IPM Conference Calls 2011: June 14, Summary and Download

First, some announcements:
1) We will have NO CONFERENCE CALL on July 5.

2) John Wise from MSU Entomology will be joining us the week after next, on Tuesday, June 28 (NOT next week). John’s research focuses on the rainfastness and performance boundaries of new insecticides. Get your questions ready.

3) Lastly, thank you to everyone who sent me their input about the call summaries. All of it was great, and I hope to nail down a good format sometime soon.

 

Next, John wanted to add something that he didn’t cover in the conference all:

I realized that there was something I should have mentioned. If people are not applying an insecticide for Codling moth, they definitely need to be sampling or have a pheromone trap out for either Oriential fruit moth or Lesser apple worm. Those two insects are the same genus, and the lure for one will catch the other, as well. I don’t care whether they have an OFM trap or an LAW trap — they should have one of them.

The reason is that the lesser apple worm fly about the same time codling moth do, and I’m seeing more LAW this year. They are also an internal fruit worm similar to codling moth.

If people are not applying something for codling moth, then they should be trapping for LAW, because, in short, we controlled the LAW because we were controlling codling moth, and if we’re not controlling codling moth with an insecticide, then we should definitely be sampling for OFM or LAW, secondary or tertiary insect pests.

 

Download the June 14 recording here:
Get the MP3 version.

 

June 14 Conference Call Summary

-          02:05 – Introduction to Dr. John Wise’s work on rainfastness of insecticides

-          04:00 – Call for recommendations for guest speakers

-          04:30 – Summary of Larry’s talk on Codling moth from last week

  • Larry started by talking about his research on Codling moth biology and behavior. He now has a grant to convert his findings on Codling moth into a workable management strategy.
  • Larry has not been a big proponent of focusing on the “biofix” as a strict management decision-making tool. He also is not very concerned with starting the degree-date counting from January 1.
  • His new management strategy will take into consideration the specific weather factors found to be important in the CM mating and egg-laying process. What’s important to him is the actual biology actually happening to those Codling moths in the orchard, and that biology can be affected greatly by weather events that the degree-day model doesn’t take into account.
  • His feeling about this year: Coolness and weather aren’t going to play as big a role in CM control. This year had good weather for first-generation weather and egg-laying. The CM population will be strong. Management decisions should be relatively straightforward from here on out.
  • Larry recommends looking at the CM’s entire generation rather than simply at the 250 degree-day benchmark. So, after biofix, if your population is over threshold but still not huge, you may want to wait until 300 or 350 degree-days from biofix before you apply larvacide.
  • On trapping in mating disruption orchards:
    • If you trap within a non-mating disruption orchard, your trap will survey about 2.5 acres.
    • If it is located within a mating disruption orchard, the trap will only sample something like 1/10 of an acre.
  • So if you use the same number of traps that you did before implementing mating disruption, you will end up sampling as little as 4% or 5% of what you used to sample. In mating disruption orchards, then, you should put out more traps to compensate for these limitations.

-          13:25 – QUESTION: On a mating disruption orchard, you said that the solution would be to put out more pheromone traps. At what rate would we need to put them out?

  • It depends on how much information you feel you need.
  • One question to ask is: How much variability did you have in your orchard prior to using mating disruption? If you experienced a lot of variability in your traps before using mating disruption, you probably have some sense of where the hotspots are, and whether they varied.
  • John usually doubles the trap numbers, in general, and would add even more into areas that you identified as pre-mating disruption hotspots (with high variability or high counts). You need to pay particularly close attention to areas that are susceptible to migration from an outside source.
  • You could also use some combo CMDA lures, paired with a regularly-bated trap, placed at a 50-feet distance. CMDA lures will sample from a larger area, because they don’t use sex pheromones as attractants. The CMDA lures won’t tell you whether to spray or not, but they will show you when CM are flying and can give you a relative sense of the size of the flight.

-          18:55 – A warning to not slack off on your trapping.

  • Once you have reached your first spray, there is a tendency to lower your vigilance around the traps, your attention to the age of the lures, etc.That is NOT a good way to do things.
  • The CM population needs to be controlled at least 650-700 degree days from biofix, when the majority of the generation is hatching.
  • You should NOT stop monitoring, and you should make sure that your lures are functioning.
  • It’s very important to control the first-generation codling moth as best as possible so that there is less to worry about in the second generation, especially around apple-picking time.

 

Diseases

-          21:42 – On scab:

  • Growers in region from the Twin Cities area down through Chicago should be well past the primary ascospore release period.
  • How do you know how many primary ascospores you have left in the leaves on the orchard floor?
    • All the ascospores will be mature by 920-something degree-days from biofix (Mac green tip), and will be ready to be released by rain event.
    • If you’ve had rainfall after reaching the 920-something degree-day point, then the last of the spores should have been released.
    • If that rainfall wasn’t an infection period (that is, it wasn’t long enough), then you should have no problems.
    • If the rainfall event was an infection period, then you have to consider the protection that was on the trees at that point. Lesions would appear 5-12 days after the event, if the infection occurred.
    • BIG POINT: You can’t assume danger is over until you release 100% maturity point AND have a rain even to release the spores. If you haven’t had a rain event, then you should assume the ascospores are still waiting in the leaves.
    • The type of heat that we had last week will help destroy ascospores that have aged.
  • If you’re from the southern 2/3 of Wisconsin, you should now be able to ascertain whether you were successful or not at controlling scab. If you were successful, then you can begin to consider reducing or cutting out fungicides by rate, by interval, or both.
  • If you varied your scab sprays across your orchard, then you should vary your scab scouting accordingly. Check all areas that received unique treatments.

