August 9, AppleTalk Conference Call

AppleTalk Conference Call Summary
Tuesday, August 9, 2016, 8:00 – 9:00 AM
Presenter: John Aue, Threshold IPM
Moderator: Peter Werts, IPM Institute of North America; questions or comments, pwerts@ipminstitute.org

August 9th call download: Click Here

Thank you for a successful season of AppleTalk! Your participation makes this program possible. Please keep an eye on your email for information on our annual survey and Apple a Day IPM Calendar. We would like to collect your favorite photos from your orchard and bring this calendar to print by the end of November. John Aue, Thomas Bernard and Peter Werts will continue to scout orchards through the end of August and are available to answer questions on the pests.

Determining fruit ripeness and harvest dates
Tracking days from full bloom can be used to plan the harvest of Paula Red and McIntosh. Paula Red harvest typically begins 100 days from full bloom and will can last two weeks. Picking for McIntosh starts 115 days from full bloom, with prime picking between 125 and 130 days. The goal is to have all McIntosh fruit harvested within 145 days of bloom.

Background color is primarily used to determine harvest of Zestar. A light greenish background and brown seeds signals a ripe Zestar. There is not currently a good measurable sugar content, i.e., brix, so taste is helpful since it seems Zestar can go from starchy to sweet overnight.

When picking Honeycrisp growers look for a good yellowish green background color and red over color. On some sites this color never develops and the amount of red can depend on the strain of Honeycrisp. Most growers do two to three picks of Honeycrisp. The first pick is usually set aside for storage or late season sales and the following two are sold as soon as possible since over mature Honeycrisp do not store well. In some scenarios the third pick will invariably end up as cider.

When using Extension recommendations for starch-iodine tests, brix, or pressure always consider your orchards unique site specific parameters and expect some variation between orchards and regions. Use the available tools to gather and generate data and determine what parameters work best for your operation. Harvest maturity equipment can be purchased from Peach Ridge Orchard Supply,
http://www.peachridge.com/harvest-2/maturity/#!/Maturity/c/12544202/offset=0&sort=normal

Plant growth regulators
Blush (prohydrojasmon) can enhance color development, especially on the backside of the fruit that does not color well. Blush does not accelerate ripening. One grower prefers to not apply blush to Honeycrisp so pickers can use visual cues based on harvest parameters.

ReTain (AVG-HCl) reduces amount of ethylene produced to prevent the abscission layer from forming between the fruit stem and spur. The general recommendations for use of ReTain on Honeycrisp are to apply a half rate 30 days before harvest. Other recommendations would allow a ¼ rate to be applied within 14 days of harvest or to include NAA, e.g., Fruitone, at 10 PPM with the ¼ or ½ rates. Honeycrisp does not produce a lot of ethylene and therefore is more sensitive to Retain. This means that a “half rate” is essentially a full rate. The use of Retain with NAA can extend harvest another seven to ten days. The combinations can continue to promote ripening and also inhibits separation at the abscission zone. See additional links below.

Using ReTain in 2015, Duane Greene, UMass
http://web.uri.edu/ipm/2015/08/using-retain-in-2015/

Retain and NAA recommendations, Michigan State University
http://msue.anr.msu.edu/news/retain_and_naa_recommendations_for_2013

How to manage young Honeycrisp, Good Fruit Grower, June 18, 2015
http://www.goodfruit.com/how-to-manage-young-honeycrisp/

It is not recommended to apply these materials in complicated tank mixes and to also read product label for compatibility statements. When first using these materials experiment with application timing and rates for specific varieties to help determine what works best for you orchard.

Late season codling moth management
Continue to monitor codling moth (CM) pheromone traps to time insecticides applications. Some locations are seeing a resurgence flight. If traps do not exceed threshold an insecticide application is not necessary. Spot spraying blocks where traps exceed threshold may be a good option to avoid early varieties and preharvest intervals. If larvae are in fruit following harvest, damage can continue to occur in storage; larvae may emerge from fruit. Continue to monitor and consider treatment for other direct fruit pests, e.g., apple maggot, lesser apple worm, obliquebanded leafroller, at this time. See notes from the August 2 for a technique that can be used to help calculate next season’s pressure by assessing CM damage at harvest.

Obliquebanded leafroller
The second generation of obliquebanded leafroller (OBLR) will begin to hatch in August. This generation typically feeds on ripening fruit rather than on vegetative tissue. The OBLR larvae will only grow to a few millimeters in length before developing a pupa and going into diapause, where the OBLR’s growth and development is suspended until spring. The CM larvicides, e.g., Delegate (spinetoram), Altacor (chlorantraniliprole), will control these larvae, whereas the neonicotinoids, e.g., Assail (acetamiprid), Admire Pro (imidacloprid), do not. Managing the second generation now, will reduce the overwintering population that may need to be controlled next spring. Three to five percent injury is possible at harvest and scouting needs to be used to determine if a treatment is warranted. Two traps per 20 acres is adequate to determine where treating is necessary.

Apple maggot
Continue to monitor traps through the first week of September. Clean traps 10-12 days after an insecticide application or one inch of rain to determine if a reapplication is necessary.

