Regional reports on Michigan fruit – June 19, 2012

MSU Extension educators’ pest and fruit updates for Michigan.

This week’s regional reports:

Southwest Michigan – Mark Longstroth, Bill Shane, Diane Brown, Michigan State University Extension

Southwest Michigan
Southwest Michigan

Weather

Last week was warm, with temperatures rising from 70 degrees Fahrenheit on June 12 to 90 on June 14, and remained hot through the weekend. Weather for this week is forecast to start hot and fall to the 80s. There is a chance of rain Thursday (June 21).

Soils are dry and crops are showing signs of drought stress. The potential evapotranspiration is about 0.2 inches of water a day and this rate will continue this week. This means established crops are using about an inch of water every five days, if it is available. Otherwise, plants are shutting down to conserve water. The dry conditions are suppressing the emergence of some insect pests from the soil. Our growing degree day accumulations continue about two weeks ahead of an average year. Southern sites are only about five days ahead of northern sites in the region.

Southwest Michigan Growing Degree Day Totals from January 1 through June 17

Location

GDD 42

GDD 45

GDD 50

Bainbridge

1439

1210

870

Trevor Nichols

1349

1120

787

Increase since 6/10/12

200

160

130

Small fruit

Japanese beetles emerged late last week, but are still scarce. Japanese beetles should emerge in greater numbers following a rain (about 0.25 inches). We did not see many rose chafers this year. We had had a general decline of this pest over the last five years. Spotted wing Drosophila (SWD) flies are being trapped in the region, but no SWD in yeast-baited traps in raspberries or strawberries in the Southwest Michigan Research and Education Center (SWMREC) high tunnels.

Strawberry harvest has ended and growers will begin renovation soon.

Bramble harvest is underway with both red and black raspberries. Growers should be irrigating to maintain fruit growth. Insect pests to scout for include raspberry sawfly, leafrollers and raspberry cane girdlers. With the hot, dry weather, growers should be on the lookout for spider mites, particularly in high tunnel raspberry plantings. Japanese beetles can be a problem at harvest. Hopper burn from potato leafhoppers is increasing in raspberry plantings.

In grapes, ‘Concord’ and ‘Niagara’ bloom is ending. Fruit on the primary shoots has reached berry touch. Fruit on secondary shoots is at buckshot berries. Wine grape development is not quite as advanced, but it shows the same degree of developmental differences between primary and secondary shoots. Phomopsis and black rot are present in unsprayed vineyards, but dry weather has kept disease severity low. We have not found powdery mildew in vineyards we scout, but it has been found elsewhere. No downy mildew has been detected.

Grape berry moth trap catches increased last week. Initial biofix for grape berry moth was set in the southern Berrien County on May 18 and on May 21 in northern Berrien and Van Buren counties. The grape berry moth model on Enviro-weather predicts the second generation should begin about June 25 for locations in southern Berrien County.

Blueberry harvest has begun. Growers should be irrigating to maintain fruit. Leaf burn from drought stress was reported in unirrigated fields. Cane collapse from phomopsis is beginning. Fruit affected by fruitworms are shriveling and turning blue and dropping off the bush. Small, black spots on green fruit are very noticeable this year. Their cause is unknown, but they become inconspicuous after the fruit colors. Controls for anthracnose should be applied as the fruit reaches 10 percent blue in a field.

dark spots
Dark spots on green blueberry fruit are very noticeable, but these spots are
inconspicuous on ripe fruit and do not cause a problem. Photo credit: Mark Longstroth, MSUE

Blueberry maggot flies are being caught in commercial blueberry fields. Growers can expect this pest to emerge in good numbers after a rain. Spotted winged Drosophila flies are being trapped in Allegan, Ottawa and Van Buren counties. Growers should be monitoring for these pests. For more insect scouting information, see the Blueberry Insect Scouting Report for June 11-17, 2012.

ripe bluetta
Bluetta are one of the earliest blueberries and these fruit will be
harvested soon. Photo credit: Mark Longstroth, MSUE

Tree fruit

San Jose scale crawlers are settling and will become protected against insecticide treatment shortly. Trap catches for most moth pests increased last week with the hot weather and warm nights. Redbanded leafroller trap catches are up marking the start of the second generation. Dry soils are causing wilting of many fruit plants in sandy sites. Growers should irrigate plant material established this spring. Growers with well-established plantings and no fruit can reduce irrigation in tree fruits to reduce growth. Irrigation should only be reduced by a quarter or a third, not cut off completely.

