In this issue
Tree fruit news
§ Summer leafroller control: Gather the information needed to make a sound management decision
§ Rainfast characteristics of insecticides
§ Sooty blotch and flyspeck disease of apple and pear – The newest addition to Enviro-weather
§ Enhancing return bloom with summer NAA 2008
Small fruit news
§ Mid-season weed control options for blueberries
§ Grape IPM Twilight Meeting
§ Blueberry IPM Twilight Meeting
§ Regional reports
§ Weather
Larry Gut, David Epstein and John Wise
Entomology
The increased
availability of several excellent leafroller control materials in the past
several years has resulted in reduced obliquebanded leafroller pressure in
Moth captures in
pheromone traps provide valuable information to the scout and grower, including
the establishment of biofix, but are not a reliable indicator of leafroller
abundance or potential damage. Obliquebanded leafroller traps have a large
active space, potentially catching moths that originate not only from within
the trapped orchard, but also from neighboring or more distant orchards, and
native habitats. Thus, high moth catches may or may not indicate that the
orchard being monitored has a leafroller problem. On the other hand, very low
catches of less than five per week strongly hint that obliquebanded leafroller
is not a problem. In either case, assessing larval activity is highly
recommended to determine if a treatment is warranted.
Scouting orchards for
surviving obliquebanded leafroller larvae in growing terminals is the best way
to judge whether intervention in the summer is likely to be needed. Larvae are
green with brown to black head capsules and are about 25 mm long when fully
grown. Often, a scout will detect signs of leafroller activity rather than the
actual larva. The name leafroller comes from the larva’s habit of rolling
leaves to form a shelter. These feeding sites are most often found at the tips
of growing shoots. Larvae will use silk webbing to attach two leaves or a leaf
and fruit together to form a shelter. The presence of webbing is a good clue
that leafrollers are around. Orchards in which less than two percent of the
terminals were infested should be monitored in the summer, but controls may not
be warranted. Inspect the undersides of leaves within the fruiting canopy,
especially where fruit are clustered. Higher levels (less than two percent) of
shoot infestation by overwintering larvae are cause for concern and control
measures are likely needed to prevent fruit injury.
|
DD° base 42 (Post Biofix) |
Event |
Action |
|
Tight cluster |
Majority of larvae have emerged from shelters |
Examine fruit buds for larval activity |
|
0 DD° = biofix (~900 DD° after Jan 1) |
First sustained moth captures |
Set DD° = 0 |
|
220-250 DD° |
Peak moth flight - overwintering generation |
|
|
400-450 DD° |
Start of egg hatch |
Timing for scouting-based treatment w/larvicides (egg materials applied
earlier) |
|
1000 DD° |
End of egg hatch |
|
|
2300 DD° |
Peak moth flight - second generation |
|
|
2750 DD° |
Start of second generation egg hatch |
Timing for scouting-based treatment |
Degree-day models are
essential tools to be used in timing insecticide sprays. Optimal timing for
summer sprays varies according to the life stage or stages that are targeted by
the product of choice. For conventional insecticides, like organophosphates
(OPs), pyrethroids, and carbamates, the first sprays should be targeted between
400 and 450 GDD (base 42°F) after biofix to control hatching larvae before they
can damage fruit. Obliquebanded leafrollers are resistant to organophosphates
in most apple growing regions of the state, and are generally not the best
option for control. The newest options for growers, Proclaim, Delegate and
Altacor, require ingestion by larvae, but have shown excellent activity against
obliquebanded leafroller. The first sprays should be targeted between 400 and
450 GDD after biofix to control young hatching larvae. Good, thorough coverage
is the key to leafroller control with materials requiring ingestion to be effective.
If Bt products are used,
the latter timing of 450 GDD may be the better choice because they have a short
residual, which must be present to control the larvae at the time and location
they are actively feeding. If the first application is applied too early, it
may take four or more sprays to keep the active ingredient on the foliage
throughout the long period of larval activity. Bt's are most effective when
applied during warm weather conditions (daily highs in the 70s ). Additionally,
they are generally more effective with a lower tank pH.
SpinTor has been a very
good leafroller management option for a number of years. It primarily acts
through ingestion, but also provides some contact efficacy. The latter activity
will help kill larvae as they move to the actively growing terminals. SpinTor
is also a good choice for leafroller control in cherry blocks where control
with organophosphates and pyrethroids is failing to provide adequate
protection.
Intrepid is another good
leafroller material that can be applied both early to target coverage of eggs
or later to target older larvae. If Intrepid is used early it should be
targeted to cover obliquebanded leafroller egg masses around 350 GDD
post-biofix, so that larvae will consume the chemical as they eat their
eggshells upon emergence. The later timing of 400-450 GDD protects fruit
against damage from older larval instars. Upon application, Intrepid has a long
residual effect, but should be reapplied where necessary on a 14-day interval
to insure coverage of new terminal growth. The addition of an agricultural
adjuvant to Intrepid 2-F is recommended to improve spray deposition.
