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| Fruit Crop Advisory Team Alert newsletter | |||||||
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| Vol. 23, No. 6, May 13, 2008 |
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| In this issue Tree fruit news
Plum curculio phenology and monitoring
Applying Apogee
CIAB referendum approved
TNRC trapline data: Redbanded leafroller
Check out the new web site for cherry growersSmall fruit news Disease control after spring freeze injury in grapes: Keep on top of Phomopsis Mummy berry shoot strikes sighted in blueberries
Small fruit meetingOther news Civil rights in employment decisions Regional reports Weather news |
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| Plum curculio phenology and monitoring
Plum curculio over-winter as adults in the soil, litter and ground cover trash in orchards and in surrounding areas. As soon as daytime and evening temperatures exceed 60ºF, Plum curculio will begin to move especially when a light, misty rain or humid night co-occurs with early spring warming trends. The weevils move into orchards and begin to feed as leaves begin to emerge. Their feeding activity expands to blossoms, stems and fruit as they become available. The Mark Whalon’s lab at MSU has been working to improve capabilities for predicting life stages for a better understanding of when egg laying occurs, and when larval instars are present. At 275 DD50°F from March 1, all female plum curculios should have at least one mature oocyte (egg). It can be expected that 340 DD50°F after petal fall (if petal fall =500, then 500 + 340 = 840 DD50°F), 40 percent of the cumulative oviposition cycle is completed in apples in New York (Reissig et al. 1998). Larvae from this overwintering brood will exit fruit into the soil, where they will pupate and emerge as summer generation adults. First catches for summer generation plum curculios in Michigan in 2007 occurred between 1542 and 1911 DD50°F (accumulated from March 1). These trap catches may be late indicators of when summer generation adults are active in cherry orchards, according to direct observations of adults in caged experiments (Table 1). |
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Table 1. Occurrence of life stages of plum curculio in Michigan fruit orchards.
Monitoring Pyramid traps are the most efficient means of monitoring plum curculio activity early in the season. These traps outperform in-tree screen traps in adult capture about 2:1 in many seasons. Baiting traps with lures (plum essence or benzaldehyde) significantly increases trap catch, but the addition of pheromone baits only slightly increase (1.2:1) plum curculio captures in either trap. Traps are a good indicator of likely plum curculio pressure in the area and should be placed on the borders of orchards where producers or scouts have observed damage in past years. Often these locations have woods, unsprayed orchards, feral trees or other sources of overwintering plum curculio populations. Table 2 provides a guide for evaluating plum curculio population pressure in three fruit crops, apple, cherry and peach. Table 3 provides a summary of adult plum curculio captures in pyramid traps to date at four sites in Michigan for 2008. Growers and scouts can track cumulative degree-days utilizing the web-based information systems Enviroweather or the MI Automated Weather Network (updates available at www.enviroweather.msu.edu and/or http://www.agweather.geo.msu.edu/mawn) (Table 4). Table 2. Population pressure rating: General trap catch/week bloom to 370 DD50 Plum curculio
Table 3. 2008 Plum curculio trap catch at various Michigan field sites: Plum curculio collection from pyramid and screen traps at tart cherry and apple sites.
