In this issue
Tree fruit news
§ Borer damage sighted in many cherry orchards
§ TNRC trapline data: Cranberry fruitworm
Small fruit news
§ Disease control in grapes critical during and after bloom
Other news
§ Small fruit meeting
§ Regional reports
§ Weather news
Nikki Rothwell, District Horticulturist
Larry Gut, Entomology
Borers, broadly grouped as insects whose larval stages feed
inside the bark of woody plants, are key pests of fruit tree systems. Researchers have found that these insects
contribute significantly to the decline or reduced vigor of stone and pome
fruits. In
Prior to the discovery of American plum borer, most borer
damage in stone fruit orchards was attributed to greater peach tree borer and
lesser peach tree borer. Lesser peach
tree borer is a pest of all stone fruits in the eastern
Borer damage has been evident in many cherry and peach
blocks throughout the northwest and west central regions of the state. We have observed many of the northwest
infestations in Balaton® orchards while in west central, peaches have been a
main target. Infestation intensity
seemed surprisingly high, so we conducted orchard walks to provide an initial
qualitative assessment of damage. Based
on 15 Balaton orchards in
Infestations are located at the ground level or in areas with previous trunk damage. Soil line infestations can be difficult to see without removing the soil from around the trunk. Growers should be looking around the base of the trees, at the soil line, for gummosis and an orange colored frass (Photos 1 and 2). Frass can be seen in small piles, and its color contrast against a dark weed sprayed strip can be a good identifier of borer damage. For damage higher on the trunk, growers can peel back bark, which is much easier to do in damaged trees than in healthy ones, to find more gummosis, frass, and often larvae or pupae. This update is to alert growers to our recent findings and to be on the lookout for borer damage in his/her orchards, especially growers with Balatons®. Based on our preliminary assessment, we think Balaton® trees on Mahaleb rootstock may be particularly susceptible to borer infestations. However, we will continue to monitor trees and trap for all three stone fruit borers to give us a clearer picture of this emerging problem.
Lastly, we would add that although we have observed what seems like a lot of borer damage, the overall vigor of most of the surveyed cherry blocks looks good. Cherry trees appear to be more susceptible to borer damage in years three to five, and based on recent findings, mature trees can withstand higher levels of infestation. This observation in cherry is unlike peaches where borers cause more outright tree mortality. As we investigate further, we will refine our initial conclusions.
|
Orchard 1 |
1.5 |
|
Orchard 2 |
2.0 |
|
Orchard 3 |
3.0 |
|
Orchard 4 |
4.8 |
|
Orchard 5 |
5.2 |
|
Orchard 6 |
8.0 |
|
Orchard 7 |
8.0 |
|
Orchard 8 |
9.3 |
|
Orchard 9 |
12.0 |
|
Orchard 10 |
14.0 |
|
Orchard 11 |
15.5 |
|
Orchard 12 |
16.6 |
|
Orchard 13 |
25.0 |
|
Orchard 14 |
45.5 |
|
Orchard 15 |
91 |
Most growers rely on handgun applications of insecticides for control of borers. The success of borer control using insecticides is heavily dependent on the timing and precision of applications. Moth captures in pheromone traps can be used to assess moth activity and to predict the time of egg hatch. Trunk sprays are most effective when applied at the start of egg hatch – generally two weeks after the start of adult flight. There are currently only two registered materials that provide adequate control of the borer complex. The most widely used material is the organophosphorous insecticide, chlorpyrifos. The other option is the lone chlorinated hydrocarbon registered for use in stone and pome fruits, endosulfan.
Mating disruption is another option for managing two of the borer species, greater peach tree borer and lesser peach tree borer. The development of mating disruption for control of greater peach tree borer and lesser peach tree borer began in the late 1970s. These efforts were based on the identification of (Z,Z)-3,13-octadecadien-1-ol acetate (ZZA) and (E,Z)-3,13-octadecadien-1-ol acetate (EZA) as the major component of the sex pheromone of greater peach tree borer and lesser peach tree borer, respectively. A series of studies have demonstrated that high levels of disruption of greater peach tree borer or lesser peach tree borer orientation to pheromone-baited traps, as well as reductions in pest densities can be achieved through the application of synthetic pheromone sources. However, deployment of two types of dispensers may be required to achieve control of lesser peach tree borer and greater peach tree borer, one releasing primarily ZZA and the other releasing primarily EZA. Purchasing and deploying a full label rate of hand-applied dispensers for both species may have limited utility. Thus, we have initiated a research project aimed at identifying effective and economical approaches to disruption of lesser peach tree borer and greater peach tree borer. Currently, there is not a commercially available, American plum borer disruption product.
