April 25, 2006
In this issue
Tree fruit news
§ The return of frost
§ Insecticide regulatory update
Small fruit news
§ Flea beetle injury to grape buds reported online in MSU’s weekly grape scouting report
§ It is not too late for “dormant” sprays against Phomopsis in grapes
§ BSP Sulforix label has been amended for blueberries
§ Irrigation options for blueberries
Other news
§ New MSU Weather-IPM Network for fruit growers
§ Regional reports
§ Weather news
Frost conditions are upon us as the weather cools down. For specific information on current weather conditions, see Jeff Andresen’s weather column in this issue. For information on frost in fruit crops, visit: http://www.ipm.msu.edu/FruitFrost.htm
Grape growers may want to watch a video presentation by Tom Zabadal on protecting vineyards from frost available at grapes.msu.edu
(Brian Olson, Dow
AgroSciences, LLC; edited by John Wise)
Dow AgroSciences has decided to initiate a voluntary phase
out and global exit of the Kelthane® miticide
business. Kelthane (dicofol) is a non-systemic, organochlorine miticide
(acaricide) that has been used for almost 50 years to control mite pests in
Kelthane WSP or Kelthane MF produced in 2006, as well as inventory in the Distribution Channel (wholesale/retail) and with end-users, can under current understanding be distributed, sold and applied legally until all supplies are exhausted. Dow AgroSciences intends to support U.S. Federal and State registrations to facilitate depletion of Kelthane inventory by end users. Kelthane WSP and Kelthane MF will be removed from the 2005/06 Distributor product package exchange program; however these Kelthane brands will continue to participate in the Distributor inventory protection program for the 05/06 marketing year.
Proclaim (emamectin benzoate) is a new insecticide registered for use in pome fruits for control of leafrollers and leafminers and suppression of Oriental fruit moth and codling moth (first generation only), psylla and spider mites. Proclaim is an Avermectin-type compound that belongs to the Naturalyte class of insecticides. Because of its novel mode of action, it is expected to be a good rotation tool for resistance management. This translaminar (locally systemic) material has long residual inside the plant, and is aided by the addition of a horticultural spray oil (1 qt/100 gallons) or non-ionic surfactant (0.25% v/v). Because Proclaim is an ingestion material quickly absorbed into the plant, impact on natural enemies is minimized.
Lorsban 75WG is a new “low odor” formulation of the organophosphate insecticide chlorpyrifos, which could be of value to growers spraying in proximity to residential populations. The new supplemental label describes foliar applications from dormant or delayed dormant through petal fall in apples, for control of leafrollers, scale, Oriental fruit worm, codling moth and rosy aphid. There are several “Specific Use Restrictions” on the label that are especially important to note:
§ Do not apply after petal fall.
§ Post-bloom application to apples is prohibited.
§ Do not make more than two applications per year. In any given year, if a single foliar application of chlorpyriphos has been made at or prior to petal fall, then only one subsequent tree trunk application can be made in the same year.
Chlorpyriphos is also known to be toxic to honey bees, so applications should not be made while pollinators are in the orchard.
Flea beetle populations have again been high this spring, causing some grape growers to apply an insecticide for this pest. The grape flea beetle is a metallic beetle (also known as the steely beetle), about 1/4-inch long, that can be seen on expanding buds during the warmest and sunniest parts of the day. Beetles may be seen feeding or mating directly on the vines, and their injury is often greatest along wooded borders.
Flea beetle injury is more of a clean hole bored into the bud compared to cutworms ragged chewing on the whole bud. Pictures of their feeding can be seen at the Grape Team’s website – www.grapes.msu.edu (click on “View the 2006 weekly scouting report”).
With some grape varieties remaining in the bud swell stage across the state, they may be at risk of injury from flea beetles on warm days when they become active. Already this spring, we have found vineyard borders with 40 percent bud feeding from flea beetles. Scouting wooded vineyard borders in these vineyards would be worth the time spent to determine whether particular blocks are being injured by this pest. As new shoots push and leaves grow out, feeding by flea beetles causes less injury and the shoots can develop properly. Samples taken in 2005 showed no damage to shoots when flea beetle feeding occurred on 0.5-1 inch shoots, but buds fed on at bud swell or doe-skin stage typically produced only secondary shoots.
