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| Fruit Crop Advisory Team Alert newsletter | |||||||
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| Vol. 23, No. 7, May 20, 2008 |
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| In this issue Tree fruit news
Winter injury in sweet cherry Optimizing insecticide sprays for plum curculio TNRC trapline data: Oriental fruit mothSmall fruit news Timing cranberry fruitworm sprays in blueberry Topsin M Section 18 request for blueberries denied by EPA Manipulating blueberries with Gibberellin Small fruit meetingOther news Emergency Ag Relief Act Regional reports Weather news
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| Winter injury in sweet cherry Winter damage has been observed in sweet cherries in the northwest as well as other regions of the state. Growers first noticed this damage because trees had no bloom. The trees look brownish and relatively bare compared to those with a true full bloom. The branches are covered with large reddish buds that feel empty to the touch (Photo 1). When these oversized buds open, there is nothing inside the buds, giving the damaged trees a brown appearance with few visible blossoms (Photo 2). This damage is likely due January 2008 weather when we had temperatures ranges from the mid-40s to single digits in a 12-hour time period. We believe that the injury showing up now in sweet orchards is a result of this mid-winter damage. |
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The next question is how to manage damaged trees this season to maximize tree health for the future. To begin, growers should assess the level of damage, as this measurement will guide their management decisions for the 2008 season. If growers do indeed have no bloom, a minimal pesticide spray program would save money and time. Sprays for cherry leaf spot are still warranted to maintain healthy leaves for photosynthesis throughout the season. However, with no fruit on the trees, growers will not need to spray for fruit-infesting insects such as plum curculio and cherry fruit fly. Additionally, American brown rot sprays can be limited as there will be no fruit for the Monilinia pathogen to infect. The dilemma is that most orchards are not likely to have a total loss of fruit. Therefore, if a small amount of fruit is present, insecticide and fungicide sprays are still warranted as pest infestation and fungal infection this season can lead to higher insect populations and increased fungal inoculum for 2009. Another potential problem is that certain varieties appear to have been hit harder than others (i.e., Schmidt), and in mixed blocks, growers would have to apply a standard spray program for only the undamaged cultivars in the block; limiting treatment for damaged cultivars may not prove cost and time effective.
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| Optimizing insecticide sprays for plum curculio The plum curculio (PC) is an important early season pest on pome and stone fruits. There is an array of insecticides available for control of the PC, but their performance characteristics vary greatly compared to our traditional broad-spectrum chemistries. These conventional insecticides, such as organophosphates and pyrethroids, work primarily as lethal contact poisons on PC adults in the tree canopy. Avaunt, a newly registered insecticide on cherry, as well as pome fruits, also works primarily by lethal activity, but ingestion is the important means for delivering the poison. Neonicotinoids are highly lethal to PC for the first several days after application, but as these systemic compounds move into plant tissue, they protect fruit from PC injury via their oviposition (egg-laying) deterrence and anti-feedant modes of activity. Neonicotinoids and OP’s can also be used as rescue treatments because they have a curative action that can kill eggs and larvae that are already present in the fruit. For organic growers, Surround WP can reduce PC injury to fruit if applied to attain a heavy coating on the tree canopy; this kaolin clay product works as a PC repellent. The following table is designed to summarize several key variables that can help growers determine how to optimize the performance of various insecticides for integrated pest management (IPM) programs. Table 1. Insecticidal modes of activity on plum curculio life stages.
Optimal timing and order selection of insecticides for PC management is based on matching the performance characteristics of each chemistry (Table 1) with PC life-cycle development and tree phenology (Table 2). Because organophosphates and pyrethroid insecticides are contact poisons, they can be used as early as petal fall to knock beetles out of the tree canopy. However, we do caution the use of pyrethroids to as they are toxic to mite predators. Because PC adults are feeding on tree parts during bloom and petal fall, we recommend Avaunt be used at this petal fall timing. The performance of neonicotinoids is optimized when sprays are made after fruit set (pome fruits) or suck-split (stone fruits), so that fruit and foliage are both covered. Surround will not work unless tree is completely covered, so multiple sprays are needed on the tree prior to PC oviposition activity. If PC infestation occurs and a rescue treatment is needed, organophosphates and neonicotinoids can provide curative action up to two weeks after PC infestation, although in some cases dead cadavers can still be found in fruit (Figure 1). Please make sure to read the footnotes in Table 2 to help with the proper order of insecticides. Table 2. Labeled control materials for plum curculio
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TNRC trapline data: Oriental fruit moth
