Some label changes and new registrations have expanded the insecticide and miticide options available to growers of Michigan fruits, and the major changes are listed below. Copies of the new labels or 2(ee) label expansions must be in the possession of the applicator before these uses.

Asana XL (esfenvalerate) has received a 2(ee) label for control of Japanese beetle in Michigan blueberry. This synthetic pyrethroid provides rapid knock-down and seven to ten days activity against adult beetles when applied to bushes as a foliar spray. This use is labeled at 4.8-9.6 oz per acre, with a 14-day pre-harvest interval, and 12-hour reentry interval. Border treatments with airblast or fogging-type sprayers are expected to be more effective against the adult beetles than aerial treatment, due to the need for good coverage. Ground application in a minimum of 50 gallons of water per acre is recommended, to achieve the level of coverage required for effective control of adult beetles.

SpinTor 2SC (spinosad) is a new class of insecticide from the naturalyte class, registered for suppression of foliar insect pests in blueberry, currant, gooseberry, and other bushberries. The primary route of entry is through ingestion, though some contact activity is expected. SpinTor provides seven to ten days of residual control, depending on the target pest, and good coverage is essential for full activity. Application with a penetrating or silicone surfactant can enhance coverage and penetration of leaf surfaces. This product must dry for one to two hours before becoming rainfast, and can be toxic to bees if wet residues are contacted. This product is expected to be most effective against thrips, leafrollers, and other foliage feeding insects. Activity against fruitworms and blueberry maggot has also been demonstrated in recent small-plot evaluations, though the biology of these pests makes control with SpinTor more challenging. In blueberries, SpinTor has a 3-day preharvest interval and 4-hour reentry interval.

Acramite (bifenazate) belongs to a new class of miticides called carbazates, which has received registration for use in pome fruits, stone fruits (cherries and apricots - non-bearing only), grapes and strawberries. Acramite is a contact miticide that is primarily active against motile stages of European red mite and twospotted spider mite, but also nymphal stages that hatch after application. Optimal timing for Acramite is to spray as mite populations reach threshold. Depending on rate and pest pressure, Acramite can be expected to provide six to eight weeks of residual control.

Esteem (pyriproxifen) is an insect growth regulator (IGR) insecticide that acts by suppressing embryo-genesis within the insect egg and by inhibiting metamorphosis and adult emergence of target insects. Esteem has no direct activity on adult insects, but hatching of eggs laid by treated adults will be suppressed. Esteem is currently registered for use in apples and pears for the control of codling moth, San Jose scale, spotted tentiform leafminer, rosy apple aphid, and pear psylla. The label for stone fruits is expected soon for use in the 2002 field season. Since Esteem is an insect growth regulator, and activity depends on the insect’s development, evidence of activity will be slower than with conventional contact insecticides. To optimize insecticide resistance management practices, use of Esteem is restricted to two applications per season. Esteem may be used in alternation with other IGR materials possessing dissimilar modes of action or other chemical classes of insecticides.

Aza-Direct (azadirachtin) is a biological insecticide available for use on most Michigan fruit crops, including blueberries, grapes, cane berries, stone fruits, and pome fruits, for a wide range of pests. The active ingredient of Aza-Direct, azadirachtin, was originally derived from extracts of the Neem tree, a native plant of India. This compound controls insects in the larval, pupal and nymphal stages by interfering with the metabolism of ecdysone, therefore preventing normal development. It can also work as a repellent or anti-feedant on the adult stage of many insect pests. Because of its short residual life, it may need to be re-applied every five to ten days if pest populations persist, but can be sprayed up to the day of harvest. This pesticide is toxic to fish and aquatic invertebrates, and to bees exposed to direct treatment or residues on blooming crops or weeds. The recommended tank water pH range is between 4.0 and 7.0.

