(6)(40)
(5)
Prepared: August, 1999
(6)(40)
(5)
Peaches are a vital part of Michigan's agricultural economy. Most of the state's peaches are grown close to Lake Michigan, in Berrien county in southwestern Michigan, and in Oceana county in westcentral Michigan. The peach season in Michigan is from late July to mid-September. In the past, many of Michigan's peaches were sold at roadside stands. Now approximately 50% of the market has shifted to chain stores. Many companies like Gerber, Heinz, and Profac/Curtis Burns now buy Michigan peaches for processing. (10) Gerber has established chemical usage guidelines that preclude the use of organophosphates and carbamates in peach. This limits chemical pest control to pyrethroids and other s with short-lived residues. The national headquarters for Gerber baby foods is in westcentral Michigan.
Deep, fine-sandy loam soils with good internal drainage and freedom from alkali or salinity are best for optimum peach growth and production. Fruit thinning is an annual practice and hand labor is preferred over mechanical or chemical options. (28) Peach trees grow about 18 feet tall and require a good deal of pruning to encourage new growth on which the fruit is borne. Fruit is grown on the previous year's growth.
Nitrogen is the most important nutrient in fruit production and is usually the only fertilizer element that should be applied annually. Trees need sufficient nitrogen to insure optimum growth and production. Too little may result in low yields, poor fruit size, and excessive cold injury. However, too much may result in excessive growth, poor fruit color, and excessive cold injury. Nitrogen should be applied as a split application, half before growth starts in the spring and the remainder if a grow is normal.(40)
Cold injury, sometimes called winter injury, might be described as injury to wood and dormant flower buds by low temperature, as compared with "frost" injury which is usually restricted to opening flower buds or blossoms. The results of cold injury are very apparent --even spectacular -- when a peach crop is lost because all the flower buds are killed, or the trees themselves are killed, by one extreme drop in temperature. Of almost equal importance, though less noticeable, are the minor injuries in the tree which provide an entrance for the peach borer and the destructive peach canker disease, which, working together, considerably shorten the life of the tree. (24)
The majority of Michigan peach pests are found in a variety of habitats that are in close proximity to orchards. These habitats provide a continual source of pests. (3) (25)
Chemical Controls: Critical Use Issues
Plum Curculio
Biology
Plum curculio is a key pest of peaches in Michigan. They
feed directly on the fruit. In the absence of effective controls they can
disfigure 50-60% of the crop. Plum curculio is capable of causing great
damage and is considered a difficult pest to control. The problem is intensified
where stone fruits and apples are interplanted. A reliable system for monitoring
this pest has not been developed. (39)
Overwintering adult beetles attack the fruit soon after it forms and eat holes through the skin and feed on the pulp. The female makes jagged, crescent-shaped wounds on the skin when laying eggs. Each female is capable of laying from 100 to 500 eggs. The complete cycle from egg to adult takes about 50 to 55 days.
Injury caused by the plum curculio can be grouped into four principal classes: The wounds resulting from feeding and egg laying by the overwintering beetles early in the spring appear as crescent-shaped scars (oviposition injury) on the fruit, or as bumps (feeding injury) that protrude from the fruit at harvest. Badly attacked fruit may be knobby, gnarled and scarred at harvest. Internal injury is caused by the larvae’s burrowing in the fruit. Most of the larvae-infested fruit drop to the ground during June.
Premature dropping of the fruit during June or later in the season is a result of larval activity within the fruit or adults’ feeding on the fruit. Feeding punctures made by the beetles in the fall just prior to hibernation are characterized by a small hole in the skin of the fruit with a hollowed-out cavity in the flesh of the fruit that extends a few millimeters on each side of the opening.
Moisture and temperature regulate plum curculio activity. The exact role of water in the biology is not known, but it has been observed that beetles need water before much activity takes place. Also, beetles are more active on warm, damp, cloudy days and in thick, heavy trees that provide abundant dampness in the centers.
Temperature is the most important factor in plum curculio activity, particularly early in the spring. Several formulas have evolved to predict when beetles leave hibernation quarters and move to the trees to lay eggs or feed. They are: Mean temperature between 55 and 60º F for three to four days, mean temperature above 60º F for several (three) days and maximum temperature of 75º F for two consecutive days.
High winds, which cause considerable movement of the trees, will shake the beetles from the trees. High winds and low humidity cause beetles to leave the trees and burrow into the soil in search of moisture. The beetles’ activities are about equally distributed between day and night.
When temperature and moisture conditions are favorable in the spring, the adult beetles leave their hibernation quarters in trash on the ground, wood lots or hedgerows, and migrate to the trees. This usually occurs just about the time of bloom. Migration continues for up to six weeks after bloom, with the largest migration occurring within the period up to 14 days after petal fall. The adults do not like strong light and prefer the dense shade of the tree’s inner canopy. (4)(22)(40)
Cultural Controls
Avoid interplanting peach trees with other host plants.
Chemical Controls
An insecticide coverage is generally recommended for the
period from shuck split to second cover because the beetles can quickly
cause damage during warm conditions. Shuck-fall sprays and the first and
second cover sprays are directed at the adult and the egg-laying period.
Once the fruit is exposed, the females can lay many eggs in a short time
causing considerable damage. If the weather is cool the beetles generally
do not cause damage. Plum curculio is considered a difficult pest to control
and requires good coverage with an effective pesticide. (4)(22)(39)(40)
Organophosphate insecticides are the primary option for plum curculio control. Experimental insecticides or non-chemical strategies currently are in the early stages of development. (3)
Oriental Fruit Moth
Biology
Oriental fruit moth is a key pest of peaches in Michigan.