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Timing cranberry fruitworm sprays in blueberry Monitoring traps We recommend the sturdy large plastic delta trap to monitor for fruitworms, because these withstand rain and keep irrigation intact, plus they can be used for multiple years. Place 1-2 traps per field near historical fruitworm hot spots or near deciduous woods. Place the trap baited with a lure containing the fruitworm sex pheromone in the top third of the bush. Traps should be in place by the start of ‘Bluecrop’ bloom, and checked twice each week until moths are trapped. Regular checking will allow you to detect the first sustained catchof moths (biofix), the peak of moth activity, and how long moths are active. The first sustained catch, or biofix, is set when one or more moths are trapped in consecutive trap visits. This is the start point for counting degree days to time the first spray for cranberry fruitworm. Degree-day based development of cranberry fruitworm Over the past four years, we have carefully monitored cranberry fruitworm development in west Michigan blueberry farms. This has revealed some patterns in the timing of their development based on growing degree days. These are shown in Table 1, using degree days accumulated above 50°F. The monitoring traps are used to set biofix, and the timing of the first spray should be aimed at the eggs or young larvae when they are first hatching, which our study predicts to start 85 degree days after biofix. This often occurs during bloom, so if a pesticide is warranted, use only bee safe insecticides. This includes Dipel, Javelin and other B.t. containing insecticides, or the insect growth regulator insecticides Confirm and Intrepid. Follow label directions regarding bee safety. A follow-up spray may be needed with the timing of this depending on the residual control provided by the first spray, the amount of new petal-fall since the first application, whether bees are still in the field, amount of rain, etc. |
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2007 small plot trial results Last year, we conducted a spray trial to test the performance of sprays timed at different numbers of degree days after biofix. Confirm was applied at 100, 200 or 300 degree days after biofix with a follow-up spray seven days after the first in each treatment. This was compared to a Guthion application immediately after bloom with another 14 days later. The results (Figure 1) show the value of making an application close to the timing that coincides with the emergence of larvae from eggs if a Confirm application is being made during bloom (100 degree days after biofix). |
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Keeping track of degree days The simplest method used to estimate the number of degree-days for one day is called the averaging method: [(max temp. + min temp.)/2]-developmental threshold = DD For example, suppose on May 13 in Grand Junction, Michigan, maximum daily temperature and minimum daily temperatures were 75° and 45°F. Using 50° F for the lower development threshold for cranberry fruitworm, degree days accumulated would be: (75 + 45)/2 - 50 = 10 DD. With a simple maximum - minimum thermometer, daily degree day accumulation can be tallied after biofix until the target spray timing of 85 degree days are reached. Degree days are also tallied electronically by MSU’s Enviroweather program, with the reports available online at www.enviroweather.msu.edu. This system has weather stations across Michigan, and provides a daily summary of degree day totals and also predicted degree days for each weather station. This can allow growers and consultants to look at when the target degree day accumulation is expected to be reached, helping to plan sprays ahead of time. If you have not used degree days in your pest management program before, there are some useful resources online to explain them. One is at: www.ipm.ucdavis.edu/WEATHER/ddconcepts.html. Your local MSU Extension educator will also be able to help with how to monitor degree days on your farm, or how to access information from the nearest weather station. A short note on cherry fruitworm There is no degree day model for this pest in blueberries, but we have been trapping this insect in the past few weeks. In fields that have experienced infestation in past years, and where moths have been trapped this spring already, protection of the young fruit should be considered as petal fall starts to expose the fruit to egglaying. |
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| Topsin M Section 18 request for blueberries denied by EPA After seven years of granting emergency exemptions for the use of the fungicide Topsin M (thiophanate methyl) as a replacement for Benlate (benomyl) in blueberries in Michigan, the Environmental Protection Agency (EPA) has not granted our emergency exemption request for the 2008 season. Of the Topsin M Section 18s originally issued to multiple states for blueberries, the only remaining applicant in 2007 and 2008 was Michigan, indicating that growers in other states had found alternatives among the currently registered products. The reason for the denial of the Topsin M Section 18 request this year was the need for a strong emergency rationale and avoided loss picture in light of the registration of a number of new fungicides directly labeled for the diseases of concern. This made it very hard to argue that this year's request could meet even the minimum requirements for significant economic loss (i.e., 20 percent yield or gross revenue loss, or 50 percent net operating revenue loss). The EPA did listen to our concerns for maintaining a resistance management program for the future, but to reasonably narrow the emergency exemption program to "urgent and non-routine" situations, the Section 18 program is geared only to cases of demonstrated fungicide resistance that result in significant economic losses. In addition, new data regarding the toxicological status of Topsin M did not favor this product in its review by the EPA. It is my understanding that if and when an emergency situation does develop, the EPA will reconsider our request. Since we cannot use Topsin M this year, and its fate regarding full registration for blueberries is unclear, we need to consider alternative fungicide options. Michigan blueberry growers have done very well in rotating different fungicide chemistries, which is important for fungicide resistance management. Topsin M has a different chemistry from all other fungicides in our arsenal. Therefore, we have to be careful to not overuse the remaining fungicides since both the strobilurins and sterol inhibitors are at risk of resistance development in target fungi. Good alternatives for control of Phomopsis and mummy berry are Pristine (pyraclostrobin + boscalid), Indar (fenbuconazole) and Orbit (propiconazole), whereas Bravo (chlorothalonil), Ziram (ziram), and Captan (captan) have moderate efficacy as protectants. It is important to remember that Indar and Orbit belong to the same chemical class (sterol inhibitors) and have a 30-day PHI. Serenade (Bacillus subtilis) is also an option for mummy berry control. Alternatives for control of anthracnose fruit rot are Abound (azoxystrobin), Cabrio (pyraclostrobin), Pristine, Switch (cyprodinil and fludioxonil), Bravo, Captan, Captevate (captan + fenhexamid), and Ziram. Botrytis blossom blight is controlled well by Captevate, Elevate (fenhexamid), Switch, and Pristine. Table 1 lists various fungicides and their efficacy against blueberry diseases. Table 1. Effectiveness of fungicides for blueberry disease control.