Assail (Acetamiprid) is a new neonicotinoid insecticide registered for use in apples and pears for the control of codling moth, aphids, leafhoppers, spotted tentiform leafminer, and pear psylla. Assail provides systemic, translaminar activity, which makes it particularly effective on sucking pests such as aphids and leafhoppers. Dose rates range from a low of 1.71 oz of product per acre (aphids, leafhoppers, leafminer) to a high of 3.43 oz/acre (codling moth). The total season use of Assail 70W cannot exceed 13.5 oz, and the pre-harvest interval is 7 days. A WSP formulation is being developed for use in grapes. (see additional comments in next article on Assail)

The EPA has granted a specific exemption (Section 18) for the use of Mycoshield Agricultural Terramycin (oxytetracycline) for fire blight control on apples in 2002. This Section 18 permits the use of Mycoshield on apple anywhere in Michigan. The use period is March 8 through June 30, 2002.

The Section 18 permits ground application by airblast sprayer. Up to five applications may be made with 1.0 lb to 1.5 lb of product per acre per application. Do not apply more than 1.5 lb of product per acre per application. There is a 12-hour re-entry interval (REI) worker entry restriction and a 60-day pre-harvest spray interval (PHI). Only one application may be made after the end of bloom. A maximum of 8,000 acres of apples may be treated. For further restrictions see the Section 18 labeling information which must be provided by Syngenta Corp Protection, Inc. with the product at the point of sale.

During the bloom period, antibiotics and other control strategies for fire blight focus on the suppression of the pathogen Erwinia amylovora on floral parts. Where E. amylovora has developed resistance to streptomycin (Agri-Mycin), oxytetracycline (Mycoshield) is considered as a substitute for streptomycin. In areas where Mycoshield has been used for several years due to the presence of streptomycin resistance or where resistance is anticipated, Mycoshield should be considered as a tank-mix complement for streptomycin.

Agri-Mycin/Mycoshield, tank mixed at 1.5 lb/acre of each antibiotic, is an ideal management strategy because it is expected to provide better fire blight control and also reduce resistance gene transfer between bacteria and dispersal risk from orchards with resistance.

The combination is particularly valuable to Michigan apple growers with plantings of high-density, high-value blight susceptible cultivars and rootstocks. In areas of Michigan where streptomycin resistant has not been detected, particularly in blocks of processing varieties, growers may wish to continue to use Agri-Mycin alone.

Recently, some new materials have been registered that show promise as alternative controls for some important pests of Michigan apples. The relative effectiveness of six novel insecticides for control of apple pests is outlined in Table 1. Insecticide screening trials conducted at the MSU Trevor Nichols Research Complex have indicated that even though these materials provide encouraging levels of fruit protection, their activity on the target pests can be very different than that of conventional materials. Whereas OP’s and other broad-spectrum insecticides are highly lethal and fast acting, these new insecticide chemistries, though effective, are generally weaker contact poisons and can produce an array of sub-lethal effects.

The neonicotinoids (Actara® and Assail®) are systemic insecticides, with various lethal and sub-lethal effects, such as feeding and egg-laying deterrence. Avaunt® is a sodium channel blocker that for some pests requires ingestion or prolonged exposure. Compounds classified as IGR’s interfere with growth and development of the various insect life stages. Intrepid® works by binding to the skin-producing receptors of insect larvae causing initiation of a lethal molt, while Esteem® interferes with the insect’s ability to mature properly. Against some fruit pests, such as codling moth, Esteem® interferes with development of the larva in the egg.

Among the new options listed are two insecticides that were registered just prior to the 2001 field season (Avaunt® & Intrepid®), a compound that was registered in the summer of 2001 (Actara®), and another compound that was registered in 2002 (Assail^TM). Thus, our understanding of the relative activity of these new materials is primarily based on small-plot trials at the Trevor Nichols Research Complex. On a more limited basis, however, we do have on-farm experience over the past year or two with some of these materials.

A summary of the activity of new insecticides against five primary pests and six secondary pests (Table 1) provides the basis for determining the best fit of each compound in an apple IPM program. Three primary caterpillar pests, codling moth (CM), Oriental fruit moth (OFM) and obliquebanded leafroller (OBLR), are important targets of the first four compounds listed in Table 1. Among these materials, Intrepid has provided the best control of CM, while both Spintor and Intrepid appear to be the most effective options for OBLR control.

