North Jersey Tree Fruit Twilight Meeting I

Tree Fruit Phenology:

Tree fruit phenology remains advanced in southern counties based on historical observations. In southern counties most varieties are nearing full bloom. PF-17 which tracks closely with Redhaven was at 90% bloom on April 2, about 11 days earlier than the median observation date. Red Delicious was at Tight Cluster on March 30, about 10 days earlier than the median observation date. Pears are about white bud to first bloom. Plums are past full bloom. Cooler weather has slowed development. Northern counties are not as advanced.

*Rain! Rain! Go Away!! There is a risk of blossom blight where there are many blossoms open or pistils exposed even though it is on the cool side. Where much bloom is open, regardless whether you were covered or not before the rain with an effective material, a cover ASAP when the weather clears would be a good idea. Fungicides with curative properties would be a good fit in this situation. Cyprodinyl (vanguard) may have some reach back as would ipridione (rovral, meteor). The Group 3 fungicides (Rally, Propiconazole, etc.) and Group 11 fungicides (Flint Extra) would also have curative properties however we don’t recommend those during bloom for resistance management. Topsin-M is another option. Recent tests at RAREC by Dr. Lalancette demonstrated good efficacy against blossom blight. If it hasn’t been used on your farm in many years it may work well but many orchards in NJ had resistance issues in the past.

Sometimes when we have heavy downpours and wind like this bacterial diseases can be troublesome. It’s still early for those to develop however. Bacterial spot could get an early start but there probably aren’t enough leaves out yet, and we haven’t seen anything that look like bacterial spot cankers. If we get severe weather it may not be a bad idea to start adding low rates of copper a little earlier than usual (see peach section below). Pears are not quite in bloom yet and it’s pretty cold for fire blight. It wasn’t that long ago that copper was applied so the risk of an infection from this weather is probably low. However there will be some blossoms open when the weather breaks and there may be trauma from wind and heavy rain so it wouldn’t be a bad idea to get kasumin, fireline, or streptomycin on where there is bloom open once the rain stops.

Lastly: Rust diseases are active in southern counties! Rust has been troublesome on Asian pear varieties and some apples in recent years. Copper and cyprodinyl are ineffective for rust. Ziram has some efficacy. If you weren’t covered before the rain, the Group 3 fungicides such as Procure (apples and pears) or Rally (apples only) at the high rate should reach back to protect the leaves (and possibly blossoms). Other group 3 fungicides may have similar properties. A protectant such as an EBDC (manzate, dithane, etc.) should be mixed in to protect the fruitlets as they develop.

Peach:

Brown Rot: Blossom infections from the brown rot fungus can occur whenever pistils are exposed and a favorable climate exists. Infections can occur during any wetting period when temperatures are between 41 and 86 °F. However, optimum conditions for infection occur with wetting and temperatures in the mid 70’s. During long wetting periods (several days or more) blossoms can be infected regardless of temperature. Generally infections that occur when conditions are sub optimal are less severe. Blossoms and fruitlets will remain susceptible until the pistil dessicates (sometime between petal fall and shuck split). Initiate coverage for blossom blight starting at pink for short petaled varieties and 5-10% bloom for showy flowers. See the NJ Commercial Tree Fruit Production Guide for recommended materials and rates.

Bacterial Spot: Copper formulations should be used starting at petal fall to suppress bacterial spot. Generally we recommend starting at 0.5 ozs metallic copper and gradually lowering the rate as the season progresses. The rate applied will depend on the formulation: Refer to  this chart listing common copper formulations and rates for peach and nectarine applications. Avoid combining copper with captan especially if it has been overcast for several days. Also avoid acidic spray solutions when applying copper. Dr. Lalancette has published a handy guide for copper applications in early covers. Antibiotics containing oxytetracycline may also be used and may offer slightly more residual activity during long wetting periods.

Peach Scab: In addition to Rusty Spot and Bacterial Spot, Peach Scab requires protective applications starting at petal fall. Peach scab cankers (Fig. 2) begin to expand at bloom and by shuck split begin to shed spores during wetting periods. Topsin, Topsin/Captan combinations, Flint Extra, Inspire Super, and especially Quadris Top applied at petal fall are the best materials for blocks that had scab last year. Quadris Top, Flint Extra or Topsin should be used at the high rate to suppress overwintering lesions on the wood. Quadris Top contains azoxystrobin which is phytotoxic to many apple varieties. Phytotoxic residues can remain in the tank for long periods after an application is made, even if a tank cleaner is used. Do not use Quadris Top or Abound in the same sprayer used for apples. Bravo (chlorothalonil) is also a good protectant that may be applied no later than shuck split. Captan is also helpful in cover sprays after shuck split where scab was troublesome last year.

