Vol. 18, No. 2, April 15, 2003

In this Issue
Tree fruit news
Time to start up your apple scouting program
Bacterial canker management with copper
Using spray oils for insect control
New post-harvest fungicide Scholar receives label for stone fruit
Small fruit news
Monitor grape buds for climbing cutworm and flea beetle damage
Mummy berry update for blueberry growers
Preemergent herbicide options for Michigan blueberries
Sinbar herbicide label expanded for strawberries
Other news
Regional reports
Useful MSU weather links on the Internet
Weather news

Next issue April 29

Time to start up your apple scouting program

John Bakker, Doug, Murray, Jim Laubach, John Wise, Mark Whalon, David Epstein, and Larry Gut

Editor's note: The following article is excerpted from a video script about scouting apples that is being developed by MSU with several growers and consultants.

As the growing season is rapidly approaching this season, apple growers might want to pause and take some time to review their scouting program for the year. The information derived from a good scouting program can ensure that you are making the right pest management decisions at the proper timings, and can ultimately save you money.

Green tip is when the scout makes a first scouting trip into the orchard for the season. The primary insects to visually scout for at this time are European red mite eggs, San Jose scale, rosy apple aphid eggs, and bud feeding that can be caused by cutworm, budmoth or leafroller larvae. It is also time to set traps with pheromone lures for spotted tentiform leafminer and Oriental fruit moth.

At any given stage of growth in the season there are many insect and disease pests that have the potential to cause significant damage, thus, a good scout is always looking for conditions that appear abnormal. Note these conditions immediately, collect a sample and get them identified.

Scouting at this stage focuses on visual inspections of spurs for European red mite (ERM) eggs and estimating population levels. Notes should be made on egg viability. Healthy eggs are spherical and dark red, whereas non-viable eggs look empty or lighter in color. Early season scouting can provide useful information noting the presence or absence of viable eggs, but actual counts of the number of eggs per spur provide a basis for future decision-making. To visually scout for ERM eggs you need a 10-X hand lens. Select a total of 100 spurs from inside and outside of 10 to 20 trees throughout the block. Record the number of spurs per 100 that have mite eggs on them. While doing this inspection also make notes on the presence of rosey apple aphid eggs, over-wintering scale, and bud damage.

At this stage of growth, pheromone traps should be set for spotted tentiform leafminer and Oriental fruit moth. Remember not to cross contaminate the trap -- carefully place the pheromone lure in the trap using a disposable stick. Be sure that the trap is securely hung in the tree and mark the tree and the row with flagging tape so that it can be easily found later in the season.

Spotted tentiform leafminer adults begin flight around tight cluster with peak flight occurring around pink. Place one trap in the southwest quadrant of each block, inside the tree canopy. Moth counts can be as high as one to two thousand per week. Using both moth counts and visual scouting for eggs and larvae will help make management decisions later in the season.

Trap for Oriental fruit moth (OFM) to identify when flight begins, also known as biofixing. This information is critical for running the OFM degree-day model, which will help determine when to apply appropriate controls. Place traps in the same general location as the spotted tentiform leafminer traps.

Several plant pathogens become active as green tissue develops on the tree. Apple scab spores are becoming mature and with rainfall, spores will discharge. Information on rainfall and temperature are needed to predict when symptoms will appear. Symptoms of scab are not visible during green tip, however, by the tight cluster period we will be actively scouting for apple scab lesions.

Bacterial canker management with copper

Gary Thornton and Jim Nugent,
NW Mich Hort Station, and
George Sundin, Plant Pathology

Due to the unprecedented severity of bacterial canker on sweet cherry throughout Michigan in 2002, the potential exists for increased canker again this year. Keep in mind though, that the severity of this disease is greatly influenced by the weather (especially by the occurrence of frost damage during bloom) in any given year and wide swings in the severity of this disease should be expected. Protection of younger trees is especially important as girdling cankers can lead to significant limb loss and tree death.

Bacterial canker is a serious disease of sweet cherry in the Eastern United States caused by the bacteria Pseudomonas syringae pv. syringae and Pseudomonas syringae pv. morsprunorum. The bacteria overwinter at the margins of cankers, systemically in the vascular system of the tree or in buds. The bloom period is the time when the bacteria are most active; rapid multiplication and spreading is facilitated by cool, wet weather and rain. Bacterial infection occurs following the invasion of wounds or natural tissue openings such as nectaries of flowers or stomata. The level of infection is greatly influenced by the occurrence of frost damage or extended periods of cool, rainy weather. Since infections are so weather dependent, the severity of this disease varies greatly from year to year.