Rimon acts by suppressing
development within the egg, as well as larvae that consume it. Hatching of eggs
laid by treated adults will also be inhibited. Eggs are particularly
susceptible to these products when laid on top of sprayed residue, thus
application of sprays should be timed for 100-200 GDD after obliquebanded
leafroller biofix. Similarly, Esteem applied at obliquebanded leafroller egg
laying timing will also provide some control, though it is more typically used
for the overwintering generation.
It should be noted that treating
the summer generation of obliuebanded leafroller with Delegate, Altacor, or
Rimon also will provide control of codling moth, Oriental fruit moth and
spotted tentiform leafminer. Intrepid applied at the earlier summer obliquebanded
leafroller timing would also assist in controlling codling moth and tufted
apple budmoth. Esteem will provide control of San Jose scale crawlers and some
added control of codling moth. Bt's also will control other leafrollers when
applied in the summer for obliquebanded leafroller control.
As with many of our key
apple pests, obliquebanded leafroller has a track record of developing
resistance to insecticides. Currently, there are some good options for control
of this pest. Practicing good resistance management should help conserve their
efficacy. We encourage you to rotate materials with different modes of action
(Table 2). For example, if Rimon was the material of choice for control of
overwintering larvae, opt for Delegate, Altacor, SpinTor or Intrepid if a
summer treatment is warranted. During periods of warm weather, Bt is an
excellent option and a good resistance management strategy.
|
Compound Trade Name |
Chemical Class |
Life-stage activity |
Optimal Spray Timing for OBLR |
Residual Activity |
Mite Flaring Potential |
|
Guthion, Imidan |
organophosphates |
Larvae |
Biofix + 400-450 DD |
10-14 days |
L - M |
|
Lannate, Sevin |
Carbamates |
Larvae |
Biofix + 400-450 DD |
5-7 days |
M - H |
|
Asana, Warrior, Danitol, Decis |
Pyrethroids |
Larvae |
Biofix + 400-450 DD |
7-10 days |
H |
|
Deliver, Dipel, Crymax |
Bt’s |
Larvae |
Biofix + 450 DD |
5-7 days |
L |
|
Altacor |
Anthranilic Diamide |
Larvae |
Biofix + 400-450 DD |
14 days |
|
|
Spintor, Entrust |
Spinosyn |
Larvae |
Biofix + 400-450 DD |
7-10 days |
L |
|
Delegate |
Spinosyn |
Larvae |
Biofix + 400-450 DD |
14 days |
|
|
Proclaim |
Avermectin |
Larvae |
Biofix + 400-450 DD |
7-10 days |
L |
|
Intrepid |
IGR (MAC) |
Eggs, Larvae, Adults (sublethal) |
Biofix + 350 DD Residue over eggs |
14+ days |
L |
|
Esteem |
IGR (juvenoid) |
Eggs, Larvae |
Biofix + 100 DD Residue under eggs |
10-14 days |
L |
John Wise
MSU Trevor Nichols Research Complex
The heavy rainfall events experienced in
In the 2007 apple study, we compared the performance of Azinphosmethyl (GuthionÒ), Phosmet (ImidanÒ), Esfenvalerate (AsanaÒ), Indoxacarb (AvauntTM), Novaluron (RimonÒ), Emamectin Benzoate (ProclaimÒ) and two neonoctinoids, Acetamiprid (AssailTM) and Thiacloprid (CalypsoÒ) on the codling moth. We sprayed all treatments on Red Delicious apple trees using labeled field rates, harvested fruit clusters 24 hours after sprays had dried and simulated half-inch of rain. These fruit clusters were then exposed to codling moth larvae in the laboratory, comparing fruit protection to untreated samples with no simulated rainfall. Parallel fruit samples were analyzed for their surface and sub-surface residue levels by the MSU Pesticide Analytical Laboratory to document the resulting chemical wash-off under the simulated rainfall event.
All treatments that were exposed to the half-inch of rain after 24 hours of drying provided good control of codling moth, even though residue losses to wash-off ranged from 10 to 50 percent. This suggests that even with significant residue wash-off, fruit protection is maintained from insecticides in the first few days after a spray. When fruit clusters were collected from the same field treated plots eight days later, some differences in performance became visible. Whereas performance of Calypso, Avaunt. Imidan and Guthion remained relatively equal between the rainfall and no-rain fruit, the activity of Rimon, Assail, Proclaim and Asana on codling moth was reduced from the half-inch of simulated rain. For the conventional insecticides Asana, Imidan and Guthion that have primarily surface residues, the amount of chemical lost from half-inch simulated rainfall ranged from 30 to 50 percent. This suggests that pyrethroid and organophosphate insecticides are similarly susceptible to wash-off from precipitation, but that the OPs’ higher toxicity to codling moth larvae maintained performance, though this may not occur in commercial orchards where OP resistance exists. Assail and Calypso, being neonicotinoids, have systemic movement into plant tissue. The residue data showed that even though losses of surface residues were similar to that of the OPs, the residues that had moved in and below the plant cuticle were protected from wash-off. For Avaunt, Rimon and Proclaim the residue wash-off from fruit was significant, but residues in leaf tissues appeared to be quite resistant to rainfall wash-off. There is much more work to be done in this area of research, including the simulation of more severe rainfall events. We expect to be reporting our findings as they develop over the coming years.
