In this issue
Tree fruit news
§ San Jose scale biology and control in fruit crops
§ New MSU web resource for cherry growers
§ TNRC trapline data: Spotted tentiform leafminer
Small fruit news
§ Intrepid 2F blueberry use directions update
§ Topsin M Section 18 request for blueberries still pending
§ Correction: PropiMax fungicide is not labeled for strawberries
§
Spartan 4F receives Section 18 label for
§ Small fruit meetings
Other news
§ How to use the Enviroweather Fire Blight Model
§ Regional reports
§ Weather news
Nikki Rothwell and Erin Lizotte, NW MI Horticultural
Research Station
John Wise and David Epstein, Entomology
In 2007, we observed large populations of San Jose scale on
sweet cherries in the northwest, and now they are showing up on tree fruit
across the state. In the northwest, populations were not readily identified
because branch and tree dieback were masked by ethephon damage due to hot and
dry weather prior to harvest in 2005-2006. This type of epidemic has never been
seen in sweet cherry in
Sweet cherries are considered hosts of this introduced pest, but more commonly, we see San Jose scale in apple, peach, pear and plum. Scales are unusual insects with a very unique life cycle that makes them difficult to control. Adult females live underneath a waxy, turtle-like covering, giving birth to live young rather than lay eggs. These nymphs are the crawler stage of the life cycle. Because the crawlers’ stage does not possess any waxy covering, this is one optimal stage for control. Crawler females will develop wax coverings; males develop wings for dispersal (Figure 1).
San Jose scale feed on sap of trees and a large population
is needed to cause injury. Depending on the size of the population, scale can
kill a young tree in two to three years. Older trees can also be killed by
scale, but they do withstand more feeding damage than young trees. In addition
to bark feeding,
San Jose scale spend the winter as partially grown scales where they adhere themselves tightly to the bark. When the sap begins to run in the spring, the scales grow, and they reach full grown status in late May. At this time of the year, male scales come out from under the scale to mate with females. Females will start to produce young, and are each capable of bearing 150-500 offspring. These crawlers start to suck sap with their needle-like mouthparts. In three weeks, the young crawlers molt and lose their old skins, legs, and antennae to become a flattened sac with waxy caps (Figure 1). They remain attached to the trees with their mouthparts.
Because these insects have two generations per year, we have
two optimal timings for control. An oil application during pre-bloom is highly
effective at targeting adults. Insecticides applied mid-June and mid-August
target crawlers before they mate. Table 1 and Figure 2 list the insecticidal
activity of several compounds in research conducted at the MSU Trevor Nichols
Research Complex in
|
Compound |
Labeled crops |
Life-stage activity |
Application timing |
|
Oil |
All fruits* |
Adult scale |
Delayed-dormant |
|
Lorsban |
Pome and stone fruits |
Adult scale |
Delayed-dormant |
|
Suforix |
All fruits* |
Adult scale |
Delayed-dormant |
|
Esteem |
All fruits* |
Adult scale crawlers |
Delayed-dormant ≈ 700 & 1700 DDb50 |
|
Calypso |
Pome fruits |
Adult scale |
Pre-Pink |
|
Warrior/Asana |
All fruits* |
Crawlers |
≈ 700 & 1700 DDb50 |
|
Assail |
Pome and stone fruits (not on blueberry label) |
Adult scale crawlers |
Delayed-dormant ≈ 700 & 1700 DDb50 |
|
Centaur |
Pome fruits, peaches |
Crawlers |
≈ 700 & 1700 DDb50 |
Pome and stone fruits, blueberry for scale control.
Nikki Rothwell, District Horticulturist
Amy Irish-Brown, MSUE educator
Joy Landis, IPM Program
We have rolled out a new cherry website for this season that is designed to concentrate all of our MSU cherry-related resources into a “one-stop shopping” location. Please check us out on the web at www.cherries.msu.edu. Throughout the year, we will continue to expand this site. Presently, you will find:
§ Current season links to the CAT Alert and newsletters produced by the Northwest Michigan Horticultural Research Station.
§ Photos and descriptions of common insect pests, weeds and diseases of cherries.
§ Photos and descriptions of beneficial insects.
§ Weather and climate topics including cold hardiness, use of degree days, etc.