Copper has been widely proposed as offering some level of control of this disease, however, the use of copper on sweet cherries to aid in the control of bacterial canker is a controversial subject. Some growers swear that it helps and others don't bother applying it, as they see little value in it.

When using copper to help control bacterial canker, full rate applications of copper should be applied during the dormant to early bud swell periods only. Some growers claim success with applications made in the fall at 75 percent leaf drop. Most applications in Michigan are applied in the spring prior to the bud burst stage. Rates are typically cut in half if the applications are made beyond the mid to late swollen bud stage. Once bud burst occurs and they begin to expose the tender, green tissue inside, then copper may cause serious phytotoxicity particularly if warmer temperatures prevail.

However, if copper is applied between bud burst and bloom, follow labeled rates for blossom blight (generally 25-35 percent of the dormant rate). Again, it should be stressed that significant phytotoxicity may occur when copper is applied to green tissue on sweet cherries. Copper applications later in the growing season are not recommended, as the bacteria do not thrive in the warmer weather.

Sweet cherries on Gisela rootstocks have demonstrated an increased susceptibility to bacterial canker, so they are good candidate orchards to receive copper treatment. One- and two-year-old sweet cherry trees partially debudded to aid in proper limb placement should be treated with copper immediately after debudding takes place - if debudded before bud opening. Also, consider treating orchards with a past history of canker problems.

The 2003 Fruit Management Guide indicates a multiple application program using Tri-Basic Copper Sulfate for bacterial canker control on tart cherries. This is not registered in the same way on sweets due to increased phytotoxicity problems on sweets. Note also that the program indicated will cause leaf defoliation even on tart cherries if applied during warm conditions.

Keep in mind that the weather does play an important role in the level of infections that take place, and some of those infections can be avoided through the use of sound cultural practices. When training young sweet cherries use clothespins to spread the main scaffolds. Steep crotch angles are more susceptible to winter injury and often leads to damaged tissue that can provide the bacteria a means to enter the tree. Pruning is best done prior to the cool, wet periods of the spring when the trees are still fully dormant and temperatures are still generally below freezing. If you have to prune later, avoid pruning sweet cherry trees when cool, wet weather is in the near forecast. A few days of warm, dry weather can allow those pruning cuts to dry off and reduce their susceptibility to canker, although it won't prevent all infections from occurring.

In the long term, reducing bacterial canker problems should be addressed by doing all of the horticultural practices that keep trees healthy. This pathogen is an opportunist that causes increased problems when trees are stressed. Factors that increase the predisposition of trees to canker infection include such things as low soil pH, exposure to wind, and low (cold) pockets, but any stress factor may lead to increased problems.

Using spray oils for insect control

By Gary Thornton
District Fruit IPM Agent

It is that time of year again to consider applying spray oils to fruit trees. For pests that overwinter as eggs, it is one of the most important sprays you can apply. Reports from throughout the Midwest have indicated an increase in scale populations in apple orchards. This very likely is at least partially due to a decline in the use of oil. Although there are more miticides to choose from than ever before, growers should think twice about abandoning the early season oil sprays.

Why use oils?

Horticultural spray oils, commonly referred to as "dormant oils," superior oils, or 70-second oils, can be effective control materials for insects that occur early in the season. Insects such as rosy apple aphid and European red mites overwinter in the egg stage, and along with San Jose scale will be suffocated and killed when oils are applied.

Oils fit well into an IPM (integrated pest management) program. Since they are applied when little else is active, they will have minimal effect on mite predators or other beneficials and are a good resistance management strategy. An application of oil at the right time will often lead to fewer applications of other insecticides or miticides later in the season.

With the introduction of Apollo and Savey miticides, the use of oil to control mites in the egg stage is extremely important in resistance management. "Apollo" and "Savey" have similar modes of action against mites, and resistance in the mite population to "Savey" will result in resistance to "Apollo" as well. If these products are used as a grower's sole defense against mites, resistance could occur within 5 to 8 years! Oil should remain as an important tool in controlling mites, and if it does, these products will be effective for many more years.