Table 4. Recent cumulative degree days base 50°F starting January 1 at various MI sites
Management In low-pressure situations in apples and peaches, growers may want to consider only one insecticide between 200 and 250 DD50. In cherries, it is advisable to cover spray trees from shuck split to 400 DD50, and, if plum curculio are still being trapped, include a third cover beyond 400 DD. Four key factors should be considered when deciding when, how often and with what to manage plum curculio populations in the spring. First, historical damage in previous years should be considered. The greater the plum curculio pressure in the previous one to two seasons, the greater the care and focus on plum curculio in the current season. Second, the best timing depends to a great extent on accumulated degree-days and insecticide(s) chosen. Third, understanding and identifying the chosen insecticide’s performance characteristics is important in evaluating control measures taken. For instance, it helps to know whether or not the insecticide selected has “curative activity” (kills larvae in fruit) and the length of its residual action window. It is also important to consider the modes of insecticidal activity that each compound has, some relying solely on lethal activity versus those that have repellent, antifeedant and oviposition deterrent effects. Lastly, a number of weather related factors could dictate re-treatment to control plum curculio, especially in processed cherries. Therefore, degree-day accumulation (for timing sprays), rain events (residue wash off), and other seasonal characteristics (like cool and cloudy versus warm and sunny) can affect breakdown of sprays and the need for additional coverage. All of these factors contribute to plum curculio control timing, insecticide selection and re-treatment. An article detailing management options available to growers will be included in next week's Fruit CAT Alert. Reference Reissig, W.H., J.P. Nyrop, and R. Straub. 1998. Oviposition model for timing insecticide sprays against plum curculio (Coleoptera: Curculionidae) in New York State. Environ. Entomol. 27(5): 1053-1061. |
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| Applying Apogee
There are four points that should be considered when applying Apogee to apples: timing, rate per acre, thinning relationships and compatibility. Timing Apply Apogee when vegetative shoot growth is less than three inches. This is about a 7-to 10-day window commencing at the king bloom petal fall stage. Most years all varieties can be treated at this time. The second application should be applied two weeks later and the third application two weeks after the second. Sometimes a fourth application is needed, but that is optional based on crop load and tree vigor. Excessive rainfall and light crops will promote vegetative growth; therefore an additional fourth application may be needed. Rate Rate per acre is usually calculated on a tree row volume basis and can be adjusted to two-thirds of the label full rate. The two-thirds rate is the starting rate growers should consider if they don’t have any experience using Apogee in the past. Past experience on your block will indicate if this rate is too high or too low per acre. This suggested two-thirds rate per acre is a season long rate per acre. For example, if your trees are at 75 percent tree row volume, then 24 ounces per acre is the seasonal rate (48 * .75 * 2/3). Best results occur when seasonal rate is split into three or four sprays. For example, 8 + 8 + 8oz per acre. When fire blight is a severe risk, the first application at king bloom petal fall timing should be increased, perhaps as much as 150 percent of a split rate. For example, increased from 8 ounces per acre to 12 ounces per acre. Subsequent sprays, the second and third sprays could be reduced, so the seasonal application would be 12 + 6 + 6 = 24 ounces per season. Thinning Apogee tends to increase fruit set, therefore more aggressive thinning is needed. Increase your thinning by 10 or 15 percent. For example, if you were going to thin with 1 pt Sevin + 8 ppm NAA, then consider 1 pt Sevin + 10 ppm NAA where you are using Apogee. Compatibility Apogee is not compatible with calcium or boron in the tank. Also, we suggest that Apogee be applied after a thinner. If the two-week timing interval is also the ideal time to thin, make your thinning application first and then a couple days later follow with Apogee. Remember to include the label recommendations for AMS and surfactants. In summary; Apogee is an excellent tool to help control vegetative growth and especially suppress fire blight spread among shoots and within shoots. Follow these tips to get the most out of Apogee. |
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| CIAB referendum approved
We received late last week word from the USDA that the referendum for the Cherry Industry Administration Board (CIAB) was approved overwhelmingly by the growers and handlers voting in the referendum. The CIAB will continue to operate for another six years.Growers approved the renewal of the order with 81 percent of the producers voting in favor of the order. These voters represented 86 percent of the voting volume. Handlers approved the renewal of the order with 78 percent of the voting processors voting in favor of the order. These voters represented 91 percent of the voting volume. To see the USDA's announcement, go to www.ams.usda.gov and then click on "Newsroom" at the top of the home page. You will find the announcement there. |
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TNRC trapline data: Redbanded leafroller
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Check out the new web site for cherry growers
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| Disease control after spring freeze injury in grapes: Keep on top of Phomopsis Since the extent of injury due to the recent spring freeze is quite variable between vineyard sites, it is important to get an estimate of the number of live buds left before making any drastic decisions with respect to disease management. A more accurate estimate of yield will not be possible until after fruit set. In previous years, the crop turned out to be harvestable after growers had given up on it. However, this year it is not clear how well the vines will be able to compensate for damage incurred. To reduce the risk of Phomopsis in the meantime, it is important to maintain some level of disease control, especially if the vineyard has a history of this disease. |
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| Mummy berry shoot strikes sighted in blueberries