§ Varieties and rootstocks information.
§ Tips on specific horticultural practices.
§ Recommendations for effective pollination and information about pollinators.
§ Links to labor management, marketing and financial management resources.
§ A directory of MSUE local contacts for cherry growers.
§
Presentations from the
We are interested in your feedback, so please do not hesitate to give us your two cents at rothwel3@msu.edu.
Also, look forward to an apple website in the near future.
Rufus Isaacs, Entomology
An updated set of use directions has been released by Dow
AgroSciences for Intrepid 2F for control of Lepidoptera larvae infesting
highbush blueberry. The recent label approved for Intrepid in blueberry
originally contained a 16oz/acre rate for fruitworms, which is a high rate. The
new label update provides greater flexibility and guides blueberry growers to
use a rate range of 12-16 oz/acre for fruitworm control, 10-16 oz/acre for
leafrollers and spanworms, 8-16 oz for cutworms, and 4-8 oz for gypsy moth. The
12 oz rate of Intrepid is expected to perform very well against fruitworms, and
we will be running trials this spring to verify this.
Intrepid 2F is an insect growth regulator insecticide, so it must be eaten to be effective on the insect. For this reason, the label guides application to be done to achieve excellent crop coverage. For this reason the label recommends application using 30 gallons of water by ground application and 10 gallons of water by aerial application.
The updated label can
be downloaded here, which also provides information on the other application
restrictions, such as the 7-day PHI.
Annemiek Schilder, Plant Pathology
The Section 18 (emergency exemption) request for Topsin M in blueberries is still pending with the Environmental Protection Agency (EPA). Do not use this fungicide unless we obtain approval for use this season. In making its decision, the EPA considers all other fungicides that are available for disease control in blueberries and the risk of major losses to diseases in the absence of Topsin M. In addition, it considers the toxicological profile and the overall “risk cup” for the product in question. We expect a final decision this week and will inform the growers immediately.
Annemiek Schilder, Plant Pathology
A few weeks ago, I introduced a new fungicide called PropiMax (propiconazole), a systemic sterol inhibitor fungicide with the same active ingredient as Orbit. PropiMax recently received a supplemental label for disease control in berries (blueberries, raspberries, blackberries, currants, gooseberries, lingonberries and a whole range of other berry crops). However, it should be clearly stated that the label does not include strawberries. The PropiMax label lists the following target diseases: mummy berry, rusts, powdery mildew and Septoria leaf spot. PropiMax has a 30-day PHI.
Bernard Zandstra, Horticulture
On April 21, the US EPA issued a Section 18 label (specific
exemption) for use of Spartan 4F on strawberries in
Spartan 4F may be applied to strawberries at renovation or after the plants have gone dormant late in the season. The primary target weeds are mayweed chamomile, puncturevine, redroot pigweed, common groundsel, field pansy, white campion and yellow woodsorrel. Spartan will control many other broadleaves and grasses as well.
Four to eight fluid ounces of Spartan 4F may be applied in any
one application. A maximum of 12 fluid ounces may be applied per year. There is
a 70-day preharvest interval (PHI), but this should not affect
Spartan may be applied in tank mixes with Sinbar and postemergence herbicides such as 2,4-D, Stinger, Poast or SelectMax. The postemergence herbicides will kill emerged weeds and the residual herbicides will maintain weed control until fall frost.
Copies of the label will be available from chemical dealers and suppliers. As soon as we receive a copy, we will post it on the MSU vegetable website: www.veginfo.msu.edu.
This is the seventh year that
Topic: Bloom meeting
Van Buren County, Cornerstone Ag (Bodtke’s)
For more information, please contact: Paul Jenkins
(jenki132@msu.edu), Rufus Isaacs (isaacsr@msu.edu) or Annemiek Schilder (schilder@msu.edu).
May 21 from 10:00 AM to
12:00 PM
2:00-4:00 PM
For more information, please contact: Paul Jenkins
(jenki132@msu.edu), Mark Longstroth (longstr7@msu.edu), Rufus Isaacs (isaacsr@msu.edu) or Annemiek Schilder (schilder@msu.edu).