In contrast, the major targets of the neonicitinoids (Acatara and Assail) are the sucking insects, specifically aphids and leafhoppers. Each of the six insecticides also has activity against at least one pest that does not fit within the two broad categories of caterpillar or sucking insect pests. Four of the materials, Intrepid, Spintor, Actara and Assail, also provide good to excellent control of spotted tentiform leafminer (STLM). Both small-plot and on-farm trials have indicated that Avaunt and Actara provide good protection of fruit from plum curculio (PC). Esteem is particularly active against rosey apple aphid (RAA) and San Jose scale (SJS).

Assail is the newest material included in Table 1, with registration granted in March 2002. The active ingredient in Assail is acetamiprid. This compound has only been tested in Michigan on a limited basis, thus the term "active" rather than a specific rating is provided in Table 1. Assail provides systemic, translaminar activity. It is particularly active on sucking pests such as aphids and leafhoppers, and on tentiform leafminer. Unlike other commercial neonicotinoids with a similar spectrum of activity, Assail is also registered for control of codling moth. Dose rates range from a low of 1.71 oz of product per acre (aphids, leafhoppers, leafminer) to a high of 3.43 oz/acre (codling moth). As a word of caution, trials conducted in the western US have raised the possibility that multiple applications of Assail may flare mite populations.

Primary pests Secondary pests

Avaunt ** ** * *** * * * ***

Intrepid *** *** *** **

Spintor ** ** *** * ** *

Esteem ** * * ** *** ***

Actara *** *** *** *** *** *** ***

Assail active active active active active active

CM-codling moth, OFM-Oriental fruit moth, OBLR-obliquebanded leafroller, PC-Plum curculio, AM-apple maggot, STLM-spotted tentiform leafminer, GAA / RAA -green / rosy apple aphid, WALH-white apple leafhopper, SJS-San Jose scale, TPB-tarnished plant bug

* some activity, ** good activity, *** best activity relative to other new insecticides

Assail has only been tested in Michigan on a limited basis, thus no rating is provided; active indicates a label use for this material

Table 2 lists some of the options for incorporating newer control materials into Michigan apple IPM programs. This is not a comprehensive summary of uses for each material. It is a list of options that we have the most experience with and that take advantage of the unique spectrum of activity for a particular compound, thus maximizing the economics of a treatment. A pre-bloom application of Esteem or Actara is a good option for control of RAA. At this timing, Actara will also control STLM, while Esteem will be active on SJS and STLM. Avaunt and Actara are good options for protecting fruit from PC damage. If pest pressure is low, a single application 14 days post-PF may be sufficient. Under higher pest pressure, two applications may be required. The PF spray of Actara will also be active on STLM and RAA, while the PF plus 14-day Avaunt spray will also be active on CM and OFM.

Assail can be used either for first or second generation CM control. An economical use of this material would be to make applications when secondary pests, such as aphids, leafhoppers and leafminers, also need to be controlled. The same strategy applies for summer use of Intrepid and Spintor. Spintor sprays for control of summer generation OBLR will also be active on STLM, AM and CM. Intrepid sprays for CM control can be timed to coincide with high periods of OFM, OBLR or STLM activity. The best fruit protection was consistently achieved in our 2001 on-farm trials when new insecticides were incorporated into a pest management program that included applications of azinphosmethyl (Guthion) or phosmet (Imidan) at two key timings. These were during peak CM activity in late May to early June and peak CM and AM activity in August.

Actara 4.5 oz Tight cluster – Pre-pink STLM & RAA

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. 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.

The bacteria overwinter at the margins of cankers, systemically in the vascular system of the tree or in buds. The bacteria multiply rapidly when weather conditions are cool and wet and are spread mostly by rain. It then invades wounds or natural tissue openings such as nectaries of flowers or stomata. Since infections are so weather dependent, the severity of this disease varies greatly from year to year.

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.

The MSU Spray Calendar 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 sound cultural practices. When training young sweet cherries, use clothes pins to spread the main scaffolds. Steep crotch angles are more susceptible to winter injury and often lead 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.