The larvae feed directly on the fruit. In the absence of effective controls
they can destroy 50% or more of the crop. Damage to the growing tips of
young trees can hinder and distort development of good tree structure.
(40)
First generation adults appear in early May; their offspring feed on tender fruit twigs and terminals. The first sign of larval activity is the flagging of peach terminals due to the burrowing larvae. Damage first appears about 10 to 14 days after emergence. Second generation adults appear in mid-July; their larvae feed internally on the fruit, causing mushy, wormy fruits. Third generation adults appear in late August, and their larvae also feed in the fruit. Oriental fruit moth over winters as full grown larvae. (23)
Cultural Controls
No information available
Chemical Controls
The synthetic pheromone for this insect is quite effective
in attracting males. Mating disruption works well in peaches. Traps
are used to determine when to apply chemicals for best adult control. Pheromone
disruption has proven effective in commercial orchards.(40) Traps are used
to detect 1st, 2nd and 3rd generation
adult flight. Insecticide sprays are timed for hatching larvae
at 200 degree days base 42 beyond the point when accumulated trap catches
of adult male moths are more than 1 oriental fruit moth per trap followed
by a second spray 200 degree days base 42 after that.
The use of pheromone traps and degree day models is a more precise way to tailor insecticide sprays to the year and orchard. Experience is the best guide for the use of these tools. (23)
Tarnished Plant Bug
Biology
Tarnished plant bug is a key pest of peaches in Michigan.
Tarnished plant bugs feed and breed on a great variety of plants. It attacks
apple, apricot, cherry, pear, peach, plum and quince. It also feeds on
small fruits, such as strawberry and raspberry as well as flowers, vegetables
and field crops. Plant bugs are difficult to control. (14) (4)
Affected fruits may exhibit both feeding and egg-laying injuries. Feeding punctures are usually small and superficial injuries, but the oviposition punctures cause deep depressions and distortion of the fruit. Most of the injuries are inflicted in the calyx tube near the base of the sepals and petals, so the blemishes on the mature fruits appear at the calyx end. Some injuries, however, particularly those made after bloom, may occur elsewhere on the fruit surface.
Overwintered adults begin feeding on peach buds soon after growth begins. They are most abundant during the prebloom and blossom periods. Egg laying in the blossom buds begins as soon as the stems in the clusters start to separate and continues in the fruit until the fruit are about 12 mm in diameter. The plant bugs then migrate to weeds and become scarce in fruit trees. Common mustard weed is the preferred host.
The adult bugs hibernate under leaf mold, stones and tree bark, among the leaves of such plants as clover, alfalfa and mullein, and in many other protected places. They become active very early in spring, when they attack the buds of fruit trees, seriously injuring the terminal shoots and fruits. They do not appear to lay their eggs on these plants to any great extent, but rather migrate to various herbaceous weeds, vegetables and flowers, where the eggs are either inserted full length into the stems, petioles or midribs of leaves or into buds, or are tucked in among the florets of the flower heads.
Warm weather in the early season before alfalfa and other ground crops have developed will cause movement into and damage in the fruit trees. Cold, rainy or windy weather at this time will reduce or prevent feeding. Fruit trees near hedgegrows, ditch banks and other hibernation locations are more seriously injured. Droughty conditions that dry up vegetation may cause plant bugs to move into trees.
Other plant bugs, such as oak and hickory bugs (Lygocoris spp.), can cause similar injury in orchards bordered by woods. Green stink bugs (Acrosternum hilare) and other stink bugs (Pentatomidae) can also cause injury, especially late in the season. (15)
Cultural Controls
Crop cover management is important in preventing the tarnished
plant bugs from moving into fruit trees.
Chemical Controls
Spraying weedy hedgerows and weedy areas adjacent to orchards
can reduce the migration of plant bugs into the orchards.
Chemical control of tarnished plant bugs is accomplished with endosulfan and synthetic pyrethroids.(40) (3) Control of this pest with insecticide is often required in Michigan peach orchards where mating disruption is used as the primary control for oriental fruit moth. (39)
Alternatives Controls
No information available
Green Peach Aphids
Biology
Green Peach aphids are important pests of peaches. They
cause damage through sucking, causing twisting and distortion of the new
growth and by transmitting mosaic viruses.
Green peach aphids are yellow-green, except for winged adults, which have black markings on their bodies. They may overwinter as eggs on an overwintering host or in greenhouses, or migrate into Michigan from southern locations. On the overwintering host, the eggs hatch in the spring and – after several generations – produce winged aphids. These adults migrate to several different weeds and crops. Winged forms are especially common when the host plant is dying or aphids are becoming crowded.
Aphids have extremely high reproductive rates – each aphid can give birth to 50-100 young, and there may be five to ten generations per year. Usually population numbers are held in check by natural enemies (lady beetles, hover fly larvae, lacewing larvae, fungal diseases, and tiny wasps), but insecticide or fungicide sprays sometimes disrupt this natural control and result in aphid outbreaks. Spraying with the wrong insecticide only increases aphid problems by killing natural enemies.
Aphids can be monitored by direct visual observation of plant foliage. Traps can also be used, but identification is difficult because many harmless aphids and other insects may also be trapped. Green peach aphids can rapidly build up resistance to insecticides because females reproduce without mating, and offspring are genetically identical to the mother.
Cultural Controls
Maintain natural enemies populations.