The hand-applied formulations being tested are three types
of polyethylene rope dispensers, Isomate GPTB, LPTB and GPTB Dual (ShinEtsu
Fine Chemical Co., Ltd,
For emergence graphs of other common fruit pests refer to our web site at http://www.maes.msu.edu/tnrc/07traplinecover.htm.
Annemiek Schilder
Plant Pathology
As bloom is approaching in grapes, we should remember that this period as well as the post-bloom period is critical for disease control in grapes. During these growth stages, the young clusters are highly susceptible to diseases, including black rot, downy mildew, powdery mildew, and Phomopsis and most of the fungi are active at this time of year (they are no dummies!). The risk is especially great if we have a lot of rain and moderate to warm temperatures during this time. Prolonged wet conditions during bloom can also allow Botrytis to get a foothold in the clusters of susceptible varieties by promoting growth on senescing flower parts.
The main aim for fungicide sprays at this time is to protect
the clusters from infection by these pathogens while simultaneously protecting
the foliage as well. Some infections that occur during this period may remain
dormant (invisible) until the berries are close to veraison (black rot) or
ripen (Phomopsis, Botrytis). As the berries grow and mature, they become
naturally resistant to black rot, downy mildew, and powdery mildew infections
and the need for protection diminishes. This happens quite rapidly (two to
three weeks after bloom) for downy mildew, three to four weeks after bloom for
powdery mildew and four to five weeks after bloom for black rot in
However, be aware that the cluster stem (rachis) and berry stems can remain susceptible longer than the berries in most cases. The only disease to which berries remain susceptible throughout their development is Phomopsis, but the risk of infection diminishes after bunch closing because inoculum levels drop off then. Botrytis is just the opposite in that berries actually become more susceptible as they get closer to harvest, especially in tight-clustered varieties. In general, aim to protect the clusters from the major diseases from immediate pre-bloom until four to five weeks after bloom. If cluster development is variable (e.g., as the result of a spring freeze or variable weather conditions), make sure that the slowest-developing clusters have caught up before easing up on the spray program.
Temperatures in the
high 70s and low 80s are perfect for black rot. At these temperatures, only six
to seven hours of wetness are needed for infection. Black rot is a tricky
disease in that infections can remain latent (dormant) for a long period of
time, so you won’t know that you have the disease until is it too late to do
anything about it. However, one can scout for leaf lesions – a lot of black rot
leaf lesions indicate high disease pressure from ascospore inoculum and also
contribute to fruit infections. In a field with a history of black rot, old
fruit cluster remnants left hanging in the trellis are major contributors to
infection. Fruit infections can take place anytime from bloom onwards, but only
become apparent sometime between bunch closure and veraison. As mentioned
above, grape berries are highly susceptible to black rot infection for the
first two to three weeks after bloom. Then they become progressively less
susceptible as they develop. In general,
In five years of
trials in
Sterol-inhibitor
fungicides (e.g., Nova and Elite) continue to provide outstanding control of
black rot, and provide several days of post-infection activity. Currently,
there are various “generic” tebuconazole products on the market, e.g., Orius
and Tebuzol, that may be more cost-effective. When using SI fungicides on a
post-infection schedule, use the highest label rates, because post-infection
activity is strongly rate-dependent, particularly when extended “kickback”
activity is required. The strobilurin fungicides (Abound,
Cane and leaf
lesions have been showing up in vineyards. Each rainfall event now will lead to
spore dispersal and can also lead to successful infection if the tissue remains
wet for a sufficient amount of time. The optimum temperature for infection is
59-68ºF, at which time about six to10 hours of wetness are needed for
infection. The longer the tissue stays wet, the more severe the symptoms will
be. Since rachis and flower clusters are now fully exposed, we should be
concerned with preventing Phomopsis infection of the rachis and fruit,
especially in mechanically pruned vineyards and vineyards with a history of the
disease. Rachis infections are most closely correlated with yield losses at
harvest.