Peach fruit are about 2 inches in diameter and the pits are hardening. Very early varieties are developing blush with some harvest expected next week. Rusty spot (powdery mildew) susceptibility stops with pit hardening. Bacterial spot susceptibility of fruit also declines with pit hardening. X-disease symptoms are becoming apparent. Trees infected with X-disease should be removed. Growth is abundant in sites with little or no crop, adequate water and fertilizer. Oriental fruit moth trap catches increased at some sites, signaling the beginning of the second generation.

Sweet cherry harvest has ended.

Tart cherry harvest has begun. Large flocks of birds are in tart cherry orchards with fruit and losses to birds are severe in most blocks with good crops. Due to the dry conditions, cherry leaf spot is not a serious problem.

Japanese plums are about 1 inch in diameter.

Apple fruits are 1.25 to 1.5 inches in diameter. Codling moth trap catch was up last week. Codling moth biofix was set as May 7 and moth flight should be declining. Obliquebanded leafroller biofix was May 19 and we are past peak egg hatch. Scout for larvae feeding in terminals. Oriental fruit moth second generation is beginning. Redbanded leafroller second generation is also beginning. European red mites should be monitored and the treatment threshold is five mites per leaf. Mature trees without fruit can probably withstand higher levels of mite infestation with little damage. The first apple maggot flies have been trapped, which is generally followed in eight to 10 days by egglaying.

Fire blight symptoms are increasing at some sites. Powdery mildew symptoms are common and growers should control this disease to prevent loss of fruit buds in the winter. Green apple aphids can be seen in some sites.

Pear fruit are about an inch in diameter on Harrow Sweet. Pear psylla is present in low numbers. Fire blight symptoms are present at some locations.

Upcoming meetings

Fruit IPM Meeting
The final Monday fruit meeting will be June 25 at Fruit Acres Farms at 5 p.m. Fruit Acres is located on the northeast corner of Friday and Carmody Roads, about 1.5 miles south of the Coloma Exit on I-94 (view map). One RUP credit is available at the meeting.

Sprayer Rodeo
Register now for the “Sprayer Rodeo” to be held at SWMREC on June 27 from 3 to 8 p.m. Even though this meeting is targeted for grape growers, other fruit growers will want to attend. RSVP to the Berrien County Extension office at 1-269-944-4126 by June 25 if you plan to attend. Cost for the meeting is $25 and includes supper and 4 RUP credits. Contact MSU Extension’s .(JavaScript must be enabled to view this email address) at 269-944-0157 for details on bringing your sprayer to have it calibrated.

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Southeast Michigan – Bob Tritten, Michigan State University Extension

Southeast Michigan
Southeast Michigan

Weather

Dry soil conditions have continued across the region, with fruit growers applying irrigation to both new and established plantings. We’ve received two to three wetting events in the last week; most fruit farms did not receive enough to overcome our moisture deficit. A few fortunate growers received close to an inch of rain, while most only received just a few tenths. All of the rain events were from scattered thundershowers. No hail was reported.

Our early, warm season is still running two weeks ahead of normal in terms of growth stages, and even more than that in terms of degree day totals.