Last week mummy berry shoot strikes, a result of ascospore infection of emerging leaves, were seen for the first time this season in four blueberry fields that are scouted as part of an IPM project (though there were some reports of shoot strike sightings at the end of the previous week). Shoot strikes are a blighting of developing leaves and shoots which often exhibit an “oak leaf” pattern of necrosis (Figure 2). All scouted plots were at late pink bud or early bloom. Declining mummy berry mushrooms (apothecia) that had already released their ascospores were observed at many of our plots (Figure 1). This week the plots had reduced numbers of apothecia when compared with previous weeks. Last week the average number of functional apothecia in Grand Junction was as high as 11.2 per bush (Grand Junction), but this week the average only reached 1.4 per bush (Grand Junction), indicating that the apothecia had started to decline. Shoot strikes begin to appear about 12 to 14 days after the initial infection, depending on the temperature. To get an estimate of the incidence of shoot strikes, pick five to ten random bushes and record the number of shoot strike infections per bush. The number of shoot strikes can range from 0 to over 100 per bush in a bad year. Shoot strikes can be identified by the brown oak leaf pattern along the veins of wilting leaves and a layer of gray powdery spores on the upper part of the leaf and petiole. Also, shoot strikes generally do not exhibit browning of the wood beyond the green tissue of the infected shoot. They can occur anywhere on the bush but are sometimes more plentiful lower in the bush. Flower strikes are much less common than shoot strikes and would normally not be present in the absence of shoot strikes. Flower strikes may be distinguished from other blights by the dense gray spore masses on the flower stem. Some cultivars are more susceptible to shoot strikes/flower strikes and less susceptible to fruit infection, whereas others are just the opposite. Susceptible varieties include Berkeley, Blueray, Bluetta, Bluehaven, Jersey, Rubel and Northland. As bloom ensues, growers need to consider applying fungicides to protect the flowers from infection. Shoot strikes during bloom are epidemiologically most important as the spores produced on the shoot strikes have the most chance of reaching the flowers via bees transmitting the spores, wind and rain. Systemic fungicides, like Indar and Pristine, work better against mummy berry flower/fruit infection than protectants. Orbit, while an excellent fungicide to prevent shoot strikes, is not quite as effective as Indar against flower/fruit infection.
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| Small fruit meeting Southwest grape IPM meeting May 21 from 10:00 AM to 12:00 PM Lawton, MI (Cronenwett Farms) 2:00-4:00 PM Benton Harbor (Berrien County Extension office) For more information, please contact: Paul Jenkins, Mark Longstroth, Rufus Isaacs or Annemiek Schilder (schilder@msu.edu). |
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| Civil rights in employment decisions While many federal laws protecting equal employment opportunity exempt small businesses, Michigan laws do not. Michigan laws protect religion, race, color, national origin, age, sex, height, weight, marital status and disability. As long as the specific disability is unrelated to the individual’s ability to perform the duties of a particular job or position with or without reasonable accommodation. Whether an applicant is a union member or an applicant’s veteran status also are questions that should have no place in employment decisions. Most laws apply to all employment decisions, including hiring, training, evaluation, promotion, compensation, discipline and termination. But questions on how to treat everybody fair and equally often come up during the selection process. As a general rule, all questions during the selection process should be relevant to the job to be filled. On an application form such questions may include name, address, phone number, the job the applicant is applying for and a summary of the applicant’s background (e.g., education and training, work history, special qualifications and skills). Citizenship and ethnicity are not typically relevant to agricultural jobs and therefore need to be avoided on application forms. An employer concerned about hiring applicants who will later fail to provide the required documentation for the I-9 form, may include a question in the application form such as “Are you legally eligible to work in the United States?” It is important to remember that many questions, which must be asked after a job candidate is hired, need to be avoided before the job has been offered. Everybody who participates in the hiring process must be familiar with the relevant qualifications, skills and experience of the job or jobs to be filled. Often times, small differences in how a question is asked differentiate a legitimate question from a discriminatory one. For example, “When did you attend college? When did you graduate?” could be construed as discriminatory on the basis of age; “How long did you attend college? Did you graduate?” are legitimate questions, if education is a relevant job qualification. By writing up questions before an interview, discriminatory practices can be avoided. In addition, interviewers should take notes during the interview in a neutral language. All interviewers must be trained how to ask legitimate questions and what topics to avoid with job applicants. If an applicant brings up any of these topics, such as family and children, disability or religion, it is best to not dwell on such information and to not ask any follow-up questions. The best practice is to follow the general rule to only ask job related questions and avoid all others, even if they legally can be asked in Michigan, such as sexual orientation. Also, interview questions should be similar for all job applicants. This information serves educational purposes only and does not constitute legal advice. For more information go to www.msu.edu/user/bitsch, under “News” click on “Civil Rights and the Hiring Process” or click on “Agricultural Labor Issues in Michigan” for a list of available newsletters. |
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Regional reports Last Monday (May 5) and Tuesday were very warm with temperatures close to 80ºF. Wednesday (May 7) and Sunday (May 11) were cold and rainy. Cool conditions between the two rain events made for poor pollinating weather. We have had several good days for pollination follow the April 30 freeze. Rainfall over the region varied from an inch to almost two inches. These rains represented infection events for some diseases. Soil moisture levels are good and some soils are still very wet. We expect continued cool weather this week. The forecast is for highs in the 60s and lows near 40ºF. Rain showers are forecast for Tuesday and another wet weekend. The forecast is for cooler than normal temperatures for the next several weeks. This means we need to be aware of the danger of frosts when we get clear calm conditions. We still have about a ten percent chance of cold down to 28ºF.
