May 6, 2003
In this issue
§ 2003 TNRC trapline data: spotted tentiform leafminer
§ New insecticide labels for fruit
Tree fruit news
§ Control options for European red mites in apple
§ Selection and deployment of pheromone traps to monitor moth activity in orchards
§ MDA to register Michigan apple orchards and certify scouts for shipping program
§ Stinger labeled for stone fruit
Small fruit news
§ Blueberry freeze injury or Phomopsis?
Other news
§ Postemergent grass herbicides for fruit crops
§ New pocket-sized scouting guides for stone fruit
§ Regional reports
§ Weather news
This past winter, some new insecticides were registered for use in Michigan fruit crops. Their properties and pest spectrum are described in the following article. Some of these compounds work differently than conventional insecticides, and a good understanding of their properties will help improve their effective use. Copies of the new labels or 2(ee) label expansions must be in the possession of the applicator before use.
Intrepid (methoxyfenozide) is labeled for grape berry moth and redbanded leafroller. The main label for this product is at 4-8 oz/acre, but Dow AgroSciences have recently released an amendment to allow 8 to 6 oz for grape berry moth. MSU research trials using 50 gallons per acre have shown good efficacy using 12 ounces per acre. This product is an insect growth regulator, and since the larvae must ingest this product for effective control, Intrepid requires excellent coverage of clusters for control of grape berry moth. It has a 30-day preharvest interval in grapes.
SpinTor (spinosad) has direct contact activity and is also active if ingested. Targets include grape berry moth and redbanded leafroller. SpinTor is in a new insecticide class called the naturalytes from Dow AgroSciences. It has a 7-day preharvest interval in grapes.
Assail (acetamiprid) is labeled for leafhoppers at 1.1 oz and is expected to have good activity against both grape and potato leafhoppers. Some protection of treated vines from damage by other insect types has been seen in recent MSU trials, including Japanese beetles. Assail is a neonicotinoid insecticide (in the same class as Provado), from Cerexagri.
Acramite (bifenazate)
should provide rapid
knockdown of mites (two-spotted and European red mite) with a long residual
activity. It is active on motile stages with some egg activity. This miticide
is a carbazate miticide from Uniroyal
Chemical.
In spite of the
announcements last fall that Guthion would be restricted on grape, strawberry
and some other fruit crops, the agreement between Bayer and EPA has not yet
been signed. As a result, it looks as if Guthion will be available for this
growing season, but it is unclear exactly when this agreement will be signed.
It will be important not to stockpile this product for use beyond this year.
GF120 (spinosad) is a fruit fly bait for blueberry maggot that uses the same active ingredient as SpinTor but in a formulation that gets sprayed in large droplets. SpinTor is in a new insecticide class called the naturalytes from Dow AgroSciences. This product acts as an attractant and bait for the flies that then get a lethal dose by feeding on the bait. This is labeled at 10 to 20 oz of product per acre that is then diluted in 1.5 to 5 times the water volume to create a concentrate mixture. This product is designed primarily for aerial application.
Entrust (spinosad) is a WP formulation of spinosad that has
received OMRI approval for use in organic blueberry. It has the same spectrum
of activity as SpinTor.
Esteem (pyriproxifen) is an insect growth regulator for control
of cranberry and cherry fruitworm and scale in blueberry. Application of this
product for fruitworms should use a 5-oz/acre rate, timed for the beginning of
egglaying. This is an earlier timing than usual for these pests and should be
done with excellent coverage to ensure contact with the eggs laid in the calyx
cup of the fruit.
GF120 (spinosad) is a fruit fly bait for cherry fruit fly that uses the same active ingredient as SpinTor but in a formulation that gets sprayed in large droplets. SpinTor is in a new insecticide class called the naturalytes from Dow AgroSciences. This product acts as an attractant and bait for the flies that then get a lethal dose by feeding on the bait. This is labeled at 10 to 20 oz of product per acre that is then diluted in 1.5 to 5 times the water volume to create a concentrate mixture. This product is designed primarily for aerial application.
Entrust (spinosad) is a WP formulation of spinosad that has
received OMRI approval for use in organic production. It has the same spectrum
of activity as SpinTor.