Neonicotinoids have limited lethal action on adult apple maggots, but provide strong curative activity on eggs and larvae. It is recommended to apply neonicotinoids as full cover spray to blocks that exceed threshold. Alternate-row-middle applications will not provide adequate control. For more information visit: http://msue.anr.msu.edu/news/managing_apple_maggots_with_insecticides

Stink bugs
August is typically when we begin to see feeding damage from adult stink bugs. We are not currently anticipating large numbers this year since we did not see many egg masses or nymphs during the early part of the season. We do not know a lot about stink bugs and there are likely many factors in addition to weather that affect insect mortality. Research on stink bugs are not as robust as many of our other direct fruit pest since they poised little threat to the crop when many of the broad spectrum insecticides, e.g., organophosphate, pyrethroids, and carbamates, were the mainstay of growers spray program.

When assessing damage at harvest it can be easy to confuse stink bug injury with that of other insect pests, e.g., apple curculio, plum curculio, tarnished plant bug, spring lepidoptera, or from mechanical damage, hail, bitter pit or cork spot. See call notes from August 2, 2016 to help diagnose stink bug injury.

Mites
Mite populations can still flare and cause damage. If mite populations exceed August 1- 15 sampling threshold of 7.5 mites per leaf consider applying a miticide. Mite days are likely high if it has taken populations this long to grow and a long period of feeding from below threshold numbers can still result in economic injury. As fall approaches mites will begin to lay eggs to overwinter on small limbs and near fruiting buds. If populations are large eggs can occasional be found on fruit, causing superficial injury.

Fall webworm
Fall webworm is a secondary pest, e.g., tent caterpillars, that has sporadic distribution and shows up by late summer. By the time they are found it is often too late for control, yet damage is typically not widespread.

Fire blight
Once shoot elongation ceases there is minimal utility in applying streptomycin within 24 hours of a damaging severe weather event, e.g., hail, high winds, since ability for bacteria to move into woody tissue is greatly reduced compared to green tissue.

Apple scab, summer disease and fruit rots
If scab lesions are present on foliage and/or fruit it is critical to maintain fungicide treatments as cooler, wet weather will create desirable conditions for the development of conidia. Use caution if stretching out fungicide, e.g., captan, coverage for more than two weeks if scab is a concern.

Growers with history of summer diseases are recommended to monitor leaf wetting hours. Sooty blotch and flyspeck can continue to be an issue on late-harvested varieties that are not picked until the end of September and October. Fruiting bodies can appear post-harvest and infections can allow moisture to exit the fruit, softening it in storage. Consider applying a fungicide that will control summer disease if apples will be on trees for another 30 days. Minimal fruit rots have been observed this year, yet there is still time for them to develop on sunburned or damaged fruit before harvest. Consider history of fruit rots when selecting fungicides for final pesticide applications.

Maintaining tree health through harvest and maximizing winter hardiness with guest speaker Dr. Amaya Atucha, University of Wisconsin- Madison, August 11, 2015 AppleTalk Conference Call

Bitter pit
• The majority of calcium (Ca) is taken into the fruit from petal fall to the end of July.
• Calcium is relatively immobile within the tree and concentrations can vary between foliage, fruit and soil. The following factors can influence Ca levels and incidence of bitter pit: Nutrient imbalances with nitrogen (N), potassium (K) and boron (B), soil moisture levels and fruit size. It is not too late to complete leaf analysis. This can be completed by collecting 30 fully mature leaves (per variety, block) from the mid-point on this year’s growth. Do not complete after trees begin senescence.

Keys to reducing bitter pit
• Submit foliar, fruit and soil samples for nutrient and pH analysis. It is recommended to test samples for all available macro/micro nutrients as many complex interactions exist. For example: an excess amount of magnesium (Mg) or potassium (K) will compete with Ca for uptake.
• Keep soils adequately hydrated throughout entire growing season.
• Reduce excessive vegetative growth; Apogee (prohexadione calcium) can be applied to curb vegetative growth. Reducing vegetative growth will redirect the transport of Ca from foliage to fruit. The pre-harvest interval for Apogee is 45 days.
• Lite crops or excessive thinning can result in large fruit. Calcium levels can be diluted in large fruit; Ca concentrations typically vary from stem to calyx end (location where bitter pit symptoms are most pronounced), excessively large fruit usually have exacerbated symptoms.
• Calcium sprays can begin at petal fall and continue to end of August; up to six applications may be necessary. Coverage is important, Ca most contact fruit to be effective. The recommended rate is 1-2 lb. Ca per 100 gallons of water. If visible symptoms are present it is not too late to apply Ca to prevent further injury.

Tips for promoting winter hardiness
• Keep soils adequately hydrated throughout entire growing season to help regulate soil temperatures and reduce tree stress.
• Consider using mulch to protect trees in years without snow. Modify rodent control if mulch is used.
• It is not recommended to apply nitrogen before harvest to promote fruit bud hardiness, more research is needed to determine rates and timing; if too much N is applied terminal buds will reinvigorate.
• Applying potassium for cold hardiness is a myth. If soil has adequate nutrients, there is no need to apply more than the crop needs. Note: If yield is 1500 bushels/ acre, approximately 80 lb. of K is removed from soil. Soils typically have high concentrations of K. Potassium is mobile and readily available.
• Newly planted trees are more sensitive to cold temperatures and extreme temperature fluctuations than established trees since they are already being exposed to replant stressors, e.g., soil pathogens. Mulching can help reduce stress.
• Terminal buds should be set one month ahead of the first frost. Apogee (45 day PHI) can be applied to halt vegetative growth, effects should be visible within a week following application.