Chemical Controls
Endosulfan
Methomyl
Alternative Controls
No information available
Japanese Beetle
Biology
Japanese Beetles are important pests of peaches. Adult
beetles are voracious feeders on numerous ornamentals, fruits, vegetables,
grasses, and weeds. Adults feed on the surface of fruit, causing irregular
damage and scarring. They chew along the margins of leaves and may eat
entire leaves. More than 400 plant species within 95 families are susceptible
to attack by this pest. Adult beetles not only damage numerous ornamental
herbaceous plants, shrubs, vines and trees, but also small fruits, tree
fruits, row crops, and many other plants. Adult female beetles will lay
eggs in the soil. The eggs hatch into white grubs that feed on turf roots.
Beetle grubs feed on plant roots, attacking mainly turf (lawns, golf courses,
and pastures) but also damage the roots of many other crop and ornamental
plants.
Grubs overwinter 8-10 inches deep in the soil. As spring temperatures increase, the grubs move up in the soil to feed on grass and other small roots. They pupate in late May to June and adults start emerging in late June to mid-July. Adults, which live from 30 to 45 days, feed through late summer or early fall. Females lay eggs 2-6 inches (5-15 cm) deep in the soil during July and August, and grubs hatch in 10 to 12 days. Grubs first feed on decaying matter but soon feed on roots and eventually move deeper to an overwintering site some months later.(40)
The beetle's life cycle takes one year in most established areas within the United States, only in the northern extremes does its life cycle require two years. The pest spends ten months underground as grub-like larvae. The adults are abundant in July and August, the female lays eggs 2 to 6 inches in the soil to start the cycle over again. Beetle emergence is retarded progressively from southern to northern latitudes. (20)
Adults are the principal injurious stage to peaches, although grubs may injure nursery stock. Adults may occasionally skeletonize leaves, but fruit feeding is the most common injury to mature stone fruit orchards. Adults are gregarious and often feed in groups chewing large chunks from the fruit. Fruit is usually injured during the last two weeks before picking. Therefore injury is most common on early to mid-season varieties ripening during periods of JB abundance, e.g. `Redhaven', `Glohaven', and `Loring'.
Traps are available for JB and are effective for monitoring the initial adult emergence. Adults may be monitored by quietly moving into the tree, jarring several branches, and observing how many fly off. Direct fruit counts are the most effective way of assessing damage. Fruit should be examined by the method outlined for other insects. Since feeding may be "clumped" or unevenly distributed, care should be taken in looking at a representative sample before making a spray decision. If feeding damage looks like it may soon exceed 1/2 to 1 percent, then a treatment is justified. (21)(40)
Cultural Controls
Healthy, vigorous plants are most able to overcome beetle
injury to foliage, so be sure all plants are provided with proper care.
Also, dispose of any over-ripe or diseased fruits, as these tend to attract
beetles. Control measures for adult Japanese beetles should be initiated
as soon as beetles appear, but before serious damage occurs. The beetles
also can be controlled by hand collecting. Place a container or sheet beneath
infested plants and dislodge the beetles. Do this when the beetles are
still lethargic in cool weather. Kill the beetles by placing them in a
container filled with a mixture of water and kerosene. In the 1930's, traps
were developed for survey work. Today's traps, which employ a combination
sex pheromone and floral lure, can be used to capture large numbers of
beetles. Be sure to place the traps away from vulnerable host plants. (17)
Chemical Controls
Control is difficult because beetles are emerging over
several weeks to a month. Surface foliar sprays of methyl parathion, carbaryl
(Sevin) or acephate (Orthene) can reduce feeding damage for two to several
days. Reapplication is needed as new beetles migrate in and the insecticide
breaks down from sunlight and summer temperatures. (16)(40)
Alternative Controls
Steinernema glaseri is effective against Japanese
beetle larvae. As we understand more about the nematodes, insect species
attacked, environmental conditions, etc., nematodes may become an important
part of biological control of insects.(18)
Milky spore disease (Bacillus popilliae) is a biological control of Japanese beetle grubs. However, it may require up to 2 or 3 seasons to become firmly established in the soil (at which time it becomes self-inoculating). It generally works best at high grub population densities. (17)
Rose Chafer
Biology
The rose chafer is an important pest of peaches.
The rose chafer is a voracious feeder and will attack almost any plant part although blossoms are preferred. The insect is more common abundant where peaches are gown on sandy soils. It overwinters as a larva and pupates in the spring. The adults emerge from the soil and young fruit feeding sites in late May to early June. Adult feeding lasts a month or more. Eggs are deposited in grassy areas. The resulting larvae burrow into the soil and feed on grass roots. Birds are sometimes killed by eating adult rose chafers which contain a chemical that affects the heart of small animals.
Single applications of pesticide do not give satisfactory control. The insects occur in such large numbers that pesticides kill off some insects but more move in from surrounding areas.(19)
Cultural Controls
No information available
Chemical Controls
Methyl paration is the most effective option. Synthetic
pyrethroids are a mediocre option at best, with very short-lived periods
of action. (39)
Lesser Peach Tree Borer
Biology
The lesser peach tree borer is an important pest of peaches.