Provado
(imidacloprid) is a neonicotinoid insecticide expecting registration anytime for use
in stone fruits for the
control of aphids, leafhoppers, tarnished plant bug, rose chafer, Japanese
beetle, San Jose scale and suppression of plum curculio.
Provado provides systemic, translaminar activity, which makes it particularly
effective on sucking pests such as aphids and leafhoppers.
GF120 (spinosad) is a fruit fly bait for apple maggot that uses the same active ingredient as SpinTor, but in a formulation that gets sprayed in large droplets. SpinTor is in a new insecticide class called the naturalytes from Dow AgroSciences. This product acts as an attractant and bait for the flies that then get a lethal dose by feeding on the bait. This is labeled at 10 to 20 oz of product per acre that is then diluted in 1.5 to 5 times the water volume to create a concentrate mixture. This product is designed primarily for aerial application.
Entrust (spinosad) is a WP formulation of spinosad that has received OMRI approval for use in organic production. It has the same spectrum of activity as SpinTor.
Superior oil applied at the right time with good coverage at 2% v/v can provide control of mites until mid-summer, but can cause phytotoxicity if applied within 48 hours of freezing temperatures.
Apollo, Savey and Agri-Mek all provide extended control of European red mites (ERM), ranging from ten weeks to full season depending on mite pressure, tree vegetative growth and predator mite populations. Savey and Apollo can be applied pre-bloom for over-wintering ERM eggs but now have in-season use with their respective 28-day and 45-day pre-harvest intervals. These compounds can be used in lieu of early season oil timings, but oils should remain as an important resistance management tool to reduce the selection pressure from consecutive use of Apollo and Savey, which have similar ovicidal modes of action. AgriMek is most effective when applied between petal fall and first cover (14 days past petal fall) with the addition of 1 gallon of paraffinic spray oil per acre.
Pyramite is a contact miticide which when used early season (after petal fall) can provide six or more weeks of control, or in mid-summer as a “clean up” application if early season products have lost control of mites. Acramite is a newly registered contact miticide that has six or more weeks of activity on ERM motile forms, and a novel mode-of-action.
Many factors affect the performance of trapping systems and the usefulness of the information gathered. These factors are trap selection, trap placement and seasonal maintenance. Ignoring any one of these fundamentals will reduce the reliability of the whole trapping system.
Every trap is composed of three essential components: the trap design, the pheromone-baited lure and the sticky surface needed to retain the moths. The three most commonly used traps are the wing, large delta and diamond traps. Each can be an effective tool for monitoring fruit pests, however, the delta trap is probably the overall best option.
Since the trap is made of a durable plastic it can be used for several seasons. The trapping area is a sticky insert that can be removed to count moths. The insert can be easily replaced if needed. Research comparing traps has consistently revealed that the delta trap catches at least 30 percent more moths than other traps. The delta trap catches more moths primarily because it has a larger trapping surface than other traps. The ability to trap as many moths as possible is especially important in situations where catches are typically low, such as when monitoring mating disrupted orchards.
There are also many lures to choose from. The most commonly used lure is the red septum. A septum loaded with 0.1 mg of a 3-component pheromone blend is a very effective lure for monitoring Oriental fruit moth in both disrupted and non-disrupted orchards. A red septum loaded with 1 mg of codlemone has been the fruit industry standard for monitoring codling moth in insecticide-treated orchards. However, recent studies have demonstrated that the performance of this lure declines after about three weeks in the spring and two weeks in the summer. Changing lures this often is difficult and expensive, thus some longer-lasting lures have been developed. These include the L2 (Trécé Inc), Biolure CM1x (Suterra), and Flex (PheroTech Inc.) lures that may last six or more weeks. We are currently evaluating the longevity of these lures under Michigan field conditions.
Lures releasing a high rate of pheromone are often used to monitor codling moth in mating disrupted orchards. A red septum loaded with 10 mg of pheromone has been the industry standard. As with the 1x red septum, the performance of the 10x version declines over a period of two to three weeks. High load lures that last at least six weeks have been developed and include the superlure or “bubble lure” (PheroTech Inc.), the megalure (Trécé Inc) and the Biolure CM10x (Suterra, LLC). Tests to determine the longevity of these lures in Michigan orchards have been initiated for the 2003 season. For all high-load lures, however, moth captures are not a reliable indicator of population densities in orchards. Trapping should be used in conjunction with visual inspection for signs of codling moth infestation. Concentrate your search for fruit injury in the upper canopy, along orchard borders, near bin or prop piles and in the most susceptible varieties, such as golden delicious.