Tree fruit Insect activity increased early last week and then dropped to low levels. Oriental fruit moth were caught and biofixed last week on May 4 at 310 GDD45 at SWMREC. Trap catch was generally low but continuous. Redbanded leafroller and spotted tentiform leafminer are flying. Plum curculio is out. This pest feeds on developing fruit. Curculio egg laying should not be a problem until warm temperatures return. Apricots are out of the shuck for most varieties. Peaches are in the shuck. Oriental fruit moth were caught and biofixed last week on May 4 at about 310 GDD45 at SWMREC. Treatment is timed for 200 GDD after biofix. We are now at about 70 GDD. With this cool weather, we will need to apply controls early next week. Sweet cherries are at the end of shuck split. The largest fruit are about 10 mm in diameter. Sweet cherries are always susceptible to brown rot. This disease requires wet and warm conditions, five to six hours of wetness at 70ºF. We are unlikely to see conditions that warm this week. Since the leaves are out and developed, they are susceptible to cherry leaf spot. The rain Wednesday, May 7 was a cherry leaf spot infection in some areas, but Sunday’s rain was not quite long enough for the cold. Tart cherries are in the shuck. The leaves have emerged enough to be susceptible to cherry leaf spot. Recent rains have been marginal infection periods due to cool average temperatures, but growers should apply shuck sprays to provide protection in upcoming rains. Plums are in the shuck. Japanese plums are at shuck split. Growers need to protect against black knot. Apples are at full bloom. Rain on Mother’s Day, May 11, was an apple scab infection for most sites. Symptoms from the April 19 and May 2 infections should be visible. We are about half way through primary scab season, so scab protection will be necessary for about another month. The rain last Wednesday following two very warm days caused the Enviro-weather fireblight prediction program to call for a fire blight infection and some growers applied antibiotics to some of their plantings. Wednesday’s rain was too cold for the fire blight bacteria, and by the end of the day no infection periods were recorded. Generally, a cold rain following a cold front has not resulted in fire blight, especially when the temperatures remain cool for several days afterwards inhibiting bacterial growth. Southern Berrien County came closest to an infection. Fireblight should not be a problem for the next few days. The cool weather has kept bacterial populations low, and there will not be enough heat this week to raise the level to dangerous levels. It seems likely that we will not have good conditions for infection until the end of bloom. Now is the time to apply Apogee sprays to reduce the spread of fire blight. A single application at petal fall for king bloom is most effective in reducing the spread of fireblight after an infection. To control vegetative growth longer into the season, applications are spread out over the next six to eight weeks. The cool weather forecast means that we will not have any good apple thinning windows soon. Generally, thinning sprays work best if applied at the beginning of a warming trend when temperatures will be above 70ºF for several days. Growers can use the next week to begin to think about which blocks will need significant thinning. There are wide differences in frost injury between varieties and sites. Pears are at petal fall. Pear psylla eggs are hatching. Growers should protect against pear scab. Small fruit Blueberry bloom has begun. Mummyberry shoot strike symptoms have been found. Symptoms from an infection following the April 30 freeze should be visible. Grapes have two to four inch long shoots, with two to three leaves out. Vinifera grapes are a little behind in development and late varieties are noticeably behind. There is no apparent movement of secondary buds yet in vineyards damaged by the freeze. Shoot growth makes severely affected vineyards very noticeable from the road. In the past, it has taken four to six weeks for new growth to become apparent. Cool temperatures will slow all grape growth. The conditions generally have been too cool for powdery mildew and downy mildew and marginal for black rot, but phomopsis does well in cool damp weather. Strawberries are at full bloom. Avoid using insecticides during bloom. These cool wet conditions favor angular leaf spot a bacterial disease. Applications of copper can reduce this disease (see notes on control in MSUE bulletin E154). Fungicides are applied at bloom to reduce gray mold, anthracnose, leaf spot diseases and leather rot. Raspberry and blackberry shoot growth has slowed. Flower bud clusters are visible on early varieties. Cranberry beds are greening up, and tip buds have burst. Miscellaneous There is a Blueberry IPM meeting this Wednesday, May 14. Last week growers were planting trees and applying fungicide sprays. The next Monday Fruit Update meeting will be Monday, May 19 at the Fruit Acres Farm in Berrien County. |