East Michigan Growing Degree Day Totals for March 1 to June 18

Location

GDD42

GDD45

GDD50

Commerce (Oakland)

1535

1285

915

Emmett (St Clair)

1510

1267

906

Flint (Genesee)

1572

1321

953

Lapeer (Lapeer)

1536

1318

951

Petersburg (Monroe)

1655

1398

1013

Pigeon (Huron)

1451

1211

863

Romeo (Macomb)

1569

1320

946

Tree fruits

Apples are approaching 1.5 inches in diameter where growers have a crop. Where growers have a crop (mostly in the very southern tier of Michigan counties), hand-thinning continues. Growers are finding a fair amount of frost rings and scarring from freeze damage. More apples are continuing to show up in these areas. The crop is so inconsistent from variety to variety, tree to tree and even limb to limb, that hand-thinning will be a time consuming and expensive process this year. Most apple trees have between 14 and 20 inches of new growth, with some terminals reaching 26 inches of new growth.

Potato leafhopper leaf curling has become very common in the last week. In most unsprayed apple blocks, almost every leaf is curled from this insect. I recommend that this pest be controlled in young apple blocks and in valuable varieties, like Honeycrisp. Otherwise, insect pressure remains low. Codling moth trap catch numbers are on the decline for the second week as we are nearing an end to first generation adult flight. We had four weeks of record-breaking numbers of codling moths caught in traps this season, even in mating disrupted blocks. Where growers have an apple crop this season, the second generation adult flight will need to be closely monitored and controlled. San Jose scale crawlers are settling down, indicating that the window is now closed for its control for the first generation. Mite numbers are being kept in check at most farms. Apple maggot traps should be set this week.

As I shared in last week’s regional report, I called an end to primary apple scab season as of June 12. I am seeing more apple blocks with sheet scab. Powdery mildew-infected terminal branches and individual leaves have become much more evident in the past few weeks; some varieties are heavily infected, and some terminal limbs are starting to die from this disease. I am encouraging apple growers to keep a close eye on powdery mildew infections in valuable and susceptible varieties, even in blocks with no fruit. Some growers without a crop are considering sulfur applications to help control it. It is hard on foliage, however. Sooty blotch and fly speck symptoms are just starting to be seen in a few apple blocks, where the threshold of 240 hours of wetting has now been reached.

Pear suckers have put on a tremendous amount of growth this season, some reaching 4 to 5 feet in length. Pear psylla populations continue to grow quickly in unsprayed blocks. Suckers need to be removed to help reduce pear psylla populations.

Peach leaves where there is no crop are looking more normal in size, color and volume, with most of the freeze-injured leaves now dropping to the orchard floor. Harvest is expected to begin for the earliest of peach varieties in a week or so. As expected, there is a fair amount of split pit in these early varieties. Hand-thinning continues in peaches.

Sweet cherry harvest has wrapped up for growers with a crop. With so little crop in the area, bird feeding was extensive. Cherry leaf spot disease needs to be controlled in blocks that have no crop and maybe cherry fruit fly in blocks with a history of this pest.

Tart cherry harvest is underway at most farms where there is a crop. Bird feeding has already begun.

Plum fruit drop continues where there is a crop. Most blocks have little to no viable fruit this season.

Small fruits

Strawberry harvest is wrapping up fairly quickly at farms in the southern part of the region and will finish up later in the week at most others. Berry size in these areas is starting to diminish. Root weevils have been found at three farms in the last week. Effected plants quickly collapse in the stress of the harvest season and heat of summer. Sap beetle feeding damage has been reported at two farms in the last week. Thrip fruit feeding damage has been seen at a few more farms in the last week. Thrip damage is rare in Michigan strawberry culture. Newly planted strawberries are runnering well where flower trusses have been removed. Black caps from angular leaf spot disease continue to be seen.

Raspberry harvest continues on summer fruiting varieties. At most farms, summer-bearing raspberries had a great deal of tip burn or dieback from the April freeze events. Canes of fall bearing types have 18 to 24 inches of new growth. Raspberry cane borer flagging damage continues to be seen. Raspberry sawfly leaf feeding damage continues to be seen at a few farms. Remember to check spotted wing Drosophila traps at least twice a week. None have been found for the season in eastern Michigan, although they have been found in traps in west Michigan for the last three weeks.