In 1998, Dr. Doug Light, a USDA-ARS scientist in Albany, California, discovered a compound that is attractive to both male and female codling moths. The attractive chemical is an ester that is present in the odor of ripe Bartlett pears. This pear ester is a stable compound that can be readily synthesized and loaded into a rubber septum to make a lure for monitoring codling moth. Trécé Incorporated produces a lure based on this chemistry that is commonly referred to as the DA lure.
The possible advantages of the DA lure over the sex pheromone lure are: 1) it attracts females and thus moth catch is more directly linked to egg laying and the potential for worms in the fruit, and 2) attraction is not impeded or suppressed by pheromone-based mating disruption. Scientists have been evaluating the performance of the DA lure for the past few years and, in general, the results have been promising but variable. The DA lure consistently attracted fewer moths than the pheromone lure when monitoring orchards that were not treated with a codling moth mating disruption product. Trials by USDA scientists indicated that DA lure-baited traps captured more moths than pheromone lure-baited traps when monitoring disrupted orchards. Others have reported that the DA lure only outperformed the pheromone lure in disrupted orchards during the second-generation flight of codling moth.
In Michigan, we have found that the DA lure was substantially less attractive than the pheromone lure throughout the season in both disrupted and non-disrupted orchards. Further tests of the DA lure in Michigan are being conducted this season.
A number of factors may influence the performance of traps baited with the DA lure and should be considered when using this trapping system. Dr. Alan Knight, USDA-ARS in Yakima, Washington, has found that the crop or cultivar in which traps are placed strongly influences moth catch in DA-baited traps. Higher catches with the DA lure were recorded in walnut and in some late season apples (e.g., Granny Smith) than in pear or in early season apples (e.g., Gala, Golden Delicious). Additional research indicates that the range of attraction is small. Pending further testing, Trécé encourages using DA-baited traps primarily in apple blocks treated with mating disruption and only in conjunction with pheromone-baited traps. They recommend changing the lure at eight-week intervals.
Even if you select the right trap and lure, if they are not maintained, disastrous decisions may be made. The effectiveness of the trap depends on maintaining the trap shape and the quality of the adhesive over the season.
Two common problems with trap shape are failure to return side flaps to the upright position of the large delta trap, and not maintaining the proper entrance space in the wing trap after the traps are checked. The second problem is that leaves, twigs and moth scales can foul the adhesive bottom of traps over time. Each time traps are checked, debris and moths should be removed and the adhesive should be redistributed. A general guideline for replacing trap bottoms is at least once per generation or when the surface has been fouled sufficiently to prevent routine capture.
Lures should not be handled with bare hands. Gloves, sticks, or an instrument for lure placement can be used, but whatever tool is chosen, pheromone cross contamination must be avoided. When handling lures for different moth species use a different instrument for each lure type, unless using an acetone dip to clean the instrument in between lure placements. Also, a trap should never contain more than one lure at a time. Replacement of lures for most species is between generations, except for codling moth, which may require more frequent changes. Check with the manufacturer for lure specific recommendations. Spent lures as well as new lure packaging must be removed from the orchard.
Trap placement is a critical factor for optimizing trap performance. The key decisions are 1) how many traps to deploy, 2) where to place them in the orchard, and 3) location of the trap within the tree. Moth species vary in their response to pheromone lures; therefore the number of traps needed ranges from one to four per ten-acre block. Oriental fruit moth or obliquebanded leafroller at one trap per ten acres and codling moth at two to four traps per ten acres can represent the extremes. The drawing range of a codling moth pheromone-baited trap is approximately 2.5 acres. Thus, the number of traps placed should be based on the history of codling moth infestation in the block. Four traps are needed in blocks with a history of uneven codling moth pressure, while only two traps should be sufficient where pressure is known to be uniform. The key considerations for effective trap placement within a block are: 1) historical “hot spots,” and 2) location relative to block perimeter. An area where moth catches from previous seasons were high, or a “hot spot,” is a good place to locate a trap.