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| Manipulating blueberries with Gibberellin Some athletes have been consumed by scandal for taking hormones or other substances to improve their performance. Plants also produce hormones or plant growth regulators that can potentially be used to improve their performance as well. Gibberellins are one group of plant growth regulators that are also synthesized and sold as commercial products (ProGibb, ProVide). In blueberries, gibberellins can increase fruit set or decrease flower numbers, depending on when they are applied. When bees are numerous and weather is warm and calm, 80-95 percent of blueberry flowers may set fruit. However, cold, rainy weather during bloom restricts honey bee activity and pollination, resulting in lower fruit set and often reduced berry size. Flowers that are not pollinated within three to five days after opening are unlikely to set fruit. After normal pollination, berry growth is dependent on the production of gibberellin and perhaps other growth promoters in the ovary tissues and viable seeds. If flowers are not pollinated, they abort. If only a few ovules are fertilized, the fruit may set, but not contain enough seeds to grow to full size. When pollination is limited by poor weather, gibberellin (GA) sometimes improves percentage set and berry size. Several GA products (ProGibb, GibGro) are labeled for highbush blueberries. GA may result in retention of some seedless (parthenocarpic) fruit that normally drop, and increases the size of berries with low seed numbers. GA can be applied in a single spray during bloom (80 gram active ingredient per acre) or two 40 g sprays, one during bloom and the second 10-14 days later. Higher spray volumes (40 to 100 gallons per acre) may improve coverage and effects. Slow-drying conditions also increase absorption. Also make sure your spray water pH is not above 7.5. Since GA is costly, it is important to know when it will help. If weather has been favorable for bee activity and the white corollas fall easily from the bushes, pollination is probably adequate. Keep in mind that blueberries can bloom over a long time, and often only a few days on good conditions are enough for adequate pollination. Consistently cold, rainy or windy weather through bloom causes pollination problems. If the corollas hang on bushes longer than usual and turn red or purple before eventually dropping, pollination may have been inadequate. The corollas of pollinated flowers drop readily while still white. Varieties with fruit set problems (Jersey, Coville, Earliblue, Berkeley, Blueray) are most likely to benefit from GA. Jersey, for example, is relatively unattractive to honeybees, and berry numbers and size are often limited by inadequate pollination. GA does not always provide a benefit and effects can be subtle. Make sure to leave non-treated check rows to tell if your money was well spent. Recent work indicates that GA may have the opposite effect of inhibiting blueberry flower bud formation. ProGibb has been commercially used to limit flowering on sour cherry for some time. Inhibiting blueberry flowering would be of great value in establishing new plants. We now recommend pruning or stripping off flower buds during the first two growing seasons to encourage vegetative growth and greater fruiting in subsequent years. This is particularly useful on more precocious varieties like Elliott. Manual flower bud removal is not always accomplished because it is very time consuming. In earlier work on potted blueberries, we observed only a slight inhibition of flowering when plants were treated with ProGibb in June or July, when we guessed flower initiation was occuring. However, Brent Black at Utah State University recently reported that flower initiation on ‘Bluecrop’ was reduced by nearly 90 percent by treating plants in August or September with ProVide (GA4+7). This suggested that flower bud initiation or differentiation occurs later in the season. In 2006 through 2007, we tested ProVide and ProGibb on the late varieties ‘Elliott’, ‘Liberty,’ ‘Aurora.’ Timings ranged from early July to mid-October. The only timing that reduced flower bud numbers was the middle timing (August 27 plus September 3), but reductions were small. No differences between the two GA products were observed. These results do not clarify the important question of when blueberry flower bud initiation and differentiation occurs. If we knew this, we could better time sprays for best results. Additional work is underway that will hopefully assist us in developing a useful treatment to reduce flowering on young bushes. |
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| Small fruit meeting
Topic: Green fruit meeting Ottawa County, Carini FarmsFor more information, please contact: Paul Jenkins (jenki123@msu.edu), Rufus Isaacs (isaacsr@msu.edu) or Annemiek Schilder (schilder@msu.edu). |
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| Emergency Ag Relief Act The Senate Appropriations Committee approved legislation sponsored by Senators Feinstein (D-Calif.) and Larry Craig (R-Idaho) that would provide relief to the agricultural employers and farmworkers on May 15. The legislation was attached to the Iraq supplemental spending bill. Different from the stalled AgJOBS legistlation EARA, this is emergency legislation with a five year sunset and does not provide a path to citizenship or a green card. However, it would grant temporary immigration status to farm wokers who continue to work in agriculture at least 100 days per year. It would also modify the H-2A guest worker program. The bill is supported by many agricultural employer organizations (e.g., American Farm Bureau), agricultural labor advocates and farmworker organizations (e.g., United Farm Workers). More information is available at http://feinstein.senate.gov/public/index.cfm?FuseAction=NewsRoom.PressReleases&ContentRecord_id=ee2d9ac8-ebdb-0a1c-48c1-484dfc65e9d9 If you or your clientele would like to support or oppose this legislation, it is paramount to act quickly. |
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Regional reports Last week’s temperatures were cool with highs in the 60s and lows near 40. There were scattered frosts with lows near freezing on Thursday, May 15th and Monday, May 19th. Little damage was reported. Rain showers fell in the area Wednesday, May 14th and Saturday, May 17th. Rainfall totals were generally light (about a tenth of an inch). Soil moisture levels are good, but light soils are beginning to dry out. We expect continued cool weather this week until the weekend when we should see temperatures climb into the upper 70’s. There is little chance of rain this week. We need to be aware of the danger of frosts when we get clear, calm conditions. There is a chance of warm rain next Monday or Tuesday. Our GDD totals have fallen back to levels not seen since the late 1990’s.