Feeding by greater and lesser peach tree borers can kill peach trees. (3)
They feed on a wide range of cultivated food plant hosts including peach,
plum, sweet cherry, tart cherry, apricot and nectarine. Wild crop hosts
include wild black cherry, wild red cherry, beach plum, wild plum and Juneberry.(4)
Larvae cause damage by feeding in the inner bark or cambium layer of the tree trunk. Their presence is indicated by their frass, which is pushed out through cracks in the bark, and by the gum the tree produces. Traps are best used, however, to indicate when trunk sprays should be applied for adult control to prevent egg laying. (4) (23)
The lesser peachtree borer differs from the peach tree borer in that the moths emerge over a long time during the summer. Also, the larvae do not confine their activity to the trunks and scaffold limbs. The larvae of the lesser peach tree borer borrow under the bark in wounded or injured portions of the tree. They may be found in injured or diseased trunks, scaffold limbs or branches. Pruning wounds, valsa cankered areas, insect-injured areas are potential sites for the lesser peach tree borer. The lesser borer can become established only in tissue previously injured by some other cause – it cannot establish itself in healthy tissue.(4)(40)
During favorable weather, mating occurs within an hour after the moths emerge, and oviposition takes place shortly after mating. The female deposits eggs in cracks and crevices near injured areas. Usually two to four eggs are deposited at a single location. Almost 98 percent of the eggs are deposited in injured areas between ground level and 8 feet up, with the highest percentage being deposited within 3 to 4 feet of ground level. Depending on the temperature, egg hatching occurs in seven to 10 days. Then the young larvae invade the wounded tissue and start feeding.
Once established in an injured area, the larvae feed freely on the tender growing bark at the margins of the injured area. If not controlled, they may enlarge the wounded area by feeding until the entire branch or limb is girdled, resulting in death of the limb. Borer infested trees are especially susceptible to attack by the valsa canker fungus organism. The presence of borers is revealed by the sap flowing from wounded areas, which contains brown frass from the larvae.
Temperature, principally during the spring, probably influences the development of the pupae and the emergence of the adults more than any other factor.Moths of the lesser peachtree borer are in flight from late May through September in the northern states. In the north central states, peak emergence may occur from early June to mid-July, depending on the location. There is a single continuous generation each year, in years with high temperatures, a partial second generation may occur. Tree injury from mechanical harvesting that results in bruised or open wounds in the bark of the limbs and trunk of the tree has been chiefly responsible for changing the status of this insect from a minor to a major pest of cherries. (13)(40)
Cultural Controls
Protect trees from injury and disease when possible. Remove
alternative hosts in the vicinity of the orchard.
Chemical Controls
A hydraulic gun with low pressure is used to apply an
effective
pesticide to the trunk and scaffold limbs. The first application should
be made about 10 to 14 days after first emergence. Spray to runoff. Pheromone
traps should be employed for timing of male emergence.(4)
Examine the trunk, scaffold limbs and exuded gum for frass. Place pheromone traps in trees early in the season. Depending on location, this may vary from early April to mid-May. In southern locations where there are two generations, replace the caps and traps for the second generation. (13)
Greater Peach Tree Borer (Synanthedon exitiosa)
Biology
The greater peach tree borer is an important pest of peaches.
(3) Feeding by greater and lesser peach tree borers can kill peach trees.
(3) The adults of these insects are typically attracted to trees that have
wounds (shaker injury on cherry, cracked bark on peach), black knot lesions
(plum), dogwood borer or burr knots (apple). However, greater peach
tree borer can and does attack healthy trees, as well as those that are
out of condition. Greater peach tree borer has become an increasingly important
pest in plums and cherries, where it was not considered a pest, and thus,
not sprayed for often until recent years. (29)
The peachtree borer kills more peach trees in the United States than any other insect. In the north central states, where there is a high incidence of valsa canker and winter injury, the lesser peachtree borer probably ranks higher as a general pest than the peachtree borer. However, control programs for the peachtree borer must begin the year young trees are planted and must continue for the life of the planting.(4)
The peachtree borer is a major pest of peaches but sometimes causes serious damage to cultivated cherry, plum, apricot, nectarine and ornamental shrubs. The peachtree borer has been reported in all fruit-growing areas of the United States and Canada. The principal damage is done by the larvae, which feed on the cambium, or growing tissue, and inner bark of the tree. Larval feeding may completely girdle and kill young trees. Older trees are less likely to be girdled but are often so severely injured that their vitality is lowered so that other insects, diseases and environmental conditions can complete their destruction.(4)
Borer-infested trees bleed or exude gum during the growing season. The frass of sawdust-like excrement in the exuded gum indicates the presence of borers. Trunk injury by diseases or environmental conditions will usually produce clear gum. Warm, sunny days favor the emergence of adults from their pupal cases; darkness retards emergence. Moist soil also favors adult emergence. The greatest emergence usually occurs the day after a rain.(4)
The peachtree borer overwinters as larvae on or under
the bark of trees, usually below the ground level. The larvae become active
and begin to feed on the inner bark when the soil temperature reaches 50
degrees F. When full grown, the larva constructs a cocoon and pupates,
usually during late May and June. Moth emergence begins in early July and
continues into September. The moths mate immediately after emerging and
the female begins to lay eggs within 30 minutes.(4)
Egg deposition occurs between 9 a.m. and 4:30 p.m., with
the majority of eggs deposited the afternoon of the day of mating. The
egg incubation period averages nine to 10 days during warn summer days
and up to 15 days during colder periods. The young larvae bore into the
bark at the base of the tree. Once beneath the bark, they feed on the cambium
and inner bark of the tree. Generally only one generation occurs each year
in the north central states. Some larvae, however, may require two years
to complete development.(4)
Identification of the peachtree borer adult male is important; currently commercially available pheromones are not specific for this pest, and other clear-wing moths such as the dogwood borer and lilac borer may be caught in pheromone traps meant for the peachtree borer. Note that the lesser peachtree adult borer is not attracted to the same pheromone traps as the peachtree borer; pheromones for the former are specifically designed to trap only that species.(4)
Cultural Controls
No information available
Chemical Controls
A hydraulic gun is used to direct an effective chemical
at the base of the tree at low pressure before the eggs hatch. One or two
years’ protection can be provided to newly planted trees by dipping the
trunk and roots into an effective chemical solution before planting. The
young trees should be inspected for crown gall before using the dip method.