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2 -- Southeast With a mix of warm and cool days and mostly cool night temperatures over the last week, the development of our fruit crops has been very slow over the last week. Our season is about normal in terms of degree day accumulations and bloom dates. Most growers received between 0.3 inch and 0.8 inch of rain from two rain events. A few have mentioned that they had 1.5 inches of rain on Sunday, May 11. This rainfall was welcomed by fruit growers across the region because of dry soil conditions. For most apple growers, it was the second apple scab wetting event of the season. I have a chance to make more visits to orchards over the week to assess frost/freeze damage. It appears that the initial assessments that I made in last week’s report are consistent with what I am seeing this week. To summarize, even though many farms had significant damage to apples from the frost/freeze of April 29 and April 30, there is still a crop at this time. Most of the freeze damage was limited to low areas of orchards and poor sites. Varieties such as Idared, Gingergold, Jonagold and Red Delicious seemed to be affected most. At some farms, it was mostly king bloom damage, along with some side bloom damage. In sweet cherries, we had a significant amount of damage with tart cherries having less injury. Other stone fruits appear to be in good shape. Southeast Michigan growing degree day totals for March 1 to May 12
Tree fruits Apples are still blooming at many farms across the region. We have seen some petal fall; however there is still a lot of side bloom that has opened up. Some of the side bloom that I see opening is a result of the frost/freeze damage to king bloom. It has been a bit unusual to see apple bloom extend over such a long window this year. Oriental fruit moth trap catches have been very high in several farms across the region, with some in the 100 to 150 moths per trap range. At most farms however trap catches are between 5 and 10. Regardless, we are long past the biofix for oriental fruit moth at most farms. No codling moth or mullein bug have been caught. Plum curculio are being seen in fairly good numbers consistently across the region. I have not seen any egg laying scars. European red mite egg hatch continues at many farms; however leaf numbers are fairly low, with one to two mites per leaf. Rosy apple aphids are starting to be seen in suckers of apple trees. Woolly apple aphids are beginning to be active; however they are still hidden underneath bark of apple trees. Spotted tentiform leafminer and redbanded leafroller trap catches have dropped off dramatically over the last week, with both being at the end of their first generation flight. A variety of larvae have been seen at farms across the region, these include redbanded leafroller, fruit tree leafroller, tufted apple bud moth, green fruitworm, inch worms and climbing cut worm. Numbers of all of these have been very low. San Jose scale and oyster shell scale are not moving. I am seeing very high numbers of a variety of predators over the last week; it is encouraging to see predator levels being so high this early in the season. I think this early high predator population is related to the weather we have had this year, and the fact that we have had more significant leaf growth early in the season. Most farms had a light to moderate infection period from rain that occurred mid-last week, and a moderate to heavy infection wetting period from rain on Sunday. I have not seen any apple scab lesions yet, however I would expect to see some on May 17 from the wetting period that occurred on May 2. I continue to catch apple scab spores at the trapping stations. The numbers have been moderate. Cool weather over the last week has allowed us to escape the risk of fireblight. Now is the time to make the first Apogee applications on apples. Pears are at petal fall for the most part with a few lingering bloom. Pear psylla are numerous at some farms with egg hatch being fairly common across the entire region. Peaches remain in the shuck. We have a good crop of peaches coming along. Oriental fruit moth is the only pest to watch in peaches. I have seen some strange gummosis or oozing from buds and twigs at a few farms across the region. I am not certain why trees are weeping sap, but will keep you informed as to details as more is known. Sweet cherries are at shuck split, with some of the larger fruit being 6 mm to 9 mm in size. There was a fair amount of crop loss in sweet cherries from the frost/freeze event of April 29 and April 30. Most of the sweets have thinned down to a point where singles are all that are left. Tart cherries are in late bloom or in the shuck. Twig death due to winterkill is being seen on tart cherries. Plums are in the shuck, with some farms having a fair amount of plum curculio activity. Protection needs to be taken against plum curculio injury as soon as shuck split begins to occur. Small fruits Strawberries are at about 5 percent bloom on most varieties in the region. Most farms report some frost injury to bloom, most likely from the April 29 through April 30 frost/freeze event. The damage ranges from 5 to 10 percent in each flowering varieties. I started to see strawberry clipper damaged blossoms as they began to emerge over the weekend and early this week. I also have started to catch a few strawberry clipper on the edges of strawberry plantings. Late this week would be an excellent time to control this pest. Raspberries are starting to show some signs of blossom bud emergence on summer fruiting types. Fall red raspberries have shown no growth over the last week with most canes being 4 to 6 inches in length. Blueberries are mostly at late pink bud to 25 percent bloom for early flowering varieties. I began to see some signs of mummyberry mushrooms at several farms over the last week, indicating that disease is now active. I have not seen any shoot strikes. |