May 9 at the Lenny Ligon’s Farm, Paolo Sabbini will be discussing viticulture practices. The meeting will take place from 3:00 to 5:00 PM. For more information, please contact: Erin Lizotte (taylo548@msu.edu), Nikki Rothwell (rothwel3@msu.edu), Duke Elsner (elsner@msu.edu) or Paul Jenkins (jenki132@msu.edu).
Nikki Rothwell, NWMHRS
George Sundin, Plant Pathology, MSU
Bill Shane and Amy Irish-Brown, MSUE educators
Growth of the fire blight pathogen is favored at temperatures over 65ºF. Degree hours using a base of 65ºF (DH65) are used to estimate fire blight bacterial population growth. To reach a level where fire blight can cause problems in the orchard, 198 degree hours (base 65ºF) from first bloom are needed to increase the population to a potentially dangerous level. These fire blight bacteria grow on the tip of the flower pistil (the stigma, which receives pollen grains), and once the population has built up on the stigma, a rain or heavy dew can wash the bacteria deep inside the flower where infection can take place.
The fire blight blossom model is based on the EIP value (Epiphytic Infection Potential), which is a way to express this heat unit accumulation on a 0 to 100 scale. ("Epiphytic" = plant surface). The EIP is calculated by dividing the current DH65 accumulation by 195 and then multiplying this by 100. If the DH65 reaches 195 (which also means that the EIP is 100), the bacteria have built up to a dangerous level, and a rain or heavy dew at this time will wash the bacterial down into the infection site and cause infection.
The current blossom blight model on Enviroweather also has the capacity to reduce the EIP value under cooler weather conditions by figuring in blossom life. In addition, the model reduces the EIP if the maximum temperature for a day is below 64ºF, because the fire blight bacteria require warm temperatures to grow. The EIP value is reduced by one-third by one cool day, another third by a second consecutive cool day, and to zero with a third. A day with freezing temperatures reduces the EIP to zero. However, once the EIP reaches 200, cool weather no longer reduces the accumulation.
The fire blight model is very different from other pest models in that it is based on degree “hours” rather than degree “days.” Since the threshold temperature for fire blight is 65ºF, we often go above that temperature for many hours in one day, so it takes a lot less time to collect degree hours above the threshold compared to collecting “daily” temperatures that average above 65ºF. Growers must be particularly diligent about checking the model because when temperatures change drastically during the day, the EIP can rise quickly and warrant a fire blight spray.
Therefore, at this time of the year, we need to be on the look out for weather conditions that favor fire blight, especially in susceptible varieties (See list of susceptible varieties). Infection can occur with a small amount of rain (or dew) following a warm period that allows bacterial populations to reach critical levels. The Enviroweather website has a reliable chart growers can use to determine if a fire blight control spray is needed:
§ Click on www.enviroweather.msu.edu, go to the weather station closest to you, then to Fruit, then to Fire Blight of Apple Blossoms.
§
Locate
the biofix date (the date bloom first opened OR the date a spray was applied to control fire blight) on the top
row.
§
Follow
that column down to determine Epiphytic Infection Potential (EIP) for that
block on each date in the left column. If this number is greater than 100, and
the average temperature is greater than or equal to 60ºF, this area will be shaded and rain or
trauma (high winds or hail) is all that is needed for infection.
At this time of year, it is particularly difficult to gauge fire blight infection potential as we often have warm and rainy weather, but we don’t want to waste an antibiotic spray if it is not truly necessary. If the fire blight model’s EIP is close to but not at 100, there are a few rules of thumb to determine if an antibiotic application is warranted: 1) a block with a history of fire blight, 2) susceptible varieties, or 3) visible cankers are all good reasons to go into a rainy period with an antibiotic spray.
Gala,
First pick the column that best corresponds to the first day blossoms opened in your orchard (see figure). The numbers in the squares gives the EIP (Epiphytic Infection Potential) for these blossoms. Bacterial populations (larger EIP) build on days with temperatures over 65ºF. When the EIP reaches 100, a rain or trauma event (strong wind or hail) will initiate a blossom infection. The higher the EIP, the greater is the risk of infection with rain or trauma.