Bill Shan,
District fruit educator and Tracy Aichele, Outreach Specialist
A model for sooty blotch and fly speck,
an important disease for Michigan apple and pear growers, has just been added
to Enviroweather
(www.enviroweather.msu.edu), a Michigan State University web site weather-based
system for making pest management decisions.
Sooty blotch, caused by the fungi Gloeodes and
Leptodontidium and flyspeck, caused by Schizothyrium
pomi, are two fungal disease complexes of apples and pears common in the
humid fruit growing regions of the
The two fungi are found on a wide range of perennial hosts commonly found in the woods, including wild brambles. Spores of the two pathogen groups are available in orchards beginning approximately from late pink bloom growth stage throughout the summer and fall.
Sooty blotch colonies are olive green to black on mature fruit (Figure 1). They may be round or have feathery, diffuse margins, and infection may cover the entire fruit. Symptoms of flyspeck are appropriately described by the name of the disease. Colonies have up to 50 small, shiny black fungal fruiting structures grouped in an irregular to circular pattern.
The fungi that cause sooty blotch survive from one season to the next on apple twigs as well as other perennial vegetation with a waxy cuticle. The fungus is dispersed by wind and in windblown rainwater to developing fruit in the spring and early summer. Secondary spread from these primary colonies occurs throughout the summer. Growth of sooty blotch on fruit can begin two to three weeks after petal fall and a week or two later for flyspeck. Growth of these fungi are favored by temperatures between 65°F and 80°F, and wet, humid conditions. Growth does not occur at temperatures above 86°F. It usually takes 20 to 25 days for colonies of sooty blotch to appear on fruit after infection occurs and three to six weeks for flyspeck.
Control of sooty blotch and flyspeck is achieved through dormant and summer pruning and tree training, which opens trees and facilitates drying and fungicide deposition, and through preventive fungicidal sprays. Removal of wild blackberry from the border of the orchard can help by eliminating a potential reservoir host.
Enhancing return bloom with
summer NAA 2008
Philip Schwallier
District Horticulture educator
Some years it is desirable
to try to enhance return bloom on apple varieties that tend to be biennial.
This is especially important on trees that have a heavy crop load. Most years
treatments of summer NAA applied at five, seven and nine weeks after bloom will
increase return bloom even on varieties that have heavy crop loads and tend to
have poor return bloom. This timing is after any potential thinning from NAA
has past. Fruits are often one-inch in diameter and won’t respond to any NAA
thinning action. Flower bud initiation has already begun, but can be enhanced
by NAA treatments during the next 30 days after the thinning period ends.
Summer Ethrel can also
enhance return bloom by treatments of 200 ppm made at the same timing of five, seven
and nine weeks after bloom. However, summer Ethrel can some years thin 1-inch
diameter fruit and summer Ethrel can advance maturity of early maturing
varieties.
Summer NAA
Apply 5 ppm (2 oz/100 of Fruitone N) of NAA starting five weeks after
bloom and apply two additional spray treatments at seven and nine weeks after
bloom. The rate of NAA applied per acre should be adjusted to tree row volume
levels. The applications can be concentrated, but treatments will benefit from
increased water amounts. Try not to concentrate water amounts greater that four
times. These sprays can be added right to the cover sprays during that time
period. Some years these treatments do not perform well, especially during
drought years. Varieties that have a moderate to high biennial bearing
tendencies should be considered for bloom enhancement sprays (see Table 1).
Summer NAA treatments will not cause any adverse affects to the trees or crop.
Treatments during extremely hot temperatures (maximum temperatures above 95°F)
should be avoided. If surfactant or oil is included with the application,
consider reducing the NAA amount by one-third. Follow the guidelines listed in
Table 2.
|
Variety |
Biennial bearing tendency |
|
Cameo |
Moderate |
|
|
Low |
|
Empire |
Moderate |
|
|
High |
|
Gala |
Low |
|
Golden Delicious |
High |
|
Honeycrisp |
High |
|
Jonagold |
High |
|
Jonathan |
Low |
|
Macoun |
Moderate |
|
McIntosh |
Low |
|
Mutsu |
High |
|
Northern Spy |
Moderate |
|
Paulared |
Moderate |
|
Red Delicious |
High |
|
|
Low |
|
1. |
The target rate/acre is 8 oz Fruitone N (5 ppm) on full size trees (100%
TRV). |
8 oz/ per acre |
|
2. |
Determine the target blocks TRV. |
Example: 75% TRV |
|
3. |
Adjust the NAA rate per acre by the TRV. |
.75 * 8 oz = 6 oz/acre |
|
4. |
Apply at 4X water concentration or less. |
0 |
|
5. |
If surfactants or oil is included reduce NAA by 1/3. |
|
|
6. |
Avoid applications during extreme hot temperatures. |
0 |
Eric Hanson and Bernard Zandstra
Horticulture
Spring-applied herbicides do not always provide adequate
weed control through the harvest season. Summer flushes of annual grasses
(crabgrass, fall panicum) or broadleaves such as pigweed often are problems. Some
Increasing leaching potential à
Solicam < Karmex = Princep < Sinbar < Velpar
This means that weed control from Sinbar and Velpar is more likely to be reduced by heavy rains than perhaps Solicam. Unfortunately, herbicide options for use in mid-season are limited by label restrictions, primarily pre-harvest intervals. The label restrictions for preemergent materials are:
§ Solicam: 60 days PHI.