Superior oil applied at the right time with good coverage at the full rate can provide control of mites until mid-summer, but can cause phytotoxicity if applied within 48 hours of freezing temperatures.

Apollo, Savey and Agri-Mek all provide extended control of European red mites (ERM), ranging from 10 weeks to full season depending on mite pressure, tree vegetative growth and predator mite populations. Savey and Apollo can be applied pre-bloom for over-wintering ERM eggs, but now have in-season use with their respective 28-day and 45-day pre-harvest intervals. These compounds can be used in lieu of early season oil timings, but oils should remain as an important resistance management tool to reduce the selection pressure from consecutive use of Apollo and Savey, which have similar ovicidal modes of action. AgriMek is most effective when applied between petal fall and first cover (14 days past petal fall) with the addition of 1 gallon of paraffinic spray oil per acre.

Pyramite is a contact miticide which when used early season (after petal fall) can provide six or more weeks of control, or in mid-summer as a "clean up" application if early season products have lost control of mites. Acramite is a newly registered contact miticide that has six or more weeks of activity on ERM motile forms, and a novel mode-of-action. Carzol early in the season provides control of adult mites (along with some insect pests), but is toxic to predator mites and cannot be applied after petal fall. Vendex provides good control during warm weather. Kelthane gives good control in all temperature conditions, but should be used only once or as a back-to-back application on the same generation of mites to prevent resistance from building. Vydate will kill some mites, but is very toxic to predators, and causes fruit drop if used within 30 days after petal fall.

The scab season starts with the release of ascospores approximately at green-tip time. Some growers will delay the first spray application past first green tip if the overwintering scab population is low with the thought that the target area (exposed green tissue) is small at this time as well. This approach requires a careful assessment of leaf scab shortly before leaf fall in the previous season to gauge the potential scab pressure. If late season scab infection level was significant, we expect that it is too risky to delay fungicide treatment past green tip.

An additional consideration is the temperatures shortly before and during green tip. In a cool early spring, the scab pathogen, with its low temperature threshold, will be primed for release earlier relative to green tip compared to a warm spring. In other words, the demand for spray coverage at green tip or shortly after will be greater in a cool spring because more ascospores are ready by this time compared to a warm spring.

I generally recommend that growers try to use fungicides such as captan, Vangard, or the EDBC-type fungicides for the green tip to pre-pink scab sprays because there is no need for mildew control at that time. Other useful fungicides for this window are Carbamate, Thiram, and Ziram. All these except Vangard, are non-systemic fungicides that run little risk of resistance problems with the scab pathogen. Copper fungicides are also effective against scab and have the added benefits of low cost and some suppression of fire blight, but increased risk of phytotoxicity if used past early green tip. All non-systemic fungicides have up to 18 hours of back-action, calculated from the beginning of the wetting period, and protective coverage of five to seven days depending on the rate and weather conditions.

The sterol inhibitor (SI) fungicides such as Nova, Rubigan, and Procure, and the strobilurin fungicides Flint and Sovran have excellent activity against leaf scab but are best used at the pink growth stage or later because they also control powdery mildew. However, these systemic fungicides are particularly useful when longer back-action against apple scab is needed. They also are valued because their spray coverage is seven to ten days, a few days longer than a classic protectant. Because resistance of scab to SI fungicides is increasingly becoming an issue, tank mixing of a protectant with SI is a standard recommendation. In general, it is better not to rely on back-action with systemic fungicides for management of apple scab, unless there are no other options, because of the prospect for accelerated development of scab resistance to these materials.

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.

An emergency exemption (Section 18) has again been issued for the use of Indar 75WSP (fenbuconazole) for mummy berry control in blueberries in Michigan. The exemption runs from April 1 to September 1, 2002. You have to be in possession of the supplemental label at the time of application.

