewhere and when your crops bloom, they are not attractive enough to get the bees "back" to where you want them. Blueberry flowers have about three days to be pollinated after the flowers open, but you want the bees to stay in the field, so move bees into blueberry fields after 5% bloom but before 25% percent of full bloom. The "late" strategy is especially important for cranberries, which is not very attractive to bees. Luckily, cranberry flowers will stay open for a while if not pollinated, and the petals will turn to a rosy color if not pollinated in time. In cranberries, it is better to wait until 10% bloom in order to maximize the yield. If you see too many flowers turning rosy, this means you did not have enough pollinators, so make sure you increase the number of bee hives next year.

Prices for pollination
Most growers will already have their pollination contracts set, but expect to pay anywhere from $40 to $70 per colony for spring fruit pollination. There is a range here because if you only need 10 hives, you might be expected to pay a higher price than the other grower who is renting 500 hives. Colonies might be also of different strengths. Try to deal with the same beekeeper year after year in your area so you know what to expect and can build a good working relationship. If the beekeeper is new in the pollination business, make sure he or she knows your requirements and make sure you sign an agreement for pollination purposes.

Do not cut corners in respect to putting enough bees in your crops. Investing some money to have enough colonies there at the right time will provide returns in the form of improved yields.

Hive placement
If possible, place the colonies in a sheltered location with the entrances facing east. This will encourage earlier activity as the hive warms in the morning sun. Hives should be spread out around the field to maximize floral visitation, with a maximum of 300 yards between colonies.

Native pollinators
Many other helpful insects are active in your fruit crop, and with 20,000 recorded species of bees worldwide, some local native bees are probably active in Michigan’s small fruit crops providing free pollination. Bumblebees and other native species can be seen looking for flowers already in and around fruit crops, and their activity generally remains high when weather conditions turn too cold or wet for honeybees. These native bees may be insufficient to provide adequate pollination for good yields, however, and cannot be relied on to stand alone as your sole pollination source. By providing the right nesting habitats and food for the bees after your crop has flowered, you can enhance the local populations of native bees around your crop. This is a long-term process and you’ll need several years of experimenting before these bees can become a reliable part of your pollination planning. Ongoing research at MSU is investigating strategies for conservation of native pollinators in Michigan blueberries, and we expect this work to be relevant to many other Michigan fruit crops.

Pest management during pollination
Do not apply broad-spectrum insecticides when flower buds are open or you may kill a significant number of pollinators. Bee hives should be removed immediately after pollination if post-bloom pesticide applications are planned. By monitoring for pest problems carefully during bloom, growers can help minimize the need for pest control. If an insecticide application is necessary during bloom, the compounds that are least toxic to bees should be used, with careful observation of the pollinator-restrictions on the label. Two insecticides that can both be applied during bloom for control of moth larvae in blueberry and cranberry are the Bacillus thuringensis (Bt) products, and the insect growth regulator tebufenozide (Confirm ®). Good coverage is required for both, and a spreader/sticker should be used to improve effectiveness. Inform the beekeeper two to three days before application so that precautions can be taken to minimize bee exposure. Evening application is better than morning application and in general liquid form is less harmful to bees compared to the powder form. More information and a list of chemicals with their toxicity to bees is available at http://www.beelab.osu.edu/factsheets/sheets/2161.html

Pollination information available online
Although it is a little outdated (first printed in 1976), the book "Insect Pollination of Cultivated Crop Plants" covers nearly all crops (fruits and vegetables) and is the best reference available for pollination to-date. It has been out of the print for many years, but the book is available free online at: http://gears.tucson.ars.ag.gov/book/. Other websites provide specific information on honeybees, native bees and pollination.

Honeybees are by far the most economically important bees in our blueberry fields, and most growers know what these bees look like. However, there are many of other types of bees native to Michigan who nest in the soil and in cavities in old plants. This article provides some tips on identifying these “other” bees and some guidelines on how to improve the landscape in and around your farm to provide some help to build their abundance.