§ Karmex DF: Before germination and growth of weeds.
§ Princep Cal-90: Not when fruit are present.
§ Sinbar: During early seedling stage of weed growth.
§ Velpar: Before budbreak.
§ Chateau: Do not apply after bud break through final harvest.
§ Callisto: Do not apply after onset of the bloom stage.
Several post-emergent herbicides can potentially be used in the summer. Some can still be used before harvest, but others cannot be applied until after harvest. Each herbicide has different characteristics that need to be considered when making choices.
Aim, Gramoxone, and Rely are burn-down materials. Pre-harvest intervals are listed on the labels for Aim (one day) and Rely (14 days), but the Gramoxone label indicates it should not be applied after growth begins. These herbicides kill treated plant parts, but do not move within the plant. As a result, perennial weeds are usually not killed because the chemical does not move to the roots. Rely may move slightly in plants, because it often provides a slightly better control of some herbaceous perennials, such as dandelion. Aim is relatively inexpensive, but does not control grasses. Rely is much more expensive, but controls broadleaves and grasses. All three herbicides kill green bark and leaves of blueberries, so take care to keep spray off blueberries.
Fusilade and Poast are selective grass killers; they have no effect on bloadleaf weeds or blueberries. Poast has a PHI of 30 days, and Fusilade is only for non-bearing plantings. These products would not be effective if applied in the summer because the grasses are too old. Grasses must be treated when they are four to eight inches tall in the spring. If grass is taller, the control is poor.
Glyphosate (Roundup) products have a PHI of 14 days, so they can still be applied to most fields. Glyphosate is the most effective postemergent herbicide for blueberries, but also the most hazardous because it is absorbed by green tissues and moves throughout the plant. Perennial weeds are killed because the chemical moves to below-ground plant parts. Translocation is a two-edged sword. Glyphosate applied to blueberry branches moves within the bush, and can kill large canes or whole bushes. The most effective time to treat perennial weeds is late in the summer because absorbed glyphosate tends to move down to the roots. This timing is also most hazardous for blueberries. Use extreme care to avoid contact with blueberry tissues.
Eric Hanson,Horticulture; Mark Longstroth, MSUE educator
Irrigation is vital for maintaining high yields in
commercial blueberries in
|
System |
Percent of |
Advantages |
Disadvantages |
|
Overhead sprinklers |
36 |
High uniformity and rates Frost protection |
High installation/operation costs Large water supply needed |
|
Drip-trickle |
16 |
Low cost to install and operate High uniformity Small water supply |
Rates too low to catch up Can’t frost-protect Limited root zone coverage |
|
Traveling gun |
14 |
Moderate initial cost |
Poor uniformity Can’t protect from frost High operating costs |
|
Sub-irrigation |
4 |
Variable initial cost Low operating costs Canopy is dry |
Not suited for all sites Can’t protect from frost |
|
No irrigation |
30 |
No cost |
High risk |
1Michigan Department of Agriculture;
Overhead sprinklers are best where the water supply is adequate and spring frosts are likely. Trickle systems are best if your water supply is limited because they apply water directly in the row with little evaporation. Traveling guns are economical, but may apply excessive water rates and have poor uniformity.
The soil water reservoir depends on texture and rooting
depth (Table 1). Assume the rooting depth is 12-inches for young plants and
18-inches for older plants or excavate beside bushes to determine exact depths.
|
Soil texture |
Available
water (inches) |
|
|
Per inch of
depth |
In root zone
(12-18 inch
depth) |
|
|
Sands |
0.03 |
0.4 - 0.6 |
|
Loamy sand |
0.07 |
0.8 - 1.3 |
|
|
0.13 |
1.6 – 2.3 |
|
Loam |
0.17 |
2.0 – 3.1 |
Evapo-transpiration (ET) is the evaporation from the field,
plus the amount of water lost by the plant (transpiration). Blueberry fields in
southwest
Allowable soil moisture depletion in blueberries is generally considered to be 50 percent, so irrigate when half of the available water is used. This means that irrigation should be applied before 0.2 to 0.6-inches of water is lost from sands and loamy sands, or 0.8 to 1.5-inches are lost on sandy loam or loam soils.
Irrigation scheduling allows water to be applied when it is needed. This reduces costs, the amount of water used and loss of nutrients. You need to how much water the soil can hold. You should irrigate when half the available soil water has been used. If you know how much water the plants are using, you can irrigate when the plant has used half the available water. For example, a root zone of 18-inches on a loamy sand soil (0.07-inches of water per inch of depth) holds 1.3 inches of available water:
(18 inches) x (0.07 inches water/inch) = 1.3 inches water
If the root zone were depleted by 50 percent you would need to apply 0.65 inches:
(0.5 depletion) x (1.3 inches) = 0.65 inches to apply
If the ET for the last several days was 0.25 inches you would need to irrigate every two days; for 0.2 inches every three days and if the plants were only using 0.1-inches then you would need to irrigate every six days.