Also keep a lookout for cutworm injury on expanding this spring. These are night-active larvae of moths in the Noctuid family, and their injury is usually the first sign of their activity. As mentioned above, cutworm damage can be separated from that of flea beetles.
Our grape IPM Project will continue in 2006, providing grape growers with weekly updates on insects, diseases, degree days etc., from four commercial vineyards (two juice and two wine). The report is posted online early in the week, and to access the latest report directly, follow the link described above. This page will be updated weekly, so check back to see what is being seen at these sites. The current version contains photos of flea beetle and cutworm injury.
Lime sulfur (calcium polysulfide) has traditionally been used as a dormant spray in crops such as apples and raspberries to eradicate pathogens and insects that overwinter in or on the wood. The disadvantage of lime sulfur is that it is odorous, corrosive and relatively expensive. In grapes, we have done several years of trials with more affordable alternatives, such as sulfur and copper, applied late in the dormant season (at budswell) for control of Phomopsis viticola, the fungus that causes Phomopsis cane and leaf spot and overwinters in canes. These trials showed that a single late-dormant application without any additional fungicides applied during the season could reduce Phomopsis rachis and fruit infection at harvest by 40 to 70%. We also saw reductions in black rot, powdery mildew, anthracnose, and downy mildew. Interestingly, downy mildew was only reduced by dormant sprays of copper, whereas sulfur was more effective against powdery mildew.
In 2005, we tested whether applying “dormant” sprays at 1-
to 2-inch shoot growth was still effective at controlling Phomopsis in ‘
|
Treatment, rate/A |
Application timing |
Phomopsis rachis infection |
Phomopsis berry infection |
||||
|
|
Severity (%) |
Control [%]*** |
Severity (%) |
Control [%] |
|||
|
Untreated |
|
26.9 |
a** |
|
11.8 |
a |
|
|
Sulfur 6L 10 pt |
Budswell* |
10.6 |
b |
[61] |
2.3 |
bc |
[81] |
|
Sulfur 6L 10 pt |
1-2” Shoot growth |
9.6 |
b |
[64] |
1.2 |
c |
[90] |
|
Cuprofix Disperss 3 lb |
Budswell |
7.4 |
b |
[73] |
4.1 |
bc |
[65] |
|
Cuprofix Disperss 3 lb |
1-2” Shoot growth |
12.2 |
b |
[55] |
5.4 |
b |
[54] |
|
Dithane Rainshield 3 lb |
1”, 6-10”, 10-16” shoot |
|
|
|
|
|
|
|
Abound 2.08 SC 12 fl oz |
Bloom, 2nd+3rd postbloom |
|
|
|
|
|
|
|
Ziram 76 DF 3 lb |
1st postbloom |
2.7 |
c |
[90] |
1.6 |
c |
[86] |
*Budswell spray:
**Values in the same column
that share a letter are not significantly different from each other at the 95%
confidence level.
***Percent control relative
to the untreated.
We did not see any phytotoxicity as a result of these
treatments in ‘
Dormant sprays should not be used as a stand-alone disease control measure. A mancozeb spray around mid-May when Phomopsis is expected to be most active may be beneficial. Mancozeb applied at immediate pre-bloom aids in control of Phomopsis as well as black rot and downy mildew. A strobilurin fungicide, such as Abound, applied at bloom or 1st post-bloom is recommended to provide additional protection of the clusters against Phomopsis as well as black rot, powdery mildew, and downy mildew.
One added tidbit of information: the company that makes Cuprofix Disperss (Cerexagri, Inc.) is in the process of changing the product formulation. This means that both the old and new formulation of Cuprofix may be hard to find. The new formulation is called Cuprofix Ultra 40 Disperss and is twice as concentrated and twice the price, so adjust the application rate accordingly (follow label). Cuprofix has worked well for us in the past and disperses well in the tank without clogging nozzles. However, if it is hard to find, there are other copper products available (Kocide, Champ, etc.) that are also expected to have activity.
The BSP Sulforix label has been amended for blueberry applications. Sulforix (27.5% calcium polysulfide) is a lime sulfur product that acts as a contact fungicide, insecticide and miticide. The product is labeled for use on apples, pears, blueberries, caneberries, cherries, grapes, peaches, nectarines, prunes, plums, hazelnuts, alfalfa, red clover, perennial ryegrass and roses. Due to the type of formulation, this product tends to have a lower use rate than traditional lime sulfur products. Depending on the pest/disease and crop, rates vary from 1 pint to 6 gallons per acre.