During bloom, the majority of bees on blueberry flowers are honeybees brought into the farm in hives. You may have also noticed bumblebees and some smaller bees on your flowers and wondered what type of bees these are.

In Table 1, we have provided a list of the different types of bees found on blueberry blooms, their common names, and the ecology of these different groups. In recent sampling of blueberry fields, we found that around 30 percent of bees were non-managed bees such as the Halictid and Andrenid bees shown in the pictures. The rest of the bees were honeybees. While this may not be a high proportion, many native bees are highly efficient pollinators of blueberry (which is a native plant). This is because they will forage at lower temperatures than honeybees, many will provide efficient transfer of pollen through buzz-pollination, they have a high rate of flower visitation, and they stay focused on blueberry flowers. Because of these factors, the overall influence of native bees may be greater than simply counting their numbers on bushes may suggest.

With this community of native bees visiting blueberry flowers and helping achieve pollination, it makes sense to consider easy approaches to help make blueberry farms more hospitable to these bees. Some basic approaches that growers can consider include providing flowering plants for bees to collect nectar and pollen from. To avoid overlap with blueberry bloom, the plants to select would be those that bloom early in the year such as willow, cherry etc., or plants that bloom after blueberry. Aggressive use of herbicides around the edge of fields are likely to prevent flowering plants from growing and will make the field less likely to have native bees. Because many native bees do not fly far, flowering plants should be provided in close proximity to fields, in the perimeter regions.

In addition to food, native bees need a place to live. Most of the native bees we have found in blueberry fields (miner bees, sweat bees, bumble bees) make their nests in the ground (Figure 1), with species aggregating their individual nests together in suitable areas. Providing areas of open ground or mounds of soil that are well-drained near fields can provide places for them to nest. We have seen bee nests in the weed-free strip under blueberry bushes and in bare areas of soil near fields. The adult native bees fly in and out of these nests many times during the year, collecting pollen to feed to their young developing larvae in the nest.

Some of the bees we have found visiting blueberry flowers are active only during the short window of time around blueberry bloom. For these species, minimal use of pesticide will be critical for their ability to emerge, survive long enough to lay eggs, and provision their nests. Other species are active through the season (e.g. bumblebees), and these species will require suitable resources throughout the season to sustain and build their abundance.

In summary, there are some simple practices that growers can adopt in and around their blueberry fields to enhance their suitability for native bees. It may take many years for populations of native bees to build, but enhancing native bees will provide a more diverse strategy for helping achieve high levels of pollination every year.

All members of the fruit industry are invited to attend a Spring Pollination Update on May 17 at the Trevor Nichols Research Complex. Our focus will be on blueberries, but the information should be of value to any growers interested in maintaining an effective pollination strategy on their fruit farm. The meeting will be from 1:00 to 5:00 PM, with registration starting at 12.30.

Topics to be covered during an indoor session will be the following: h oneybees and blueberry pollination, use of bumblebees for blueberry pollination, experiences with Osmia bees in cherry orchards, cultural practices and gibberellic acid to improve blueberry fruit set, and an update on native bee research in Michigan blueberry.

In outdoor demonstrations at our research blueberries, the presenters will talk about the following issues: assessing honeybee hive strength and health, bumble bee quad demonstration, identifying pollinators and assessing fruit set, and using native plants to attract bees and other beneficial insects. Presenters at the meeting will include MSU scientists Zachary Huang, Eric Hanson, Rufus Isaacs, Nikki Rothwell and John Wolfe from Koppert Biological who produce bumblebees for pollination.

A small registration fee of $10 per person is being charged for this meeting to cover expenses. Please make check payable to: Michigan State University and send to Carlos Garcia-Salazar, Ottawa County MSU Extension, 333 Clinton Street, Grand Haven, MI 49417, before May 10.