Tree fruit Insect activity remained generally low last week. Oriental fruit moth trap catch continues. Oriental fruit moth were caught and biofixed May 4 at SWMREC. Trap catch has been low but continuous. Codling moth trap catch has been sporadic. Redbanded leafroller flight is finished. Plum curculio is out and egg laying scars have been found. Generally, it has been too cool for egg laying, but warm temperatures return this weekend and growers should have their fruit protected. We expect widespread egg laying early in the weekend warm up. Apricots fruits are 12 to 18 mm in diameter. Growers need to protect against plum curculio. Peaches are out of the shuck. Fruit are about 8 to 10 mm in diameter. A lot of fruit disappeared due to fruit drop in the last week. Oriental fruit moth was biofixed on May 4th at SWMREC. Treatment is timed for 200 GDD45 after biofix and we are now at about 120. We will need to apply controls during the weekend warm up. We will reach the 200 GDD45 treatment window Monday or Tuesday. Plum curculio egg laying should be a problem at the same time. Sweet cherry fruit are about 12 mm in diameter. Growers should be prepared to protect against plum curculio egg laying during warm weather. Sweet cherries are always susceptible to brown rot. This disease requires wet and warm conditions, 5 to 6 hours of wetness at 70°F. We may see conditions that warm and wet early next week if it rains. Remember to protect against cherry leaf spot. We have not had many infection periods this year. Tart cherries are emerging from the shuck and fruit are 4-6 mm in diameter. Exposed fruit will be susceptible to plum curculio during the warm weekend. The leaves are susceptible to cherry leaf spot. Recent rains have been marginal infection periods due to cool average temperatures. Growers should apply protectant materials before rains. Because of widespread SI resistance in cherry leaf spot, alternating sprays of Gem and copper are recommended for leaf spot control. This saves the SI materials for brown rot control near harvest. Plums are out of the shuck. Japanese plums are about 8 mm. European plums are about 6 mm. Plum curculio egg laying scars were found in Japanese plums. Growers also need to protect against black knot. Indar or a tank mix of Topsin M and Captan are the most common controls used. Apples are at petal fall with scattered late bloom. Fruit size is in the 4 to 8 mm range. Rain last Wednesday, May 14, caused a wide spread scab infection. We are nearing the end of primary scab season. Most of the scab spores are mature and about three-fourths of the spores have been released. Scab protection will be necessary at least through the next rain event. Last week was too cool for fire blight. The cool weather will keep bacterial populations low this week. We will not have enough heat for infection until the warm weekend. Growers with open bloom should be prepared to apply controls Monday or Tuesday, if we receive rain. Some growers with small plantings of young trees and risk of infection plan to remove the blossoms. Only those blossoms that open this week should be vulnerable since only young blossoms are susceptible to infection. We are past the time to apply Apogee sprays to reduce the spread of fire blight. To control vegetative growth into the season, applications are spread out at 14-day interval over the next six to eight weeks. Southern Berrien County biofixed for codling moth on May 14th at 278 GDD50. There were only light catches elsewhere across the region, and we have not set a regional biofix. With the cool week and warm weekend, we will be at about 100 GDD50 early (Tuesday) next week. We expect most of the region to biofix Friday, May 23rd with the return of warm temperatures. Spotted tentiform leafminer sap feeders should be out, and they will move into the leaves soon. European red mite motiles are moving about, and we expect to see San Jose scale crawlers soon. Apple fruitlets are 4 to 8 mm in diameter, and we are just starting to see the early drop of injured and unpollenated flowers. The cool weather forecast means that we will not have any good apple thinning windows until the weekend. A warming trend when temperatures climbing above 70°F for several days will offer us the best thinning window we are likely to see this spring. Due to scattered frost injury and poor pollinating conditions fruit set may not be as heavy as the bloom indicates. I am recommending a moderate thinning strategy. I think the poor pollination and long bloom combined with the excellent thinning window means that the fruit will not be hard to thin. We also run the risk of having high temperatures rise into the 80’s, which would make thinners very effective. Growers need to determine if any blocks need to be aggressively thinned. There are wide differences in frost injury between varieties and sites, where there is a wide variation in bloom density. Thin for the trees with the heaviest fruit set. Thinners will remove more from heavy set trees and less from trees with a light set. Where there is a heavy bloom on trees with a strong biennial bearing tendency, thin aggressively. Using moderate thinning rates growers may need to apply follow up thinning sprays later. There will certainly be another thinning window later, but this one is likely to be the best. Winter injury has been reported in young apples. Weak trees in last year’s plantings show poor growth and brown cambiums, while more vigorous trees show no damage. Where the wood beneath the cambium is white, the trees are likely to make a recovery. If the wood is brown beneath the cambium, the trees are unlikely to recover and will remain stunted because of the dead wood in the interior of the trunk. Pears fruit are 6-8 mm in diameter. Growers have been applying thinning sprays. Pear psylla nymphs are hard to find. Growers should protect against pear scab. Small fruit Blueberry bloom is well underway. Mummyberry shoot strike symptoms from infections following the April 30 freeze are visible and easy to find in some