What to use?

We have several highly refined spray oils for use in tree fruit, which can be used without fear of phytotoxicity. Any oil named as a "superior," supreme, "70-second," or similar names are paraffinic spray oils and are appropriate for insect control.

These oils have a high percentage of unsulfonated residues, which make them safe for tender leaves. Vegetable oils and mineral oils have not shown themselves to be effective pest control agents and should be avoided. Be sure to use "heavy" oils such as Sun Ultrafine oil, which are safe for summer foliage and developing fruit and are most appropriately used post-bloom.

When to use oils?

For European red mite control, oils are best applied at the tight cluster to early pink stage. Blossom damage can occur when oils are applied at full pink in warm weather. Oil suffocates the eggs when the eggs are most active just prior to hatching, so the closer your oil application is to egg hatch the better.

Keep in mind that the weather is not always ideal at this time of the year, so some growers start applying oil with the first acceptable weather after half-inch green. At half-inch green, the addition of Lorsban 4E will provide additional control of rosy apple aphids and San Jose scale.

How to use oils

Oils work by suffocation and work because they can get into cracks and crevices where insect eggs are laid. To get the best effect from oil you must have lots of water on the tree in order to get optimal coverage. No one likes to spray dilute sprays, but for oil treatments, dilute applications will provide the best control.

Keep in mind that at tight cluster time a dilute application takes roughly 60 percent of the full dilute rate of water. For example, a 400-gallon equivalent tree will be sprayed dilute with roughly 240 gallons of water at tight cluster. If you must spray with a concentrate sprayer, concentrate no more than 2X. Remember, the more water, the better efficacy you will have.

Precautions on using oils!

Oils are highly refined petroleum products and, as such, will have some compatibility problems. Generally speaking, oils should not be used within 14 days of a pesticide containing sulfur (such as Captan, Sulfur, or Morestan). If applied closer than 14 days, phytotoxicity can occur with symptoms such as leaf tip burn showing up on trees.

Many fungicides are compatible with oil, such as Nova, Rubigan, EBDCs, and others. Be sure to check the compatibility chart in the 2003 Fruit Management Guide (MSU Extension Bulletin E-154) or the pesticide label, if you are unsure of the compatibility with oil.

Temperature also plays a role in the safety of oil sprays to the tree. Generally speaking, oil sprays will make plant tissue more susceptible to cold injury and should be applied when temperatures are going to be above 40°F. This makes it difficult to apply oils under typical Michigan conditions. Leaf tip burn and blossom damage can occur when there are sub-freezing temperatures after oils sprayed at half-inch or later.

Overall, an oil spray that is properly timed is one of the most important insecticide applications you will make all year. Often, insect and mite populations are controlled well enough with this spray so that later aphid, scale, and mite control can be reduced or eliminated.

New post-harvest fungicide Scholar receives label for stone fruit

Bill Shane
SW District Agent and Horticulture Specialist

Scholar has been in use as a post-harvest fungicide for peaches in California, New Jersey, and South Carolina since 1998 under special Section 18 labels. Scholar received a full label for stone fruit in late 2002. Scholar helps to fill a void left by the loss of Rovral (iprodione) as a post-harvest fungicide.

The active ingredient of Scholar, manufactured by Syngenta, is fludioxonil, a contact-type fungicide. It has a different mode of action than the sterol biosynthesis inhibiting fungicides such as Indar or Nova, or the strobilurin fungicides such as Abound or Flint. Scholar is used as a post-harvest fungicide for brown rot, gray mold. Scholar has shown broad-spectrum efficacy against postharvest pathogens and is very effective against brown rot, gray mold, Rhizopus rot, and Gilbertella rot as a preventative treatment and as a wound protection.

Brown rot caused by M. fruticola will show up as a fruit rot before and after harvest whereas Rhizopus and Gibertella are primarily diseases of overripe fruit in storage. Gilbertella and Rhizopus cause a brown-colored rot with a loose skin, as opposed to the relatively firmer brown fruit rot caused by Monilinia fruticola, where the skin does not slip. Rhizopus and Gilbertella form sporangiophores on the surface of fruit. The spore heads of Gilbertella are shiny-black; Rhizopus has grey-black sporangiophores. Rhizopus, with its whisker-like growth of fungal strands and sporangiophores is more commonly reported in Michigan than Gilbertella, which has fungal growth more tightly adhering to the fruit surface.