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3 -- Grand Rapids Area Degree day accumulations at the Sparta weather station have moved back to being closer to normal averages due to the cooler weather pattern of the last several days. Current degree day totals put us only about three to five days ahead of average. Tree fruit Most apples are in the full bloom stage with some petals falling in earliest varieties. Growth continues to be slower than normal due to the cooler temperatures lately, but there is quite a bit of foliage present – more than usual for bloom time. Sweet cherries are done blooming and small fruits can be seen. Peach bloom is just about over, and small fruits can be seen in early peaches as well. Growers using Apogee to control growth in apples should watch tree growth closely to determine when to apply. The ideal time to begin applications is at petalfall of the king bloom, or when there is one to two inches of shoot growth on spurs. Some varieties are at the right stage now to begin Apogee applications. It’s better to err on being too early rather than too late with this growth regulator to get the best results. Rain on May 7 did not result in an apple scab infection for the greater Grand Rapids area. Rain on Mother’s Day, May 11, was an apple scab infection for the data recorded at the Sparta weather station, but not in Fremont or Belding where the rains started later and it dried off sooner. According to degree days for apple scab spore development, we were at about 75 to 80 percent spore maturity right now, so cover sprays are still very important and probably will be for at least another three weeks. Spore numbers in the last two rains have seemed to drop off, but they are still discharging. MaryBlyt is calling for a high risk for blossom blight in apples with open bloom for the potential rains May 13 into the 14. It is not an all out infection because the EIP, or bacteria level, is still below 100, but it would be wise to be covered up with something in your most susceptible fire blight varieties and in high risk blocks because there is so much bloom out there. Even a full cover of Mycoshield would be a good idea ahead of the rain tonight, especially if you are in or near a known strep resistant block. Then if it gets warmer or stays warm, you could always come back with strep or AgryGent if you feel you need it. Remember that with AgryGent it cannot be the first antibiotic you use for blossom blight for this year. European red mite egg hatch started last week, but seems to be moving slowly. Motiles can be found on the undersides of leaves. It’s a good time to do some careful scouting for red mites to determine how or if you might manage them at petalfall. Obliquebanded leafroller larvae are getting large, but are still very difficult to find in most blocks around this area. Aphids are active. Both apple grain aphids and rosy apple aphids have been seen. Rosies are curling up in the leaves, but seem to be controlled well where pink sprays were used. Oriental fruit moth is flying, but numbers are sporadic and a biofix has not been set for this area yet. Small fruit As of May 13, most blueberry varieties north of Allegan County are in late pink or early bloom. So far, despite the prevailing low temperatures, no frost damage has been reported in the main varieties, Bluecrop, Elliott and Jersey. However, blueberry fields in Ottawa and Allegan counties located alongside major highways (US 31, M-45, I-196) suffered sever damage due to road salt blown into the fields by passing vehicles. For example, in Ottawa County despite the Ottawa County Road Commission Integrated Road Salt Management Program, road salt damage to flower buds in blueberry fields facing US 31 and M-45 reached up to 93 percent in bushes located 100 ft away from the road. Also, a blueberry field facing a secondary road such as 120th Ave had the most extensive damage. Up to 100 percent of the flower buds examined were completely dead including shoots and whole bushes (see Figure 1). Due to the daily low temperatures from the past five days, no insect activity has been reported yet. And in both Allegan and Ottawa counties growing degree day accumulation varies from 200 to 250 GDD (Base 50° F, Bakerville-Emin method). The daily growing degree day accumulation from the past five days has been around 4.5 GDD/day. Thus, the emergence of the cherry fruitworm and cranberry fruitworm overwintering adults is still more than 10 days away. Market prices for fresh blueberries fluctuated between $21 and $30 per flat; 12 4.4 oz cups. The highest prices are reported in California and the lowest in Detroit. At this time, most blueberries are coming from Florida and Georgia (USDA Fruit and Vegetable Market News).