A freeze on Wednesday,
April 30, with lows in the 20ºF to 29ºF range, caused wide spread damage,
but the severity of damage varied from extensive to very little. Every freeze
is different. A great deal depends on the crop’s stage of development,
the characteristics of the fruit site and the duration of cold temperatures. This
freeze was radiation freeze similar to freezes in 2002, 2004 and 2006. Apples, grapes and
sweet cherries were the hardest hit.
Good pollinating weather with high temperatures near 70ºF and lows near 50ºF followed the freeze. Rain fell in the region May 2. Rainfall amounts varied greatly, from an inch to less than a tenth of an inch. These rains represented infection events for some diseases where more than a tenth of an inch fell. Soil moisture varies quite a bit depending on soil type. Light sandy soils are dry, and heavier soils are still very wet. We expect cooler temperatures this week. The forecast is for dry conditions with highs in the 60s and lows near 40ºF. Rain showers should begin Friday with a wet weekend.
|
Grapes, from April 1
|
|||
|
Location |
GDD 42 |
GDD 45 |
GDD 50 |
GDD 50 |
|
389 |
308 |
201 |
195 |
|
|
417 |
334 |
221 |
216 |
|
|
348 |
271 |
175 |
171 |
|
Tree fruits were not damaged as much as one would expect from the reported lows during bloom. Insect activity increased last week. Oriental fruit moth were caught and biofixed last week on Thursday (275) and Sunday (305). Redbanded leafroller and spotted tentiform leafminer are flying.
Apricots are in the shuck. Shuck split has begun in early varieties. Damage was slight on good fruit sites.
Peach bloom is
ending. Damage is generally light at good sites in the major production area of
Sweet cherries are in the shuck. Damage seems to be variety specific, varying from heavy to light. Better sites and later varieties suffered less damage. Many growers have enough cherries to feed the birds; others will have a good crop. Sweet cherries are always susceptible to brown rot. Since the leaves are out and developed, they are susceptible to cherry leaf spot. The rain May 2 began a cherry leaf spot infection in some areas.
Tart cherries are at full bloom. Damage is generally light. Tart cherries seldom get blossom brown rot unless the conditions are very warm and wet. As the leaves emerge, growers need to protect against cherry leaf spot.
In plums, Japanese plums are in the shuck and were damaged by the freeze. European
plums are at petal fall.
Apples are at king bloom. Damage to apples was severe in some sites. Early and late varieties were damaged and the damage seems very variety specific. Rain on May 2, was an apple scab infection for some sites. Symptoms from the April 19 infection should be visible. Fireblight should not be a problem for the next few days. Not enough heat units have accumulated since the freeze to pose a risk of infection. 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 6 to 8 weeks.
Pears are at full bloom. Pear psylla are laying eggs. Growers should protect against pear scab.
Blueberries are at pink bud and suffered little damage. Early varieties are nearing bloom and a few petals were damaged and may not open. Few growers used sprinklers to protect their plantings. Mummyberry mushrooms had dried out, but I expect more to emerge after this weekend’s storms. Many growers sprayed for mummyberry sprays immediately following the freeze. Symptoms from this infection should be visible in about 10-14 days. No mummyberry shoot strikes have been reported.
Grapes buds are opening. Juice grapes shoots are 2
to 3 inches long with one to two leaves out. Wine grapes are a little behind.
Damage to juice grapes in the Paw Paw area was severe. In Berrien County damage
varied. It was not unusual to see the buds at the tip, which had burst to be
killed by the freeze and buds at the base of the shoot at bud swell undamaged. Southern
Strawberry flower trusses are out and bloom has begun. Many strawberry growers protected their crop with sprinklers. Growers have spread straw between the rows. Fungicides during bloom can reduce fruit rots at harvest.
Raspberry and blackberry shoots are growing. Damage from the freeze was minor. In fall bearing plantings where all the shots have been removed, the new primocanes are about 6-inches tall.
Cranberry beds are greening up and tip buds have burst.
Last week growers were planting trees and applying fungicide sprays.
The next Monday Fruit Update
meeting will be Monday, May 12 at
the Fruit Acres Farm in
The frost/freeze event on the night of April 29 and the morning of April 30 is the big news of the week. I have made a concerted effort to visit as many fruit farms as possible over the last week to gain a greater sense of the impact of that frost/freeze event on our fruit crops. Every frost/freeze event is unique in terms of the damage to our fruit crops; this one was different than any that I have experienced. Please understand that this is still a preliminary assessment, as the true effects of this frost/freeze event are several weeks away from being fully determined.