Scholar is used as a dip or spray solution at a rate of 8-16 oz product for treating up to 200,000 pounds of fruit. A rough estimate of price for Scholar is $32 per ounce, which translates to approximately 6.5 cents per 50 lb bushel, assuming no waste. Scholar is classified as a reduced risk fungicide. Since it will be labeled as a single application post harvest material in peaches, the prospects for the development of resistance by pathogens should be relatively low.

Monitor grape buds for climbing cutworm and flea beetle damage

Rufus Isaacs
Entomology

Two important insect pests of grape become active around the time of bud swell, and both have the potential to cause significant damage to early growth if populations are high. The predicted cool weather over the weekend gives grape growers a good opportunity to scout their vineyards to determine their bud swell stage and to look for the first signs of damage from these two pests.

Cutworms

This term covers many species in the moth family Noctuidae, and as their name suggests, these insects are nocturnal. Both the adults and the larvae are only active at night, and so direct observation of feeding requires a late-night trip to the vineyard. During the day, cutworms hide in the soil or leaf litter. Many of these insects feed on weeds but some climb the stems of plants to feed on buds and other young foliage. These climbing cutworms are the ones causing damage to grape plants.

In Michigan grapes, the spotted cutworm, Amathes c-nigrum, is our main pest species, and the larvae feed on buds from bud swell through bud break, and until the shoots are 10 to 15 cm long. Feeding on young leaves has also been reported.

While the vine can compensate for primary bud removal by production of secondary buds, these shoots are less fruitful than the primary buds. Removal of primary and secondary buds results in tertiary buds that produce shoots, but which do not fruit.

The high potential for rapid damage by cutworms requires that growers make good timing decisions. Even 1 or 2 percent bud injury justifies an insecticide treatment to prevent further damage. Currently, Lorsban 4E has a special local needs label for use against climbing cutworms in grapes. Growers must possess the Special Local Needs label at the time of application.

Flea beetle (Steely beetle)

This insect attacks buds of both wild and cultivated grape, and Virginia creeper, and is another early season grape pest. The adult insects move to the vines at bud swell, and usually are localized within the vineyard. Sites near overwintering habitats such as woods or abandoned vineyards are especially at risk.

Adults are shiny blue, about 4-5 mm long, and have strong hind legs that enable them to jump if disturbed (hence the name!). The overwintering adults cause the greatest damage by boring into the developing bud and hollowing out the inside, while the larvae and summer adults feed on leaf tissues. Bud feeding is similar to that caused by cutworms, with similar effects to the vine (see above cutworm description).

Wherever possible, cleaning up overwintering sites (wasteland and woodland) near to vineyards can help combat grape flea beetle. Early sprays for grape berry moth will also help to reduce the later larval populations of this insect.

Scouting for bud damage

Growers should watch for damage by both these pests, especially if the vines remain in the susceptible bud swell stage for a while with this cooler weather. An appropriate insecticide application should be considered if scouting shows significant damage is occurring, and assessments of damage should include wooded borders where flea beetle pressure may be higher, and areas where cutworms have been a recurring problem. Both of these insects can cause damage quickly if the temperatures warm up, and since they are difficult to catch "in the act," regular scouting for the first signs of damage is essential to prevent significant bud loss.  

Mummy berry update for blueberry growers

Annemiek Schilder
Plant Pathology

This is the time of year to start looking for mummy berry mushrooms in blueberry fields. Germinated mummies look like tiny black pumpkins with brown finger-like projections (stipes). Depending on how wet the site is only 10 to 20 percent of mummies actually germinate in any one year. There can be anywhere from one to six or seven stipes on a mummy. The stipes have a hole in the tip that develops into a small mushroom cup, 1/16-¼ inch in diameter. The mushrooms start shooting spores when the cup is about 1/8 inch in diameter. The spores all get shot out at once when the mushrooms are disturbed or the air pressure changes, appearing like a little wisp of smoke. Over a million spores can be released per day by a single mushroom. These spores get picked up by the wind and carried to susceptible green tissue. Prolonged cool, wet weather is conducive to infection. At the optimum temperature (57ºF) only 4 hours of leaf wetness are required for infection.