Indar used to be a Rohm and Haas product, but is now manufactured by Dow AgroSciences. While the material is locally systemic, it only has a limited amount of back action. Therefore, it is best used on a preventative basis. The recommended application rate is 2-oz per acre using ground or air equipment. Sprays should begin at early green tip and subsequent applications should be made at seven to ten day intervals. The label mentions ten to 14 day intervals, but under high disease pressure, this does not appear to be adequate. Do not make more than five applications per season or use within 30 days of harvest. Do not use any spray adjuvants with Indar 75WSP. Applications are not permitted within 75 feet of streams, rivers, ponds, lakes, or reservoirs. Carefully read the label before use.

In 2000 and 2001, different application timings of Indar were evaluated (Tables 3 and 4). Shoot strike pressure was especially high in 2001. In both years, the number of shoot strikes and mummified berries was lowest when four sprays were applied. These data seem to indicate the least benefit from the early green tip spray.

With the limited number of days with frozen soil during our warm winter and the relatively mild spring, the Japanese beetle has survived the winter well. The beetle overwinters as a white grub that can tolerate cold temperatures. Grubs that are in the soil now grew from eggs laid last summer, and are clearly visible if a patch of infested turf is turned over. Recent samples taken from around and inside some blueberry fields in west Michigan have shown that grubs are most abundant in field perimeters under permanent sod. Rotovated sites in row middles had the lowest grub densities.

Adult beetles typically emerge from grassy sites in July, but the grubs can be found now if you look for them. In the next few months, turn sod over using a spade in sites that are suspected to harbor Japanese beetle, to identify the source of adult beetles seen in the summer. By cutting a one-foot square and turning it over, the number of grubs per square foot can be determined to allow comparison between different parts of the farm.

The grubs are white, C-shaped and are just under the root zone. The soil contains some grubs from eggs laid in early July 2001 that were able to feed and grow to almost an inch long before the cool weather last year. Others were laid by the last adults, and were only a quarter of an inch long when the soil temperature dropped. These are still this size, but will catch up when the warm weather comes and they will start feeding on grass roots. An article on options for control of Japanese beetle will be prepared for a future Fruit CAT Alert.

Nearly all fruit plantings in Michigan require annual nitrogen (N) applications for optimum production. Inefficient fertilization practices increase fertilizer bills and the potential for N movement into water resources. Here are a few tips for using N efficiently.

Usual N rates are 40-80 lb N per acre on apples and pears, 60-80 lb on stone fruit, 50-100 lb on grapes, 50-70 lb on blueberries, and 50-80 lb on raspberries. Efficiency (percent of N used by the plants) declines as rates increase above these ranges. Generally, the highest rates are needed on sandier soils lower in organic matter. These soils are more prone to leaching and less able to supply N from organic reserves.

Fertilizers supplying all or part of the N as ammonium (urea, ammonium nitrate) are good choices early in the season because the ammonium adheres to soil particles and does not leach. As soils warm and plant demand increases, ammonium is converted by soil microbes to the mobile nitrate form. Fertilizers containing nitrate (calcium and potassium nitrate) or ammonium are suitable later in the season. Although nitrate is easily leached by rain or irrigation water, it can be applied efficiently when the crop demand is high. Ammonium sources are also suitable for later applications since ammonium is quickly converted to nitrate once soils warm. Be aware that if urea granules remain on the soil surface during warm weather, significant amounts of N may be lost to the atmosphere. Avoid losses by applying urea before rain or irrigation. Also consider the cost per lb of N when choosing fertilizers. The cheapest sources of N are high analysis fertilizers such as urea (46% N) and ammonium nitrate (32% N). Ammonium sulfate and urea are the best materials for blueberries.

Before budbreak, grapevines, tree fruit and blueberries have little demand for or ability to absorb N. Plants begin absorbing significant amounts of N only after leaves begin emerging, and the demand for N remains high through the period of active growth. With these crops in Michigan, the demand is high from June through most of August. One approach to maintaining sufficient available N in the root system throughout this extended period is multiple N applications. Greater efficiency can be achieved by splitting the annual fertilizer needs into two applications; one a couple weeks after budbreak, and one a month later. Split applications help assure sufficient N is in the root zone throughout the two to three months when the crop demand is high. Split applications are most important on sandier soils where N leaches most readily. Splitting N applications also provides the option of adjusting rates according to cropping levels. The second application can be reduced or skipped if fruit set is poor due to frost, poor pollination, or lack of bloom.