Cold temperatures started late in the night of Tuesday, April 29 and continued through sunrise on the next morning of April 30. The length of the cold is as much a factor as the actual cold temperature in this event. At most of the Enviro-weather stations we had between 3 and 7 hours of temperatures below 28ºF degrees. The low temperature recorded at our Enviro-weather stations ranged from 23ºF to 27ºF. We did sustain injury to apples, sweet cherries, tart cherries and pears. There appears to be no visible damage at this point in time to peaches, plums or blueberries.
There is extensive frost/freeze damage to the apples across the region, even on late flowering varieties like Northern Spy that were at ½-inches green to tight cluster with about 10 to 12 days away from bloom. Idared, Empire, McIntosh and Red Delicious seem to be the varieties which were affected the most. Damage to varieties varies from farm to farm. Low sites were hit the worse. At some farms, I have seen a complete kill of the king bloom with much of the side bloom remaining undamaged. There is damage in other varieties that were not as far along as Idareds, however that damage is usually limited to a king bloom. So, at this time, I am stating that we have had more than a thinning frost/freeze event, but we still have the potential to have a nice apple crop across the region.
Pears were damaged, but not quite as significantly as apples. Around 40 percent of the buds have been damaged.
Peaches were at early bloom at most farms across the region. It appears that there is little to no damage in peaches.
Sweet cherries were at full bloom at many farms and sustained a fair amount of injury. It appears to me when I cut sweet cherry buds there is about 50 percent crop loss. I think the real story in sweet cherries was the lack of good pollinating weather as blooms were opening.
Tart cherries were just coming into bloom when this frost/freeze event hit. I estimate that we had a 20 to 30 percent bud kill.
Plums were just coming into bloom; it appears that there was not much damage.
Blueberries were at early pink bud at most farms, and it appears at this time that they were undamaged. Blueberries are a bit tricky and will need a couple more weeks to determine if there was injury.
With spring like temperatures over the last week, our growing season was slowed a bit back to more of a normal range. The on again-off again season has been very difficult for fruit growers to determine insect and disease stages.
Most of the region had their first true apple scab wetting
event on Friday and Saturday of last week, with infection occurring at three-quarters
of the Enviro-weather stations. The amount of rainfall from this event was
about 0.3 to 0.5-inches, it was not enough to do what growers needed to
replenish the surface moisture supplies. Things continue to be rather dry at
fruit farms across the region.
|
Location |
GDD42 |
GDD45 |
GDD50 |
|
Commerce ( |
407 |
315 |
197 |
|
Emmett (St Clair) |
392 |
303 |
189 |
|
|
401 |
321 |
216 |
|
Lapeer (Lapeer) |
431 |
340 |
222 |
|
|
439 |
341 |
214 |
|
Romeo ( |
354 |
281 |
179 |
Apples are currently at full bloom for most varieties. Red Delicious are at early king bloom. We are seeing a number of new insect pests show up in apples this week. Most notably is hatch of European red mite and a few apple grain aphids. I think that you will see earlier populations of our aphid species because of the early season development of our leaf crop. Spotted tentiform leafminer trap catches are generally in the range of 200 to 400 per trap with no eggs being seen at this time. I am seeing high numbers of redbanded leafroller adults in traps, in the range of 80 to 100/trap. While this number seems high, it is fairly typical for this time of year. I am beginning to see a few larvae of obliquebanded leafroller and fruit tree leafroller, however their numbers are very low at this time. While no plum curculio has been seen in commercial fruit blocks, I am finding it in some abandoned blocks as well as fence rows.
With rain events last Friday and Saturday, most growers had their first apple scab wetting event of the season, and most had their first apple scab infection period of the season. There were a moderate number of spores at our trapping stations. Apple scab lesions will begin to show up around the May 13 to 15 from this event. With most of our apples and pears in full bloom, growers need to do a good job of monitoring for fireblight conditions. It appears we are several days off from a possible infection, but time will tell.