If at this time you
find a lot of lesions on the leaves and canes, infection pressure will be high
for the fruit also. Best fungicide options for control of Phomopsis during and
after bloom will be Abound, Sovran or Pristine (do not use Pristine on
No powdery mildew
has been sighted in vineyards yet. However, we have had several occasions for
primary ascospore release this spring. Ascospore discharge is initiated in the
spring if 0.10-inch or rain occurs at an average temperature of 50ºF or more.
This results in thorough wetting of the bark where the cleistothecia have
overwintered. When the cleistothecia are sufficiently wetted, infectious
ascospores are discharged within four to eight hours and are carried by wind to
susceptible plant tissues. They can infect any green surface on the developing
vine and do not need water for infection. The fungus then grows on the plant
surface and produces a second type of spore (conidia) which are windborne and
cause secondary infections. Under optimal conditions, the disease can spread
rapidly, as the time from infection to production of conidia can be as short as
seven days. Although infections can occur at temperatures from 59 to 90ºF,
temperatures between 68ºF and 77ºF are optimal for disease development.
Temperatures above 95ºF inhibit spore germination, and the fungus may be killed
at temperatures above 104ºF.
Sulfur remains an
effective and inexpensive protectant fungicide for powdery mildew control in
non-sulfur-sensitive grape varieties. The most effective systemic fungicides for
powdery mildew control are the sterol inhibitors (Nova, Elite, Vintage, etc.)
and the strobilurin fungicides (Pristine, Sovran, Abound and
Downy mildew primary
infections start if rains occur (at least 0.4 inches) and temperatures are
above 50ºF over a 24-hour period. Check the recent weather conditions at or near
your location on the Enviro-weather website (www.enviroweather.msu.edu/).
It takes seven to 12 days for the lesions to form after infection has taken
place, so keep an eye out for downy mildew. Early in the season, downy mildew
lesions may be confused with low-concentration Gramoxone and possibly Chateau
herbicide injury, which also cause yellow spots on leaves. However, if no
herbicide was used and no herbicide spots are present on lower leaves, the
spots may be downy mildew. To confirm that you can enclose a leaf with lesion
in a ziplock bag with a moist paper towel and leave it out in the dark
overnight. If white sporulation appears on the underside of the leaf, it is
downy mildew.
A spray for downy
mildew before or just after bloom is recommended for susceptible varieties,
especially in vineyards with a history of disease. Early infections can lead to
severe downy mildew infection and premature defoliation of the vine. Ridomil
Gold MZ and Ridomil Gold Copper have excellent curative and protectant activity
against downy mildew. Under moderate infection pressure, they will provide three
to four weeks of protection. Of the strobilurins, Pristine, Abound, and Sovran
are good choices. Other effective fungicides are mancozeb, ziram, and fixed
coppers. ProPhyt and Phostrol are also good alternatives: they provide
excellent curative and about seven to 10 days of protective activity. Under
high disease pressure or when spraying after an infection period, use higher
rates.
Small fruit meeting
Blueberry twilight IPM meeting
Topic: Pre-harvest meeting
Van Buren County, Cornerstone Ag (Bodtke’s) For more information, please
contact: Paul Jenkins (jenki123@msu.edu),
Rufus Isaacs (isaacsr@msu.edu) or Annemiek Schilder (schilder@msu.edu).
Last week’s temperatures were warmer with highs in the 60s and 70s, and lows near 40°F. There were scattered frosts on Wednesday and Thursday mornings that caused little damage. Friday was windy and cloudy and offered a little rain. Rainfall totals varied from a trace to a third of an inch. This was a disease infection period for some areas, depending on where the rains fell. Soils are really drying out and shallow rooted berry crops will benefit from irrigation. The weekend was warm. Temperatures will be cooler for the next couple of days near 70°F, with a good chance of rain. We expect hot temperatures at the end of the week with highs in the upper 80s. Our GDD totals are still lagging ten days behind normal.
|
Grapes from April 1
|
|||
|
Location |
GDD 42 |
GDD 45 |
GDD 50 |
GDD 50 |
|
729 |
581 |
379 |
373 |
|
|
814 |
658 |
439 |
434 |
|
|
665 |
522 |
333 |
329 |
|
Insect activity increased last week. We are now in the treatment window for Oriental fruit moth. Few fresh plum curculio egg-laying scars were found. Leaf roller larvae are feeding on the leaves and are common in some orchards. Codling moth biofix was set as May 26 for most of the region. For a May 26 biofix, we are at 100 GDD50. We expect codling moth egg hatch at 250 GDD past biofix, which is around next Monday.