The Trevor Nichols Station is located south of Holland, 3 miles east of I-196 on M-89 and west of Fennville ( 124 th Ave between 63 rd and 62 nd Streets). Questions? Please contact: Carlos Garcia-Salazar in the Ottawa Co. Extension Office at (616) 846-8250.

For more information, see the brochure at: http://www.ipm.msu.edu/cat06fruit/pdf/PollinationDay2006.pdf

Regional reports
1 -- Southwest
Mark Longstroth
Bill Shane
Al Gaus

Weather
Last week was relatively mild. Temperatures were generally above 50 and near freezing at night. A hard freeze occurred on the morning of Saturday (April 8) with temperatures into the low 20s. Little damage was reported. GDD accumulations are about average for this time of year. This week’s forecast is for much warmer weather, with highs near 70 and lows near 50. This should move all fruit quickly so that our bud stages are more similar to last year when we have been about a week ahead of normal. The longer the warm weather lasts the more advanced we will be. This also means that our fruit will be more susceptible to frost when the warm weather ends. Rain and thunderstorms are forecast for later in the week and rain Sunday and Monday. These could be infection periods for early fruit diseases if the wetting periods last long enough.

Apricot buds are first white, and we should see bloom next week. Poor growth in some sites and varieties indicates that there was some winterkill of fruit buds.

Peach buds are generally at green caylx. Some winter fruit bud loss has been reported in some varieties and on lower, colder sites. This damage is more common in inland areas away from the lake. We are at the end of the window for applying oil to peaches to kill San Jose scale. Oil applications should probably not be applied after red calyx, which will be in a couple days at these temperatures. With warm weather we may see bloom late next week.

Both sweet and tart cherries are past the swollen bud stage; early sweet cherries are at green tip, most sweets are still at green side, Montmorency tart cherries are generally at green side, but Balaton® cherries are more advanced at green tip. Growers are applying copper to reduce bacterial canker. We expect to see white bud next week.

In plums, Oriental plum buds have burst and are at tight cluster and will probably bloom next week. European plums buds are at white side in Berrien County and swollen bud in the rest of the region. Bloom is still a couple weeks off. Black knot control normally begins at bloom when shoot growth starts, but if you have black knots in the orchard, apply controls as soon as green tissue emerges.

Apples are at green tip and growers need to worry about apple scab. Because of the mild winter, scab spores are being released with rains now. Many growers have applied copper as a protectant against scab. Some areas were wet long enough on April 8 for a scab infection, but generally very little green tissue was exposed.

Pears buds are swollen and the bud scales are separated. Pear psylla adults are out.

Grapes are breaking dormancy. Buds at the tips of pruned shoots are starting to swell. Some growers are finishing pruning but many have finished tying. Some growers are applying dormant sulfur and copper sprays to reduce overwintering phomopsis. Sulfur should not be applied to concords after green tissue is present. Grape growers should look at the MSU Grape Resources Page at http://grapes.msu.edu.

Strawberries are putting out new leaves. Growers are applying herbicides, putting down straw mulch and setting up their irrigation systems.

Raspberries are at quarter inch green and new shoots are emerging from the ground. The window for applying delayed dormant applications of lime sulfur is closing rapidly.

Cranberries are still dormant.

The next Monday Fruit Update meeting will be, Monday April 17, at the Fruit Acres Farm in Berrien County, at 5:00 PM . Growers should check out the new MSU Weather IPM site under development at http://www.enviroweather.msu.edu/home.asp

The first Grape IPM meetings will be held on April 20. Check http://www.ipm.msu.edu/cat06fruit/f03-28-06.htm for more details.

2 -- Southeast
Bob Tritten

Weather
The weather over the last two weeks has been relatively mild with the exception of a hard freeze on Sunday morning (April 9). With warmer temperatures occurring throughout this week, spring bud break and “green up” will develop at a rapid pace. At this writing, our bud development is a few days ahead of normal, but this could change rather quickly as spring progresses. GDD totals are also a few days ahead of normal for this time of year, but one week or so behind last year.

