Fruit IPM for 5/14/20

Peach:

Plum Curculio (PC): PC adults are active and will damage fruit if not controlled. PC is a key pest to control during the first few weeks after petal fall. Imidan, Avaunt, Actara and Belay are very effective. However, try to delay the use of Actara and Belay for when brown marmorated stink bugs (BMSB) are more of an issue.

Oriental Fruit Moth: The second insecticide application in southern counties is due late this week. Depending on the material used, the first application for OFM is due in northern counties now (Altacor, Voliam, Besiege, Exirel, Verdepryn), and a few days later if using pyrethroids and other materials. Application timings are updated below:

OFM trap counts in several North Jersey orchards showed a sudden increase in activity this week, with trap counts averaging 150 moths per trap. These farms had heavy apple scab pressure during 2019, leaving many apples on the ground. Along with peaches, apples are also a host crop. With the mild winter we had, these insects likely survived quite well in their silken cocoons around those fallen apples.

Tarnished Plant Bugs and Other Catfacing Insects:  This is the other key insect complex at this time of year. In orchards with pure turf ground covers, these insects are rarely a problem. In weedy orchards tarnished plant bugs will become more of an issue as temperatures warm and mowing and other ground cover activities become more common. General spray timing at this time of year should still be targeted for Oriental Fruit Moth and/or Plum Curculio (PC).

Spray Programs with little to no crop: Since assessment of crop load caused from frost and freeze injury can often take some time, the following is repeated from the last newsletter. If certain blocks have little to no fruit, disease control is more important that insect control. Without a minimal Scab program this year, you will have a difficult program next year. If you can afford Captan through second cover, perhaps with sulfur through mid-July, then 2021 will be a lot easier than if nothing is done this year. See Dr. Norm Lalancette’s article from April 24. Maintaining copper applications through June will also suppress Bacterial Spot, preventing excessive defoliation and minimizing overwintering cankers for 2021. Oriental fruit moth has 4 generations per year. Most growers had 1 insecticide application on by the time any cold injury occurred. With no crop, this should be all that is needed. Peach tree borers, however, will have to be controlled in September. If you already had your mating disruption dispensers up, then nothing more is needed. For normal crops see below:

Bacterial Spot: Bacterial spot leaf symptoms appeared last week on highly susceptible varieties in southern counties approximately one week after the severe weather of May 1. Maintain coverage with the standard copper/oxytetracycline suppression program. Leaf infections appear water soaked, stay within the leaf veins, and gradually darken. (Figure 1.) Eventually the chlorotic tissue abscises from the leaf, leaving a “shot-hole”. Copper injury appears similar, but the injury marks are round, and are not bordered by the leaf veins. Copper injury will often appear at the leaf bottom where the spray collects as it runs off, and the shot-hole will cross over leaf veins. Copper injury often has a red appearance at the shot-hole margins.

Figure 1. Peach leaf with a mix of old and new bacterial spot lesions.

Figure 2. Copper injury to peach leaf.

Peach Scab: Maintain good coverage with captan or other effective fungicides until July where scab was an issue last year.

Rusty Spot: Rusty spot infections are ongoing until pit hardening. Maintain coverage with effective materials such as Rally, Rhyme, or potassium bicarbonate products. Other choices include Flint Extra, Inspire Super, Luna Sensation and Quadris Top, although usually at a higher cost.

Brown Rot: Maintain coverage with effective materials until pit hardening. Do not rely on sulfur alone unless a dry weather pattern develops. The Captan program, developed by Dr. Norm Lalancette would be a good program to follow, particularly as we get a little further into the growing season.

Apple:

Codling Moth (CM): The first codling moth flight has started. CM treatments will be required starting late this week to the middle of next week, depending on the material use. Rimon applications can go on 5/15-18 (see table below), or diamides can be used during the middle of next week. Since PC is also a target, along with European Apple Sawfly (EAS), insecticide combinations are often needed in this application. For northern county orchards, these CM timings are coming earlier than normal with respect to tree phenology. Since EAS is more of an issue in northern orchards, make sure to use one of the more effective materials for this insect. These include: Imidan, Avaunt,  – effective for all pests at this time, and several pyrethroids. However, the pyrethroids (Asana, Baythroid, Danitol, Lambda-Cy, and Warrior, tend not to be as strong on PC.

Oriental Fruit Moth (OFM): There is a considerable over-wintered population on certain farms in northern counties. Make sure to include an effective insecticide for this pest in your petal-fall insecticide application.

Plum Curculio (PC): This is THE insect to control at petal fall. Avaunt, Imidan, Actara, VoliamFlexi are the top options for control. Of these, Avaunt, Imidan and VoliamFlexi also do a good job controlling EAS (see below).

European Apple Sawfly (EAS): This insect is active through bloom and into petal fall and first cover. Adult females lay eggs just under the skin of freshly set fruit, and the young larvae mine just under the skin. Where present, it is a primary target at petal fall. In orchards of mixed variety plantings, the petal fall spray for the entire planting is prolonged. This enables EAS to start damaging the first varieties where petals fell earlier before a petal fall spray could be applied to the entire block. DO NOT SPRAY ANY INSECTICIDE DURING BLOOM FOR THIS PEST! Doing this will kill bees, hurt pollination and fruit set, and is highly illegal!