Apricots are about one to 1.25 inches in diameter. Bacterial spot lesions have been found.
Peaches are 16 to 19 mm in diameter. The peach crop looks lighter every week, although some blocks have a good crop. No Oriental fruit moth shoot strikes have been reported. Oriental fruit moth was biofixed at SWMREC on May 4 at 310 GDD45. Egg hatch should end at about 646 GDD45 after biofix (956 GDD45). Peach fruit needs to be protected from rusty spot (powdery mildew) until pit hardening. Growers can consider trunk sprays for lesser peach tree borer or greater peach tree borers after hand thinning is done. A post harvest spray for borers can be done instead. Pheromone disruption of these pests is also effective and eliminates the need to balance hand labor in the orchard with pesticide sprays and restricted entry periods.
Sweet cherries are about 16 to 18 mm in diameter. Sweet cherries are always susceptible to brown rot. Brown rot requires warm, wet conditions, five to six hours of wetness at 70°F. We may see warm and wet conditions this week when it rains. The rain event Friday was cherry leaf spot in central Berrien and southern Van Berrien counties, depending on where it rained.
Tart cherries are 12 to 14 mm and the pits are hard. The tart cherry crop looks pretty good. The crop is throughout the tree, with lots of doubles. Few fresh plum curculio egg laying and feeding scars were found. Friday’s rain was a moderate cherry leaf spot infection for some areas.
Japanese plums are about 16 to 18 mm. European plums are about 14 to 16 mm. Growers still need to protect against black knot and plum curculio.
Apple fruit size
is generally in the 14 to 18 mm range.
King fruit are generally 15 mm or larger. Apple
scab symptoms are very common on unsprayed trees and have also been found in
sprayed orchards. The new
symptoms are probably from the May
14-16 infection period. Friday’s
rain was a moderate scab infection in
A few southern Berrien County orchards biofixed for codling moth on May 14 at 278 GDD50, more commonly other orchards in the region Biofixed May 23 at 284. We are at about 140 and 112 GDD50 after biofix for those two dates on Monday, June 2. Codling moth Biofix was set as May 26 for most of the region. For a May 26 biofix, we are at 100 GDD50. We expect codling moth egg hatch at 250 GDD past biofix, about next Monday. The application timing of control materials varies greatly (see the article on codling moth in last week’s Fruit CAT Alert). Spotted tentiform leafminer sap feeders are out and will form leaf mines soon. European red mites are moving about. San Jose scale adults are flying. Sprays for San Jose scale crawler should be targeted for 300 to 530 GDD50 after biofix (June 1). Due to the cooler weather this year, sprays for crawlers will be a week or two later than last year.
We can now see initial fruit set. Side fruits are about 2mm smaller than the kings. Many growers applied thinning sprays, but fruit set is still heavy and the thinners do not appear to have been very effective in the cool weather. We have had several short, two day warm periods offering good apple thinning windows. Apparently growers have applied their thinners too early in the cool periods (50 to 60°F) before these window. The wet and windy weather forecast means that we will not have another good apple thinning windows until Thursday when conditions are good for spraying. Unfortunately, the temperatures will be very warm in the mid- to upper 80’s. We recommend a moderate thinning strategy using 1/2 to 2/3 rates due to the very warm temperatures, which favor over thinning. These high temperatures with high thinner doses will be very effective. Use aggressive rates only with large fruit size (over 18mm), with heavy set and lots of fruits in the cluster.
Pear fruit are 12 to 14 mm in diameter. The crop is variable. Pear psylla adults and nymphs can be found in unsprayed trees. Leaf and fruit symptoms of pear scab have been reported. Growers should continue to protect against pear scab, through the next rain.