The first shoot strikes appear about two weeks later, depending on the temperature. Under humid conditions, gray spore masses develop on the infected shoots. These spores (conidia) then get carried to the flowers by bees, wind, and rain, which then leads to the infection and mummification of the fruit.

In lowbush blueberries, it has been shown that frost (28°-30ºF) can predispose the shoots to infection for up to four days after the frost event. This hypothesis was tested in small plot trial in a highbush blueberry (Jersey) field in Michigan in 2002 by adapting the spray schedule to incorporate Indar sprays immediately after a frost event (if the previous spray had been applied at least five days earlier).

For comparison, Indar was also applied on a 7 to 10 day schedule. Applying Indar soon after frost significantly improved disease control over the 7-10 day schedule, which seems to indicate that frost is also a predisposing factor in highbush blueberries. In 2003, we will be repeating the same experiment and will also directly test blueberry shoots for increased susceptibility to shoot strike infection after a frost.

Preemergent herbicide options for Michigan blueberries

Eric Hanson
Horticulture

The next two weeks will be excellent timing for applying preemergent herbicides to blueberries. The herbicide choices are described in detail in Extension Bulletin E-154. Preemergent herbicides are soil-applied chemicals that kill germinating weed seeds or young seedlings. Many materials applied at high rates also kill established weeds. Properly chosen and applied preemergent herbicides will provide effective weed control through most of the growing season. Here are several considerations in using these materials effectively.

Princep 90WG ( simazine), Karmex 80DF (diuron), Sinbar 80W (terbacil), Solicam 80DF (norflurazon)

These are the workhorse preemergent herbicides in established blueberries. They are moderately priced, reasonably safe on blueberries, and control many germinating annual weeds for one to three months. Princep and Karmex tend to be stronger materials on broadleaf weeds, whereas Sinbar and Solicam are stronger on grasses. Use these only on established plants that have been in the ground for two years or more. Use rates per acre are 2.2-4.4 lb Princep 90 WG, 2-4 lb Karmex 80DF, 1-2 lb Sinbar 80W, and 2.5-5 lb Solicam 80DF. These rates are for an acre of treated surface area, so if you only treat a strip beneath the plant row, you will use less per acre of blueberries. To prevent injury to blueberries, use the lower rates on smaller plants or on sandy soils low in organic matter. This is particularly true of Sinbar.

Other preemergent herbicides

 Other preemergent herbicides labeled for blueberries are Casoron, Devrinol, Kerb, Surflan, and Velpar. The utility of Kerb, Casoron, and Velpar in blueberries is limited by either cost (Casoron, Kerb) or crop safety (Velpar). Devrinol and Surflan are primarily grass materials that are very safe on blueberries (can be used on new plants), but have no post-emergent activity and must be applied before weeds germinate.

Herbicide resistant weeds

Continued use of herbicides from the same chemical families (see accompanying table) can result in weeds resistant to all herbicides in that family. Many weed species have developed resistance to the triazine family, which includes the blueberry herbicides Princep and Velpar. Triazine-resistant weeds may also be more tolerant of herbicides from other chemical families that share the same mode of action. For example, Princep, Karmex and Sinbar all affect weeds through the same mechanism; they kill weeds by inhibiting photosynthesis.

We found triazine-resistant marestail and ladysthumb (a smartweed) on Michigan blueberry farms during 2001. If you suspect that triazine resistant weeds are present on your farm, try switching to herbicides that have a different mode of action. Solicam and Surflan offer different modes of action and would be good choices to rotate with the photosynthesis inhibitors to control resistant types or to avoid the development of resistant populations.

Specific weed problems

An increasing problem in blueberries is late-season grasses such as fall panicum and crabgrass as well as broadleaf species such as marestail and redroot pigweed. These annuals often become troublesome when the early spring-applied herbicides begin losing their effectiveness in July. If grasses are the primary problem, Surflan may be useful because it is a strong grass herbicide (as long as it is applied before weeds germinate) that has a long residual life in the soil. Surflan may work well in combination with Princep or Karmex to control a wider range of species.

We have also found that delaying preemergent herbicide applications until mid-May and adding Roundup to the spray to kill emerged weeds provided 30 to 50 percent greater late season control compared to the same preemergent herbicide applied three weeks early without Roundup.