The evapotranspiration rate varies during the year depending
on the amount of leaves on the plants and the weather condition, heat and
relative humidity. The temperature is the most important factor, increased heat
increases ET much more than increasing humidity decreases ET.
Estimated blueberry water use in
|
Month |
Monthly use |
Weekly use |
Daily use |
|
May |
0.48 |
0.12 |
0.02 |
|
June |
2.87 |
0.72 |
0.10 |
|
July |
5.09 |
1.26 |
0.17 |
|
August |
2.13 |
0.53 |
0.07 |
The amount of water applied by sprinkler systems is determined by the size of the nozzle and the water pressure at the nozzle. For example a 9/64-inch nozzle at 45 psi will deliver about 0.15 inches an hour. If the system delivers 0.15 inches water per hour, 0.6 inches would be pumped in four hours. However, about 20 to 30 percent of water from overhead sprinklers may be lost to evaporation, so increase the operating time accordingly. Also, irrigation systems are not completely uniform; they apply more water in some areas than others. The uniformity of sprinkler systems can be measured (Ley, 1994b), but are usually only 70 percent uniform. This means that to recharge all areas of the field, 30 percent more water than calculated would need to be applied. In our example, operating time should be increased by 20 percent to account for evaporation losses, plus 30 percent due to non-uniformity. So, increase operating time of four hours by 50 percent to six hours to ensure all areas receive 0.6 inches.
The application rate for lower volume trickle systems (48-inch spacing, 0.42 gph emitters) is about 0.17 inches per hour. The more common moderate flow systems (24-inches spacing, 0.42 gph emitters) deliver about 0.3 inches per hour. Since evaporation and uniformity are not significant in trickle systems, we do not need to increase the application time. We would need to run the lower volume system twice as long to apply the same amount of water. These systems should be run at least one to two hours every day to replace the water used by the plants.
When: Thursday, June 19, 6:00-8:00PM.
Where: Tim
Seppala’s Farm,
What: Timely updates for control of diseases, insects, and weeds. This is a
free meeting with a light dinner served at 6:00 PM. Spray credits available for
attending. Hope to see you there!
For more information, contact Paul Jenkins at:
jenki132@msu.edu; or 517-432-7751.
When: Tuesday, June 24, 6:00-8:00 PM.
Where: Carini
Farms,
What: Timely updates for control of pre-harvest diseases, insects, and weeds.
This is a free meeting with a light dinner served at 6:00 PM. Spray credits
available for attending. Hope to see you there!
For more
information, contact Paul Jenkins at: jenki132@msu.edu;
or 517-432-7751.
Last week’s weather was generally dry with highs near 80°F, and lows in the 50s and 60s. Scattered storms passed through the region over the weekend. These storms brought rain and hail in some areas. Rainfall totals from these storms was generally light, from a tenth to less than an inch. Soil moisture levels are falling and sandy soils are becoming dry. We expect cool temperatures for the coming week with highs near 70°F and lows near 50°F. Our GDD totals are now about three or four days behind 2007.
|
|
Grapes, from April 1 |
|||
|
Location |
GDD 42 |
GDD 45 |
GDD 50 |
GDD 50 |
|
1161 |
971 |
699 |
693 |
|
|
1237 |
1038 |
750 |
745 |
|
|
1061 |
877 |
617 |
613 |
|
Deer browsing
continues to be a problem in many fruit plantings. The warm temperatures
increased insect activity. Leaf roller larvae are
feeding in some orchards. Young trees should receive sprays to kill potato leafhoppers. Tarnished plant bug feeding
damage has been reported in apples and peaches. Rose chafer is out and Japanese
beetles are emerging. Obliquebanded
leafroller adults were trapped last Monday, indicating the flight of the
overwintering generation has started. Aphid numbers are
building. We are catching lesser
peach tree borer. Trunk sprays or pheromone disruption are recommended for
borer control.
Apricots are almost two inches in diameter.
Peaches are 1 to 1.5 inches in diameter. Growers are hand thinning excess fruit. Oriental fruit moth egg hatch has ended and few shoot strikes have been reported. Pit hardening has not yet begun. Bacterial spot has been reported, but not peach scab or rusty spot (powdery mildew). Green peach aphid populations are climbing.
Sweet cherries are coloring and showing red color. Harvest of early varieties such as Cavalier should begin late this week. The cool, dry weather has suppressed brown rot infection. Brown rot requires warm, wet conditions, five to six hours of wetness at 70°F and growers should be prepared to protect against this disease at harvest. The weekend rains were cherry leaf spot infections in some areas.
Tart cherries are coloring. Growers should wait until all the fruit are straw-colored before applying ethephon sprays. Recent rains were cherry leaf spot infections in some areas. No cherry leaf spot symptoms have been reported. Bacterial canker symptoms can be found on tart cherry leaves and fruit.
Plums are almost an inch in diameter and the pits are hardening. Growers still need to protect against black knot. Plum trees also need to be protected from the peach tree borers.