Blueberry bloom is ending. There is still bloom in most fields as well as green fruit. Many growers irrigated for Wednesday and Thursday mornings’ freeze when temperatures dropped below freezing in cold areas, especially where the soils were dry. There were losses in cold sites. Overall, it looks like we will have a very large blueberry crop. Growers with trickle irrigation should be irrigating. It is hard to catch up with trickle irrigation when you fall behind. Rainfall has been spotty and soils are dry. Blueberries can use 0.2 tenths of an inch of water a day or more in June and July when the sun is up from 6:00 AM until 9:00 PM. A full-grown plant needs four gallons or more of water a day during the fruit growth. For light sandy soils, frequent light irrigations of about an inch of water twice a week will wet the root zone and avoid leaching fertilizers and nutrients below the roots. Leaves are greening up with the warm weather. Trap catches of cranberry fruitworm and cherry fruitworm have been spotty. These pests lay their eggs in the calyx cup of the fruit and no eggs have been found yet, but growers have been applying Confirm and BT formulations. These applications are too early. Cranberry fruitworm biofix was expected at about 350 GDD50 with egg hatch following at 85 GDD50 after biofix. Only the warmest sites in the region have 485 GDD50. Growers should scout for eggs in the calyx cup of fruit. Sprays of bee-safe materials are planned when the weather warms up if there is still open bloom and bees are in the field. Post bloom fungicide sprays should target anthracnose.
Grape growth increased dramatically with warmer
temperatures. Freeze damaged vineyards
still look pretty ragged.
Strawberry bloom is ending. Primary fruit are an inch or more in diameter and starting to color. The secondaries have thimble-sized fruit. Pre harvest fungicides should be applied to reduce fruit rots such as gray mold. Early harvest may begin this weekend.
Raspberry flower
buds are separating in the cluster.
Early varieties such as Prelude and Nova are starting to bloom. In Blackberries
bloom has begun in early varieties such as
Cranberry shoots are elongating and flower buds are visible. Active growth before bloom is time for a protectant fungicide spray to protect new foliar and reduce fruit rots.
The next Monday Fruit Update
meeting will be Monday, June 9 at
the Fruit Acres Farm in
There is a Blueberry IPM meeting this Wednesday, June 11 at
Cornerstone Ag.
A series of twilight
grape scouting IPM meeting will start in two weeks. The dates and locations
are: June 19 at Tim Seppala's farm,
southeast of
These meetings start at 6:00 PM. For more information, on these meetings call Mark Longstroth at (269) 675-8313.
Another round of
frost/freeze occurred in southeast
Dry soils are the
other continuing concern at many fruit farms across the region. A few fruit growers received 0.75-inch of
rain from slow moving thundershowers over the weekend, mostly Friday night and
early Saturday morning. However most of
the region received less than .10-inch of rain.
Rainfall totals varied greatly, and depended on where the thundershowers moved
over your farm in terms of total precipitation from the event. Farms a half mile away might have received no
rain and to 0.75-inch. Fruit growers are
generally irrigating newly planted tree and small fruits on a regular basis to
help them become established.
We did have some hot
temperatures Monday, June 2, but with that exception our season still remains
about three to five days behind normal in terms of degree day totals, and a few
days behind normal when I look at pest development as well as the phonology of
our fruit crops.
|
|||
|
Location |
GDD42 |
GDD45 |
GDD50 |
|
Commerce ( |
740 |
591 |
387 |
|
Emmett (St Clair) |
700 |
565 |
367 |
|
|
755 |
609 |
405 |
|
Lapeer (Lapeer) |
740 |
597 |
400 |
|
|
800 |
642 |
428 |
|
Romeo ( |
769 |
593 |
383 |
Apples are mostly at 12 mm to 15 mm in size, with Red Delicious appearing to
be very typie this season. We have had a
significant amount of new growth this year, with many apples having an average
of 10 to 12 inches of new growth..
A lot of thinning
has taken place over the last week, with many growers applying two thinners in
the southern part of the region, and mostly one application in the north. This is one of the most difficult thinning
seasons that I have seen for apple growers.