However, Roundup needs to be used with caution. Roundup is absorbed through the green bark of young canes and branches. If your nozzles are not aligned to keep the spray off the base of young canes, treated canes will stop growing and often die during the following year. Although some cane loss can be tolerated, repeated treatments can eventually limit cane numbers and reduce yields. Roundup can be used most safely in old plantings where the bushes have tall crowns and most of the new canes originate above the ground where they are less likely to be treated with the spray.

Marestail is a troublesome winter annual that can germinate during the winter and early spring and develops small flat rosettes visible in March around last year's seed stalks. Sinbar is usually the most effective springtime treatment, followed by Karmex. Princep is weak on marestail. The little seedlings are even tolerant to spring applications of Roundup.

Wild buckwheat is an annual vine that looks much like field bindweed. We have found that standard rates of Princep, Karmex, and especially Sinbar applied in April control this weed. Solicam is weak on it.

Sinbar herbicide label expanded for strawberries

Bob Tritten
Southeast District Horticultural/Marketing Agent

The label for one of the more commonly used herbicides in strawberries has recently been expanded to include its use in several other "windows." The first new window for Sinbar use is on newly planted or first-year strawberries. Sinbar may now be applied in spring after transplanting but before daughter plants begin to root.

The second new window is late in the summer or early fall when Sinbar can be used around Labor Day. In both these cases it needs to be followed immediately by some rainfall or irrigation to wash Sinbar off the foliage. If you need additional information on the new Sinbar label, you can contact any of the district fruit agents or your supplier representative.

1 - Southwest

Mark Longstroth
Bill Shane
Al Gaus

Weather

Cooler weather marked the beginning of the month. Rain fell on April 3 marking the beginning of the plant disease season. Several Sunday freezes caused some damage to stone fruit. The weekend was warm and plants moved along quickly. Cooler weather is forecast for late this week. Check the Critical Bud Temperature Chart to see what your plants can withstand. Soil temperature is about 40°F.

There is still a wide variation in bud development between the Southern areas of the district and those further north.

Tree fruit

Apricot bloom has begun in Northern Berrien County. In Van Buren apricots are at white bud.

Peaches are at red calyx and leaf buds are unfolding. Showy peaches are showing pink. Growers are busy pruning. Oriental fruit moth should be out.

Montmorency tart cherries are green side and green tip. Several freezes have caused little damage to most sites. Balatonâ tart cherries are more advanced at bud burst and have suffered more damage so the crop will be light.

Sweet cherries are at bud burst to tight cluster. The more advanced varieties have suffered up to 50 percent damage but the crop potential still looks good.

European plums are at white side to green tip. Japanese plums are at green cluster.

Apples are from green tip to 1/2-inch green. The first leaves are just starting to fold back. Spotted tentiform leafminer and Oriental fruit moth should be out. An apple scab infection occurred over most of the region on April 3 with 44 hours of leaf wetness at 39°F. Scab lesions should be visible April 22. At the time of the rain only the early apple varieties were showing green tissue. Scab spores were trapped during the rain. Few growers had fungicides on before the rain and windy conditions prevent post infection sprays. Growers should be aggressive in maintaining fungicide coverage until they determine the level of infection in their orchards. Examine the spur leaves after April 22 for lesions.

Pears are at bud burst. Pear psylla adults are out.

Small fruit

Blueberry flower buds are swollen. There appears to be some winter damage, dead shoots off older canes that had died. Leaf buds have burst and green tissue is showing. Growers should be looking for mummyberry trumpets. Mummy berry trumpets have been found in Grand Junction. In last year's trials, Indar applied after frost effectively reduced mummy berry shoot strikes.

Grapes are at scale crack. In southern Berrien County, Concords and Niagara grapes are at early swell. Vinifera grapes are also moving. Growers should be prepared to control climbing cutworms as the buds swell and phomopsis when the leaves unfold. Grape growing degree days since April 1 are 30 GDD50.

Strawberry leaves are emerging from the ground. Now would be a good time to apply grass herbicides.

Raspberries are at 1/4 to 1/2 inch green tissue. In early varieties such as Prelude the leaves are unfolding.

Cranberries are still dormant with purple leaves. No green up yet!

Miscellaneous

The next Monday Fruit Management meetings will be at Borge's Fruit Acres Farm South of Coloma on April 21 and 28 at 5:00 PM.