Blueberries continue to color, with most being 14 mm in size. Harvest is expected to begin in the next 10 days for early maturing varieties. Leaf growth is beginning to pick up on freeze-damaged varieties. It is odd to see all of the fruit exposed as it has been thus far this season. Some of this fruit on the effected varieties will most likely not mature correctly. Fruit drop continues on freeze-damaged varieties. No blueberry maggots have been caught in traps. Remember to check spotted wing Drosophila traps.

Grapes are now buckshot in size. Grape berry moth trap catch is on the decline.

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Grand Rapids Area Tree Fruit– Amy Irish Brown and Phil Schwallier, Michigan State University Extension

Grand Rapids Area
Grand Rapids Area

Crop update

Tart cherry harvest has started in some areas. Sweet cherry harvest has also begun and fruit has been large and of good quality up until the heavy rain moved through Monday (June 18). It will be a short cherry harvest. Strawberry harvest is winding up with only the latest cultivars having fruit left.

Horticultural tasks to consider

Some areas had rain over the past weekend and into Monday (June 18). Rainfall totals were quite variable across all of the west Michigan area. Even where rainfall was over an inch, the soil has absorbed it quickly and the overall soil condition is still drier than it should be for late June. Irrigation continues to be recommended in newly planted trees and trickle irrigation should be on in blocks that have it.

Rainfall totals for the past few days and the year’s total

Weather station

Rainfall (in.) on June 16

Rainfall (in.) on June 17

Rainfall (in.) on June 18

Rainfall (in.) June 16-18

Rainfall (in.) since Jan. 1

Belding

0.36

0.11

0.64

1.11

11.98

CHES

0.00

0.09

0.52

0.61

12.31

Fennville

0.20

0.07

0.00

0.27

11.55

Fremont

0.26

0.37

1.15

1.78

13.20

Hart

0.01

0.63

1.06

1.70

11.29

Hudsonville

0.06

0.10

0.05

0.21

9.18

Kent City

0.31

0.12

0.94

1.37

12.79

Ludington

0.05

0.43

1.33

1.81

13.44

Sparta

0.11

0.19

1.08

1.38

14.88

Data from MSU’s Enviro-weather.

Fire blight update

There were some high winds and reports of hail from the storms over the weekend and on Monday (June 18), but it appears that the hail missed primary tree fruit growing areas. If we have storm situations that tear foliage, you need to cover up for the possibility of trauma fire blight until we get to terminal bud set.

Apple scab

Continue to monitor blocks where primary scab became established and apply fungicides as needed to prevent spread to leaves. With the light crop load, you might think that you can just let the scab go, but heavy infections could lead to early defoliation which will weaken trees and open them up to winter injury.

Powdery mildew

Mildew continues to spread, especially with the humid weather of late. Some apple orchards have 30 percent of terminals infected. Mildew on peach fruits is also being seen.

Tree fruit insects

Obliquebanded leafroller adult flight is declining. A regional biofix was set for May 26. We have accumulated 498 degree days base 42 since then. Early egg hatch should be started. Larvae will be very hard to find until later in the week. In blocks with viable fruits and high pressure from obliquebanded leafrollers in 2011, cover sprays are needed now. In low pressure blocks, you could scout for larvae and then manage them.

Codling moth. We have accumulated 583 DD50 since the May 3 biofix on the Ridge, indicating egg hatch is at a peak. Adult males in traps continue to decline, but are still being caught in some areas. Some sites set a later biofix around May 18 – we have accumulated 464 DD50 since that date which indicates about 40 percent of the eggs are hatched for that timing and cover sprays are essential for those blocks that are over threshold and have viable fruit planned to be harvested. Codling moth larvae will be active until at least the first week in July.

Oriental fruit moth. A regional biofix was set for oriental fruit moth on April 15 and we’ve accumulated 767 DD45 since then. Flight of second generation has started. Egg hatch is likely to reach 10 percent by June 21 or 22, a bit earlier than predicted last week due to the very warm weather. Cover sprays to protect growing shoots and fruits of stone fruits will be needed again by the end of the week.