A “hot spot” does not represent pest pressure in the whole orchard; thus traps should also be placed elsewhere or you may be applying unnecessary control applications to large areas of the orchard when the problem is confined to the “hot spot.” Avoid placing traps on the perimeter row. Instead place traps at least three to four rows in. Placing traps well within the orchard will increase the likelihood of capturing local moths, rather than your neighbors’.
The location of the trap within the tree is the third critical factor. A trap needs to be located where moth activity is greatest and should be placed in a tree in a way that allows moths easy access to the trap. Where necessary, remove branches or leaves that block easy moth access into the trap. For most situations, traps can be placed in the middle third of the tree canopy. Truck window height is not acceptable. The height at which a trap is placed is especially important for codling moth. If traps are placed low in the canopy, too few moths will be captured to make effective management decisions.
One exception to placing traps in the middle third of the tree canopy is in blocks where mating disruption for codling moth is being used. In a pheromone-disrupted orchard, codling moth traps need to be placed in the upper third of the tree canopy.
It is time for apple growers to register with the Michigan Department of Agriculture if they plan to ship fruit from the 2003 crop to Brazil or Arizona. The certification process allows growers’ fruit to be shipped to Brazil or Arizona without cold treatment to kill apple maggot. The required forms, available from the MDA Pesticide and Plant Pest Management Division, should be received by their office by May 16, 2003.
MDA will be providing certification of all scouts setting and monitoring apple maggot traps as part of the certification process. All scouts or growers who set and monitor these apple maggot traps must attend the training session scheduled for Thursday, May 29, 2003 at 9:00 AM, Erie Conference Room - 2nd Floor, State of Michigan Building, 350 Ottawa Avenue, NW, Grand Rapids, MI.
For further information and forms contact: Barry T. Menser, Region III Plant Pest Specialist, Michigan Department of Agriculture, Pesticide and Plant Pest Management Division, 350 Ottawa Avenue, NW – Unit #1, Grand Rapids, MI 49503-2348. Phone: 616-356-0600, fax: 616-356-0622.
The herbicide Stinger (clopyralid) has been labeled for postemergence weed control in several crops, including stone fruits (apricot, peach, plum, sweet cherry, tart cherry, nectarine).
Stinger primarily controls weeds in the Asteraceae (Compositae) family, including dandelion, marestail, common groundsel, ragweeds and Canada thistle among others. It also gives some control of nightshades, smartweeds, clovers and other legumes and plantains. It has essentially no activity on other weeds or crop plants.
Apply 0.3 to 0.67 pints per acre (.125-.25 lb active ingredient) to actively growing weeds. Weeds are more susceptible before flowering occurs. Use a maximum of 0.67 pints product per acre per year. Stinger may be tank mixed with other herbicides. There is a 30-day preharvest interval.
This spring, tip dieback is prevalent in some blueberry fields. In some cases, the damage seems to be due to freeze injury, while in other cases the Phomopsis fungus may be to blame. While the two symptoms are often difficult to tell apart, there are a few differences that may help you diagnose the problem.
If the dieback is
due to Phomopsis, the infection would have taken place the previous year
or the year before that if it wasn’t pruned out. The infected twig or cane
tends to be dark reddish brown with a gray-bleached area at the tip or farther
down the twig or cane. Often, the border between the dead and live portions of
the cane is fairly distinct. The bleached area may range from one to several
inches long and may contain tiny black pimples, which are the fruiting bodies
of the fungus. The fungus is most likely to sporulate in the bleached area.
More recent twig infections may appear dark brown to almost black. The lesions
may be enlarging down the twig from the tip or up and down the twig from an infected
lateral bud, which will die before or during bud break. Also, if you notice
that the lesions keep expanding, it is most likely Phomopsis and not freeze
injury. The fungus can infect twigs and canes anywhere on the bush. Young green
canes lower in the canopy often display reddish brown lesions (cankers) that
may be flattened.
Freeze injury tends to turn cane tips a light reddish brown, without a bleached area, and the border between dead and healthy tissue is more gradual. Freeze injury may especially affect young green canes that did not harden off well last fall. Also, the damage may be widespread throughout the field and more severe in low-lying areas that are prone to frost.
Phomopsis twig blight incidence can be reduced by pruning out and destroying infected canes and twigs, which act as inoculum sources. Fungicide options for controlling Phomopsis twig blight are Topsin M or Benlate (tankmixed with Ziram or Captan), Bravo, Indar, and Cabrio. Benlate has been discontinued, but some growers may have remaining stocks. The Section 18 label request for Topsin M is still pending, but a decision is expected this week.