Apples are an
inch in diameter. Fruit drop over the several weeks has been heavy and for some
varieties the crop is very light. Apple
scab leaf symptoms can be found in sprayed orchards. These lesions will
release spores during every rain. Growers with active scab should continue to
protect against scab infection. Waxy fruit is resistant to scab. Fire blight
infections are becoming more common, but they are not severe in most orchards. Trap catch for codling
moth remains high. We are now in the treatment window for codling
moth and egg hatch is underway throughout the region. Spotted tentiform leafminer
will form leaf mines soon. White apple leafhopper is
hard to find. European
red mites are moving about. San Jose scale
adults are flying. Sprays for San Jose scale crawler should be targeted for 300
GDD50 after biofix (June 1), about June 20. Green aphid populations
are climbing.
Pears are 24 mm in diameter. The crop looks good.
Blueberries are growing rapidly. Cranberry fruitworm trap numbers are still high, and controls have been applied to many fields. Post bloom fungicide sprays should target anthracnose. More growers are reporting dead blossom clusters caused by phomopsis infections of the flower clusters. Shoestring symptoms are easy to find.
In grapes,
Strawberry harvest has begun. Warm temperatures and dry conditions following the rains of June 5-7, have moved the crop rapidly. Fruit size and quality are excellent. Cool conditions should extend the season. Leather rot and sap beetles can be found in some fields.
Raspberry and blackberry bloom is ending. Growers should be scouting for Japanese beetles. Raspberry sawfly larvae and leafroller larvae are feeding in some plantings. Raspberry sawfly eats the leaves between the veins, while leaf rollers curl and web the leaves together. Raspberry cane borers are laying eggs, so look for wilting shoot tips and a ring of parallel girdles at the base of the wilting. The eggs are laid between the girdles. Primocanes in fall bearing raspberries are 12 to 18 inches tall.
Cranberry bloom has begun.
The next Monday Fruit Update
meeting will be Monday, June 23 at
the Fruit Acres Farm in
There is a twilight
grape IPM meeting Thursday, June 19
at Tim Seppala's farm, southeast of
There is a Blueberry IPM meeting Wednesday, June 24 at Carini
Farms in
Most areas of southeastern
|
Location |
GDD42 |
GDD45 |
GDD50 |
|
Commerce ( |
1145 |
954 |
679 |
|
Emmett (St Clair) |
1106 |
929 |
660 |
|
|
1161 |
969 |
699 |
|
Lapeer (Lapeer) |
1142 |
957 |
691 |
|
|
1224 |
1024 |
740 |
|
Romeo ( |
1153 |
961 |
682 |
Apples have taken on a big swell of growth over the last week. Most apples
are in the range of 1.0 to 1.25-inch in diameter. Apple drop from thinning and
frost/freeze injury seems to be coming to an end here. I would assess our apple
crops as being a good crop overall, however with some varieties being very
light, most notably Northern Spy, and other varieties, like Golden Delicious,
being generally being too heavy.
Codling moth trap
catches have remained high over the last week. Overall, as I look at codling
moth trap catches this season, we’ve had some very high trap catches. Even in
some pheromone disruption blocks that have been disrupted for a good number of
years; I am seeing some fairly high trap catch numbers. I think this bears
watching throughout the rest of the season.
I reported last week
that apple scab lesions were more prevalent across the district. I continue to
find it on both the top and bottom of the leaf, and generally the leaves are a
little over a month old. I think that most of this scab came in early May
sometime. It’s puzzling why we are seeing so much scab this year around the
district, as many growers have done a good job of trying to keep them under
control. The apple scab lesions appear to be burned out at most farms, and I
think that the story is pretty much history.
With the rain event
of Saturday night, I caught apple scab spores. One of the two trapping stations
had a rain event on Sunday night, and from that station I caught no spores. Based
on the time of year and more importantly the fact that we didn’t catch any spores
at one of our trapping stations, I am calling an end to primary apple scab
season as of Sunday. Fireblight strikes continue to be seen, however the
numbers are very low and does not appear to be getting any worse.
Pears are about one-inch in diameter. There is a fair amount of pear psylla
showing up in suckers. I believe that fruit finish may be an issue this year
from frost/freeze injury. We generally have a light crop of pears this season.
Peaches have a wide variety of fruit sizes on them, with the largest fruit
being 1.25-inches in diameter, and most of the fruit is between 18 mm to 23 mm.
It is now pretty evident what fruit is going to remain on the tree at harvest
time, and therefore many peach growers are thinning quite aggressively. Tarnished
plant bug continues to be seen in fairly high numbers in some peach blocks.
Sweet cherries are nearing harvest for some of the early maturing
varieties; I estimate that we will begin harvest at most farms in about a
little under a week. The maturity cycle in sweet cherries has been shortened
this year. Most fruit are around 20 mm to 22 mm in size, with some of the
larger fruit being 24 mm. On some of these early varieties, it has been amazing
to see how much the fruit have colored over the last week. Cherry fruit flies
have been caught in traps at two farms in the last two days. It seems as if
cherry fruit flies have been flying much earlier the last several seasons, as
this is the earliest that I have ever caught cherry fruit fly in sweet
cherries. Some signs of plum curculio stinging have been seen in both sweet and
tart cherries. There have been some reports of bacterial canker infected spurs
in sweets as well.