Dogwood borer adult flight started a week ago and numbers are still low. Timing for dogwood borer trunk sprays is at peak adult flight, usually around July 4. Peak flight could be a week earlier this year, so trunk sprays could begin the last week of June – it is a bit early to get it started yet.

Cherry fruit flies continue to be reported. In general, once you start catching them, you have about 10 days to get the fruit off before you end up with a detectable problem of larvae being large enough to be found floating in the tanks. You have to be trapping to know what’s going on.

A bigger potential problem in tarts is spotted wing Drosophila, especially if you are not getting those insecticide sprays on for fruit flies. They could build in numbers quickly. Again, you have to monitor for them to know what’s going on.

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Grand Rapids Area Small Fruit– Carlos García-Salazar, Michigan State University Extension

Grand Rapids Area
Grand Rapids Area

Weather conditions during the last week have been dominated by high temperatures reaching the lower 90s. Rains have been spotty with an average accumulation over the past week of less than 1 inch. Degree day accumulation in the area since March 1 has reached 967 (base 50 degrees Fahrenheit) and 1,588 (base 42 degrees Fahrenheit).

Strawberry harvest is coming to an end due to intense heat that occurred during the past week. Yields were not as expected. There was a decrease in the size of the crop attributed mainly to the spring frosts that occurred early in the season. On the other hand, spotted wing Drosophila traps on strawberries are not showing any infestation. Most insect problems during the present season have been related to tarnished plant bugs (Lygus spp.) and sap beetles.

Blueberry harvest has started for the early varieties Wayman, Bluetta and Duke. However, the size of the blueberries is disappointing. Since the king blooms were killed by spring frosts, the secondary flowers are not compensating for the lost portion of the crop. Those flowers are producing small blueberries and the size is smaller than usual. Because of this problem, growers will not hand harvest those berries; instead, they will machine harvest the blueberries with their destination being for processing.

Presently, insect pest problems in blueberries are related to cranberry fruitworms and spotted wing Drosophila. During the past week, there was an increase in the activity of adult cranberry fruitworms, but we do not expect new fruit damage. For Drosophila flies, so far they have been found in several blueberry fields, but no fruit damage has been reported.

Blueberry IPM Twilight Meeting

On June 21, we will continue with our series of Blueberry IPM Twilight meetings. The pre-harvest meeting will be held at the main conference room of the Ottawa County Fillmore Complex from 6:30 to 8 p.m. Topics that will be discussed at the meeting are:

Also, Ottawa County Drain Commissioner Paul M. Geerlings will present an update on the situation related to the Park West Drain project. This is an important issue for blueberry growers in Ottawa County since the implementation of this project may affect blueberry fields located in the proximity of the proposed drain project. We encourage growers to attend this meeting to be better informed.

There is a $5 charge that includes handouts and light refreshments. Participants will receive 2 RUPs. The address for the meeting is 12220 Fillmore Street, West Olive, Mich. (view map).

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Northwest Michigan – Nikki Rothwell, Duke Elsner, Erin Lizotte, Michigan State University Extension

Northwest Michigan
Northwest Michigan

Weather report

In the past week, our temperatures varied from the mid-70s into the high 80s over the weekend, and the forecast is predicting temperatures to hit the 90s in the next two days (as of June 19). Humidity has also been high, and this situation is cause for concern with the cherry leaf spot symptoms showing up throughout the northwest. In 2012, we have accumulated 1383 GDD base 42 and 816 GDD base 50, and these accumulations are still higher than our 22-year averages: 1018 GDD base 42 and 566.5 GDD base 50. We have also received substantial rainfall over the past week. Here at the Northwest Michigan Horticultural Research Station (NWMHRS), we received 1.72 inches on June 17, 0.18 inches on June 18 and another 0.72 inches on June 19. The rainfall over the last evening came as a thunderstorm coupled with high winds and an intense downpour.