Place fertilizer so it is accessible to the crop. In orchards, efficiency is improved by spreading fertilizer in a broad band beneath the dripline of trees. Banding may provide some benefits in vineyards or blueberry plantings, but this has not been tested. Growers irrigating with trickle systems should consider fertigation. Fertigation places N where most roots are located, and multiple applications can easily be applied so that N supply matches the demand of the crop. Research indicates that N rates can be cut in half due to the efficiency of fertigation programs.

Given the strong dependence of many IPM activities on weather, there are a number of reasons for monitoring conditions yourself. Perhaps most important is the fact that many weather variables are highly variable across space, and are best measured where they are to be used. There are many options when it comes to weather monitoring, so before you spend money or time on a new system, there are several critical questions to ask that will help you to find equipment that is most economical and suitable for your needs.

The first question should always be, "What are my real weather monitoring needs?" For example, it really doesn’t make sense to purchase a temperature sensor with 0.1°F accuracy when you will only be using the temperature data for simple growing degree day calculations. Buyer or lease options on weather systems typically include:

1. Sensor accuracy. Sensor costs increase quickly for sensors with high accuracy. For many IPM applications, research-grade measurements are not necessary.
2. Robustness. Will the system perform when I really need it? Get a company’s previous track record or advice from professionals.
3. Simplicity. Simplicity can sometimes be an asset when under other time constraints.
4. Number of variables measured. Do I need more than precipitation and temperature? Multiple sensors may require a larger, more expensive datalogger.
5. Degree of automation. How often can I afford to take observations?
6. The method of telemetry. How do you plan to retrieve the data? Options include everything from a manual read of the sensor recorded on paper to radio, telephone, direct RS232 link to a personal computer, or even satellite.

In general, the greater the complexity and sophistication of the system, the greater the cost. Similar to tools and other purchases, there is a rule-of-thumb that applies here: "You get what you pay for." Remember this especially if you are looking for a system that needs to be working properly during many seasons of use.

For some users, there are a couple of other options available besides purchasing your own equipment. Many states and some private companies have networks of automated weather stations that collect the information needed for IPM. If you are fortunate enough to be located near one of these stations, this may be a cost-effective option. Lastly, some companies are now offering localized weather information derived from larger-scale meteorological and climatological data. These so-called "off-site" data may be a less expensive and adequate alternative for some users, depending on the sophistication of the application. For most applications, however, data taken on your farm is still the best strategy.

As you prepare to put your new weather equipment in the field, there are some important issues to consider. The first is where to place the instruments. You likely only have one set of instruments, so it is therefore critical to place them in a location that will represent your orchard environment as closely as possible. In general, greatest spatial variability in a given region will be observed with leaf wetness, followed by precipitation, relative humidity, and air temperature. Thus, if you have the resources for extra sensors, the best investment would probably be in additional leaf wetness sensors or precipitation gages.

In deciding where to place your instruments, a rule-of-thumb is that the station should be at least four times the height of the closest obstruction and away from any large paved areas. Keep grass and weeds near the station trimmed. Also consider the effects of microclimate. Microclimate refers to time-averaged weather conditions over distances of less than half a mile, and includes climate effects from the orchard level down to the microscopic level. Endless combinations of characteristics such as crop canopy structure, topography, and soil type can create unique microclimates. Solar heating and airflow are the most significant factors determining the microclimate in a particular area. For example, locations within or very close to vegetation acting as a windbreak tend to be warmer and more humid than locations in the open. Low-lying basin-shaped areas tend to be prone to cold temperatures during the growing season since cold air ponds there after moving from surrounding areas. Besides serving as a location for a frost alarm for the first location to reach the freezing mark on a frosty night, these sites should generally be avoided for siting IPM instruments.

Try to select an area that is:

• Relatively open with few obstructions to air flow in all directions
• Relatively flat, to minimize the impact of cold air drainage or forced turbulence around topographical obstacles;
• Easily accessible to you night and day;
• Close enough to an orchard to place a leaf wetness sensor if one is available with your system.