Tart cherries have not sized much over the last several
weeks, with most fruit being in the 12 mm to 14 mm size. We are at pit
hardening. There continues to be a fair amount of drop in tart cherries. Fruit
finish is also poor due to freeze and frost injury.
Plums continue to drop quite heavily with most fruit averaging about one-inch
in diameter.
Strawberry harvest is now underway across the entire region. We have a nice crop
of strawberries coming along this year at most farms. Strawberry harvest and
heat don’t go well together, so growers are welcoming this recent cooler
weather. Leather rot is a new problem to report at a few strawberry farms this
past week. I have also seen some strawberries grown in southeast
Raspberries are nearing the end of bloom and are at fruit
set for just about all of our summer bearing varieties. Fall raspberries are
about 15-inches to 20-inches in length. Raspberry sawfly feeding injury to
foliage has now slowed a bit. There are several farms that had significant
amounts of sawfly damage at this time last week.
Blueberries are at fruit set to small green fruit across the region. In cutting a
good amount of fruit over the last week, there appears to be some brown
discoloration from frost/freeze injury that is lingering in the fruit. Where
the damage is severe, I expect that fruit to drop prior to harvest, where
damage is lighter, I would expect fruit to continue to mature, however not
being as large in size as normal. Cranberry fruitworm and cherry fruitworm
covers were applied over the last week at most farms.
Phil Schwallier
Amy Irish Brown
Carlos Garcia-Salazar
Degree day accumulations at the Sparta
weather station continue to be right at or slightly ahead of average. Most
apples are in the 20 to 25 mm stage or bigger. There seems to be quite a heavy
fruit drop going on in apples with some blocks nearly completely without fruit.
Overall, we might be looking at 50 percent of an apple crop in the
If there was any trauma blight from high winds or isolated hail during the June storms, it will probably start to show up at any time now, so be watching closely for that. There are a few reports of trauma blight showing up.
Nectria canker is being seen in Romes. At first, it will look like a fire blight strike, but if you look closely, you won’t see any oozing bacteria, but rather a sunken canker area from the nectria fungus.
No new egg laying scars from plum curculio have been found in tree fruits, but there are reports from other areas of the state where they are still active. Continue to monitor for plum curculio closely.
Additional newly laid European red mite eggs can be found. New nymphs are expected to be seen soon. Continue to monitor mites closely.
For codling moth, a regional biofix has been set for the
Obliquebanded leafroller are starting to fly, but not very regularly so a biofix has not been set for the region yet.
A regional biofix for Oriental fruit moth has been set on May 8. We have accumulated 601 degree days base 45 since that biofix, so Oriental fruit moth should be just past peak egg hatch right now. Cover sprays are still very important in stone fruits to prevent shoot damage and fruit damage as well, especially peaches and sweet cherries.
Blueberries
in central
Regarding other weather related damages, we are finding that
many fields located in
Another effect of late frosts is seen in young plants. There was injury to tender growth that became a port of entry for Phomopsis infections (Photo 2). Growers need to take measures to control these infections in order to prevent further damage. One measure is to prune the infected shoots and apply any of the fungicides recommended in our Michigan Fruit Management Guide. The freeze/frost damage is also observed in some early varieties across the central region, mainly in fields located in low lands (Photo 3). These fields are showing shoot dieback resulting also from Phomopsis infections. Again, it is advisable that growers observing these symptoms in their fields take samples and send them to the MSU Diagnostic Lab for identification and take the appropriate control measures.
A series of storms and rain have occurred over the past
week. This area has not seen so much rain in such a short period in time in
many years, if ever before. Reportedly,
Crop report
Our “short” crop is getting smaller.
There is a lot of fruit drop in apples, cherries and peaches.
West
|
|
|
|
|
Rainfall in last week |
Rainfall since 4/1 |
|
Hart |
949 |
776 |
531 |
3.31 |
9.9 |
|
Ludington |
902 |
734 |
494 |
6.31 |
13.39 |
|
Manistee |
935 |
765 |
527 |
5.92 |
12.9 |
Stormy conditions created a suitable environment for disease
development. Last week there were two apple scab infections for Oceana and Mason
counties and three infections in Manistee and
Fireblight is of major concern, after all of the rain, wind and hail and quite warm temperatures that followed, fireblight symptoms are starting to show up. Canker margins started oozing just before the storm providing plenty of inoculum to be dispersed around and find a home within the tender newly developing leaves, broken shoots, hail-injured leaves, shoots and fruit.
Nectria shoot blight symptoms are present in
There were two (Oceana and Mason counties) to three (
Bacterial leaf spot and bacterial canker symptoms are spread widely throughout the district.
Brown rot symptoms are starting to appear on the frost and freeze injured cherry fruit that has not fallen off and is beginning to crack as the fruit is gaining in size.
Cherry leaves with cherry-yellows symptoms are starting to drop profusely.
