Tree Fruit IPM Report for May 10, 2023

Peach:

Fig. 1 Bacterial Spot leaf symptoms about 2 weeks old.

Fig. 2 Bacterial Spot leaf symptoms about a week old.

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 such as Mycoshield or Fireline may also be used and may offer slightly more residual activity during long wetting periods. Bacterial Spot leaf symptoms have begun appearing in southern county orchards. These infections probably occurred mostly during the heavy rains that occurred on 4/30-5/1. There is a small amount of older symptoms which probably occurred the previous weekend of 4/27-4/28 (Figs. 1&2.).

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. 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. Aphid colonies are now visible in southern county orchards.

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 320 DD base 50 in southern counties, and 264 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 starting activity, but will become more of an issue as temperatures warm and mowing and other ground cover activities become more common. Small amounts of catfacing injury are present statewide.

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 the neonicitiniods Actara and Belay (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: Apple Scab, Rust diseases, and Powdery Mildew are the main targets at this stage. The NEWA apple scab model is estimating about 100% ascospore maturity in southern NJ with 100% of cumulative ascospores discharged as of April 15. Northern counties were at Green tip on or about 4/3. The model estimates about 100% ascosppsore maturity for Northern Counties with 100% ascospores released as of April 30. Between tight cluster and first cover include products effective for powdery mildew and cedar apple rust.

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. Fire Blight symptoms began appearing in southern county apple and pear orchards this week. Typically it is 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.

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 disease development on junipers should now be producing large spore releases during wetting periods. See this link for pictures of rust on pome fruit and juniper.

Dogwood Borer: Growers who plan to use mating disruption for Dogwood Borer should have ties in place by the end of May. See the Product label and the NJ Commercial Tree Fruit Production Guide for more Information.

Codling Moth (CM): The first codling moth flight has started. A biofix was set for CM on April 17^th in both northern and southern counties.

Pear Diseases:  Continue managing for Rust, Fire Blight and Fabrea Leaf Spot through May.

Grapes: The most important diseases to manage at this time are Phomopsis, Black Rot, and Powdery Mildew. More information about early season disease control can be found in this blogpost from Virginia Tech. SLF hatch began in southern counties sometime during the last week of April. There is no need to control SLF at this time.

Tree Fruit Trap Captures – Southern Counties

Tree Fruit Trap Captures – Northern Counties

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