Tufted Apple Budmoth (TABM): A biofix was set statewide on May 6. Predictions for insecticides timings are too far out at this time. More on this in later reports.

Diseases: Apple Scab – Primary Scab should be over in Southern Counties with the next infection period. Models predict 100% ascopore maturity on May 7 in southern counties and May 9 in northern counties.

Fire Blight: Favorable infection conditions are predicted for 5/16-18 in northern counties on any bloom that is still open. The high risk period for blossom blight infections is a function of having the blossoms open, having the right amount of bacterial inoculum, temperatures above 60⁰F, and enough wetting. Phenologically, this usually occurs between 20% bloom through 80% petal fall.

This period is over in southern counties, but favorable weather conditions can still favor the spread of infections that have already taken place. Fortunately, because of the cool weather we have not had very favorable infection conditions in southern orchards. That may not be the case for orchards in northern counties over the next few days. If bloom is still present, then antibiotics can still be used. Continue antibiotic applications just prior to infection periods (or 24 hr after). These treatments are primarily to prevent the initial blossom blight phase. If you get fire blight and it works its way into the shoots, then the shoot blight phase can harbor bacterial inoculum for further infections. Windy and violent thunderstorms and hailstorms can produce trauma events if shoot blight already exists. This is one reason why pruning out the shoot strikes is so important. In order to minimize inoculum levels if strikes are still present, growers have used preventative Cu sprays (.5-1 lb actual Cu/A) to prevent further spread, but that will also scar the fruit, especially under slow drying conditions. Coppers should not be used in acidic spray mixtures; and do not use coppers with foliar nutrients or spreader stickers, especially penetrants and silicon based wetting agents. Given these issues some growers may wish to extend the use of antibiotics. This is not good resistance management, but is justified if shoot blight is present and used around a trauma event. Agri-Mycin may be applied after petal fall, but it must be rotated with oxytetracycline (Mycoshield or FireLine 17WP). Kasumin 2L may not be applied after petal fall. DO NOT use consecutive Agri-Mycin (strep) applications if 2 applications were already used during bloom. This will increase the likelihood of antibiotic resistance developing. See the May 4 article on fire blight by Kerik Cox and Anna Wallis in Scaffolds for a more in-depth treatment of fire blight management.

Thinning Precautions: Several growers have made comments about thinning for this year’s apple crop. Remember that this is NOT a normal year, and many trees are injured. Don’t do anything until you can assess the fruit when they reach 10-12mm size. Anything less than that may be injured and still fall off. See the Apple Crop Load Management article by James Schupp and the carbohydrate thinning model article by Rob Crassweller for more discussions.

2020 Tree Fruit Production Guide: The updated guide has been on the Rutgers Publications website for about a month, and available as a free electronic download. The printed edition was requested by numerous growers. In order to honor that request, and still conform to the COVID-19 pandemic cautions, we have made the printed edition available on the Rutgers Continuing Education website. Register on the Rutgers Continuing Education website; go to Product Search; Click Pesticide Applicator Training Manuals; Select “2020 New Jersey Tree Fruit Production Guide-Table Edition.” Selecting that link should give you the following screen below. The cost is $25 plus $7 postage and $1.66 tax.

Scouting Calendar Tree Fruit Southern Counties

The following table is intended as an aid for orchard scouting. It should not be used to time pesticide applications. Median dates for pest events and crop phenology are displayed. These dates are compiled from observations made since 1995 in Gloucester County. Events in northern New Jersey should occur 7-10 days later.

Tree  Fruit Trap Counts – Southern Counties

Tree  Fruit Trap Counts – Northern Counties

Blueberry:

Leps and Other ‘Worm’ Larvae:  Levels of Leps are still minimal.  We observed a few spanworm and green fruitworm larvae, but no treatments are needed.

Gypsy Moth: Very minimal activity in fields this week.

Plum Curculio (PC) and Fruit Sampling: PC activity is still low, but will increase with the warmer weather. Since many fruit are set, we are starting to assess fruit quality. The photo below shows a fresh egg scar resulting from the female PC laying her egg on the fruit. A larva will develop in that fruit, and if the grower is lucky, the larva will mature and the fruit will drop before harvest. The problem is that this egg laying has been going on since about 4/15, or 1 full month. The long bloom has given PC females plenty of time to lay eggs. With warmer weather coming and bloom still remaining, the females will continue to lay eggs until the bees are out and the first insecticides can be applied. Make sure to use a highly effective material for PC in your first post pollination spray.

Figure 3. PC egg scar on newly formed berry. (Photo – Carrie Denson)

Botrytis, Phomopsis and Mummy Berry Strikes:  Disease has still been very minimal in the fields.  Where disease is present, there is a maximum of 0.5% of  bushes showing symptoms.

Cranberry Fruitworm (CBFW): Traps have been set for over a month, and we had our first catch last Friday in Atlantic County.