Pheromone traps are used to time sprays.(4)
Timings for trunk sprays will vary based on emergence of the pest; it is acceptable timing to apply borer sprays 7-10 days after first flight of the male insects. (29) Lorsban, Thiodan, and to a lesser degree, Asana, provide residual control of borers by leaving a barrier of insecticide for the young, hatching larva to chew through.
Spotted Mites
Biology
Twospotted spider mites are important pests of peaches.
(3) They feed on a wide range of plants including deciduous fruit trees
such as apple, pear, peach, nectarine, plum, apricot and cherry. The injury
from twospotted mites is similar to that of European red mites. Plants
exhibit bronzing-gray coloration and webbing. (4)
Full-grown female mites and some immatures overwinter under bark scales on the trunk of the tree or among fallen leaves and in other protected places on the ground. With the arrival of warm weather in the spring these mites begin to search for food. They feed on weeds and grasses. They begin to lay eggs. A full generation can take only three weeks. Five to nine generations occur in the orchard each season, depending on the weather. (4)
Drought conditions cause mites to migrate from grasses to orchard fruit trees.
Twospotted spider mites have a considerable propensity for developing resistance to miticides. (4)
Cultural Controls
No information available
Chemical Controls
Leafhoppers
Biology
Potato leafhoppers (Empoasca fabae) are infrequent
pests of peaches in Michigan. (40) (3) Adult potato leafhoppers are 1/8
inch long, wedge-shape, and yellowish to pale green in color. Immatures
or nymphs look similar but are wingless. Leafhoppers are found primarily
on the underside of the leaves where they pierce the veins and feed on
plant juices. This causes the leaf to turn yellow to red in color from
the feeding point outward. (11)
Several species of leafhopper transmit X-disease, including Paraphlepsius irroratus. These leafhoppers feed during the day on plants in the orchard ground cover and at dusk migrate to peach trees, where they remain until dawn. The main damage they cause is the incidental transmission of X-disease. (2)
Cultural Controls
No information available
Chemical Controls
Control of potato leafhopper is generally not needed if
an organophosphate insecticide is used for plum curculio or other pests.
(3)
San Jose Scale (Quadraspidiotus perniciosus)
Biology
The San Jose scale is a pest of peaches and other cultivated
fruits. It is capable of killing mature trees if not controlled. The scales
feed on sap. The feeding causes a decline in plant vigo, growth and productivity.
Fruit can be deformed and small. (41)
Immature scales called crawlers are able to move to feeding sites. The crawlers insert their beaks through the bark to feed on tree sap. They become sessile and develop a waxy protective covering. The San Jose scale overwinters as a nymph, extremely low temperatures can cause mortality. (41)
San Jose scale are reported to be a concern in Southwest Michigan. (40)
Cultural Controls
No information available
Chemical Controls
Thorough spray coverage is essential for chemical control
of San Jose Scale. (41)
Thrips
Biology
Thrips are very small (1/16 inch), yellow or brown insects
which damage cole crops by rasping the leaf surface and sucking the sap.
Damage appears as spots on the inner leaves. Large areas of leaves can
be affected during heavy infestations. Thrips damage usually increases
during the hot, dry weather of late summer. Thrips overwinter in plant
debris as adults and nymphs.
Thrips are reported to be a concern in Southwest Michigan. (40)
Cultural Controls
No information available
Chemical Controls
Insecticide Profiles:
Azinphosmethyl (Organophosphate)
Apollo SC is recommended for use on mites at a rate of 4-8 oz (32) limited to one application a year. It has some action against Japanese beetles and green peach aphid(40)
Imidacloprid is excellent for potato leafhopper, but not registered
Spinosad is good for plum curculio and oriental fruit moth and perhaps borers, but not registered
Pheromones - good efficacy on oriental fruit moth, lesser peach tree borer, greater peach tree borer. Products are not compatible in mixtures, require different products and applications.
Biological control is effective for mites and indirect pests.
References: (3) (32) (9) (7)
Brown Rot
Biology
It is the most important disease in peaches
in Michigan. (36) Brown rot is caused by a fungus, Monilinia fructicola.
It reduces yields primarily by rotting fruit both on the tree and after
harvest. In seasons with weather favorable for infection, entire crops
may be lost, almost overnight. (2)
Brown rot attacks blossoms, spurs, shoots and fruit. Disease outbreaks are more common on mature fruit than immature fruit. Initially, small, circular light brown spots develop on the surface of the fruit and expands rapidly under favorable conditions, destroying the entire fruit.
Warm, wet, humid conditions that persist for several days favor the production of spores. The amount of inoculum is important in governing the rate of infection. (2)
The pathogen overwinters in mummies in trees and on the orchard floor in infected plant material. Spores are disseminated by splashing or wind-driven rain and carried to blossoms.
Cultural Controls
Alternative Controls
No information available
X - Disease
BiologyThe X-disease phytoplasm is transmitted by a several leafhoppers. These leafhoppers feed during the day on plants in the orchard ground cover and at dusk migrate to peach trees, where they remain until dawn. The main damage they cause is the incidental transmission of X-disease. (2)
Cultural Controls
Remove chokecherry near orchards.