The herbicides Fusilade (fluazifop-P), Poast (sethoxydim), and Select (clethodim) are labeled for use on many fruit crops to control grasses. Although they represent two chemical families (Fusilade; aryloxyphenoxypropionate, Poast and Select; cyclohexanediones), they all kill grasses by inhibiting fatty acid synthesis and stopping growth. Broadleaf species and rushes and sedges are not affected. The accompanying table summarizes current labels. Note that not all herbicides are labeled on all fruit and some are labeled only for non-bearing plants, meaning they cannot be applied within 12 months of harvest.
|
Uses of
postemergent grass herbicides on Michigan fruit crops (NB = non-bearing). |
||||||
|
Herbicide |
Apple, Pear |
Stone fruit |
Grape |
Bramble, Blueberry |
Cranberry |
Strawberry |
|
Fusilade DX |
NB only |
Yes |
NB only |
NB only |
|
|
|
Poast 1.5 E |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
|
Select 2 E |
NB only |
NB only |
NB only |
NB only |
Yes |
Yes |
Application timing is critical with these materials. Grasses are most sensitive when actively growing. Annual grasses should be 2 to 6 inches tall; quackgrass 6 to 10 inches tall. If grasses have produced seed heads or are stressed from drought, control will be poor. Perennial grasses will require more than one application for control. Apply Select with 1 percent crop oil concentrate (COC), and Fusilade and Poast with COC (1%) or a nonionic surfactant (0.5%).
|
Use rates
and additives for postemergent grass herbicides. |
||
|
Herbicide |
Rate |
Comments |
|
Fusilade DX |
1-2 pt |
Stone fruit, 14 day PHI |
|
Poast 1.5 E |
2-4 pt |
Apricot, cherry, peach, 25 day PHI strawberry, 7 day PHI |
|
Select 2 E |
6-8 oz |
Cranberries, 30 day PHI strawberries 4 day PHI |
Fusilade is the most effective of these three herbicides on quackgrass. Select is the most effective against annual bluegrass. All of them are weak on large crabgrass. These products can provide complete control of most emerged annual grasses if applied at the right time, but they generally only suppress quackgrass. None provide residual activity, so grasses emerging after applications will not be affected.
This plastic-coated scouting guide with 3.25 X 5 inch pages fits in your pocket for easy use in the orchard. With color pictures and descriptions, it helps identify insect and disease pests, pest damages and beneficial species. Some guidelines for monitoring and thresholds are included.
The publication can be purchased through the MSU bulletin office by calling 517-353-0240. You can also purchase it at your local Extension office. The price is $12.
This guide is intended to be a field supplement to more comprehensive reference publications. It does not include pesticide recommendations. To view sample pages and further descriptions of this guide and guides for other crops, visit the publications section of the MSU IPM Program website at:
A Pocket Guide for IPM Scouting in Michigan Apples E-2720
A Pocket IPM Scouting Guide for Woody Landscape Plants E-2839
A Pocket Guide for Grape IPM Scouting in the North Central and Eastern U.S. (available June 2003)
We received almost two inches of rain last week. We got an inch each in two rainy periods last week April 30-May 1 and yesterday morning, May 5. The heavy one-inch rains we have received would have washed protectant pesticides off the plants, so that they need to be reapplied. Our soils are now saturated. This week's weather is forecast to have highs near 70 and lows near 50 with showers or thunderstorms possible most days.
Growing degree day (GDD) totals through May 4
|
||
|
Location |
GDD 42 |
GDD 50 |
|
440 |
214 |
|
|
Lawton |
453 |
231 |
|
Grand Junction |
433 |
223 |
|
328 |
151 |
|
Most stone fruit are in the shuck. Apricots, peaches and sweet cherries should be protected from brown rot. Stone fruit growers need to scout for plum curculio as fruit emerges from the shuck and is exposed. Generally warm humid nights and daily highs in the 70’s are needed before plum curculio egg laying begins. We are still catching Oriental fruit moths and redbanded leafroller.
The apricot crop looks good.