On blueberries, BSP Sulforix is labeled for control of blueberry bud mite, Phomopsis cane canker and twig blight, and mummy berry. The amendment expands the application timing. Sulforix can now be applied at post-harvest as well as during the dormant season until prebloom for control of blueberry budmite (1 gallon per acre). In addition, sprays can be applied post-harvest and during dormancy for control of Phomopsis and mummy berry (1-2 gallons per acre). While we have not specifically tested BSP Sulforix against Phomopsis, a single spray at 1 gallon per acre before bud break (April 11) in 2005 reduced the incidence of mummy berry shoot strikes to 1.4 per bush (8.1 shoot strikes per bush in the untreated control), which was equivalent to four sprays of Indar, and the number of mummified berries to 10.8 per bush (14.5 in the untreated control). Incidence of anthracnose fruit rot at harvest was not significantly reduced by a late dormant Sulforix spray. Further evaluation of Sulforix at higher disease pressure is needed to confirm results, but certainly indicate promise as a complement to seasonal fungicide applications for mummy berry control. A note of caution: do not use BSP Sulforix within 14 days of an oil spray or when temperatures are above 85ºF as burning of foliage may occur.
Most blueberries grown commercially in
Every 10 to 20 years, droughts occur that are severe enough
to kill
Irrigation is particularly critical for young plantings. Young plants with shallow roots (12 inches) need
more frequent irrigation than older plants with deeper roots. The goal for
young plantings is to optimize vegetative growth so that plants reach full
production quickly. Non-irrigated new plantings usually require two or more
seasons to reach maturity, so returns on investments are delayed. Severe
drought during establishment can delay maturity and returns for many years.
Various irrigation systems are used in
|
System |
%
of |
Advantages |
Disadvantages |
|
Overhead sprinklers |
36 |
High uniformity & rates Frost protection |
High installation and operation costs Large water supply needed |
|
Drip-trickle |
16 |
Low cost to install & operate High uniformity Small water supply |
Application rates too low to ‘catch up’ Can’t frost-protect Limited root zone coverage |
|
Traveling gun |
14 |
Moderate initial cost |
Poor uniformity Can’t frost-protect High operating costs |
|
Sub-irrigation |
4 |
Low-moderate initial and operating costs Keep canopies dry |
Not suited for all sites Can’t frost protect |
|
No irrigation |
30 |
No cost |
High risk |
|
1Michigan Department of Agriculture |
|||
Water holding capacity of soils varies depending on texture and rooting depth (Table 2). Blueberry soils are sandy and variable, which complicate irrigation scheduling. These sandy soils may hold less than 1 inch of available water in the root zone, and half of this can be lost in two warm summer days. Many blueberry soils are complexes (e.g., Au Gres-Saugatuck, Pipestone-Kingsville) with slightly elevated areas knolls and ridges that dry much more rapidly than lower areas. Hardpan may limit rooting depth in specific areas of fields. Many areas have a shallow water table that also limits rooting depth. Plants may benefit from capillary ascent of water from saturated zones, but the volume of water supplied by capillarity is not understood. These variable characteristics all add difficulty to scheduling.
Rooting depth varies considerably. Where the summer water table is shallow, roots may be confined to the top 12 inches. In well-drained soils without physical obstructions, such as hardpan, blueberries may root to 24 inches or deeper. For irrigation purposes, assume a root depth 12 inches for new plants and 18 inches for established plants, or excavate beside bushes to observe depths in your fields.
|
Soil texture |
Available water (inches) |
|
|
Per inch of depth |
In root zone (12-18 inch depth) |
|
|
Sands |
0.03 |
0.4 - 0.5 |
|
Loamy sand |
0.07 |
0.8 - 1.3 |
|
|
0.13 |
1.6 – 2.3 |
|
Loam |
0.17 |
2.0 – 3.1 |
Allowable soil moisture depletion is generally assumed to be 50% of available water, but this has not been studied adequately for blueberries. This means that irrigation should be applied before 0.2 to 0.6 inches of ET losses on sands and loamy sands, or 0.8 to 1.5 inch losses on sandy loam or loam soils.
