Tree Fruit Phenology:
Tree Fruit Phenology remains advanced. In southern counties most varieties are at or near full bloom. Redhaven was at approximately 50% bloom on March 24. Plums are in bloom and Pears are nearing Green Cluster. Red Delicious is at 1/2″green. Plums are in full bloom. Pears are starting to bloom.
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). The weather forecast for this coming week may be favorable for blossom infections. 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.
Oriental Fruit Moth: A biofix point for OFM has not yet been set. The first insecticides for first generation Oriental Fruit Moth control should be applied at 170-200 degree days after biofix. This timing generally coincides with petal fall in peaches.
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 are starting activity but 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.
Apples and Pears:
Diseases: Apple Scab and Fire blight are the main targets at this stage. The NEWA scab models are estimating about 4% ascospore maturity during this period in southern NJ. Predictions for next week are for 10% ascospore development. Northern counties will have less ascospore maturity. 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 2019. If your orchard had scab last year, include a protectant such as vangard or syllit at 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.
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. 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 disease development on junipers is very close to producing large spore releases during wetting periods. Looking around this week galls for cedar apple rust started to develop teliohorns and quince rust cankers were showing signs of spore development. See this link for pictures of rust on pome fruit and juniper.
Rosy Apple Aphid: Products containing Chlorpyrifos may be used up until 1/4″ green for rosy aphid control. Esteem is also effective and may be applied up until 1/2″ green. If a pre-bloom application cannot be made, monitor for colonies during bloom and use a treatment threshold of 1 colony/tree at petal fall.
European Red Mite; San Jose Scale: Oil applications for mite suppression and scale control should start at 1/4” green. Combinations of oil with the IGR’s Esteem or Centaur should improve scale control in heavily infested orchards when applied at 1/4″ green. Sivanto Prime and Closer are recent additions to the insecticide toolbox that have excellent ratings for Rosy Aphids and efficacy against scale. Both should be compatible with oil. Based on the ratings in our production guide addendum, Sivanto Prime is the better scale material. Closer has not been evaluated for control of overwintering scale so it should be saved for summer use. Apply 4-6 gals oil/acre at 1/4”green to tight cluster; 2-3 gals/acre at tight cluster to pink. An additional oil application at 1-1.5 gals /ac may be made at pink (optional). 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 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. See the 2019 blogpost from Peter Jentsch at Cornell for a more detailed control discussion.
Pear Diseases: Include effective materials such as Ziram or EBDC formulations for Pear Scab and Rust diseases beginning at the cluster bud stage. At white bud use products effective for pear scab, rusts, and fabrea leaf spot. 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. which ever material you use, the addition of Actigard or other plant defense elicitors may improve control. More information can be found in this 2019 blogpost from Penn State.