In peaches, Oriental fruit moth trap catches are up again. We first caught Oriental fruit moth after some warm weather on April 13 through April 15. Cooler weather reduced the flight until about April 19 when we caught moths again. Cool weather again shut the traps down until late last week. We are biofixing Oriental fruit moth on Thursday April 24 at about 250 GDD45. In Southern Berrien County biofix was on about April 19 at 225 GDD45. We are now at 345 GDD45. Treatment for Oriental fruit moth is targeted for early egg hatch at 150 to 170 GDD45 after biofix. With temperatures near 70 for highs and 50 for lows we should be picking up about 10 to 15 GDD45 per day. Treatment of peaches to prevent shoot strikes should be on by the end of the week in southern and central Berrien County. Growers to the north should wait until the weekend. To protect the fruit growers can wait until shuck split.
Tart cherry fruit stems are starting to elongate. In the next two weeks we will have a good idea of the crop. Growers should protect against cherry leaf spot.
In sweet cherries, it looks like we have about 30 percent of a full crop.
Plums are in the shuck. Black knot sprays are important through shuck split. Rain and temperatures above 55°F favor black knot infections. Bravo is not labeled for plums after shuck split.
Apples are at full bloom. Bloom appears heavy for most varieties. A scab infection period occurred on April 29. We have not found any scab lesions yet. We are not at significant fire blight risk yet in the bloom period. Cool temperatures have kept bacterial populations down. We need high bacteria population as well as warm temperatures and rain during bloom before there is risk of fire blight infection. Unless we get warmer than forecast temperatures bacterial population should be low this week. No codling moth adults have been trapped yet. European red mites are scarce. Spotted tentiform leafminer adults are out in large numbers and egg laying has begun. We have not found larvae or mines yet. Redbanded leafroller trap catches are down. Some leafroller larvae are attacking fruit buds. Growers should plan on petal fall sprays after bloom to control Oriental fruit moth that will begin egg laying soon.
Pears fruitlets are about 6 mm in diameter. Growers need to protect against pear scab.
Blueberries are at pink bud. Early varieties such as Earliblue and Weymouth are beginning to bloom. Another cause of cane dieback this winter seems to be that they were damaged last year during harvest. Growers should be spraying for mummy berry. Mummy berry shoot strikes have been found in Van Buren County. Redbanded leafroller trap catch continues and some feeding larvae have been found.
Grape shoots are one to three inches long with one leaf out and the flower cluster are exposed. Winter damage to wine grapes is spotty and bud break is uneven. Some shoots have three inches of growth while over buds are still in swell. Cutworm feeding has been a problem on later buds. Growers protect against black rot and phomopsis as the leaves unfold. Apply protectant materials before rains to keep flower bud clusters protected. The heavy one-inch rains we have received would have washed protectant fungicides off so that they need to be reapplied.
Grape growing degree day totals from April 1 to May 5
|
|
|
Location |
GDDbase 50 |
|
SWMREC from April 1 |
155 |
|
Lawton From April 1 |
187 |
Strawberry bloom has begun in Southern Berrien County. Growers should be scouting for strawberry clipper and spittlebugs.
Raspberries shoots are one to three inches long. Flower buds are visible in early varieties.
Cranberry fields are greening up and fruit buds are starting to swell.
The next Monday Fruit Management meeting will be at Bjorge's Fruit Acres Farm, at the corner of Friday and Carmody roads, approximately two miles south of the Coloma exit I-94, on May 5 at 5:00 PM. For more information check the Fruit Hotlines at Van Buren (269) 657-6380 and Berrien (269) 944-4126 ext. 1 counties.
Most areas of Southeast Michigan have received around 1 ½ inch of much needed rainfall over the last week. Some fruit growers have received as much as 2 ½ inches of rain from thundershowers. A few isolated areas in Flint, Lapeer and Port Huron also received hail and wind damage from a late evening storm on Monday, May 5. Pea to dime sized hail and winds gusting to 70 mph were reported in the Flint area. With temperatures ranging in the mid-60’s to low 70’s many days last week, our growth has now jumped ahead of last year.