In choosing a site to meet your needs, remember that it may be virtually impossible to meet all of these criteria. Try to minimize the number of overall potential problems.

The two weather variables most commonly monitored by growers are air temperature and precipitation. For precipitation, try to site your gage on level ground away from any overhead obstructions. Typical installation height is 3-4 feet above the ground. When installing on a post, make sure that the opening of the gage is above the top of the post. Keep the gage level, especially if using tipping bucket-type rain gages. When the gage is in use, periodically check for any cracks, insects, accumulated dust or bird droppings.

For placement of temperature sensors in the field, there is one special rule. Never allow the sensor to be directly exposed to the sun or open sky, as such exposure can lead to erroneous or misleading measurements. If at all possible, use a screened or ventilated shield or enclosure if one is available for this purpose. By convention, the sensor should be placed at a height 5-6 feet above the ground surface. Avoid installation near paved areas, on walls of buildings or other artificial heat sources, or near low places where water tends to pond after rain.

Relative humidity and leaf wetness measurements are of special importance, as one or both are typically needed for monitoring plant disease risk. For relative humidity, placement in the field is fairly easy. For many sensors and automated systems, the relative humidity probe is combined with a temperature sensor, and the entire probe is installed in a shielded enclosure. For leaf wetness, however, there are few set rules, as there are no agreed upon standards for measurement of the variable.

The first issue is what type of sensor to choose. Options range from a rope wick connected to a mechanical recorder to an electronic grid plate across which resistance can be measured. For simplicity and automation, many users choose an electronic grid. Some users prefer to have the sensor professionally coated with a latex paint. Paint causes the sensor to be physically more representative of a plant leaf and tends to spread out any water droplets over the surface, making the painted grid generally more sensitive to dew formation. For leaf wetting events associated with rainfall, painted and unpainted grids respond similarly. Placement of your leaf wetness sensor in the field may vary greatly depending on crop and disease. In contrast to other meteorological measurements that are taken in more open locations, the best bet with leaf wetness sensors is placement within the plant canopy. While there is no standard, some plant pathologists recommend placement in an apple canopy on the north side of the tree above the first scaffold about midway between the tree trunk and the drip line. Past research indicates a consistent response with the plate sloped at a 20-degree angle downwards towards the north.

After you your weather system is in the field, remember that upkeep and maintenance of the system and its sensors are essential for it to provide useful information for your IPM program. Plan to check sensors at least once and preferably twice per year. Follow the manufacturer’s guidelines closely for checking operation of the system and maintaining calibration. In general, the more sophisticated the sensor or device, the greater the need for periodic checks. For example, electronic relative humidity probes can lose calibration relatively quickly, and should be checked carefully at least once per year, and replaced if necessary. In contrast, manually read sensors such as liquid in glass thermometers and rain gages can provide years of service with minimal care. Many problems with sensors are spontaneous and easily detectable. Other problems, such as sensor drift, may be more difficult to detect without regular inspection or comparative analysis of the data from a second, nearby data source.

Cool weather the last two weeks has kept plant growth at a standstill. Because of the cool spring our growing degree-day totals are behind. These are the lowest totals for this date since we began tracking from the beginning of the year in 1995. Warmer weather with no frosts is forecast for this week. This means that plant growth should proceed rapidly. Cover crops are beginning to green up.

Flower buds for most fruit are swollen. We expect rapid growth this coming week. The buds should be open exposing green tissues by the end of the week. Since we are at the beginning of the growth and disease cycles this spell of warm weather would be a good time to apply copper to trees that would benefit, such as apples for scab and fire blight, and cherries for bacterial canker.

Apricot buds are swollen, approaching red bud. Growers are reporting that less than half the flower buds are dead from freezes in the early March cold snap.

Peach buds are swelling. Early varieties are at green calyx. Where the buds have opened it is probably too late to apply sprays to control peach leaf curl.

Tart and sweet cherry buds are swollen. No green tissue is showing. Now is an excellent time to apply copper materials to suppress bacterial canker in cherries.