areas. Some growers used their sprinkler systems for the frosts Thursday, May 15th and Monday, May 19th. Growers in cold pockets reported lows in the lower 20’s and suffered some damage. More damage is being reported from the April 30 freeze in cold pockets. Flower buds were killed at 19°F at bud burst. We are also seeing winter injury in young plants planted last year. Shoot tips are growing poorly while leaves and shoots lower in the plant are growing well. The dividing line between the injured upper part of the plant and the healthy lower part of the plant is probably the snowline on a cold calm night in the winter. While the snow acts as an insulator, the temperatures above the snowline can get very cold during a calm clear winter night. Blueberry stem gall wasps are flying. There is no good control for this pest, which emerges during bloom and lays its eggs in the stem. Scattered catch of cranberry fruit worm has been reported in Van Buren and Berrien counties. We expect that there will be a strong flight over the weekend. Grapes have six-inch long shoots with two to three leaves out. ‘Vinifera’ grapes are a little behind in development and late varieties are noticeably behind. Cool temperatures have slowed grape growth. In vineyards damaged by the April 30 freeze, secondary and tertiary buds have begun do grow and are easy to find on and near live shoots, but no new growth is visible from dead buds in severely affected vineyards. In the past, it has taken four to six weeks for new growth to become apparent. 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 and we have probably had a few infection periods. New phomopsis lesions were found in grapes. Strawberries are at past full bloom. Most of the primaries have set fruit. Avoid using insecticides during bloom. Many growers irrigated during the recent frosts. These cool wet conditions favor angular leaf spot a bacterial disease. Applications of copper can reduce this disease (see notes on control in E154). Fungicides are applied at bloom to reduce gray mold, anthracnose, leaf spot diseases and leather rot. Raspberry and Blackberry flower bud clusters have emerged. Orange rust symptoms are common in wild brambles. Nova is an effective protectant for preventing infection by this disease. It suppresses symptoms, but does not cure the disease after infection. Cranberry beds are greening up and tip buds have burst. Most of the movement is taking place on the edge of the beds. When the shoots begin active growth before bloom is time for a protectant fungicide spray to protect new foliar and reduce fruit rots. Miscellaneous There are a pair of Grape IPM meetings on Wednesday, May 21st. The morning meeting will be from 10:00 AM to noon at the Cronenwett Farm Shop at 70123 28th Street, east of Lawton. The afternoon meeting will be at 2 PM in the Berrien County MSU Extension Office at the Southwest Michigan Research & Extension Center. These meeting are co-sponsored by National Grape Cooperative and MSU Extension and are open to all grape growers. There will be no Monday Fruit Update May 26 due to Memorial Day. There will be a short Fruit IPM meeting at Fruit Acres Farm on Tuesday, May 27th at 5:00 PM. There will be no credits for this Tuesday meeting. The next Monday Fruit Update meeting will be, Monday, June 2nd at the Fruit Acres Farm in Berrien County. |
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2 -- Southeast Unseasonably cool temperatures have continued to slow our season down and the development of most of our fruit crops and insects and diseases over the last week. Our season is running about three to four days behind normal. The southern tier of counties continues to see moderate amounts of rainfall; however areas to the north are generally dry. With the exception of the nice rain early last week and rain showers on Thursday, May 15, major rain events occurred more than seven weeks ago. Rain showers last Wednesday and Thursday created an apple scab infection period. The dry soils are most notably affecting the green up of newly planted tree and small fruits. I have begun to make a recommendation to several growers to begin to irrigate these newly planted fruit crops. Southeast Michigan growing degree day totals for March 1 to May 19
Tree fruits Apples are mostly at 5 mm to 6 mm and there has been a fair amount of late bloom in apples that continues. This late bloom has partially been the result of frost and freeze injury. There is a fair amount of drop in some apple varieties that were damaged from cold, most notably Red Delicious, Gingergold and Idared. The effects of the frost and freeze injury are more noticeable in many blocks of apples with some blocks on poor sites having little to no crop. We have had a good number of insects show up for the first time over the last week. My first codling moth trap catch of the season was late last week. This is an early indication that once we get our first warm night, that codling moth trap catches are expected to rise dramatically. Mullein bug was the second new pest that was seen for the first time this season and with some good numbers in some blocks. Growers who have had difficulty with mullein bug in the past are taking heed and are now applying early petal sprays to control them. White apple leafhopper nymphs are starting to be seen as of this morning. A few plum curculio continue to be seen in orchards, however no oviposition damage has been observed. Again, I feel that it has been too cold for plum curculio development. Once we get a warm night or two we will see them begin to flourish. Apple grain aphid is another new pest to show up over the last week. Rosy apple aphids are curling leaves on the inside middles of apples at a few farms. San Jose scale crawlers have not been seen, however we are seeing evidence that the adult females are getting ready to release crawlers fairly quickly. Oyster shell crawlers are starting, however their numbers are fairly low. Eastern tent caterpillar tents are starting to be seen at a few farms across the