Pears are early to full bloom at most farms across the region. Pear psylla egg hatch occurred late last week.
Peaches are mostly at full bloom to early petal fall. Most growers have applied a brown rot spray on peaches over the last week.
Sweet cherries are at petal fall at most farms across the region. Again, brown rot control sprays were applied during bloom of sweet cherries.
Tart cherries are at full bloom to early petal fall.
Plums are at full bloom.
Strawberries have grown very well over the last week. The flower tresses are now up and exposed. In scouting done on Monday, I have not seen any evidence of strawberry clipper or tarnished plant bug. Other species of plant bugs are starting to be seen in fence rows and other plants around strawberries, so expect to see tarnished plant bug to show up in about 7 to 10 days. Most strawberry growers to frost protected during the frost/freeze event on Tuesday and Wednesday of last week. Some were close to needing frost protection on Sunday morning; however most did not need to in the end.
Raspberries were burned back with the cold event of last week and much of the new foliage was damaged. Raspberries will regrow very quickly and not show any significant long term damage. Fall red raspberries have not grown very much over the last week most canes are 2 to 4-inches in length. I have also seen damage to the terminal growing points in many fall red raspberries fields.
Blueberries are at early to late pink bud at most farms across the region. As mentioned earlier, there does not appear to be any frost/freeze damage of blueberries at this time.
Phil Schwallier
Amy Irish Brown
Carlos Garcia-Salazar
Most apples are in the pink stage, but some bloom can be found in early varieties. Growth has been slow due to the cooler temperatures lately. Mid- to late sweet cherry varieties are in full bloom. Peaches are in full bloom.
Overnight lows early last week were reported in the mid-20’s with some damage to pistils of all tree fruits being found. Sweet cherries seemed to have been the hardest hit. Depending on the site and variety, there is some damage in apples as well. Perhaps 10 to 15 percent of all the flowers in the whole area are hurt overall, but some growers might experience more damage in certain sites.
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 10 days.
A heavy apple
scab infection was recorded for the general
As we move into bloom, growers will need to be ready for potential fire blight conditions that would lead to blossom blight. The weather forecast over the next several days is not looking very favorable for building up fire blight bacteria on the flowers, but a couple of days of warmer weather could change things in a hurry.
European red mite eggs can be found, but numbers appear to be normal so far. Some egg hatch has been reported.
Obliquebanded leafroller larvae have been observed feeding in terminals, but they are very difficult to find in most blocks.
Redbanded leafroller continue to fly in normal numbers.
Aphids are active. Both apple grain aphids and rosy apple aphids have been seen. Rosies are curling up in the leaves and pink sprays are advised in blocks with more than one rosy apple aphid per terminal.
Oriental fruit moth should start flying at any time.
As of May 5, blueberry growth and development continues
without problems. The variety Bluecrop is in early pink and in Elliott the
development ranges from ¼-inch to early pink. Despite the low temperatures
these past few days, no substantial damage has been observed. At this time, no
mummy berry damage has been observed. However, in some fields in both
Regarding fruitworm monitoring, pheromone traps to detect
the beginning of the emergence of cherry fruitworm and cranberry fruitworm male
moths should be out in the next 6 to 10 days, depending on the growing degree
day accumulations. So far, the amount of GDDs (base 50° F) accumulated since
March 1 in the area of
However, for blueberry fields located around
According to our cranberry fruitworm phenology model, we recommend to install the pheromone traps at approximately 300 GDD accumulated since March 1. Once the first sustained moth trapping occurs, the model is biofixed and the first application of insecticides is programmed to be applied 100 GDD after biofixing.
Prices for fresh blueberries continue to be high. In the
past five days, prices for fresh blueberries remain around $24 and $30 per flat
(12 4.4 oz cups), and most blueberries in the market are from
Last week’s freeze-events between April 27-30 have left
their mark on the crop. Based strictly in the temperature report and the flower
bud cold tolerance, it appears that the temperatures reached critical lows (low
20’s) in Oceana and Manistee counties on Tuesday through Wednesday night. The
coldest night of the three for
Sweet cherries have suffered the most all across the area. Reportedly, there are significant varietal differences: Sams have had the highest bud damage while Hedelfingens come out of the event in pretty good shape. Tart cherries are looking good with very little damage. Any damage to the peaches is mainly from the winter injury. This last cold spell did not cause damage other than to the low-lying blocks. Apples in the flats have lost kings and a few side blossoms. On better sites it appears that the main damage occurred on the lower part of the canopy.