A new agriculture weather station has been added to a statewide network maintained by our Agricultural Weather Office at MSU. That weather station is in Lapeer. Data from that weather station is updated hourly and will be a great resource to fruit growers in the Genesee, Lapeer, St. Clair and Macomb county areas. The station was added on March 31, 2006, so there is some data missing for March. Information from the website can be assessed at: www.agweather.geo.msu.edu .

Click on the MAWN link, and then click on the Lapeer button on the map or table. We now have three weather stations across the southeast region, with hopefully another one to be added this season.

I’ve been taking peach and sweet cherry branch cuttings over the last month or so and forcing them indoors. In three separate cuttings there appears to be little to no winter kill of flower buds. It is much too early to give a forecast of how many of these buds will make it through springtime, but it is an early indication that growers can be pruning those varieties knowing that they have an excellent bud survival over the winter.

The soil moisture is currently running a bit toward the dry side. Many growers are considering beginning planting of tree fruits and small fruits any day now.

Pear flower buds are very tight to showing some early signs of bud swell. Pear psylla adults have been flying for a few days now, but with no egg laying. I have seen below normal amounts of pear psylla adults this season.

Peaches are at bud swell with no green tissue showing. Peach leaf curl sprays have been applied in the last two weeks.

Plums are fairly tight, with the exception of Oriental plum varieties, which are at green tip to bud burst.

Raspberry buds are still very tight. Fall red raspberries should have been pruned or mowed a month or so ago. With the mild winter that we’ve experienced, it appears that we had little to no winter kill in the more tender red and black raspberry varieties. Lime sulfur has been applied to summer raspberries.

Blueberry fruit buds are beginning to swell. Pruning of blueberries is progressing quite nicely this year with most farms about 60 to 80 percent complete.

Grapes are still very tight with no bud swell.

3 -- Grand Rapids Area
Amy Irish-Brown

Tree fruit
Earliest to midseason apple varieties started to show the first signs of green as of April 6 – just about the same date as the 2004 and 2005 seasons. Sweet cherry buds are swelling.

Growers are wrapping up winter pruning of apples and removing brush from blocks. Ground applied fertilizer applications should be started soon. Tree planting should start soon.

Apple scab spore rods are in place and running. First spores were found with the rains on Friday, April 7. Numbers were light (11 spores per rod), but for the first catch of the season, this is a significant number. Monitoring equipment is in a commercial block this season – that adds to the significance of this early spore catch. Friday’s rains were an infection period for the Sparta area but not for Belding or Fremont. There was very little green tissue showing so this rain shouldn’t have been one to worry about for apple scab. Be sure to have a cover fungicide application on before the next rain event – there is much more green tissue showing that is susceptible to infection. The prediction is that apple scab spores will develop earlier this year and that’s already looking to be true.

If you are planning on using dormant oil sprays for overwintering mite eggs, aphid eggs and scale, these applications will most l ikely be timed within the next week to 10 days. Remember to watch the weather forecast closely for possibilities of freezing temperatures within three days before or after oil sprays to avoid tissue injury.

Copper applications to sweet cherries for bacterial canker should be considered at this time. Cherries will move quickly with the predicted warm temperatures.

The Annual Spring Spray Meeting and IPM Update is scheduled for Thursday, April 20, 2006. We will begin at 4:00 PM and end by 6:00 PM. Location is Rasch Brother’s Apple Packing Facility located on Stage – between 7 and 8 Mile Roads in Kent County.

4 -- West Central
Mira Danilovich

On the spore maturation front of apple scab, using the MacHardy-Goudary method we have about 10% mature spores at this time. Last Friday’s rain did not cause any spore release. Copper sprays will provide an early scab protection and at the same time will aid in fire blight control by reducing the epiphytic bacteria population.