region; however I expect to see many more later this week. Oriental fruit moth trap catches remain high at many farms, some in the range of 100 to 120 per trap. Most farms are in the range of 20 to 30 per trap. I am seeing a good number of redbanded leafroller and obliquebanded leafroller larvae over the last few days. Green fruitworm larvae continue to be seen, however their numbers have been fairly low, as have fruit tree leafroller. European red mite eggs continue to hatch in problem blocks from the 2007 season with egg laying reported this morning. I continue to see increased numbers and species of predators, these include lady bugs, thrips, solider bugs, velvet mites, lacewing adults and predator mites. Most growers had a moderate apple scab infection last week on Thursday. I have not seen any apple scab lesions, but I would expect to see them later this week as leaves develop more quickly as a result of increased temperatures. Fireblight has not been an issue thus far this season, as the EIP values have been relatively low. The Enviroweather fireblight model is predicting higher EIP levels when temperatures begin to rise on Sunday and Monday of next week. Most of our apples will be out of bloom and will not be an issue. I have not seen any powdery mildew, but I expect to see it any day. With predicted warmer temperatures expected late this week and over the weekend, most apple growers are considering applying a thinner to reduce the crop load in many blocks at that time. I am advising growers to take more of a moderate approach to thinning this season, as opposed to an aggressive approach. I think that with frost and freeze injury at many farms this year, thinning may be done a bit easier. We also had a long bloom period in apples, which would mean that apples would tend to thin more easily. This will be a difficult decision for many growers to make. Pears are mostly at 6 mm to 7 mm with a fair amount of drop from frost and freeze damaged flower buds. Pear psylla egg hatch continues at most farms across the region that have not done a good job of controlling the adults earlier in the spring. Peaches are mostly in the shuck to some at shuck split for earlier fruiting types. While some blocks continue to have a potentially good crop for 2008, others are starting to show signs of a fair amount of drop. Tarnished plant bug adults were seen as a new pest in peaches this week, their numbers were fairly low to moderate. Green peach aphid was another new pest of the week. Oriental fruit moth trap catch remains high in some blocks and low in others. Last week, I reported a gummosis or oozing from twigs and buds on some varieties of peaches. I now believe that this is from winter injured flower buds. Sweet cherries are mostly at 11 mm to 13 mm in size with some degree of fruit drop. There is a wide variety of crop potential at this time. Most blocks have only a crop of singles left, and other blocks will have no crop for 2008. Tart cherries are at shuck split to 5 mm to 6 mm in size. We have a better crop of tarts than sweets this season. Plums are at early shuck split with a fair amount of drop being seen from frost damaged fruit. Small fruits Strawberries are at 40 to 60 percent bloom across the region. A few strawberry growers have frost protected twice over the week; however most have only frost protected one time. New plantings of strawberries are beginning to look better with new leaf growth. I am seeing a fair amount of strawberry clipper adults and damage at a few farms, but most farms are clean. Fungicides sprays are being applied for grey mold control. I have not seen any tarnished plant bugs in strawberries this week, but I expect to see them over the next few days as temperatures begin to warm up. Many existing strawberry fields are looking a little bit peaked. I have recommended a light application of urea to many strawberry growers across the region. Raspberries blossoms are emerging from the bud, however they have not expanded or opened. I would expect to see raspberry bloom in the next week or so. Fall red raspberries continue to show poor growth this year, most likely due to cooler than normal temperatures. Most raspberries have 6 to 8 inches of new growth. Blueberries are at 25 percent bloom for Jersey’s, and full bloom in earlier fruiting types. There have been a few reports of mummyberry shoot strikes being seen late last week; however their numbers are fairly low. Blueberry stem gall wasp adults have been observed emerging from galls at few farms across the region. This is a difficult pest to control, as the emergence is typically timed with bloom. Prebloom sprays with the traditional insecticides do not seem to work well in controlling this pest. There are a fair amount of flower buds that appear not to be opening at this time in blueberries. The buds most likely were damaged from the frost and freeze event of April 29 and 30. So, at this point in time the crop potential has been reduced a bit due to frost and freeze injury. |
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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 couple of weeks. Current degree day totals put us at one day ahead of normal averages for this time of yet. Tree Fruit Most apples are in the petal fall stage, but there is still a lot of bloom out there in some varieties in some blocks. Sweet cherries are done blooming and small fruits can be seen. Peaches bloom is over, and small fruits can be seen in early peaches as well. Rain on May 14th resulted in a moderate apple scab infection for the greater Grand Rapids area. According to degree days for apple scab spore development, we were at about 90 to 95 percent spore maturity right now, so cover sprays are still very important. Spore numbers in the last two rains have seemed to drop off, but they are still discharging. We will probably mature all the ascospores with the warmer weather predicted for the coming weekend, but at least two good rains are needed to discharge them all. Primary scab fungicide rates are still important