Crop report

Growers are currently applying ethephon to sweet cherries, and harvest in early varieties will start within the next week. Ethephon applications in the forecasted heat may cause phytotoxicity, and we are recommending growers reduce their rates to 75 percent of a full rate if temperatures are over 84 degrees Fahrenheit. Cracking may be a problem with such a light sweet cherry crop and the recent rains. Apples are still looking good and, as of this morning (June 19), we have had no reports of hail associated with the thunderstorms of last evening. However, with high winds and extreme downpours, trauma may have been caused to apple trees in some orchards. Strawberry harvest is still underway, and although the size is small, the quality is good. This coming heat will not be conducive for stretching out the strawberry harvest.

Pest report

Cherries. There is tremendous leaf loss in tart cherries (see Yellowing leaves and leaf loss reported in tart cherries). Defoliation will vary from orchard to orchard, but there are reports of extremely high levels of leaf loss throughout the region. We suspect that this leaf drop is due to the following: sour cherry yellows, cherry leaf spot, bacterial canker, green ring mottle virus and potential chemical phytotoxicity. Although the leaf yellowing and potential drop may be the result of a combination of issues above, growers should be out scouting the orchards for cherry leaf spot.

With the heat and recent rainfall, we have the potential for a serious cherry leaf spot epidemic. We are recommending that growers come back in after the next rain that is coming across the lake now with a full cover of Syllit/captan as soon as they can get into the orchard. Growers in Wisconsin have reported Syllit damage in Montmorency, but we have only seen this type of phytotoxicity in Balatons. Growers should not use Syllit in Balatons with the predicted heat in the next few days. Half sides at this time will not be effective in reducing the amount of cherry leaf spot fungi in the orchards. If growers are using the 24(c) with Bravo Weather Stik, applications will need to be discontinued 21 days prior to harvest. Powdery mildew is present in cherry orchards, but at levels much lower than apples.

Bacterial canker on sweet cherry fruits is evident in orchards. In 2011, we saw these canker infections provide an entry for the American brown rot pathogen. With canker on the fruit and these warm and wet conditions, growers should be diligent about spraying for American brown rot to protect the small crop in the trees. Additionally, this last rain may have caused some cherries to crack, and these fruits are also susceptible to the American brown rot pathogen; cracking is more of an issue in a small crop than a large one. The sterol inhibitors (SI) are the best products to protect fruit against American brown rot, but Pristine is also good against American brown rot and will provide some protection against powdery mildew if the infection has not already been established.

Some insects are more abundant this week. Plum curculio is evident in all orchards across the region, and because there are fewer fruit this season, they are competing for the remaining fruit on the trees. We are well past the 375GDD mark to use the PITS model, so growers should keep their fruits covered until harvest. Michigan State University Extension’s Duke Elsner has reported that plum curculio have been found in houses due to their high population size and lack of available hosts.

We captured an average of 13 cherry fruit flies here at the station this week and we predict their emergence to be prominent across the region after the recent rains. Fruit is susceptible to cherry fruit fly egglaying in the coming weeks, and growers should keep covered for this insect as well. Lesser peach tree borer numbers remain high this week and we have captured an average of three peach tree borers in our traps this week. A trunk spray targeting both of these trunk boring pests may be optimal at this time.

Obliquebanded leafroller trap counts are up this week with an average of 29 moths per trap. These adults will be mating and females will be laying eggs – the larvae hatching from these eggs are the ones that have the potential to be present in tanks at harvest. There are many effective insecticides for obliquebanded leafrollers, but growers should be sure to check the pre-harvest intervals (PHIs) for these products as we near harvest in sweet cherries.

The materials that target the larval stage of obliquebanded leafrollers include Delegate, Belt, Altacor, Voliam flexi, Entrust and Bts. Because larvae were difficult to find at the petal fall timing, growers should be prepared to treat for the summer generation of obliquebanded leafroller larvae, particularly if trap counts or larvae rolling terminals or found in fruit clusters are at high levels. Larvae that web together sweet cherry fruit clusters will result in less penetration of fungicides into the clusters, which will likely increase American brown rot infections. Growers in northwest Michigan should not expect organophosphates or pyrethroids to provide effective control of obliquebanded leafrollers because of insecticide resistance.