Apple buds are swelling. Some varieties are at silver tip. Apple scab applications should start this week. Growers may want to use copper as their first spray at green tip to provide early season scab control and suppress fire blight bacteria on the outside of the tree.

Grapes are dormant. Winter damage has been reported in vinifera grapes. This damage is probably due to the cold temperatures in January and March near zero. GDD base 50 for grapes are accumulated from April 1^st. We are at zero now.

Raspberry buds are showing green tissue. Now is the time for lime sulfur sprays to suppress anthracnose.

Van Buren County Code-A-Phone (616) 657-6380.

Berrien County Code-A-Phone (616) 944-4126 ext. 1

SWMREC Code-A-Phone (616) 944-1477 ext. 4

The season is getting underway a little later than normal this year. We are slightly behind normal in growing degree days, but very similar to the 2001 season.

Applications to sweet cherries for bacterial canker should be considered in the next 7 to 14 days. Cherries will move quickly with the predicted warm temperatures.

The Annual Spring Spray Meeting / IPM Update is scheduled for Thursday, April 18 at 7:00 PM. We will be meeting at the Jack Brown Produce facility near Sparta.

Dwarf Sweet Cherry Pruning Demo is scheduled for Tuesday, April 16. We will be meeting at Joe Klein’s farm on the northeast corner of Fruit Ridge and 13 Mile Road in Kent County. Speakers include: Dr. Greg Lang, MSU Dept. of Horticulture; Dr. Bill Shane, MSU Extension SW District Fruit Agent; Mr. Jim Nugent, MSU Extension, NW District Fruit Agent; and Mr. Phil Schwallier, MSU Extension District Fruit Agent. The time is yet to be determined. Call Amy Brown for more information about either of these meetings: 616-490-1079 (mobile) or 1-800-767-1345 (office).

A cool, but more tranquil weather pattern developed across the region in early April in response to more zonal, west-to-east jet stream flow across North America. While not a favorite pattern for humans this time of year, the cool weather was beneficial for the fruit industry as it slowed any early vegetative development of overwintering crops. During the month of March, mean temperatures generally ranged from 1 to 3 degrees F below normal in all but southern sections of the state, where temperatures were near to slightly above normal. Climatologically, it was the first month of below normal temperatures since September last fall. December through February mean temperatures were among the mildest on record.

Precipitation totals have been variable across the state in recent weeks, but have tended to remain at above normal levels for the same time frame. As a result, soil moisture levels are also at or above normal levels for early spring.

Looking ahead, the jet stream troughing feature is expected to develop in the western U.S. with southwesterly flow across the Great Lakes region. This pattern should result in a significant warming trend and the mildest temperatures of the season thus far within the next week. The latest NOAA six-to-ten day outlook for April 14-18 calls for a continuation of this pattern, with above normal temperatures and precipitation totals expected during this period. Forecaster confidence in this outlook is rated as greater than normal. During the eight-to-fourteen day period (April 16-22), the jet stream is once again forecast to become more zonal across North America. Normal to above normal temperatures and precipitation are expected to continue in Michigan.

All long lead outlooks are weighted heavily on the gradual development of a warm episode (El Nino) in the equatorial Pacific region by this fall. Even so, the outlooks for the Great Lakes region are vague at best, especially for the next few months. The most recent NOAA Climate Prediction Center outlook for April calls for the "climatology" scenario for temperature and precipitation. Climatology scenario means there are near equal odds of below-, near-, and above normal levels. The outlooks are the same (i.e. climatology) for the April-June three-month period continuing into the middle of the upcoming growing season.

Beyond that, the climatology scenario continues for precipitation totals for the remainder of 2002, followed by greater than normal probabilities of below normal precipitation totals by January 2003 continuing into spring of 2003. The climatology scenario also applies to temperature during the three-to-twelve month time frame. The exception is July to September period, and from late fall 2002 through spring of 2003, when odds favor warmer than normal temperatures. While the outlooks offer relatively little guidance in terms of the upcoming summer, the return of subsoil moisture levels to near or even above normal levels is a positive development, with relatively low odds of a repeat of the drought conditions experienced by many growers in the state last year.