Powdery mildew is becoming more visible in the blocks.
Insects
have been quite active. Codling moth numbers have gone up significantly. The
average catch is from 8.6 moths per trap in
|
|
GDD at Biofix- May 24 |
Accumulated GDD since Biofix |
|
Hart |
229 |
315 |
|
Ludington |
217 |
289 |
|
Manistee/Bear |
242 |
299 |
There are reports of the first rose chafers in the area.
Nikki Rothwell
Duke Elsner, Erin
Lizotte, Rob Sirrine
GDD42 906
GDD50 490
Apples are at 16-18 mm.
Sweet cherries: Hedelfingen amd Napoleon have 13 mm fruit. Gold have 12 mm fruit.
Tart cherries: Montmorency and Balaton have 13 mm fruit.
Apricots have 28 mm fruit.
Plums are 15 mm.
Grapes have 10-16 inch shoots.
Weather
The weather continues to surprise us again this week. Despite the meteorologists’ best efforts, we never know what to expect with the current weather conditions. Last week, temperatures were more seasonable as daytime highs were in the mid- to upper 70s, and nighttime temperatures were in the mid-50s to the 60s. Growing degree accumulations are behind where we were at this time last year, and at base 42 and 50, we have accumulated 906 and 490 GDD respectively.
We received significant rainfall in the region in the past
week. Here at the NWMHRS, we accumulated 0.4 inches of rain on Thursday, June
12, 0.95 inches on June 13 and another 0.12 inches on June 15. The rain continues
this Tuesday morning. We also have reports of significant hail in southern
June 17, a 19-day period, we have had only five days without some recorded precipitation. Overall, we have had good moisture this season, which is much needed after droughty summer conditions in the past three seasons.
The final verdict on the cherry crop report is still out as
much of the region is experiencing June drop. Sweet cherry orchards with what
initially appeared as a healthy crop have dropped a lot of fruit in the past
week. The surprisingly sizable June drop may be attributed to poor pollination,
freeze/frost damage, or to the past years’ droughty conditions. Additionally,
many sweet cherry orchards do not appear to be as healthy as we would expect
with all the good moisture; we have observed tattered foliage, yellowish
leaves, and symptoms of bacterial canker. Tart cherries continue to size, and
the crop is estimated at 60 million pounds in northwest
We are still in the grips of the primary apple scab season,
but it is winding down with 90 percent of the ascospores or sexual spores,
estimated to have been released from their overwintering structures. The rain
we received over the weekend caused a predicted light to moderate infection
period in most of the region. Protectants to prevent apple scab should continue
to be applied. The fire blight model has slowed EIP accumulation due to the
cooler weather, which is predicted to last through Wednesday. Most varieties
have finished blooming, but we have been seeing a great deal of tag bloom which
needs continued protection for fireblight. Strep applications are recommended
to treat fire blight in northwest
Cherry leaf spot is still predicted in the region based on Saturday and Sunday’s rainfall. If growers applied a protective fungicide, such as Pristine or Gem, these are locally systemic and rainfast after two hours, the foliage in these cases should be protected. If fungicides have been applied on alternate rows, then the interval between sprays should be shortened by two to three days. We are seeing a great deal of bacterial canker in sweet cherries at the Northwest Station, particularly on those in low-lying sites that were hit hard by the freeze after Memorial Day weekend. Powdery mildew is also showing up on tarts at the station. We continue to see plum curculio stings on cherries. We are continuing to catch American plum borer and lesser peach tree borer at approximately 15 per trap. We are also catching low levels of greater peach tree borer in our station traps.
In grapes, we have
been seeing potato leaf hopper and an unusual insect, grape plume moth.
Grape phylloxera, Daktulosphaira
vitifoliae (Fitch) was sited in one of our commercial vineyards. These insects
rarely make serious pest status in areas with our sandy soils; they are
considered to be more problematic in regions with heavier clay soils. Despite
the fact we rarely see damaging numbers of phylloxera in the north, we remind
growers to be vigilant about control. This caution should be particularly noted
in choosing a phylloxera-resistant/tolerant rootstock for newly planted vines.
If populations reach high enough levels, the foliar or aerial part of the
phylloxera life cycle can result in premature defoliation, reduced shoot
growth, and reduced yield and quality of the crop. We often observe foliar
damage on wild grape, labrusca and some vinifera vineyards as raised galls on
the undersides of leaves in the eastern part of the
Jeff Andresen
Agricultural Meteorology
Geography
A large area of training thunderstorms (storms which form
and move repeatedly across the same areas) brought torrential rains and
widespread flooding to sections of northwest lower Michigan last Thursday and
Friday (June 12-13). More than six inches of rain fell from Mason and Manistee
counties northeastward into Wexford,
In contrast to the turbulent and quickly changing weather
experienced during the past couple of weeks in
In the medium range forecast, the
National Weather Service 6‑10 day
and 8-14 day outlooks covering June
22 through June 28 and June 24-30, both call for precipitation totals to remain
at below normal levels. Mean temperatures are forecast to remain at below
normal levels during the 6-10 day period, moderating to near normal levels
during the 8-14 day time frame.