Evapo-transpiration
(ET) is 0.18 to 0.24 inches per day during the summer in the blueberry
region of
How much water to apply? Irrigate enough to recharge the root zone. For example, if established plants with an 18 inch-deep root zone, on a loamy sand soil (0.07 inches water per inch of depth) was depleted by 50% of available water, 0.6 inches water would need to be applied:
(18 inches) (0.07 inches water/inch) (0.5 depletion) =
0.6 inches
If your irrigation system delivers 0.15 inches water per hour, 4 hours of operation would theoretically deliver 0.6 inches. However, 20 to 30 % of applied water may be lost to evaporation, so operating time may need to be increased because of this inefficiency. In addition, most irrigation systems do not approach uniformity; they apply more water in some areas than others. Overhead sprinkler systems often are only 70% uniform. This means that order to recharge all areas of the field, 30% more water than calculated would need to be applied.
For the 2006 season, MSU will be unveiling a newly upgraded
weather-IPM system for fruit growers. Last fall, a team of MSU educators and
specialists secured a grant to improve and integrate two independent output
systems that linked real-time weather data to IPM-related fruit models in
In 2006, many more weather stations will be updated hourly. This improvement will be particularly helpful for growers monitoring infection periods for rapidly developing diseases, such as fire blight, apple scab, cherry leaf spot and grape black rot. Insect prediction charts (formerly assist charts) will also be updated hourly for these same weather stations. The system will contain historical data, so if a grower misses an infection period, he or she can call on past information for disease control.
One major difference with Enviro-weather compared with MIFRUIT is that the new system does not generate an email message for growers after a wetting event. Growers will be responsible for checking Enviro-weather for the most current information. Enviro-weather is part of a major revision and improvement for the MSU weather and pest management network. Users will be pleased with the new look and easy access to important information for the agricultural community. The new web address for the system is http://www.enviroweather.msu.edu
Once you reach that web site address, click on the station of interest (example: Northport, SWMREC, etc.). At the station page, click on fruit for all fruit models and weather information.
We hope that all growers are as excited as we are about our new system. Also, please be patient as we may have many bugs to work out over the course of the season. We look forward to hearing your thoughts and ideas!
The last two weeks were warm and mild. Temperatures were often in the upper 70s and above 50 at night. GDD accumulations are a week ahead of normal for this time of year. We are caught up with 2005. We are still behind 1998 and 2000 by a week or more. Little rain has fallen over the district this spring and conditions are becoming very dry. Soil temperatuers have fallen into the 50s. This week’s forecast is for cooler weather, with highs near 60 and lows about 40. This should slow down development. There is a chance of frost Wednesday and Thursday mornings. See the new Weather for IPM decisions in Michigan site at http://www.enviroweather.msu.edu/home.asp. The weather stations in the table are linked to the respective pages at this new site.
|
GDD totals March 1 through April
23, 2006 |
Grapes, from April 1 |
|||
|
Location |
GDD 42 |
GDD 45 |
GDD 50 |
GDD 50 |
|
334 |
260 |
162 |
132 |
|
|
345 |
261 |
159 |
127 |
|
|
358 |
274 |
165 |
131 |
|
|
308 |
230 |
139 |
117 |
|
|
Lawton (est.) |
373 |
287 |
178 |
137 |
|
341 |
262 |
161 |
124 |
|
|
289 |
216 |
127 |
99 |
|
|
|
||||
Tree fruits are blooming. Bee activity has been heavy.
Apricots are in the shuck. Early varieties are at shuck split.
Peaches are petal fall. Bloom was very heavy. Some growers are blossom thinning. We caught the first Oriental fruit moth last weekend. We set biofix as April 16 with a GDD45 of 180 at SWMREC. We are about 80 GDD past biofix. Egg hatch should begin about 150-170 GDD45 after Biofix and chemical controls are focused on egg hatch. We will pick up about 5 GDD per day next week so this spray should be applied in about a week. Growers planning to use pheromone disruption should have their dispensers out now. Western flower thrips have been a problem in the past during bloom and droughty conditions. These small insects feed on the developing fruit in the shuck. Growers may want to target sprays for this pest when bloom ends and bees are removed from the orchards. Be aware of tarnished plant bug, which feeds on the flowers of weeds. Mowing can drive them into the canopy where they will feed on the fruit, deforming it.