This is primarily due to the fact that we have had a wide range of a
cold damage within most blocks of apples, and have experienced a long bloom
period. For the most part, I have been
advising growers to take a moderate approach to thinning, with the exception of
a few varieties like Jonathon, Jonagold and Golden Delicious, where we have a
heavy crop load in most blocks. Now is
the time to keep an eye on whether or not fruit that you desire to remove from
chemical thinning slowing its growth rate, or stopped growth entirely. Most growers in the mid- and northern part of
the region will have one more window of opportunity for thinning.
Codling moth
emergence is now widespread across the region and most growers biofixed on May
26 or 27. Oriental fruit moth adult
flight is down significantly across the region.
Mullein bug is still being seen, however the numbers are much lower and
it is now most likely a predator.
Apple scab spore
discharge has continued even with the light rain events at both of our trapping
stations. So, while the number of spores
being caught is decreasing, until I get a couple of rains without any spore
discharge, I am not ready to call an end to our primary apple scab season. Apple scab lesions were just starting to be
seen late last week and early this week on both the top and bottom of
leaves. Most of the lesions appear to be
burned out. There are a few possible
fireblight strikes that I am seeing around, however it is a bit early to
determine for certain if they are fireblight, so I am keeping an eye on them. According to the Enviroweather models,
we have not had any fireblight infections this season. Powdery mildew was seen for the first time
last week infecting terminals of apples.
Pears are mostly at 15 mm, again with some crop loss with farms to the west
and north of
Peaches are at 12 mm to 14 mm in size, and some fruit continues to drop. We are not at pit hardening. There is a fair amount of variability in
terms of crop load on peaches across the region. Bacterial spot seems to be affecting the
leaves on peaches at a few farms. Some oozing is coming from trunks.
Sweet cherries are not at pit hardening yet, and are mostly
at 15 mm to 18 mm in size where fruits are generally light due to frost and
freeze damage earlier in the spring.
Some bacterial spot continues to be seen on sweet cherry’s leaves.
Tart cherries are mostly at 11 mm to 13 mm in size. There is some off coloration of fruit at
farms that had a second freeze event.
Plums are mostly at 12 mm to 15 mm in size for
Strawberries are mostly ending bloom to thimble size
fruit in the south and about 80 percent to 90 percent bloom in the north. I anticipate some harvest to begin at farms
in the south over this coming weekend, with most of those farms starting to be
open a week from now. Farms to the north
appear to be 10 to 14 days away from the beginning of harvest. Low numbers of two-spotted spider mites being
seen in strawberries.
Raspberries are at first bloom at many farms across the region, and about 12 to 15
inches of new growth on fall bearing raspberries. There appears to be some blocks that have
two-spotted spider mites, however those are limited to a few farms. A few raspberry plants are starting to show
signs of anthracnose disease.
Blueberries are at fruit set for the most part with some farms that had frost and
freeze damage showing a 40 percent to 60 percent crop loss.
Phil Schwallier
Amy Irish Brown
Carlos Garcia-Salazar
Degree day accumulations at the Sparta weather station continue to be right at or slightly below average now. It continues to be dry. A half to three-quarters-inch of much needed rain fell on May 30, but we could use more.
Most apples are in the 10 mm stage, but there is still some bloom out there on one-year-old wood of some varieties. We are currently in a significant thinning window, but growers are apprehensive from the effects of the cold weather mid-last week.
The last apple scab infection for the greater
For any susceptible varieties with open bloom on them, MaryBlyt is calling for several days of possible blossom blight infections over the next week. Growers will also want to be ready for the possibility of trauma blight if any of the rain events predicted for the next several days have hail or high winds included.
A few egg laying scars from plum curculio continue to be found in non-sprayed apples, but there are no reports of damage to commercial blocks. Growers will want to continue to scout closely for any damage in small apple fruits. Apples are subject to plum curculio damage until they are about 20 or 25 mm.
European red mite eggs should all be hatched. No new eggs have been seen yet, but could be reported at any time. Monitor mites closely to determine if early controls are needed.
Codling moth flight has been reported in high pressure
blocks for about two weeks now. The warmer weather over the holiday weekend has
caused a push of codling moth flight in other blocks as well. A regional biofix
has been set for the
Obliquebanded leafroller are mostly all pupated, and flight for the summer generation could begin at any time.
