Archives for May 2022

Peach:

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.

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.

Fig. 2 Peach Scab lesions on peach twig.

Oriental Fruit Moth: A biofix point for OFM was set on 4/11 in southern counties, and on 4/14 in northern counties. The first insecticides for first generation Oriental Fruit Moth control should be applied at 170-200 degree days base 45 after biofix. This timing generally coincides with petal fall in peaches. Currently we have accumulated 87 Degree days from the biofix. The timing for the first insecticides for OFM will be on or about 4/26-4/28 in southern counties. In northern counties the timing will be about a week later.

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. 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 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: White peach scale (WPS) crawlers are close to emergence in southern counties, probably in about a week to 10 days. San Jose scale (SJS) crawlers usually begin emergence about a week or ten days later, usually late May/Early June. If you have scale infestations on your trees, it is important to note if crawlers are present, even if you treated with oil in the early spring. If crawlers are present then treatment options include Esteem, Movento, Centaur, Venerate, and Diazinon. Esteem, Centaur, Venerate and Movento should be applied at the beginning of crawler emergence. Venerate needs to be applied at the low rate of 1 qt/A and may need more than one application. Diazinon is labeled for only one post bloom or foliar application on stone fruit (Rec = max. of 2 lb/acre of the 50W). The apple label allows up to 2 foliar applications per year as long as a prebloom application was not made. Foliar applications may cause russet on apples, but has worked in the field for scale crawlers as long as applications are made 1-2 weeks after the start of crawler emergence and again 2 weeks later. Belay and Assail are also effective against scale crawlers but may need more than one application during the emergence which typically lasts about 4 weeks for WPS and 6 weeks for SJS.

Apples and Pears:

Diseases: Fire Blight, Apple Scab, Rust diseases, and Powdery Mildew are the main targets at this stage. The NEWA apple scab model is estimating about 98% ascospore maturity as of 4/26 in southern NJ with 98% of cumulative ascospores discharged. We are nearing the end of primary scab season in southern counties. Northern counties will have less ascospore maturity. Primary apple scab spores are released during any substantial infection period. More information can be found in this blogpost from Penn State. 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 which ever 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 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.

Codling Moth (CM): The first codling moth flight has started. A biofix was set for CM on April 25^th in southern counties. No biofix has yet been set for northern counties.

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. Some orchards have colonies that require treatment in southern counties.

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 petal fall. If using Surround through the bloom period stop at petal fall and switch to applications of 1% summer oil @ 1gal/ac in no less than 150 gals/ac. these should be made at no more than 2 week intervals. At petal fall insecticide options for Psylla control include Actara, Assail, Belay, Movento, Sivanto Prime, and Agri-mek. See the NJ Commercial Tree Fruit Production Guide for recommended materials and rates.

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. 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.

Grapes: Grapes are at the 1″-3″ stage of development in southern counties. The most important diseases to manage at this time are Phomopsis and Powdery Mildew. At 3″ growth start managing for Black Rot. Insect pests to monitor are Grape Flea Beetle, and Climbing Cutworms. Controls for these insects are rarely needed. If control is determined to be necessary, use one of the materials recommended in the New Jersey Commercial Grape Production Guide. Remember that Lorsban has lost all food tolerances and should not be used. It’s also not too late to scout for and destroy SLF egg masses on posts and trunks.

Tree  Fruit Trap Counts – Southern Counties