Insect control against leafhoppers (2)
Chemical Controls
Post harvest injection of oxytetracycline into the trunk
of infected trees offers some temporary symptom remission. Oxytetracycline
sprays have not been as effective as injections. (2) This is not practical
for commercial operations. (40)
Alternative Controls
No information available
Peach Leaf Curl
Biology
Peach leaf curl is an occasionally severe disease of peach
and nectarine. Peach leaf curl does not generally cause major economic
losses. (36) The pathogen infects peach buds from bud swell to bud opening
under wet conditions and air temperatures in the 50º to 70ºF
range. Infections can take place in the spring from bud swell to bud opening.
(12)
Once leaves are infected in the spring there is no treatment. The leaves are infected in the bud and once they have emerged they are not susceptible to infection. Leaves will become thick and crinkled, turning orange or red. When the fungus sporulates the leaves will become powdery. The leaves will eventually fall off and the tree will grow new ones. Peach leaf curl will only weaken the tree by removing leaves. This may also cause fruit drop and reduce the size of the remaining fruit. (12)
Cultural Controls
No information available
Chemical Controls
Bravo and copper compounds are both very effective against
this disease. Ferbam (Carbamate) and Ziram are not quite as effective.
Copper compounds have the benefit of providing some slight suppression
of bacterial spot as well. Bravo has been rumored to help suppress Cytospora
canker. However, there may be little data to support this. Early spring
applications are needed to control this disease, or you can take
advantage of fall applications to get the job done when the pace is less
hectic.
Alternative Controls
No information available
Bacterial Spot
Biology
Bacterial spot is caused by Xanthomonas campestris
pv. pruni.
This disease can be serious in peaches in Michigan. Highly susceptible
cultivars cannot be grown profitably because entire crops can be lost in
outbreaks. Extended periods of warm, wet, humid weather during the growing
season favor bacterial spot development. The most common varieties in Michigan
have moderate to good resistance to bacterial spot, such as Redhaven. Some
susceptible varieties are grown in Michigan, such as Suncrest and Babygold
5. (2)
Small, angular lesions may be present on leaves, fruit and shoots of infected plants. Severely infected leaves turn yellow and drop. Defoliation can result in decreased yield, sunburn and cracking of the fruit.
The pathogen overwinters in twig lesions and buds and on symptomless plant surfaces. In spring, the bacteria are spread by wind blown rain to leaves, fruits and shoots. Moisture from fog and dew tends to wash bacteria towards the tips of leaves. Water congestion of tissues is important for infection to occur and for disease development. (2)
Cultural Controls
Resistant varieties, avoid susceptible varieties
Maintain adequate nitrogen
Shield susceptible varieties from blowing sand(40)
Chemical Controls
Chemical sprays help to reduce the amount of fruit and
leaf infection. For optimal control, they must be applied before symptoms
occur.
Peach Perennial Canker
Biology
Perennial canker of peach, also called Leucostoma canker,
Cytospora canker and Valsa canker, is caused by two fungi, Leucostoma
cincta and L. persoonii.
Cankers on branches, scaffold limbs, branch crotches and trunk are oval to elliptical in outline and often are surrounded by a roll of callus at the margins. Characteristic white, circular stromata of the fungus are visible when the bark is removed from the cankered area. Weak limbs may experience die back. Water-soaked tissue and gumming may be observed on branches and limbs at the bases of infected shoots. Later cankers may develop, often with a dead shoot in the center. Cankers gradually enlarge each year until the limb or trunk is completely girdled. Active cankers often have gum associated with them, but "gummosis" by itself is not diagnostic. Leaves on limbs girdled by cankers collapse and die.
The fungi overwinter in cankers or on deadwood. Spores are disseminated from diseased tissue by splashing and wind-driven rain. Infection is through damaged or injured bark. Cold injury is the most important factor predisposing trees to canker; pruning wounds, mechanical damage, insect punctures and leaf scars are other entry points.
Moisture is required for spore germination. The rate of canker development after infection depends on temperature and the species of fungus. Callus formation occurs when temperatures are not favorable for canker development. Canker activity resumes when temperature again favor the fungus. (2)
Cultural Controls
Alternative Controls
No information available
Peach Rosette Mosaic
Biology
Peach rosette mosaic is caused by the peach rosette mosaic
virus. It is a disease of peach in southwest Michigan. Peach rosette mosaic
has limited distribution. (36)
The infected trees exhibit a few twigs or limbs with darker than normal but small leaves that are crowded together. The crowding is due to the shortening of internodes on affected limbs and is referred to as rosetting. Symptoms will eventually develop throughout most of the tree. PRMV is a nematode-transmitted, soil-borne virus. It is transmitted by dagger and needle nematodes from diseased peach trees to healthy trees. Natural field spread is slow. The virus moves systemically to aboveground portions of the tree. Trees infected when young may exhibit symptoms throughout the tree, while trees infected when mature may exhibit symptoms on isolated limbs. (2)
Although PRMV is graft transmissible, there has been little spread of the virus by infected scions, possible because the striking symptoms and limited natural distribution of the disease in peach make it easy to avoid. (2)
Cultural Controls
Eradication by rouging (40)
Chemical Controls
Soil fumigation for nematode control(40)
Alternative Controls
No information available
Prunus Necrotic Ringspot
Biology
Prunus necrotic ringspot is also called necrotic leafspot
and is caused by a virus. The virus is seed-borned, and can be transmitted
through graftin and via pollination. It can cause economic loss.