Oriental fruit moth is flying, with numbers still sporadic
in some locations. A regional biofix has been set on May 8. We have accumulated
275 degree days base 45 since that biofix, so egg hatch is probably well
underway. Now is the time to apply control materials in stone fruits for early
larvae if you haven’t already. Flagging of new growing shoots could be seen at
any time in stone fruits.
Because of the low temperatures that prevailed during the
last weeks, blueberries in the Central Region, north of Van Buren County, are
in different bloom stages. There are
blueberry fields in which we find blossoms still in full bloom, while in the
same bush there are fruit clusters in the early green fruit stage. Despite the freezing temperatures observed on
May 28, little damage has been observed in most blueberry fields. If the weather conditions remain above the
freezing temperatures, we may have another large blueberry crop similar or
bigger than the last year’s blueberry crop. In 2007,
Lack of rain has been an issue that may affect some fields,
however during the past week there were some rains mainly in
So far, the growing degree-day accumulation in
The blueberry harvest has continued in
Before the frost event of Tuesday and Wednesday night (May
28 and May 29) this region had good crop set and potential for a very nice
crop. Wednesday morning revealed a picture that was not so bright. We expected
to see some damage from the frost, but not to the extent that we are
finding. Hour-by-hour temperatures
indicate the loss of cloud cover around midnight on May 27 in
Where we had the cloud
cover, wind machines were useful in bringing the warmer air from the higher
elevation down into the canopy. Once the
clouds were gone, any warm air that was there dissipated into the clear sky and
radiation freeze did the rest. Radiation freeze had done most of the damage in
Mason and Manistee counties. Crops did not fare well. By my assessment and the
grower accounts, apples, sweet cherries and plums have sustained the biggest
losses.
Overall, perceived damage is
about 50 to 60 percent, though in certain spots that damage is almost 100
percent. Tart cherry loss is about
60 percent. Pears are looking better
than expected, though they too sustained significant crop reduction. Apples have been hit hard, particularly
in the northern parts of the district and the lake-shore throughout the
district. A few grape growers in the
area are reporting significant damage up to 100 percent. Peaches are holding surprisingly well for now. Plums are just about a total loss.
|
Station |
May 27 |
May 28 |
|
|
|
|
|
|
|
|
|
11:00PM-Midnight |
Midnight- 1:00 AM |
1:00-2:00 AM |
2:00-3:00 AM |
3:00-4:00 AM |
4:00-5:00 AM |
5:00-6:00 AM |
6:00-7:00 AM |
7:00-8:00 AM |
|
|
35.4 |
33.9 |
32.7 |
28.9 |
27.3 |
27 |
25.9 |
26.3 |
34.3 |
|
Ludington |
36 |
31.2 |
29.3 |
29.5 |
27.9 |
26.9 |
26 |
26.5 |
36.2 |
|
Hart |
41.4 |
39.7 |
36 |
34 |
33.8 |
31.2 |
27.5 |
30 |
38.7 |
The second frosty night of May 29 had slightly higher but still sub-freezing temperatures, but the damage had been done a night before.
In the next week or so, after careful damage assessment, growers will be making decisions whether or not there is economic justification for continuing with the full insect and disease protection programs. In many cases, they might choose to put one more fungicide sprays to get them through the apple scab primary and then go to a bare minimum in order to preserve the foliage and work on next-years crop.
|
Location |
DD42 |
DD45 |
DD50 |
Rainfall in last week |
Rainfall since April 1 |
|
Hart |
594 |
465 |
291 |
0.45 |
4.8 |
|
Ludington |
564 |
438 |
268 |
0.6 |
5.49 |
|
Manistee |
596 |
468 |
299 |
0.35 |
5.74 |
The rain that started early Friday morning and for the most
of the district, ended Saturday morning, May 31 was an infectious rain for
Mason and
This same wetting event of May 30-31 is responsible for the low (Manistee) and moderate (Ludington) cherry leaf spot infections. We did not have fireblight infections during the bloom period. This freeze event reset the Maryblyt model to zero. Our EIP numbers have been well below the threshold for the most of the season. The old fireblight cankers are becoming soft and with predicted rain, will start to ooze any day now. It appears that starting towards the end of the week and all next week, we will have high temperatures facilitating disease development. Bacterial leaf spot, bacterial canker and European brown rot are present in some stone fruit blocks. There is increased potential for brown rot development in all the stone fruit blocks affected by the recent frost/freeze injury. Damaged fruit that does not drop will present brown rot hazard.