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4 -- West Central Weather and crop development
There were two rain events last week but only one resulted in a low apple scab infection period in Manistee County. No infections developed in Oceana and Mason counties. Each rain caused spore discharge. The numbers of released spores have significantly dropped. Since the peak release on May 2, just short of 20,000 spores per rod, the last two counts were 2,890 (May 7) and 556 (May 11). The Ascospore maturation model is indicating that we have about 56 percent mature spores. With the beginning of bloom in apples and pears, fireblight is becoming more and more of a focus. With the cooler weather conditions, EIP numbers stayed well below the threshold and did not cause reason for alarm. With today’s temperatures, that are predicted to go into the low to mid-70’s and rain in the forecast, Maryblyt is calling for moderate potential for blossom blight infection. For cherry leaf spot, there were no infection periods this past week. Scouts are reporting relatively low insect activity. Oriental fruit moth has been found in a couple of traps in Mason and Oceana counties. The flight has been sporadic, and no biofix has been assigned. Redbanded leafrollers are flying in high numbers. There are small larvae of green fruitworm and cutworms throughout the area. Spotted tentiform leafminers are present in apple blocks. |
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5 -- Northwest Growing degree day accumulations at NWMHRS Growth stages at NWMHRS from May 12 at 4:30 PM Apples are in pink. Bartlett pears are at first bloom. Sweet cherries: Hedelfingen and Napoleon are at early petal fall. Golds are in full bloom. Tart cherries: Montmorency are at 75 percent bloom. Balatons are at 25 percent bloom. Apricots are at late petal fall. Plums are at 50 percent bloom. Grapes are at bud burst. Weather Spring does not seem to be coming to northern Michigan this year. We continue to have cool days and cold nights. Our average temperatures remain in the high 40’s to low 50’s. We are at 151 growing degree days (GDD) base 50 and 334 GDD base 42. Last year at this same time, we had accumulated 196 GDD base 50 and 430 base 42. We have had no substantial rainfall in the last week. Today, Tuesday, May 13, will be the warmest day of the week where meteorologists are predicting temperatures in the low 70’s. Tree fruit Because of the low temperatures, we have moved very slowly in terms of phenology. Sweet cherries are still in bloom and in early petal fall all over the northwest, and unfortunately we have had little honeybee activity with this cool and cloudy weather. Montmorency tart cherries are at 75 percent bloom at the NWMHRS, and Balatons seem to be moving along more slowly at 25 percent bloom. Apples are at the pink stage for most varieties. Many area growers have observed unusual sweet cherry buds in some orchards in the region. Some of the buds on a branch look reddish in color and are fairly swollen in appearance, almost like they are ready to open. These buds are on the same branch as others that are in full flower. The strange buds look puffy and when squeezed, they feel empty. In fact, when the buds do finally open, they are indeed empty. These vacant buds do not contain the normal flowers or blooms, just a few small leaves. We have concluded that the recent loss of flowers is due to cold temperatures, and most likely this winter injury happened in January. We have also been detecting more damage in Montmorency than we anticipated last week. These findings have come as a bit of a surprise as our initial estimates showed little damage to blossoms. The damage also seems spotty, and we have detected damage even in good fruit sites. Aphid nymphs have been sighted in higher numbers throughout apple orchards in the area. Larger obliquebanded leafroller larvae are also on the move. Red mite eggs are hatching, and adults are moving onto leaves. Two-spotted spider mites still appear to be at relatively low levels, but have begun laying eggs where they are observed on the underside of leaves. Our trap line at the station is showing moderate spotted tentiform leafminer pressure. American plum borer and green fruitworm moths have also been caught in baited traps in our cherry blocks. No significant rainfall has occurred since May 7, and no apple scab infections have been predicted since May 6. |
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