There will be several Grape IPM Meetings in the Southwest this year. The first will be April 30, 2003. These meetings will be held in both Berrien and Van Buren counties on the same day. On April 30, the first meeting will be in Lawton at 10:00 AM and the second at SWMEC at 1:30 PM. The focus of this first meeting will be early season insect and disease control in grapes. For more information check the Fruit Hotlines at Van Buren (269) 657-6380 and Berrien (269) 944-4126 ext. 1 counties.

2 - Southeast

Bob Tritten

Weather

We have experienced a more typical late winter and early spring temperature pattern this year than we have in the last three to four growing seasons. Looking back at historical weather data, our season seems to be running about normal to a little behind normal. Soil moisture conditions are much below normal however. Soil temperatures are still cool in the high 40's to low 50's. The soil temperatures are taken under bare soil at a depth of 2 inches.

Tree fruit

Apples are just beginning to get started. We have not had a true wetting period thus far this year. With a possible rain event later this week, that may be the first wetting event for most growers. Apples are at early green tip for orchards in the Ann Arbor area and south and mostly at silver tip in areas to the north. In areas to the north, I would expect that with our recent warm temperatures that we'll move into green tip fairly quickly. It appears that we have a good crop of flower buds at this time on apples. The only pest problem to report on apples is a little early spotted tentiform leafminer flying. European red mite eggs are not abundant this year, and those that are present are mostly clear at this time, indicating that they either are a ways off from hatching or nonviable. Again, no apple scab spore discharge has occurred as of yet. However, I would expect that to begin taking place with the next rain event. With that event many growers will be applying their first sulfur sprays.

Pears are mostly at swollen bud. Pear psylla adults have been seen flying for several weeks now. I would say that pear psylla eggs and adults have not been very prevalent this year.

Peaches are at bud swell. It appears that we have an excellent crop of flower buds coming along on peaches this year with little to no winter injury.

Small fruit

Strawberries are yet to emerge from the ground on mulched plantings. Plantings that were unmulched have some early leaf growth developing.

Raspberries are at early swollen bud for summer bearing plantings and no canes have emerged on fall bearing raspberries.

Blueberries are at early bud swell. I have detected some winter damage to twigs in blueberries over the last week. Most likely this winter damage was done the first week of December 2002 when we had a rapid decline of temperatures. Mummy berry "mushrooms" are just starting to be seen.

Miscellaneous

Just a reminder that the Fruit Pest Management Code-A-Phone for Southeast Michigan is now up and running for the 2003 growing season. It is updated generally once a week and more often as needed (i.e. - during apple scab season). The phone number is 810-732-1005.

3 - Grand Rapids Area

Phil Schwallier
Amy Irish Brown
Tom Kalchik
Carlos Garcia-Salazar

Tree fruit

Earliest developing apple varieties are showing the first signs of green tissue as of April 14. By the next Fruit CAT Alert issue (April 29), we might see the first signs of pink showing in this area, so it's not too early to get the first scouting of the season started and start planning for pink sprays in apples.

There appears to be high mortality of European red mite eggs, but overall egg numbers seem to be low in most orchards. Dormant oil sprays for overwintering mite eggs, aphid eggs and scale will most likely be timed between now and the next Fruit CAT Alert issue (April 29) - remember to watch the weather forecast closely for possibilities of freezing temperatures within three days after oil sprays to avoid phytotoxicity problems.

Sweet cherry buds are starting to swell. Some winter bud mortality in sweet cherry and grapes in the area, but it does not appear to be a high percentage at this time.

Meeting announcements

The 32^nd Annual Spring Spray Meeting and IPM Update is scheduled for Thursday, April 24, 2003. We will meet at the Fruit Ridge Apple Company on 10 Mile Road, just west of Fruit Ridge in Kent County. We will begin at 7:00 PM and end by 9:30 PM.

4 - West Central

Mira Danilovich

Weather

There has not been much movement in vegetation until now. High temperatures predicted for today and tomorrow will certainly induce some changes in that respect.

The most recent ice storm and temperature drop (well below freezing) did not cause further significant damage to the buds. In actuality, all that ice protected the buds from freezing.

Growing degree day totals since March 1 as of Sunday, April 13

 Insects

Except for a few canker worms and some pear psylla activity, there is not much else happening at this time. European mite eggs are mostly clear indicating high mortality over the winter months.