to maintain for the next few rains. There are some reports of scab on leaves from earlier infections. MaryBlyt has only been calling for low to moderate risk for blossom blight infections over the past several days. Looking ahead to the warmer weekend weather, we will most likely be at high risk for blossom blight infections of any open bloom left, beginning on Friday or Saturday. Most apples should be well into the petal fall stage by then, but some varieties will still have ragtag bloom on them that could still give you a blossom blight infection if conditions are right and we get some precipitation. A few egg laying scars from plum curculio have been observed in sweet cherry. This pest could really be poised to do some damage in apple if the temperatures get as warm as predicted for the upcoming weekend. Apples will be in exactly the right stage for plum curculio to easily lay eggs. Growers will want to scout closely for any damage and not delay petal fall applications for too long. European red mite eggs are mostly all hatched. 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 petal fall. Aphids are active. Both apple grain aphids and rosy apple aphids have been seen. Rosies are curling up in the leaves which will make it difficult to control them at petal fall. Some predators can be seen more readily in aphid colonies now. A few green peach aphids were seen this past week in peaches. Black cherry aphids should be found at any time. Some early codling moth flight was reported last week in high pressure blocks. The warmer predicted weather for the upcoming weekend will probably bring codling moth flight on in other blocks as well. A regional biofix has not been set for the Grand Rapids area. Oblique banded leafroller larvae are getting large and should be pupating, but are still very difficult to find in most blocks around this area. Oriental fruit moth is flying, but numbers are still sporadic in some locations. A regional biofix has been set on May 8th. We have accumulated 83 degree days base 45 since that biofix and early egg hatch controls based on the May 8th biofix will probably be needed early next week or around May 26th or 27th for stone fruits. It’s always best to set your own biofix based on traps in your own orchards. Small fruit As of May 20 blueberry varieties north of Allegan County are in early to 50 percent bloom. So far, despite that in the last few days minimum temperatures have been in the 30’s no frost damage has been reported. Because of the prevailing low temperatures, the growing degree day accumulation in Allegan and Ottawa counties has been on average of six GDD. Up until now, GDD accumulation varies from 350 in south Allegan County to 250 in Ottawa County. Regarding pest and disease problems, there are not major disease or insect problems affecting blueberries at this time. Most of the disease problems are related to few sites with some shoot strike damage and Phomopsis damage in tender growth that occurred the past year after harvest. Blueberry insect pests have been active, but so far only cherry fruitworm adult moths are present in pheromone traps. Based on our newly developed cranberry fruitworm phenology model, we are expecting the beginning of the emergence of cranberry fruitworm adult moths at any time in south Allegan and Van Buren counties where temperatures are higher than in Ottawa County. Regarding the nutritional program for this growing season, growers need to take in consideration the amount of fruit that was removed during the past harvest. According to the last USDA Noncitrus Fruit and Nuts summary published in January 2008, the Michigan’s blueberry production has been increasing every year for the last four years. The total blueberry production increased from 64 million pounds in 2002 to 93 million in 2007. The average yield per acre increased from 3,790 to 5,030 pounds per acre. Thus, nutrition requirements of producing fields need to be adjusted accordingly to prevent sharp fluctuations in productivity due to depletion of soil nutrients. Fertilization programs need to be dynamic to replenish at least the amount of nutrients removed from the soil with each harvest. Therefore, fertilization recommendations need to be adjusted periodically to suit the crop requirements. So far, blueberries are in full harvest in Georgia, North Carolina and Florida. There are also blueberries from Guatemala and Mexico, but in very small quantities. Prices for fresh blueberries started declining. As of May 19, the highest prices for blueberries are in California where a 12 4.4 oz flat is sold for $18 to $20. However, in Philadelphia, Pennsylvania the 12 4.4 oz flat is sold for $10 to $12. This is in sharp contrast with fresh organic blueberries. In San Francisco, California, organic blueberries are sold for $48 to $51 per 12 4.4 oz flat. |
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4 -- West Central The weather conditions for the last week could be described with two words: unseasonably cool. Nightly temperatures dropped below the freezing mark three times last week. The lowest temperature for the week (29.40F) was recorded early morning in the Manistee/Bear Lake area. In the rest of the district, temperature readings at the weather stations was between 30-32°F. Precipitation was below normal for this part of the season. Tree Fruit Apples are in full bloom to early petalfall. Pears are in petalfall with some straggly blooms still out. Sweet cherries are in shuck split to small fruit (5mm). Tart cherries are from petalfall to being in the shuck. Plums are in the shuck. West Central Michigan growing degree day totals from March 1 as of May 18