Infected trees show symptoms acutely in the first year following infection. Early leaves are damaged, while later leaves show less damage. In following years infected trees display less symptoms, although tree vigor and size may be affected. The extent of damage is related to temperature, shoot dieback being more severe in warmer weather.(2)
Cultural Controls
Nursery certified disease free new trees(2)
Chemical Controls
No information available
Alternative Controls
No information available
Tomato Ringspot Virus
Biology
This virus is widespread throughout the Michigan fruit
growing area. It causes disease in stone fruits (peaches, plums, cherries,
etc.), pome fruits (apples, pears, etc.), blueberries and grapes. Affected
peaches look stunted, low vigor and weakly rooted. Wood below the bark
below the soil line is pitted and disorganized.(40) Tomato ringspot virus
has a very wide range of hosts, including many weeds such as dandelion,
curly dock, plantain and chickweed. The virus is spread by the dagger nematode
Xiphinema
americanum from the roots of diseased raspberry bushes or weeds to
the roots of healthy bushes. (31)
Cultural Controls
Purchase and plant only Certified Virus-Tested nursery
stock. Such stocks have been tested for the presence of known virus and
other systemic diseases. If planting stocks are not certified, they probably
will contain one or more of the viruses described in this publication.
Plant stock in soil free of virus-vector nematodes (Xiphinema americanum
- dagger nematode). If soil is found to contain this or other plant pathogenic
nematodes, use a preplant soil fumigant. Pull out and burn any plants that
show virus disease symptoms. (31)
Control broadleaf weeds that harbor the virus, especially dandelions.(40)
Chemical Controls
Fumigation to reduce dagger nematodes.(40)
Herbicides to control broadleaf weeds.(40)
Alternative Controls
No information available
Powdery Mildew and Rusty Spot of Peach
Biology
Powdery mildew is caused by a fungus Sphaerotheca
pannosa. (2) Infected plants are covered by white, felt-like mycelium.
White circular spots on young fruit expand in size. Layer the mycelium
sloughs off, leaving a rusty-colored patch with dead epidermal cells. The
rusty spot expands as the fruit enlarge.(2)
The fungus overwinters in dormant peach buds. When infected shoots emerge in the spring spores are produces. The spores are transported by wind and rain. Young fruit are the most susceptible to the pathogen. (2)
The disease is most severe following periods of moderate temperatures and high humidity. (2)
Cultural Controls
Two varieties planted in Michigan are susceptible: Rio-Oso-Gem
and Redskin.(2)
Most varieties planted in Michigan are resistant to powdery
mildew.(2)
Chemical Controls
Fungicides are used with susceptible varieties.
Sprays begin at petal fall and continue every 10-14 days. (2)
Alternative Controls
None are currently available.
Peach Scab
Biology
Peach scab is an important disease in southwest Michigan.
It is caused by the fungus Cladosporium carpophilum. Peach scab
attacks peaches, apricots and nectarine. It reduces the appearance and
quality of the fruit. Fruits, twigs and leaves develop dark, velvety spots.
These can lead to fruit cracking. (2)
The fungus overwinters in twigs. Spores are carried by air and water. Fruit are susceptible from shuck fall stage until harvest. (2)
Cultural Controls
Pruning helps increase air circulation and facilitate
drying. It also improves spray penetration.(2)
Chemical Controls
Fungicide sprays beginning at shuck fall. (2)
Alternative Controls
None are currently available.
Fungicide Profiles:
Benomyl (Benzimidazoles)
Chlorothalonil (Nitrile Compound)
Sulfur (Inorganic Compounds)
Alternatives
Ziram 76 DF 3 3/4 - 6 lb for peach leaf curl (32)
Bravo
Ferbam(40)
References: (5) (9) (1) (7) (32)
Parasitic nematodes, especially, are more likely to build up to a damaging level in sandy and loamy soils than in the heavier clay soils. The root-lesion (Pratylenchus penetrans) and dagger (Xiphinema americanum) parasitic nematodes are two serious pests commonly found in orchard soils. (30) (26) Root-knot and ring nematodes can also be problems in peaches.(37)
Key Nematode Pests
Root-lesion nematode is the most economically significant
nematode in Michigan orchards. (33) Root-lesion nematodes are migratory
endoparasites. They primarily feed within newly formed feeder roots of
fruit trees, they are concentrated in areas of root hairs. (1) As root-lesion
nematodes feed they produce wounds in root tissue. These wounds have the
potential to allow pathogens to enter into the roots. Root-lesion nematodes
tend to build up to higher population densities and cause more damage in
sandier soils than in heavier soils. (33) (30)
Dagger nematodes are ectoparasites that act as a pathogen to plants along with vectoring diseases, such as tomato ringspot virus. Dagger nematodes feed along root surfaces, causing swelling of the root and preventing the root from functioning in a normal manner. (33) (30) (26)
Root-knot nematodes can build up to levels that cause economic damage in orchards. They are difficult to control with post-plant nematicides, so it is important to have good preplant control. (37) Root-knot nematodes are sedentary endoparasites causing knots or galls on roots. (33)
Ring nematodes are ectoparasites that commonly occur in Michigan orchards. At high population densities ring nematodes can ring nematodes can inhibit normal plant growth and development of roots. (33)
Cultural Controls
Resistant or Tolerant root stocks
Selection of Planting Stock and Planting Sites
Cover crops and companion crops may modify nematode
populations, decreasing the number of plant parasitic nematodes.(37)
Fallowing
Chemical Controls
Nematicides
Soil fumigants
Nematicide Profiles
Dichloropropene (Fumigant)
Phenamiphos (Organic Phosphate)
References: (9)(32)(33)(34)
Biology
Ground cover is important for tree yield and vigor, it
also helps to stabilze soil pH and structure and hold the soil in place.