Growing degree day totals for March 1 to May 6 |
|||
|
Location |
GDD42 |
GDD45 |
GDD50 |
|
Flint |
429 |
315 |
212 |
|
Romeo |
381 |
291 |
178 |
|
Petersburg |
426 |
319 |
217 |
Apples are mostly at early bloom in the southern part of the district to full
pink in the northern part of the district. It still appears that we have a
fairly strong crop of flower buds this year on most apple varieties with a
possible exception of Golden Delicious. They’re starting to emerge a few
reports where other varieties may be on the light side as well. Spotted
tentiform leafminer trap catches continue to rise and some egg laying is now
being detected. Green fruitworm larvae have been seen at several farms.
Tarnished plant bug continues to be seen feeding on apple buds. Oriental
fruitmoth have biofixed (late last week or over the weekend) at a few farms
across the region. Most farms are expected to biofix Oriental fruit moth this
week. European red mite egg hatch has not occurred as of yet. There are very
few viable European red mite eggs this year. Plum curculio have not been
spotted in commercial orchards as of yet. Dogwood bore larvae have been found
feeding below the graft union at several farms.
Pears are mostly at white bud. Pear psylla adults continue to be seen,
however no egg laying has been detected as of yet.
Peaches are at full pink and will be in bloom fairly quickly. Oriental
fruitmoth have biofixed at a few farms across the region; see the apple section
for other details.
Sweet cherries are at full bloom across the region. There
are many farms where sweet cherry bloom has been very disappointing for fruit
growers with only 20 to 40 percent of the buds being viable. Up until early
last week it appeared that most of the sweet cherry buds were going to continue
the flowering process, however many have stopped developing well before bud
opening. It is my opinion that sweet cherry flower buds were damaged last
December when temperatures turned cold quickly.
Tart cherry buds continue to move along quite nicely and are currently at white
bud.
Strawberry flowers have emerged from the crown at most farms. Little to no open
bloom has been seen as of yet. Some strawberry clipper was detected at a few
farms late last week.
Raspberry canes from fall-bearing raspberries continue to emerge from the soil
and have grown to a length of 2 to 3 inches. I’m continuing to watch several
varieties of summer raspberries as they suffer from leaf wilting that was
caused from this cold weather in early December of last year. Canes appear to
have been green and viable when they were pruned and tipped this spring,
however the canes have continued to collapse as spring has progressed.
Blueberries are currently at pink bud. Mummy berry shoot strikes have been seen at a few farms. New wood (wood that formed last year) continues to show signs of winter injury.
Most apple varieties are in the pink stage right now with some king bloom open on early varieties. The very first rosey apple aphids can be found in blocks that did not have pink sprays applied. Spotted tentiform leafminer continues to fly. Oriental fruit moth started to fly in the area over the past weekend in light numbers. We’ve had three infection periods for apple scab this season, and lesions from the first infection should start to be found at any time.
Sweet cherries are in full bloom. Buds appear to be healthy.
Tree planting is still going on. Bees should start to be moved into orchard blocks at any time.
Because of the potentially large crop, apple growers are encouraged to consider petal fall thinning if the weather is favorable.
There will be two thinning meetings in the Grand Rapids area – the tentative dates are May 13 and May 20. Call the Clarksville Horticulture Experiment station (616-693-2193) for more information or check the Code-A-Phone at 616-451-8065.
Blueberries in west central Michigan are still in the early growth stages. Bluecrop and Blueray are in the early pink stage while Jersey is in ½ inch green tip. There have been some low temperatures in the region with no deleterious effect to the crop (on May 3, the lower temperature registered in the Grand Haven–Holland area was 30.5°F). Most early blueberry varieties are still in a growth stage where they can sustain up to 18°F without major problems. Growers have initiated application against common blueberry diseases (mummy berry and phomopsis twig blight).
However, there have been problems regarding the use of some of the most important fungicides such as Indar and Topsin M that require a Section 18 permit issued by the EPA. So far, only Indar has been authorized but Topsin M, the fungicide that substitutes Benlate is still pending. Without the availability of Topsin M blueberry growers have been left with only one option; Bravo WeatherStik for phomopsis, and Ziram, for Mummy berry to initiate the disease control program. That has created problems for growers that in the past used Benlate in a mix with Ziram or Captan to combat both diseases.