Sweet cherries
are at petal fall. Sweet cherries are very susceptible to brown rot. Cherry
leaves are unfolding so growers need to protect against cherry leaf spot.
In tart cherries, Montmorency cherries are in full bloom. Balaton cherries are less advanced at early bloom. Cherry leaf spot is concern as leaves begin to unfold. Growers can cherry leaf spot and several other pests at the Weather for IPM decisions in Michigan site.
In plums, Oriental plums are in the shuck. European plums buds are at full bloom. Black knot control needs to be maintained if we have rain.
Apples are at
pink. Early varieties such as Ida Red are opening. Several wetting events have
been marginal infection periods for apple scab. Scab symptoms from these rains
should be appearing but none were found Monday. Growers can monitor wetting
periods for scab and fire blight infections at the Weather for IPM decisions in
Michigan site. The dry conditions have kept fire blight cankers from doing
much oozing. We are now trapping redbanded leafroller
and Oriental fruit moth.
Leafroller should be feeding in shoot tips and flower clusters, but none were
found Monday. European
red mite should be hatching and Rosy apple aphid should
be out. Growers who did not control
these pests at pink should plan their
post bloom sprays. Spotted
tentiform leafminer should be flying.
Pears are in bloom. Growers need to monitor pear psylla and protect against pear scab.
Blueberries are at early pink bud and early varieties are beginning to bloom. Leaves are unfolding. Mummy berry mushrooms are hard to find in this dry weather. A mystery beetle was found feeding on buds in Van Buren County. This beetle appears occasionally at and before bloom. It looks like a small black Japanese beetle about 3/8-inch long. It is a member of the genus Hoplia, a flower beetle. It is attracted to white and feeds on flower buds. A mild insecticide before bloom begins should knock them down.
Grape buds have burst but the leaves have not unfolded yet. Some growers applied dormant sulfur and copper sprays to reduce overwintering phomopsis. Otherwise growers will need to apply protective spray soon. Flea beetles are out in large numbers and have caused a lot of damage in some areas. Growers should also be scouting for cutworms.
Strawberry
flower buds are emerging from the crown. Bloom has begun in some areas of
Raspberries leaves are emerging on blackberry and summer raspberry canes. Fall raspberry shoots are 4 to 6 inches tall.
Cranberry buds are beginning to swell and some areas of the beds are greening up.
Growers are planting trees and report that soils are very dry.
The next Monday Fruit Update
meeting will be, Monday May 1, at the Fruit
Acres Farm in
The weather over the
last two weeks has continued to be warm to mild. There has been a dramatic push
ahead of our growing season to a point where we are a week to 10 days ahead of
normal (whatever normal means these days). Warmer temperatures have changed the
normal pattern of leaf development – there is a much greater leaf surface
present now than what there typically is at this stage of flowering. Even with
the cooler nighttime temperatures that we’ve experienced over the last week,
with these warm day time temperatures our growth has continued to press along
at a very rapid rate. The mild winter may be another factor in this faster than
normal growth rate.
Over the last week
or so forsythia has been in full bloom in many areas. This year forsythia has
had a tremendous crop of blossoms, with bloom from the tips of the branches all
the way to the ground. You may ask why I am talking about forsythia in a Fruit CAT Alert Report. It has been my
observation that in years we have had flower bud damage to fruit crops, there
is also damage or a sparse bloom in forsythia. The great “crop” of flowers on
forsythia is indicating to me that our flowers on the more sensitive tree
fruits and tender varieties of summer red raspberries have survived the mild
winter very well.
Some growers have
received between 0.2 inches and 0.4 inches of rain over the last week and
between 0.6 inches and 0.8 inches over the last two weeks. Soil moisture is
normal at most farms with some areas remaining on the dry side. Most growers
have now planted tree and small fruits as soil conditions were ideal last week.
We’ve had several
reports of softball-size hail in the Blissfield, Deerfield,
|
Location |
GDD42 |
GDD45 |
GDD50 |
|
|
297 |
229 |
134 |
|
Lapeer |
330 |
254 |
164 |
|
|
339 |
261 |
164 |
|
Romeo |
312 |
240 |
145 |
Apples are mostly at open cluster to pink in the south and first pink in the
We continue to get
moderate to heavy apple scab spore release with each of the three to four
wetting periods at our monitoring station over the last two weeks. Growers have
applied one or two fungicides to control this early apple scab spore release
and marginal wetting periods. I continue to be concerned about this combination
earlier than normal bud and leaf development and higher than normal apple scab
spore release this year. All these indications lead to the fact that apple
growers need to be aggressive in controlling apple scab earlier this season
than most years.