Apples. With the heat and rain, an infection period was triggered for apple scab. Based on the March 20 biofix (McIntosh green tip), the Enviro-weather apple scab model is estimating that approximately 98 percent of primary scab spores have been discharged around the region and 100 percent are mature and ready to be discharged. Although the model does not predict the end to primary apple scab, the recent rains and heat have likely caused all spores to mature and be discharged.

Growers should be aware of the 77-day PHI for the EBDCs as we are approaching that date depending on variety and time of harvest. Growers should also note that strobilurin resistance has been confirmed in all major apple growing regions of the state and the mutation confers complete resistance – fungicides containing strobilurin will not work against apple scab and increasing the rate of a strobilurin is not an effective option. Powdery mildew is evident in area orchards, and other areas of the state are reporting sever powdery mildew infections.

Fire blight strikes have started to show up across the region. Growers should be aware of trauma events with these recent, intense thunderstorms. Mycoshield will not be effective after a storm event – it needs to be applied prior to the event.

For some reason, codling moth trap counts are still low here at NWMHRS. However, higher trap counts have been reported in commercial blocks in northwest Michigan. Codling moth numbers are also up across the state. Growers should continue to monitor for this pest in their own orchards as there is tremendous variability in the pest population from block to block; the degree day accumulation is highly dependent on the biofix date (the first date of sustained codling moth trap catch) for each apple block. Growers should track the progress on their farms using the Enviro-weather codling moth model and on-farm trap catch data. Treatments for first generation codling moth should only be applied when a single trap location reaches a cumulative catch of five or more moths. Based on the unusual patterns of emergence we have observed in other pests this season, growers should be carefully monitoring for codling moth and weighing the pros and cons of treatment in no crop situations. There are a number of effective codling moth materials. Refer to the E-154 2012 Michigan Fruit Management Guide for more information.

Obliquebanded leafroller numbers are also up in apples and we caught 16.5 moths per trap this week. The summer generation larvae will begin showing up in regional orchards in the coming weeks, and fruit should remain protected from these larvae as the fruit are less likely to drop as a result from insect feeding.

Rose chafers have been observed in extremely high numbers across northwest Michigan. Rose chafers have a long list of host plants, including, apples, cherries and winegrapes. Rose chafers are often more problematic in crops that are adjacent to grassy areas, particularly those with sandy soils where grubs overwinter and feed on grass roots. Rose chafer adults are tan, long-legged beetles and feed on tree fruit foliage. The adult beetles feed on the leaf tissue between the large veins, a type of injury known as skeletonizing. The good news is that mating and egg-laying last only about two weeks, and the average life span of the adult is three weeks.

Rose chafer management can be questionable in orchard or vineyard systems both because the insects are only present for a short time and because they can re-infest an area quickly after an insecticide application. The feeding damage and population size of this pest may not warrant an insecticide, particularly on older trees or vines with ample leaves present. Many insecticides will knock down the beetle population effectively, but most are only rated as fair or good because of the beetles’ mobility and potential to re-infest an orchard or vineyard. There are many options for control, and growers should consult the E-154 2012 Michigan Fruit Management Guide for specific insecticides.

Grapes. High temperatures over the last few days have brought most cultivars into full bloom. Fortunately, the same warm weather has rushed along the period of rose chafer activity; the numbers of adult beetles have dropped quite rapidly over the last few days. Potato leafhoppers can be found in most vineyards, with nymphs now present and easy to find.

Powdery mildew is the principle concern for vineyards for the next few weeks. Even if scouting reveals no infections at the moment, it is advisable to keep vines protected during this time to protect the newly set berries.

Saskatoons. Fruit is maturing and gaining color. Even near Northport, Mich., a few ripe fruits can be found. Potato leafhoppers are easy to find on succulent terminal growth, but their injury does not seem to be significant to leaf condition or shoot growth. The feeding of the first generation of leafroller caterpillars is nearly over. I’m rearing out a few leafrollers to see what species are involved in saskatoons.

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