Tree Fruit IPM Report for May 8, 2024

Peach:

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. Dr. Lalancette published a 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. We have not seen any bacterial spot symptoms as of this writing except for one location in a northern county.

Oriental Fruit Moth: A biofix point for OFM was set on 4/10 in both northern and southern counties.  The first of two insecticide timings for first generation Oriental Fruit Moth control fall at 170-200 degree days base 45 after biofix. This timing generally coincides with 100% petal fall in peaches. Timings are updated below: Note that timings have been pushed back from last week due to cooler than forecast weather. Do not apply insecticides until all bloom is off. No Insecticides for OFM are needed where Mating Disruption is implemented.

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. This is particularly important for nectarine blocks. Check 10 trees per block with the beating tray. Collect 50 blossoms per block and examine for the presence of aphids. If more than 1 colony of aphids are found in nectarines, or 2-3 colonies are found in peaches, an insecticide for aphids will be needed when all petals are off. See the NJ Commercial Tree Fruit Production Guide for recommended materials and rates. The first aphid colonies curling leaves was noted in southern counties the week of 4/22.

Plum Curculio; Tarnished Plant Bugs; and Other Catfacing Insects: Plum Curculio start to move into orchards at about 88-100 degree days base 50 after January 1. Applications for PC should be initiated once all petals are off, with a second application made with ovicidal materials at 379-402 DD. Currently we have accumulated about 331 DD base 50 in southern counties, and 237 DD base 50 in northern counties. Growers can monitor degree day development at their site by finding the nearest weather station and using the degree day development tool at NEWA. Catfacing insects are active now and can cause injury.

Scale Insects: White peach scale crawlers have not yet emerged but usually begin emergence about the third week of May and continue emergence until about the middle of June. San jose scale crawlers typically begin emergence about late May or Early June and continue emergence for up to 6 weeks. Control options during crawler emergence include Neonicitiniods (suppression only), and the IGR’s Esteem and Centaur. See the NJ Commercial Tree Fruit Production Guide and the product labels for more information.

Lesser and Greater Peach Tree Borers: Growers using mating disruption for borer control can begin placing dispensers around the end of April and should have them in place by mid-May.

Apples and Pears:

Diseases: Now that primary scab is nearing the end, or has ended, the focus turns toward summer diseases such as fruit rots (esp. Bitter rot), and sooty blotch and fly speck. Bitter rot control has been difficult at best in recent years even where management programs have been rigorous. Research has suggested Products such as Merivon, Luna Sensation, Inspire Super, and Aprovia may be effective, and longtime reliable broad spectrum fungicides such as omega, captan and ziram should provide control. Experience has suggested that the addition of phosphorous acid products such as Prophyt or Rampart to captan sprays may improve control. Observations are that these products improve control of other summer diseases such as sooty blotch and flyspeck, and may help suppress scab infections where present.

Fire Blight: Infections can still occur post bloom so covers with antibiotics when infection events are forecast using the NEWA fire blight model may be beneficial. Remember to rotate streptomycin and oxytetracycline products. If symptoms appear, it is generally recommended to cut out infected limbs however this is a practical decision that must be made. This blog post from Michigan State may be helpful to decide whether it is worth cutting out infected tissue.

Codling Moth: A Codling Moth Biofix was set in Southern counties on 4/22. See the NJ Commercial Tree Fruit Production Guide for recommended materials and rates. Where Mating Disruption has been employed, supplemental Madex applications should be made at the timings listed below.

Scale Insects: Dormant oil applications are standard recommendations for scale control but in some years when conditions are not optimal for oil application scale control may be less than desired. Where oil was not applied or in orchards where scale is a recurring problem, an application of Centaur at petal fall or Movento between petal fall and first cover should “clean up” problem blocks. Centaur is recommended at 34.5 ozs./ac and Movento should be applied at 6-9 ozs./ac. A penetrant must be included to Movento as per the product label. Movento will also control apple aphids, including Wooly Aphid, when used at this timing. In pears Movento may also control aphids and 2nd generation pear psylla (if eggs or recently hatched nymphs are present).

Rosy Apple Aphid:  If a pre-bloom application was not made, monitor for colonies during bloom and use a treatment threshold of 1 colony/tree at petal fall. Rosy aphid colonies were noted in a few southern county orchards last week.

Wooly Apple Aphid (WAA); Green Apple (Spirea) Aphids (GAA): GAA colonies are beginning to appear in some apple blocks. GAA is generally a pest that can be tolerated since they do little direct damage. Treatment thresholds for GAA are if 50% of the shoots are infested with no beneficial insects present. WAA aerial colonies are also beginning to form in southern counties. This is about a month earlier than usually observed. In most years these are controlled by beneficials however in some years like 2022, serious outbreaks can occur. The best control for WAA is Movento applied before or when the first colonies appear. Diazinon is also effective at knocking down infestations. Movento will also control GAA and should control san jose scale when applied in mid-May, and suppress scale when applied in late May or early June.  Do not combine Diazinon with Captan.

Ambrosia Beetle : Trap captures continue at precious week’s levels. Infested trees should be showing signs of stress or will be soon. Once these beetles bore into the trunk, they will form a gallery in the heartwood of the tree to lay their eggs and farm the ambrosia fungus to feed themselves and their larvae. Once the female lays her eggs, it will take about 30 days for them to become adults and emerge from their host tree to begin the second flight. If you have had a history of this pest in your orchard, you should begin scouting for damage and remove any trees that have been attacked. It may be beneficial to leave attacked trees in the orchard for a few weeks before removal so they can act as trap trees to reduce populations. Beetles generally do not leave the host tree once they’ve attacked it. They will attract other beetles to the stressed tree and adjacent trees so they tend to stay in one area rather than spread throughout the orchard.

Pear Psylla:  Second generation pear psylla have not appeared yet, but usually begin hatching mid-late May. Options for control include spynosyn products such as Delegate and Entrust, and the neocitinoids (IRAC group 4A). The addition of 0.25-1 gal of summer oil may improve control. Other options include Movento, and products containing abamectin. Be sure to read and follow the label instructions regarding the addition of penetrants for these products.

 Grapes Grapes: The most important diseases to manage at this time are Phomopsis and Powdery Mildew. At 3″ growth start managing for Black Rot. More information about early season disease control can be found in this blogpost from Virginia Tech. SLF have started hatching in southern counties and will continue to hatch over the next few weeks. There is no need to control SLF at this time.

Phenology Table: Based on annual observations made in Gloucester County.

Tree Fruit Trap Captures – Southern Counties

Tree Fruit Trap Captures – Northern Counties