Pears are at open cluster with a few being at white popcorn or white bud. Pear
psylla continue to fly in many blocks. I am starting to see a few pear psylla
eggs being laid. Many growers have applied an insecticide to control this early
season flight of pear psylla.
Peaches are at first bloom with about 10% to 20% of the blossom now open. Again
we are catching Oriental fruit moth at fairly low numbers in the range of 2 to
4 per trap. Many growers are now working away at pruning peaches.
Sweet cherries are at full bloom. There appears to be a
good bloom on sweet cherries at this time. At this full bloom stage they will
most likely tolerate temperatures down to 30 degrees. However at temperatures
of 25 degrees, I would predict a 90% bud kill. Brown rot sprays have been made
on many blocks. Cherry leaf spot sprays will go on early next week.
Tart cherries are currently at early bloom. There seems to
be quite a spread of flower stages this year.
Plums are at popcorn or white flower and could be blooming later in the week
with warmer temperatures. Japanese plum varieties are in bloom to early petal
fall. Growers are going to need to be concerned about black knot sprays in the
next week or so.
Strawberries are growing a good consistent crop of
foliage. Flower buds have emerged from the crown on strawberries growing in the
southern part of the region and are just at the tip of the crown in the
Raspberry leaves continue to emerge on summer red raspberries. There appears to
be no winter injury to canes of summer raspberries. Fall red raspberry canes
have now begun to emerge from the soil.
Blueberries are currently at early pink bud. Blueberries have been moving along
quickly over the last week. Pruning is now nearing completion at most farms.
Grapes are at bud burst. I am starting to see a few grape flea beetles,
however, note the very high populations occurring in southwest
|
Weather Station |
GDD42 |
GDD50 |
|
West Olive |
287 |
133 |
|
|
341 |
167 |
Tree planting is ongoing.
Most apple varieties are in the open cluster
to early pink stage at this time. Sweet
cherries are in bloom. Peaches
are nearing full bloom across the Ridge. According to 30-year averages from the
Temperatures on the
morning of April 25 reached lows right around freezing. There could be some bud
damage to all tree fruit crops in the low pockets of orchards – but it’s much
too early to tell if there is any damage. Damage should be very light due to the
fact that there was a light rain and winds were about 10 mph, keeping
temperatures up.
With just about
every rain since green tip, we’ve had enough wetting to cause light infections
for apple scab. Spore discharges have been rather high for this time of year.
According to GDD32 accumulations, about 20 to 30% of the ascospores mature at
this time.
In apple, green fruitworm and red-banded
leafroller adults started flying last week. Spotted tentiform leafminer should
start to fly at any time if not already. Climbing cutworm damage in apple buds
has been reported. European red mite eggs appear to have overwintered very
well.
Oriental fruit moth traps should be up in both peaches and apples – they should be flying – pheromone for OFM mating disrupted blocks should be going on now. Pink sprays in apple will begin at anytime in this area.
With bloom getting
close, apple growers will need to think about adding a mildewcide in the tank
for powdery mildew in the next week or so for those varieties that are susceptible
to it.
Brown rot sprays in
sweet cherries and peaches in bloom should be applied as
well.
Blueberries in West Central Michigan are showing a range of development from tight cluster to 1/4-inch green. However, due to the past days’ low temperatures all development has been slowed down. So far, no freeze/frost damage has been reported. However, the weather forecast for the region indicates a high probability of low temperatures 20-26ºF. This could occur from Thursday night (April 27) and over the weekend. This change in temperature may cause some damages to early varieties. Thus, frost protection measures should be considered for those fields at risk.
Our study on the environmental impact of deicing salt on blueberry fields showed that despite the implementation of the Ottawa County Road Salt Management Program in November 2005, even before any salt was applied, Sodium and Chloride concentrations in water samples taken from the blueberry root zone in a field located in front of US 31 were already 20 time higher then in those from a non-salted road.