Oriental Fruit Moth: A biofix point for OFM has not yet been set. OFM biofix is defined as the first sustained trap captures (2 or more consecutive days of trap captures of more than one adult.) It usually coincides with full bloom (about 4/13 in southern counties) but can start as early as late March. The first insecticides for first generation Oriental Fruit Moth control should be applied at 170-200 degree days (base 45 deg F) after biofix. This timing generally coincides with petal fall in peaches. Timings can be calculated using the degree day calculator at the NEWA website by choosing the weather station nearest your farm, entering the biofix date as the start date, and choosing base 45 in the “degree day type” menu. Mating disruption may be substituted for insecticide applications by placing dispensers or initiating sprayable formulations of pheromone in the orchard anytime before biofix. See the NJ Commercial Tree Fruit Production Guide for more information.

Green Peach Aphid: GPA colonies begin forming sometime during bloom. Examine trees for the presence of colonies from pink to shuck split. Count the number of colonies on ten trees and use a treatment threshold of 2 colonies/tree at petal fall for peach, and 1 colony/tree for nectarine. The best way to scout for aphids during bloom is with a beating tray. Blossoms may also be collected, opened, and examined for the presence of aphids using a hand lens. See the NJ Commercial Tree Fruit Production Guide for recommended materials and rates.

Tarnished Plant Bugs and Other Catfacing Insects:  Catfacing insects cause little damage at this time of the year. Catfacing insects will become more of an issue as temperatures warm and mowing and other ground cover activities become more common after bloom. Insecticides for catfacing insects are not recommended until after all petals are off.

Pome Fruit:

Diseases: Fire Blight, Apple Scab, Rust diseases, and Powdery Mildew are the main targets at tight cluster. The NEWA apple scab model is estimating about 11% ascospore maturity as of 4/2 in southern NJ with 9% of cumulative ascospores discharged. Northern counties were at Green tip on or about 3/18. The model estimates about 6% ascopsore maturity for Northern Counties with 6% ascospores released. Primary apple scab spores are released during any substantial infection period. Between tight cluster and first cover include products effective for powdery mildew and cedar apple rust. To manage Fire Blight in both apples and pears, consider using Kasumin at bloom. Kasumin is an antibiotic like Streptomycin and Oxytetratracycline. It contains Kasugamycin which is a different chemistry. Kasumin is only labeled for bloom and petal fall applications while strep and oxytet are labeled for post bloom use. Using 3 different chemistries in rotation allows for resistance management while extending the protection into the post bloom period when late blossoms typically appear. Whichever material you use, the addition of Actigard or other plant defense elicitors may improve control.

Rust Diseases: The two most common rust diseases that affect pome fruit are Quince Rust and Cedar Apple Rust. In some years these diseases can be troublesome in commercial orchards. Most disease control programs for scab will also control rust. In organically managed blocks in the east options are limited for approved materials that are effective for rust. Potassium Bicarbonate products have shown good efficacy for rust diseases in trials performed in Virginia. Organic growers should seek out and plant rust resistant cultivars. Cultural controls are not practicable due to the widespread presence of alternate host Junipers both wild and cultivated. Rust galls on junipers should now be producing spore releases during wetting periods. See this link for pictures of rust on pome fruit and juniper.

Scale and Rosy Apple Aphid: One sees many recommendations for mixing materials efficacious for scale such as the insect growth regulators (Centaur; Esteem) with delayed dormant oil applications. The general consensus from data review seems to be that the addition of scale insecticides to oil do not significantly improve control over oil applied alone. Recent tests performed by Dr. Neilsen’s lab indicate that Sivanto Prime, Centaur and Venerate when applied alone in the pre-bloom period are comparable to dormant oil for scale control. Esteem has good efficacy for scale when applied up to to 1/2″ green. Closer has some efficacy against scale, however it has not been evaluated for control of overwintering scale. Esteem, Closer, Sivanto Prime, and a new product: Versys, applied either alone or with oil at 1/4″ to 1/2″ green all have good to excellent ratings for rosy apple aphids. See the NJ Commercial Tree Fruit Production Guide for more information. Note that the Virginia Spray Bulletin for Commercial Tree Fruit Growers lists syllit as incompatible with centaur.

European Red Mite; San Jose Scale: Oil applications for mite suppression and scale control should start at 1/4” green. Apply 2% dilute or 4-6 gals oil/acre concentrate at 1/4”green to tight cluster; 1% dilute or 2-3 gals/acre concentrate at tight cluster to pink. Oil should not be applied if temperatures are expected to dip into the mid 30’s within 48 hours of application, and captan or sulfur should not be applied within 14 days of any applications of oil or oil based formulations. Check the product labels for additional phytoxicity precautions.