It is especially important to manage ground cover for young trees where
weeds compete for nutrients and moisture. Trees grown in weed free conditions
have higher productivity. Weeds may serve as a habitat for insects and
nematodes that can be harmful to the fruit trees. Since predator populations
can also be maintained in ground cover, it may be desirable to maintain
a cover crop to encourage natural enemy populations while suppressing weeds.(32)
The plant bugs migrate to the weeds and become scarce in fruit trees. Common mustard weed is the preferred host.Thrips are favored by flowering weeds.(40)
Many weeds harbor the tomato ring spot virus.(40) Chokecherry plants can act as a source of X-disease.
Cultural Controls
Cover crops can suppress weed growth through allelopathic
effects. Wheat, rye, barley and oat cover crops have been used. They are
sprayed with glyphosate or paraquat when it is 2 feet high or just beginning
to bloom the following spring. The residue inhibits weed seeds from germinating.
(32)
Cultivation is important in removing weeds.
Chemical Controls
2,4-D
Glyphosate
Diuron
Norflurazon
Oryzalin
Paraquat
Simazine
Terbacil
Sethoxydim
Fluazifop-butyl
Oxyfluorfen
Dichlobenil
Isoxaben
Pronamide
Napropamide
Sulfosate
Alternative Controls
Integrated pest management programs that utilize predator
mites and insects as part of the pest control strategy often encourage
some plant growth under the tree as habitat for predators. Broadleaf weeds
appear to be favored by some predator mites. (32)
Herbicide Profiles
2,4-D (Phenoxy Acid)
Carol Bronick
207 Pesticide Research Center
Michigan State University
(517)432-3194
Larry Gut
Department of Entomology
Michigan State University
Lynnae J. Jess
Pesticide Research Center
Michigan State University
(517)432-1702
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Pathology. San Diego, California, Academic Press, Inc.
2. Jones A. and T. Sutton. 1996.
Diseases
of Tree Fruits in the East. North Central Regional Extension
Publication 45.Michigan Agricultural Statistics Service (1995).
3. Gut, L. and J. Wise 1999 PEACH:
summary of Constraints and IPM Concerns.
4. Howitt, Angus H. Common
Tree Fruit Pests, by Michigan State University. NCR-63
5. Michigan Rotational Survey:
Fruits - 1995. Lansing, Michigan, Michigan Department of Agriculture.
6. Michigan Department of Agriculture
(1997). Michigan Agricultural Statistics. Lansing, Michigan, Michigan Department
of Agriculture.
7. United States Department of
Agriculture, N. A. S. S. (1996). Fruit Chemical Use Survey. Washington,
DC, US Department of Agriculture
8. United States Department of
Agriculture, N. A. S. S. (1998). Agricultural Statistics 1998. Washington,
DC, US Department of Agriculture: 47.
9. Ware, G. (1994). The Pesticide
Book. Fresno, California, Thomson Publications.
10. http://www.msue.msu.edu/swmrec/peach/mipeach.htm#Present
11. http://www.msue.msu.edu/msue/imp/mods1/00000057.html
12. http://www.msue.msu.edu/vanburen/peacurl.htm
13. http://www.msue.msu.edu/vanburen/flptb.htm
14. http://www.cips.msu.edu/whalonlab/PestPictures/tarnishedplantbug.htm
15. http://www.msue.msu.edu/vanburen/tarnish.htm
16. http://www.msue.msu.edu/msue/imp/modc1/71594008.html
17. http://www.msue.msu.edu/msue/imp/modop/00001767.html
18. http://www.msue.msu.edu/msue/imp/modc4/90794001.html
19. http://www.msue.msu.edu/msue/imp/modop/00001746.html
20. http://www.ceris.purdue.edu/napis/pests/jb/facts/facts.txt
21. http://www.ento.vt.edu/Fruitfiles/JBPeach.html
22. http://www.msue.msu.edu/vanburen/plumcurc.htm
23. http://www.msue.msu.edu/vanburen/fruitbug.htm#ofm
24. http://www.msue.msu.edu/msue/imp/mod03/01701539.html
25. http://www.msue.msu.edu/msue/imp/mod03/01701540.html
26. http://orchard.uvm.edu/AIM/9697neapmg/nmtds.html
27. http://www.msue.msu.edu/msue/imp/modsr/sr329201.html
28. http://pmep.cce.cornell.edu/chemnews/1998/mar-98/calipears.html
29. http://www.msue.msu.edu/msue/imp/modc3/f6279501.html
30. http://osu.orst.edu/dept/infonet/handbook/dnemlh.htm
31. http://www.msue.msu.edu/vanburen/e-1730.htm
32. Gut, L. and J. Wise 1999 Fruit Spraying Calendar
1999.Michigan State University Extension Bulletin E-154. East Lansing,
Michigan.
33. Bird, G.W. and H. Melakeberhan 1993 Avoidance
and Management of Nematode Problems in Tree Fruit Production in Michigan.
Michigan
State University Extension Bulletin E-2419
34. Bird, G.W. 1999 Nematodes and Soil Quality from Pest
Ecology and Management, Michigan State University Extension.
35. Thomson 1995 Agricultural Chemicals Book III -
Miscellaneous Agricultural Chemicals. Thompson Publications, Fresno,
CA.
36. Jones, A. Comments
37. Warner, F. Comments
38. Bills, P. PAR.
39. Gut, L. 1999 Comments
40. Shane, W. 1999 Comments
41. Hogmire, H. W., S. C. Beavers 1998 http://www.caf.wvu.edu/kearneysville/pest_month/insectfocusapril98.htm
42. Thomson 1993-4 Agricultural Chemicals Book IV
- Fungicides. Thompson Publications, Fresno, CA.
Database and web development by the
NSF Center for Integrated Pest
Managment located at North Carolina State University. All materials may be used freely
with credit to the USDA.