Insect activity is picking up. Scouts are reporting increased activity in lesser peachtree borers. American plum borers are still very active. Trap catches have gone up significantly for both species since last week. Codling moth catches have exploded. The average trap catch has reached two-digit numbers. Biofix dates are being established on block-by-block basis for the growers that have scouting service or are monitoring codling moth emergence themselves. Our regional biofix was set for May 24.
|
Location |
GDD at Biofix |
Accumulated GDD since Biofix |
|
Hart |
229 |
62 |
|
Ludington |
217 |
51 |
|
Manistee/Bear |
242 |
57 |
Nikki Rothwell
Duke Elsner, Erin
Lizotte, Rob Sirrine
GDD42 575
GDD50 271
Apples are in late petal fall.
Sweet cherries: Hedelfingen have 9 mm fruit. Napoleon have 10
mm fruit. Gold have 10 mm fruit.
Tart Cherries:
Montmorency and Balaton are in late shuck split.
Apricots have 15 mm fruit.
Plums are in shuck split.
Grapes have four to eight inch shoots.
We are at 271DD base 50 at the NWMRHS. Temperatures warmed for the first time since April, the daytime high’s reached into the low 70s on Thursday, Friday, Sunday, and Monday (May 29- June 2). We received 0.22 inches of rain on Friday evening, and last night the region received between 0.1 and 0.25 inches of rain.
Damage from last week’s freeze event resulted in variable
amounts of damage across the northwest.
Unfortunately, we have observed that apples have been hit particularly
hard as they are planted on some of our lower sites. We have also seen a lot of damage in sweet
cherries, especially those fruits on the upper sides of the branches where
cherries were not covered by foliage.
Tart cherries in most places look fairly good as many orchards in the
region were still in the shuck.
Winegrapes have sustained some damage, even on sites that have been
optimal for winegrape production in the past.
Strawberries have moderate damage as most growers have been frost
protecting in the past few weeks. All
fruit in moderate to poor sites has been hit exceptionally hard.
Most of the northwest
region had an apple scab infection predicted over the weekend. The infection period ended overnight as
temperatures and humidity levels dropped.
The fire blight model is predicting EIP values to exceed 100 yesterday,
today and tomorrow. Rain is in the
forecast throughout the region over the next few days and into the weekend and
with blossoms still vulnerable, streptomycin sprays should be applied. Codling moths have biofixed in the southern
areas of the region and sporadically as far north as the research station. Spotted tentiform leafminer catches are
decreasing, and we are catching our first few Oriental fruit moths in the
station trap line.
Most of the region
had a cherry leaf spot infection period predicted over the weekend due to the
warm, wet weather. American plum borer
moths have been caught in increasingly larger numbers (about 12 per trap at the
station), and lesser peach tree borer are beginning to emerge. Green fruitworm moths continue to fly, and we
captured our first male San Jose scale in pheromone traps on
Grapes have been
slow in growth, but grape berry moths have been caught in one
Jeff Andresen
Agricultural Meteorology
Geography
Last week, I mentioned the gradual change of the upper air
configuration across
Rainfall totals during the next five days are expected to be highly variable, ranging from 0.25 inch in some locations to more than one inch in others. Some one to two inch totals are possible, especially across far northern sections of the state. Temperatures during the next few days will warm to above normal levels with highs Wednesday in the mid-60s to mid-70s increasing to the upper 70s to upper 80s on Thursday and Friday and lows from the mid-40s to mid-50s Wednesday morning increasing to the mid-50s to mid- or upper 60s Thursday and Friday mornings. Some 90EF high temperatures are possible in southern sections both Thursday and Friday. Humidity levels behind the warm front will also increase with dew point temperatures Thursday and Friday reaching the 60s to near 70EF in some spots, leading to uncomfortable conditions especially during afternoon and early evening hours.
The medium‑range forecast guidance calls generally for
the upper air pattern mentioned above with a broad upper air ridge expected
across central and eastern sections of the