Regarding insect pests, redbanded leafroller (RBLR) catches in pheromone traps are high and larvae and feeding damage have been observed in low numbers in Ottawa and Allegan Counties. No fruitworm moths have been caught in pheromone traps, yet. The past week we reported cherry fruitworm (CFW) moth catches. However, the moths trapped were misidentified. Those moths are very similar to the Oriental fruit moth but bigger than the cherry fruitworm moth. No cranberry fruitworm (CBFW) catches have occurred, yet.
|
Weather Station |
Base 42°F |
Base 50°F |
|
West Olive |
362 |
174 |
|
Holland |
381 |
183 |
In the last week’s events rain and some mild frost are the two worth mentioning. Our total precipitation for the week is slightly below or just above 1 inch depending on the location. The frost of May 3 and 4 may have caused some damage to the fruit in low-laying areas but overall, damage is not expected to exceed 10 percent.
|
Location |
GDD42 |
GDD45 |
GDD50 |
|
Hart |
239 |
206 |
117 |
|
Ludington |
264 |
194 |
99 |
|
Bear Lake |
269 |
201 |
99 |
Apples are in tight cluster (Red Delicious) to early
pink (Idared). We are having an ongoing infection of apple scab at the time of
this report. Apples are at the growth stage when the most significant spore
discharge occurs, so good coverage is strongly recommended. Powdery mildew is
another disease that needs consideration at this time. Early season control,
tight cluster to pink, will prevent rapid spreading of the inoculum to the new
leaves. Keep in mind that powdery mildew does not need a rain event in order to
cause the problem. If the mildew has been the major problem in a given block, new foliage should be protected with fungicides even when no
scab infection periods are predicted.
Scouts are reporting finding green fruitworms, cutworms, rosy apple aphids, redbanded leafrollers, spotted tentiform leafminers and European mite eggs (no hatch yet). In all, there is still not much activity.
Pears are in green cluster stage. We are under the pear scab advisory at this time. Pear psylla eggs are still very difficult to find.
Peaches are in a whole spectrum of bud development…from calyx red to first bloom depending on the variety. There is a report of a first Oriental fruit moth catch in Oceana County. We did not have any other OFM catches in the district. I would expect increased flight activity in the next several days. Scouts are reporting finding tarnished plant bugs in low numbers.
Plums are in open cluster to first white bud. Brown rot and black knot are of concern at this time.
Sweet cherries are starting to bloom. Tart cherries are just starting to show some white. This is a prime time for bacterial canker development. Brown rot (blossom blight) and cherry leaf spot are of concern as well at this time. Blocks need to be covered on a tight schedule.
GDD42 239
GDD50 97
An inversion freeze event occurred on Saturday, May 3, causing some flower bud damage on tart and sweet cherries. Much needed rain fell on May 5.
Apple growers need to keep the foliage protected
against apple scab, particularly during the critical high spore release period
of tight cluster to petal fall. Until mildew needs to be controlled, the
protectant EBDC fungicides or Captan are good options, assuming they can be
applied prior to infection periods. On blocks where mildew control is critical,
Rubigan, Nova, Flint or Sovran should be used as apples approach the pink
stage. Peak flight for spotted tentiform leaf miner typically occurs between
tight cluster and pink. European red mite eggs continue to mature, but no hatch
has been reported. It is an ideal time to apply oil sprays. Oil should be
applied at a 2 percent concentration by volume.
Sweet cherries will be coming into bloom, and growers need
to start thinking about brown rot and consider spraying if conditions warrant.
First bloom is coming out on Napoleons in warm sites. Some additional bud
damage has occurred with frost events, but most damage occurred as winter
damage on March 3. Many flower buds damaged in the March 3 event will never
produce flowers. Some blocks that depend on a badly damaged dark variety for
pollenizing may find a shortage of pollen.
Frost conditions on May 3 caused some damage to tart cherry buds. Preliminary assessment of damage indicates that crops are probably reduced in low areas and on colder sites.
Climbing cutworms are becoming active. Newly planted trees are the most susceptible to serious injury, but second leaf trees are susceptible, too. Grapes are also very susceptible. Lorsban can be used on grapes for control but is limited to one spray per season. The trunks of tree fruits may be treated with an appropriate insecticide, or place a barrier on the trunk.
Last week’s rains brought the precipitation totals for the last 30 days to normal levels throughout the state. The 6-10 day outlook for May 11-15 forecasts above normal temperature and precipitation. Rain and thunderstorms are likely for Friday and Sunday May 1, but temperatures should remain favorable for the week.