Regarding blueberry
plant damage, flower bud damage in mid-January was 82% at the field located
alongside US 31 and 20% in the control site located at
Warm weather was the
norm for last week. Though we did have some cooler night temperatures, the
vegetation has been moving very rapidly. Apricots, Japanese plums
and sweet cherries are blooming. Tart cherries are just
starting to show white bud and a few open blossoms here and there; there is not
much segregation among the apple varieties. It appears that they are all
showing pink king bloom. Pears are in open cluster. In other words, they
are in a quite vulnerable stage of development in respect to the low
temperatures. Forecast for the next several days are indicating the cold front
of Canadian origin moving into our area. With it, there is a possibility of
having an environmental condition that might cause some serious damage to the
developing buds.
|
Location |
GDD42 |
GDD45 |
GDD50 |
|
Hart |
256 |
194 |
116 |
|
Ludington |
251 |
191 |
114 |
|
Manistee |
258 |
199 |
122 |
There has been some bud damage in the apple block. The whole inside of the bud was eaten away. Most likely, this is the doing of climbing cutworms. European red mite eggs are present in low numbers. No egg hatch reported yet. Green fruitworm has been active for the last two to three weeks. No reported catch of the Oriental fruit moth. Pear psylla is very active. Looking at GDD accumulation as a guide for insect emergence, we need to be on a lookout for rosy apple aphids, black cherry aphids, tarnished plant bug, San Jose scale, Oriental fruit moth, redbanded leafroller, American plum borer, dogwood borer and spotted tentiform leaf miners.
With regards to apple scab, ascospores are maturing at very accelerating rate. Given the mild winter, most of them have survived in good shape. Spores are being released with each wetting period regardless of its duration and whether or not it resulted in the infection period. Last Saturday (April 22), we had a heavy infection period in Ludington and moderate infections in Hart and Manistee/Bear Lake areas. During that rain event, 786 spores per rod were released. It is extremely important that the apple blocks receive cover sprays, particularly during rapid tissue expansion. Newly developed tissue is not protected and is an easy target for infection.
Growers are advised to do black knot protection sprays. This is the prime time for the spore discharge and infections. From now on, fungicides like Captan, Bravo (until shuck split) and/or Topsin-M sprays will aid in disease control.
Blossom blight on stone fruit: All the mummies that are still on the trees will be a source of inoculum for the blossom blight infections. Meteor and Balaton, being susceptible to European brown rot, would require a few extra sprays starting at white and through bloom. Sweet cherries are blooming and require protection with one of the available materials (Elite, Indar, Nova, Orbit).
GDD42 261
GDD50 115
Warm weather the past two weeks has advanced tree development beyond normal. Precipitation has been below normal for April.
Apricots reached full bloom at the NWMHRS on April 21.
Sweet cherries are showing first bloom on early blooming varieties at the NWMHRS. A lot of dead wood is present in sweets this year. We'll put an article in next week's Fruit CAT Alert to address this problem. Not much to report for pests on sweet cherries, except that the time has passed for copper use for bacterial canker.
Apples are in
tight cluster. A wetting event was reported for Saturday, April 22 that
resulted in a moderate scab infection period in the
There are no insects or diseases in tart cherry at this point.
We have seen many cutworms in grapes, and we have witnessed missing buds in warmer vineyards where buds are beginning to swell.
Jet stream steering currents across the
With high pressure in control across the region, fair and dry weather is expected statewide through Friday. The threat of frost and freezing temperatures should end by late Friday (April 28) as milder air moves back into the region from the southwest. Look for daytime temperatures ranging from the upper 40s in northern lake shore areas to the low 60s south.
Further ahead, jet stream flow across North America is
forecast to shift once again by the upcoming weekend, with the possible
formation of an upper air “cut-off low” feature across the Great Lakes region. Should
this feature develop as forecast, an extended period of unsettled weather is
likely with a chance for showers and a few rumbles of thunder Saturday and
Sunday continuing into early next week. Further ahead, medium‑range
forecast guidance suggests the formation of a broad ridge of high pressure
across central and western sections of the
The NOAA 6-10 day outlook (covering April 30 through May 4) calls for above normal temperatures statewide and for below normal precipitation totals over all but extreme southeastern sections of the state, where near normal totals are forecast. During the 8-14 day period (covering May 2-8), the outlook calls for temperatures to range from above normal across northwestern sections of the state to near normal elsewhere, and for precipitation totals to range from below normal levels across extreme western and northern sections to near normal levels elsewhere.