Growers are encouraged to use dormant oil applications to insure good early insect and mite control.

Diseases

Though last fall was long and had favorable conditions for apple scab inoculum built up, good snow cover played significant role in the development and survivability of the spores in the fungal fruiting bodies so we can expect some reduction in the inoculum pressure.

Last year we had disease outbreak of bacterial canker of epidemic proportions particularly in sweet cherries and some plums. Use of copper sprays for EIP bacteria reduction is strongly recommended.

 Miscellaneous

There is a high danger of fire incidence due to the combination of extremely dry conditions in the area and strong winds.

5 - Northwest

Gary Thornton
Jim Nugent
Jim Bardenhagen
Duke Elsner

Growing degree day accumulations

GDD42             94

GDD50                   32

Weather

Two major cold events have affected fruit crops in Northwest Michigan. The first was a late winter cold event that occurred on the morning of March 3, when temperatures reached lows of
-10° to -20° F. The event followed daily high temperatures in the upper 30's on February 28 and March 1. At the NWMHRS, temperatures dropped from 39° F to -13° F in 37 hours. There was enough deacclimation to cold in the plants preceding the cold snap to result in much worse bud damage in sweet cherries and grapes than expected. The second event (though much less significant than the first) occurred on April 6, when low temperatures ranged from -1° F to 16° F in Northwest Michigan. This caused some additional flower bud damage.

 Tree fruit

Pear psylla adults are already flying and laying eggs. Egg numbers are light at this time.

In apples, growers should keep in mind how moist last fall was when they plan for this year's scab season. Fall wetness can lead to a scab build up on leaves, leading to high inoculum levels in spring. With high inoculum, it is especially important to have protectant sprays on in a timely manner.

Sweet cherries have suffered substantial damage. Dark varieties have generally sustained more bud damage than light varieties. Emperor Francis looks the best of the major varieties grown.

In tart cherries, Montmorency looks good at this time. There is some injury in Balatonâ.

Small fruit

Grapes show extensive bud and wood injury.

Useful MSU weather links on the Internet

Mark Longstroth District Horticultural Agent

I had several growers ask about weather links I use. I use commercial weather links like Accuweather.com and Weather.com, but I also use MSU Agricultural Weather Office at http://www.agweather.geo.msu.edu/ a lot. The MSU site has the current weather and forecasts for the different regions of Michigan. I can also get the projected Minimum temperatures for the next morning, which are usually posted at noon. I also access the MSU Automated Weather Network or MAWN at http://www.agweather.geo.msu.edu/mawn/. This site allows me to get the current weather from automated weather stations in my growing region and elsewhere in Michigan.

The site I like the best from a fruit IPM point of view in the MSU ICM or Scud site at http://scud.geo.msu.edu/ipm/. (Scud is a type of cloud.) This site allows me to run several predictive models for fruit pests and diseases using the weather data collected from the automated weather system. This means that growers can use real weather data from automated weather systems close to their plantings to predict things like apple scab, fireblight, codling moth, Oriental fruit moth, cherry leaf spot and black rot of grapes.

When you access the Scud site you should create a User ID and password for yourself. This will allow you to enter data for the various models such as green tip and the data will be remembered from session to session so you do not need to reenter that data each time.

Weather news

Tracy Aichele
Agricultural Meteorology
Geography

For the Lower Peninsula, a dramatic drop in temperatures is forecast for April 15, with daytime highs near 80°F and lows in the 30's in the Northern Lower Peninsula. Freezing rain is possible in some areas for Tuesday night through Thursday (April 15-17) with thunderstorms possible on Tuesday night through Wednesday. Near-freezing low temperatures should continue for the next week with a gradual warm-up starting on Friday (April 18). Precipitation remains likely through the week.

The 6-10 day outlook for April 20-24 predicts above normal temperatures and precipitation, while the 8-14 day outlook (April 22-28) calls for normal to above-normal temperatures and normal to below-normal precipitation.

Drought is a slight concern throughout much of the Lower Peninsula, but is of greater concern in the West Central region (Mason, Lake, and Oceana Counties). This is the only area of the state currently subject to short-term drought risk, with 3 to 6 inches of precipitation needed to return to normal conditions over the long-term.