In regards to bacterialcanker remember that this is an opportunistic cool season disease that will multiply reaching its peak at just about bud break. Starting early next week, there is a potential for another cool front that will bring colder temperatures and with them favorable conditions for disease development. Bacteria overwinter in the buds near the cankers or near the affected spurs as well as in the vascular tissue. It will invade the trees through the wounds resulted from pruning in spring.

Black knot is a common sight in many plum blocks. This disease has favorable hosts in apricots, tart cherries, wild cherries, wild plums and ornamental Prunus sp. Checking surrounding areas for the presence of one of the less known hosts and eliminating them may have far reaching positive consequences in managing the disease in the commercial blocks. Cutting out the knots and removing them from the orchard right now, before the bud break, is the first important step in disease management. The disease affects only woody parts of the trees. Early symptoms are manifested as roughness or corky-like lesions on the shoots. Older knots are elongated, black, brittle and often massive growth. The infection starts in spring with the first spore discharge right around the green tip and continues until the terminal growth stops, reaching the peak between the white/ popcorn bud stage and about two weeks after the full bloom. Moisture and temperatures from mid-50s to mid-70s will facilitate disease development. The fungus penetrates into the cambium layer and continues its growth through the conductive tissue of the shoot (xylem) inducing the production of extra layers of “spongy-like” parenchyma cells that form the knots.

This early in a season, copper sprays will provide sanitation after pruning. From green tip on, fungicides like Captan, Bravo and/or Topsin-M sprays will aid in disease control.

Assessing the damage and the amount of inoculum in sweet cherries, peaches, plums and pears is essential for planning the control measures.

Growing Degree Day Accumulations
GDD42 75.1
GDD50 21.6

Weather
Weather over the weekend was chillier than anticipated, but Monday (April 10) warmed up to the mid-50s. We expect this weather to continue for the remainder of the week. The temperature has been 50° to 60° F during the day and 35° to 40° F at night. Our last wetting event was reported on April 4, and we received over 0.75 inches at the NWMHRS.

Tree fruit
Although the trees are beginning to move slightly beyond the dormant stage, we have not had any remarkable change in over a week. Red Delicious are at early silver tip, and all cherries are at the early bud swell stage.

Jet stream flow across North America has recently shifted to a western troughing, eastern ridging pattern, leaving Michigan and the Great Lakes region under southwesterly flow aloft. This pattern is expected to continue for the next one to two weeks and should lead to warmer and wetter than normal weather and a prolonged period of spring-like conditions.

In the short term, an area of low pressure and associated cold front over the Great Plains region Tuesday morning (April 11) will move across Michigan during the day Wednesday. This will bring the likelihood of widespread showers and a few thunderstorms to the state beginning late Tuesday in western sections of the state. Rainfall totals will generally reach the 0.25 to 0.5 inch category, with a few areas possibly reaching the 0.5 to 1.0 inch category, especially in northern sections of the state. Drier weather is expected Thursday, followed by a chance of scattered showers again Friday. After Tuesday’s 70+ degree highs (the warmest of the season thus far), temperatures will fall back to daytime highs from the 50s north to 60s south Wednesday through Friday, with low temperatures generally in the 40s.

For Easter weekend (April 15-16), a few scattered showers will be possible Saturday, with most areas remaining dry. Another area of low pressure and accompanying frontal system is forecast to move towards Michigan by Sunday, bringing the likelihood of showers and thunderstorms to most of the state by later in the day continuing into Monday.

Further ahead, medium‑range forecast guidance suggests a continuation of the southwesterly jet stream pattern mentioned above along with the passage of several weather systems. The official NOAA 6-10 day and 8-14 day outlooks (covering April 16-20 and 18-24) both call for above normal temperatures across Michigan and much of the eastern United States. Precipitation during the 6-10 day period is forecast to continue at above normal levels, falling back to near normal levels during the 8-14 day time frame.