Three rain events last week that resulted in light apple scab infection in Ludington on May 14 and light scab infection in the Manistee/Bear lake are on May 16. Spores were discharged with each wetting period, though their number has been on significant decline. The last rain of May 17 produced only ten spores per rod. Ascospore maturation model is indicating that slightly above 80 percent of spores have matured. First lesions from the infection in early May have been found in the abandoned block in the Ludington area. Fireblight in apples and pears has not been an issue due to the cold temperatures. At this point, the EIP numbers are at zero. With the predicted temperature rise for the end of the week, it is anticipated that the EIP’s will be 51-56. Generally, potential for blossom blight infections is going to be of concern in blocks that have secondary or rag-tail blossoms still open. There have been no cherry leaf spot infection periods. Cool weather has slowed down insect activity. Scouts report some European red mite nymphs, black cherry aphids and green peach aphids in low numbers. Green fruitworm and obliquebanded leafroller larvae are present in a few blocks. Redbanded leafroller trap catches have significantly dropped since last week. American plum borer trap catches are on the rise. Oriental fruit moth is present, but the flight is still rather sporadic. Plum curculio is present throughout the area, and their increased activity is expected with the onset of warmer temperatures. Sweet cherries and plums will be the main target due to their stage of development and sizing. |
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5 -- Northwest Growing degree day accumulations at NWMHRS Growth stages at NWMHRS from May 19 at 10:00 AM Apples are at first king bloom to 50 percent king bloom. Bartlett pears are at 95 percent bloom. Sweet cherries: Hedelfingen are at late petal fall. Napoleon are in shuck. Gold are in mid-petal fall. Tart cherries: Montmorency and Balaton are in early petal fall. Apricots are at early shuck split. Plums are at early petal fall. Grapes are at late bud burst. Weather Our weather summary seems to be a bit of broken record here in the northwest, but again our temperatures remain on the cool side. High daytime temperatures loom in the mid-60s, but with the wind the actual temperatures feel much cooler. We have had many windy days in the past week, and many growers have been spraying at night when the conditions are calm. Nighttime temperatures remain in the 30s, and we have experienced frost on a few nights in low spots. We are at 400 GDD base 42, which is 112 fewer GDD than last season. At base 50, we are at 178 GDD this year compared with 239 GDD last year at this time. Crop report We continue to find damage to tart cherries in various blocks around the region. Some of the damage looks recent, and we are finding missing or dying pistils on good fruit sites. In a nutshell, the damage to tart cherry blossoms is extremely variable. We are wondering if the past few years of drought have made trees more susceptible to cold temperatures. Another major concern for all cherry crops in the northwest is pollination. We have been slow to warm up in the mornings, and we do not often reach our daily highs until late in the day. Secondly, as mentioned above, conditions have been extremely windy, and both cool temperatures and winds are not conducive for honeybee flight. We have been conducting many orchard walks for pollination studies, and very few honeybees have been present in blocks in full bloom. Sweet cherries are at petal fall and into shucksplit for early varieties. Montmorency are at early petal fall, and Balatons are in full bloom to early petal fall here in the northwest. In apples, king blooms are out on many varieties and in Benzie and Manistee counties, some varieties are approaching full bloom. Reports of damage in apples have been minimal. Grapes are at variable stages depending on variety. Early strawberry varieties are starting to bloom, and most growers have been frost protecting this crop in the past week. As the weather remains cool, everything is moving slowly up north. The apple scab season is longer than usual, with infection periods being predicted a few times over the past weeks, yet the model is still showing only 38 percent of the ascospores have been discharged. This may present some management issues for growers as the cool spring drags on. As we move into this weekend, the fire blight model is predicting an EIP of above 72 and a 40 percent chance of rain by Friday. If the predicted weather trends continue, streptomycin applications are being recommended. The forecast for Sunday and Monday is predicting temperatures approaching 80°F, so we may see our degree hours accumulate quickly over the weekend. Spotted tentiform leafminers are approaching peak emergence with our trap catches at the station approaching 150. European red mite nymphs are increasing. The weather over the weekend was conducive for cherry leaf spot infection in the northern part of the region but few trees in the area are leafing out yet. We saw more San Jose scale on sweet cherries on Old Mission, once again associated with drought stress and ethrel damage. European brown rot is a concern with the cool wet weather and preventative sprays are being applied in Balaton cherry. Plum curculio are on the move with relatively high populations being trapped out of Montmorency in Benzie County last week. Grapes are still pretty quiet. Cut worms have been spotted, but it’s too cold for them to feed now. We are also starting to see a few flea beetles. |
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Weather news As noted in last week’s column, while the next couple of nights are expected to be cloudy and relatively windy, frost is a possibility Wednesday and Thursday mornings should clear, calm conditions develop. Greatest chances for any frost would be in inland, northern sections of the state. Further ahead, a significant warming trend is expected to begin by late in the week as the upper air ridge approaches from the west. Temperatures by Saturday and Sunday should climb back in the upper 60’s north to the low or mid-70’s south by Sunday with lows back into the 40’s to low 50’s. It is possible that high temperatures may approach 80°F in some sections of the state by Memorial | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