Pear:

Pear Psylla:  Dormant oil applications should have already been started to deter psylla egg laying. At the green cluster stage a pyrethroid is generally included with oil to knock down adults migrating into the orchard.  In lieu of oil, Surround may also be applied starting at swollen bud and continued through bloom. If using Esteem for psylla control make one application delayed dormant through popcorn or two applications; one at delayed dormant through popcorn and one at petal fall. Centaur is also effective and one application may be made pre-bloom or at petal fall. Sivanto Prime is also labeled for early season applications and should be combined with oil.

Pear Diseases: Copper for fire blight suppression should not be applied past the green tip stage if fruit russet is a concern. Include effective materials such as Ziram or EBDC formulations for Pear Scab and beginning at the cluster bud stage. At white bud use products effective for rust, pear scab, and fabrea leaf spot. Particular attention should be paid to rust on asian varieties. Start planning for blossom sprays using antibiotics. For both apples and pears, consider using Kasumin at bloom. Kasumin is an antibiotic like Streptomycin and Oxytetratracycline. It contains Kasugamycin which is a different chemistry. Kasumin is only labeled for bloom and petal fall applications while strep and oxytet are labeled for post bloom use. Using 3 different chemistries in rotation allows for resistance management while extending the protection into the post bloom period when late blossoms typically appear. Whichever material you use, the addition of Actigard, Lifeguard or other plant defense elicitors during bloom may improve control.

Tree Fruit Phenology:

Tree fruit phenology is advanced in southern counties based on historical observations. In southern counties some early blooming varieties are 50% bloom. Redhaven was at pink on March 25, about 11 days earlier than the median observation date. Red Delicious was at ¼” green tip on March 18, about 14 days earlier than the median observation date. Some apples are at ½” green tip, and pears are about green cluster to white bud. Plums are full bloom. Cooler weather has slowed development.

Peach:

Brown Rot: Blossom infections from the brown rot fungus can occur whenever pistils are exposed and a favorable climate exists. Infections can occur during any wetting period when temperatures are between 41 and 86 °F. However, optimum conditions for infection occur with wetting and temperatures in the mid 70’s. During long wetting periods (several days or more) blossoms can be infected regardless of temperature. Generally infections that occur when conditions are sub optimal are less severe. Blossoms and fruitlets will remain susceptible until the pistil dessicates (sometime between petal fall and shuck split). Initiate coverage for blossom blight starting at pink for short petaled varieties and 5-10% bloom for showy flowers. See the NJ Commercial Tree Fruit Production Guide for recommended materials and rates.

Bloom Cankers: Bacterial Spot is a key pest of Peach, Nectarine and Plum and in some years can cause significant losses. It is caused by the bacterium Xanthomonas arbicola pv. pruni. Black tip cankers caused by bacterial spot usually appear during or just after bloom. Typical symptoms are a gradual blackening of the tip with dead tissue moving down the twig and is often observed on highly susceptible cultivars (Fig. 1). Tip die back may also occur from abiotic factors such as frost. Tip die back from frost is often accompanied by blind wood usually 6-8 inches below the tip where leaves and flowers have fallen off after being killed by a freeze. Spring cankers that are caused by bacterial spot may also form around flower buds and may be confused with constriction canker or brown rot (see below) Spring cankers are not commonly observed in our region.

Fig. 1 Tip die back likely caused by bacterial spot (photo D. Schmitt)

In some cases the twig may appear healthy and a shoot begins growing from the tip only to die back after leafing out and flowering. This is often a symptom of fall infections of leaf scars by constriction canker. Many times a bud that was infected in the fall and never leafed out may be found just below the new shoot that is dying (Fig. 2a). Mild gummosis around the dead bud may also be observed. These symptoms may be more prevalent in old trees that have a history of the disease. Growing tips may also be killed if the leaf scar was infected and may be confused with black tip from bacterial spot.

Fig 2a. Dead bud and canker from fall infection by constriction canker. (photo D. Schmitt)

Another disease that causes cankers on flower buds is Monolinia fructicola, the cause of brown rot blossom blight. During bloom flowers that are infected by the brown rot fungus will rapidly dessicate and form a canker around the bud similar to late winter or early spring infections by constriction canker (Fig 2b.). These can be distinguished from blossom blight by waiting a few days to see if the brown rot sporulation appears on the canker. Symptoms of brown rot also differ from constriction canker in that excessive gummosis will appear at the canker site (Fig. 3).

Fig. 2b. Early onset symptom of late winter/early spring infection by constriction canker. (photo D. Schmitt)

Fig. 3 Blossom blight canker. Note sporulation and excessive gumming around detached flower

Oriental Fruit Moth: A biofix point for OFM has not yet been set. OFM biofix is defined as the first sustained trap captures (2 or more consecutive days of trap captures of more than one adult.) It usually coincides with full bloom (about 4/13 in southern counties) but can start as early as late March. The first insecticides for first generation Oriental Fruit Moth control should be applied at 170-200 degree days (base 45 deg F) after biofix. This timing generally coincides with petal fall in peaches. Timings can be calculated using the degree day calculator at the NEWA website by choosing the weather station nearest your farm, entering the biofix date as the start date, and choosing base 45 in the “degree day type” menu. Mating disruption may be substituted for insecticide applications by placing dispensers or initiating sprayable formulations of pheromone in the orchard anytime before biofix. See the NJ Commercial Tree Fruit Production Guide for more information.

