June 18th Apple Talk Summary

Apple Talk Conference Call Summary
Tuesday, June 18th, 8:00 – 9:00
Presenters: John Aue, Threshold IPM.
Moderator: Peter Werts, IPM Institute of North America; questions or comments, pwerts@ipminstitute.org.

June 18th Call Download
Call Download

Call Summary

Tarnished plant bug
John is not seeing many tarnished plant bugs, including adults and damage.  Also not seeing many in strawberries.

Obliquebanded leafroller
OBLR are beginning to fly in southern portions of Wisconsin. (see OBLR model).http://www.agbioresearch.msu.edu/nwmihort/summerleafrollercontrol.pdf

Rosy apple aphid
Some orchards are still beginning to see RAA colony expansion.  RAA does seem to be sticking around longer into the summer this year.  If we are seeing RAA flare up we need to assess what is happening. 1. All we see are healthy purple and pink aphids; 2. Populations of aphids plus worm like predators, eg, cicimoia are syrphid fly larva, Black aphids that have been parasitized; 3. Colonies have winged aphids, and is an indication the colony is going to fly to the summer host.  If more than 1/3 of the colonies are healthy and do not have predators or winged aphids, it is important to manage.  Even though we are approaching midsummer, they can grow rapidly.

White apple and potato leafhopper
We are beginning to see white apple leafhopper nymphs.

Spider mites
We have yet to see any significant populations of two spotted spider mites.  There is damage from apple rust mites showing up.  Damage shows up on terminals and shoots, by the time it starts showing up the numbers are pretty high.  Only worth paying attention to the high value crops.  Turn new shoots over and look at undersides of leaves, if there are rust mites the leaves will look olive drab, vs. bright green.

Right now we can be trapping dogwood borers, plum borers, and lesser peach tree borers.  Potentially last year could have been lots of borer attacks and this year would expect to see more adult moths of those species.  Not necessarily going to see big burnouts, but should look at trees that are particularly stressed, e.g., trees that did not get water last summer.

Parasitic wasps
Typically this time of year we only see several species of parasitic wasps active, however, John is seeing many more species of parasitic wasps in the orchards.  Their work will help our IPM programs if we avoid wiping them out.  Note that Delegate is toxic to parasitic wasps.

Beginning to show up on shoots and blossoms in southern WI.

Black rot
Showing up from frog eye leaf spot and the canker forming part of the fungus that kills branches and trees.  We can expect the possibilities that trees may die suddenly from black rot. This may impact one scaffold or a whole tree.  Removing damaged wood from black rot ASAP will help reduce the incidences of fruit rots.

Cedar apple rust
Nothing can really be done about it at this point.

Powdery mildew
This year has been good for PM, not seeing much PM likely because we have lacked the hot and dry weather.

Apple scab
If significant scab has now appeared, options are limited for conventional and organic.  Applying some sulfur is about the only option for organic producers.  Once terminal buds set leaves and lesions get older and less conidia may be developed, but the risk continues to be high.  Often when we have scab on fruit, there are areas of the apple that do not take up the insecticide.  For example, CM will still bore into scab infected fruit, even when good CM materials have been applied.  Options for conventional growers – if you have scab it is advised to not use any SI, strobilurins, APs or SDHIs. None of these will fully eradicate scab and will hasten resistance.  Options are to keep fruit protected with captan.  Syllit (dodine) and Topsin are in different fungicide families are anti sporulants.  They do not kill the fungus, but kill the conidia structures and prevent the development of secondary spores. Due to how these works, they are also very susceptible to resistance.

If you have scab should also not use strobilurins or SDHI for sooty blotch.  Nova/rally not effective on summer disease, Indar is an option.  Topsin still works on sbfs, this is a good choice for orchards that have scab, since most orchards are resistance to scab.

Plum curculio
Over the last week we are seeing more damage inside the orchard perimeters.  Most damage has been less than a week old. If you have only applied a perimeter insecticide it may be important to scout interior blocks.  Damage is also not done.  Can follow the degree day model from Mac petal fall at 308 degree days.  Once we reach 308 DD we can presume that PC will no longer be moving from overwintering sites, but damage can occur well into July.

Do not rely on codling moth materials for PC control, especially if you are experiencing lots of PC damage.

Codling moth
Last week we discussed ignoring biofix for early flights around May 21 and 22.  Another flight occurred between the 28 and 30th of May and since flights were small options to delay from 250 DD biofix is an option.

John has found some stings that may be CM that were able to fly and lay eggs after the May 21 and 22 biofix.

Organophosphates and neonicotinoids would have some curative properties because they are somewhat systemic.  Since the first CM instar is spent very close to the surface of the fruit, we can still manage these early-hatched CM larva.

Need to be considerate of rate, rainfall and their efficacy, e.g., neonics loose efficacy even after .5 inch of rain 7 days after application for Assail and calypso.

See John wise article re rain fastness for CM materials. Should not assume 14 days of protection of Delegate when we have significant rain fall.

Ten or less moths in a trap in a week’s time are a low population.
Whatever we do for first gen is going to be more effective now than during second because of the size of fruit and difficulty in getting good coverage.  It is better to be aggressive now with an additional spray, or putting up more mating disruption.

Apple Maggot
Since a number of growers did not have a crop last year, we need to pay extra attention to apple maggot this year. Need to presume that any fruit left out on the trees last summer could have been infested with apple maggot.  Typically we put up traps around July 1st, but have caught them in June, when traps were hung early.

We should focus right now on the cultivars that have a history of AM.  We are not talking about perimeter traps, rather need to sample in the orchard and in the cultivars that may have been infested last summer.  We can start with unbaited traps and then as fruit nears maturity we need to add fruit bait, especially where we know we have maggots.

As time allows we can hang perimeter traps, but should hang on the susceptible varieties first.

San Jose scale
John has yet to find any crawlers. Crawlers may be appearing in southern WI and northern IL may be appearing soon.

Rainfast characteristics of fruit crop insecticides