Apples are in pink. In the southern part of the district, a few surviving kings in Idareds are starting to open up.
Pears are in white bud.
In peaches, Redhavens are from 50 percent bloom in the southern areas to less than 5 percent bloom further north.
Plums are in white bud.
Tart cherries are at 30 to 50 percent bloom.
Sweet cherries are entering full bloom.
|
Location |
DD42 |
DD45 |
DD50 |
Rainfall since |
|
Hart |
299 |
230 |
142 |
4.13 |
|
Ludington |
299 |
231 |
141 |
4.35 |
|
Manistee |
311 |
243 |
156 |
4.77 |
An apple scab
wetting event from May 2 to May 4 resulted in a heavy apple scab
infection in
A cherry leaf spot wetting event resulted in a low infection period for Oceana and Mason counties and moderate infection in Manistee/Bear lake area.
Black knot is a cool season disease that affects plums and tart cherries. Infections are very likely at this time. Spores may come from the infected choke cherries or wild cherries in the surrounding areas or from the knots within the blocks. Sanitation, knot removal, is a very important step in disease suppression. Fungicide (Bravo) treatments during the spore release provide some control in preventing black knot infections.
Nikki Rothwell
Duke Elsner, Erin
Lizotte, Rob Sirrine
GDD42 272
GDD50 125
Although the weather has seemed chilly, our growing degree day (GDD) accumulations are similar to last year’s GDD: 125 base 50 this year compared to 127 base 50 in 2007. The numbers are likely due to the extremely warm temperatures in the third week of April. However, temperatures have dropped since then, and the last week of April and first of May have remained cool. Average temperatures have been in the mid- to upper 40’s. On April 28, 29 and 30, cold overnight temperatures were recorded in the mid-20’s to low 30’s.
Apples are in tight cluster.
Sweet cherries: Hedelfingen are at 80 percent bloom. Napoleon are at full bloom. Gold are at first bloom.
Tart cherries are at early white bud.
Apricots are at full bloom.
Plums are at early white bud.
Grapes are at early bud burst.
The cold overnight temperatures varied in the northwest regions last week, but overall we believed there was minimal damage to cherry or apple buds. However, as we have been cutting buds and hearing grower reports, we may have sustained more damage than our original assessments indicated. In some tart cherry blocks, we recorded about 50 percent damage, while adjacent blocks sustained no damage. King bloom in some apple blocks was impacted by the cold temperatures, and sweet cherry damage appears to be minimal in many tested blocks. With time, we will have a better assessment of overall damage.
Things are starting to move along in the region despite the
consistently low temperatures of the past week.
Jeff Andresen
Agricultural Meteorology
Geography
A relatively zonal, west to east jet stream pattern is
expected across North America during the next one to two weeks, which should
lead to an unsettled weather pattern across the Midwestern United States including
Temperatures will fall from highs in the low 60's north to mid-70's south Tuesday to a range from the mid-50's north to low 60's south by Thursday. Low temperatures should fall from statewide levels in the 40's Wednesday morning to a range from the low 30's north to near 40 south by Friday morning. Some frost and freezing temperatures are possible in inland northern sections of the state later this week, especially Friday and Saturday mornings. Temperatures are expected to moderate (upward) a few degrees by Sunday, although means will likely still remain below normal.
Current medium‑range forecast guidance suggests more
of the same recent pattern, with a series of upper air troughs moving eastward
across the
New NOAA long lead outlooks for the upcoming few months reflect a significant weakening of the La Niña event that has been in place across the equatorial Pacific region since last fall. The outlook for the month of May calls for a continuation of an active storm track across the western and Midwestern United States leading to a forecast favoring cooler and wetter than normal conditions for Michigan and the Great Lakes region. However, given the recent weakening of La Niña conditions in the Pacific, there have been additional changes in the longer lead forecast periods (mainly moderations in precipitation forecast).
For May through July, mean temperatures and precipitation
totals in