Green Peach Aphid: GPA colonies begin forming sometime during bloom. Examine trees for the presence of colonies from pink to shuck split. Count the number of colonies on ten trees and use a treatment threshold of 2 colonies/tree at petal fall for peach, and 1 colony/tree for nectarine. The best way to scout for aphids during bloom is with a beating tray. Blossoms may also be collected, opened, and examined for the presence of aphids using a hand lens. See the NJ Commercial Tree Fruit Production Guide for recommended materials and rates.

Tarnished Plant Bugs and Other Catfacing Insects:  Catfacing insects cause little damage at this time of the year. Catfacing insects will become more of an issue as temperatures warm and mowing and other ground cover activities become more common after bloom. Insecticides for catfacing insects are not recommended until after all petals are off.

Scale Insects: Oil applications may be safely applied up to pink on peach. Other options include Centaur, Sivanto Prime, Esteem, and Venerate. These products can be combined with oil or applied alone. See the apple section below for more information.

Apple:

Diseases: Fire blight is the main target at this stage. Copper formulations applied for fire blight suppression should be adequate for scab control at green tip to 1/4″ green, unless scab was not controlled in 2022. If your orchard had scab last year, include a protectant such as vangard or syllit at 1/4″ green tip. Copper should not be applied after 1/4″ green where fruit russet is a concern. Beginning at 1/2″ green highly effective scab materials should be used. Primary apple scab spores are released during any substantial infection period. At tight cluster include products effective for powdery mildew and cedar apple rust. See the NJ Commercial Tree Fruit Production Guide for recommended materials and rates.

Scale and Rosy Apple Aphid: One sees many recommendations for mixing materials efficacious for scale such as the insect growth regulators (Centaur; Esteem) with delayed dormant oil applications. The general consensus from data review seems to be that the addition of scale insecticides to oil do not significantly improve control over oil applied alone. Recent tests performed by Dr. Neilsen’s lab indicate that Sivanto Prime, Centaur and Venerate when applied alone in the pre-bloom period are comparable to dormant oil for scale control. Esteem has good efficacy for scale when applied up to to 1/2″ green. Closer has some efficacy against scale, however it has not been evaluated for control of overwintering scale. Esteem, Closer, Sivanto Prime, and a new product: Versys, applied either alone or with oil at 1/4″ to 1/2″ green all have good to excellent ratings for rosy apple aphids. See the NJ Commercial Tree Fruit Production Guide for more information. Note that the Virginia Spray Bulletin for Commercial Tree Fruit Growers lists syllit as incompatible with centaur.

European Red Mite; San Jose Scale: Oil applications for mite suppression and scale control should start at 1/4” green. Apply 2% dilute or 4-6 gals oil/acre concentrate at 1/4”green to tight cluster; 1% dilute or 2-3 gals/acre concentrate at tight cluster to pink. Oil should not be applied if temperatures are expected to dip into the mid 30’s within 48 hours of application, and captan or sulfur should not be applied within 14 days of any applications of oil or oil based formulations. Check the product labels for additional phytoxicity precautions.

Pear:

Pear Psylla:  Dormant oil applications should have already been started to deter psylla egg laying. At the green cluster stage a pyrethroid is generally included with oil to knock down adults migrating into the orchard.  In lieu of oil, Surround may also be applied starting at swollen bud and continued through bloom. If using Esteem for psylla control make one application delayed dormant through popcorn or two applications; one at delayed dormant through popcorn and one at petal fall. Centaur is also effective and one application may be made pre-bloom or at petal fall. Sivanto Prime is also labeled for early season applications and should be combined with oil.

Pear Diseases: Copper for fire blight suppression should not be applied past the green tip stage if fruit russet is a concern. Include effective materials such as Ziram or EBDC formulations for Pear Scab and beginning at the cluster bud stage. At white bud use products effective for rust, pear scab, and fabrea leaf spot. Particular attention should be paid to rust on asian varieties. Start planning for blossom sprays using antibiotics. For both apples and pears, consider using Kasumin at bloom. Kasumin is an antibiotic like Streptomycin and Oxytetratracycline. It contains Kasugamycin which is a different chemistry. Kasumin is only labeled for bloom and petal fall applications while strep and oxytet are labeled for post bloom use. Using 3 different chemistries in rotation allows for resistance management while extending the protection into the post bloom period when late blossoms typically appear. Whichever material you use, the addition of Actigard, Lifeguard or other plant defense elicitors during bloom may improve control.