-          27: 26 – QUESTION from Deirdre Birmingham: Why use Mac as a reference variety for timing of scab model?

  • Probably because Macs were so prevalent and so susceptible to scab when they were developing this model.
  • Cortlands, Jonamacs, or Liberty would be pretty close to Mac. John would recommend talking to other people in the area who have more traditional varieties to get a sense of what is breaking when.

-          29:15 – On black rot

  • We are still in prime black rot sporulation period, in this first month after petal-fall. If you have older trees nearby and you want to protect younger trees from infection, then fungicides used in a conventional system (like Captan) will help keep those spores from spreading.
  • If a storm breaks limbs in the orchard, there is not a whole lot you can do to prevent spread.
  • If you have a lot of black rot in the orchard, that’s a good argument for keeping a high rate of Captan spray.

-          31:05 – On summer diseases, disease monitoring, and counting wetness hours

  • You should be counting leaf wetness hours from petal fall.
  • BUT if you applied a full rate of Captan or a strobilurin, then you should start counting your leaf wetness hours from that point.
  • If you’re using a Spectrum data logger, you should count all the leaf wetness hours and should not exclude wetness periods less than 4 hours.

-          32:51 – On fire blight:

  • If you’re going to have fire blight, blossom blight, or shoot blight, you should be able to see it by now.
  • He has seen bad cases of blight already, although it hasn’t been alarmingly prevalent.
  • BUT some of the new plantings of first-year are still in bloom – that’s very dangerous. Make sure to pick the blossoms off. If the blossoms get covered with bacteria and then a rain event occurs, those small trees will be in trouble.
  • If you’ve had fire blight in the last 3 or 4 years, assume that your bacteria count is sufficient to cause problems for new trees.

-          34:50 – On silver leaf:

  • He saw something in an orchard the other day that looked like powdery mildew but turned out to be silver leaf.
  • Is more common in older orchards and older plantings, but can be brought into new orchards from the nursery.
  • The only way we know how to control it is by getting the infected wood out of the orchard.

 

Insects

-          36:10 – On Plum curculio:

  • Everybody in the southern part of the region should have reached the base-fifty 308 degree-day point. At this point, all the Plum curculio are in the orchard.
  • If, after this point, you apply something for CM that also affects PC, then you should be rid of your PC problem for the season.
  • On the other hand, if the last time you applied something for CM was at 150 degree-days from petal fall, or if you haven’t yet put an insecticide out, then you should make sure to keep up your PC scouting.
  • PC seems to be coming back in some orchards more quickly than in others.
  • If you haven’t put anything on and you still haven’t suffered much damage, then you might have gotten lucky.
  • However, PC will continue to lay eggs. PC can live a long time in mild weather. Through persistent feeding, PC can cause lots of damage in small increments.

-          39:36 – On Apple curculio:

  • Can be confused with PC. The ovoposition scar is not the same, but the feeding damage can look almost the same.
  • It seems to occur in orchards that haven’t sprayed much insecticide at all post-bloom.

-          40:10 – John’s take on “pushing the envelope” by not using insecticide and relying only on thinning sprays to control insects.

-          41:10 – On Codling moth control

  • Larry talked about not spraying for CM until 300 or 350 degree days if your flight hasn’t been heavy.
  • According to John, you need to be careful about this. If you had serious CM numbers in the hot period of the first part of June, then you probably have lots of eggs waiting to hatch. In this case, waiting until 350 degree-days might not be a good idea.
  • However, if your numbers have been low, and you expect to see higher numbers in the coming weeks, then waiting until 300 or 350 degree-days makes sense.

-          43:05 – On Codling moth lures supplied by DATCP

  • These lures should not be relied on beyond 3 weeks. Hot weather might even reduce their lifespan to 2 weeks, and direct sunlight and high wind can reduce their efficacy, too.
  • If you’re relying on them to make you decisions, you should change them every 2-3 weeks.

-          44:30 – On Oblique banded control in mid-summer:

  • John will take to heart what people in Michigan have been saying: if you have a high count of Obliques, you have a relatively higher threat for hatching than if you have low counts of Obliques.
    • That means that if I have a high number of Obliques, I should increase the relative count of the Oblique traps I set out in the orchard
    • This is critical to be able to monitor for different parts of the orchard, particularly if you are interested in not putting an insecticide out in the next 3 weeks.
  • John has begun to put out Oblique traps at about half the rate of CM traps.
  • If you have enough traps out, you will be able to better monitor differences in the orchard. Having this level of detail will help you limit your insecticide use, as well.
  • Controlling the over-wintering generation is the most critical. If overwintering generation is controlled well at bloom, pink, or petal fall (with Bt, for example), then you will minimize the hatch of 2nd-generation Obliques in late August or early September.
  • BUT if you do have a high 2nd-genereation hatch, resist the temptation to not do anything.
    • You must control these: 1) to protect from fruit damage (those larvae are hungry); and 2) to minimize the next over-wintering population.
  • You can use sampling of terminals to determine whether you have a problem with Obliques in the next 2 weeks. Putting more traps out might help you be able to better concentrate your sampling efforts.

-          50:15 – On Thrip control:

  • If anyone applied anything to control Thrips and still found Thrips after the application, don’t worry too much. The materials are probably still working. Those Thrips are probably ones coming in from outside. Evidence shows that Thrip control does cut out Thrip damage.
  • Also, many predators are attacking Thrips right now, and more are coming.

-          52:10 – Response to question about Rosy apple aphid. Should it be controlled?

  • John has been lax about controlling them in the past because so many predators exist that will control it as long as we don’t wipe out the predators first.
  • Most of the good aphid predators we have (Green lacewings, Coccinellids, Ladybeetle larvae, Syrphid larvae) don’t seem to be greatly affected by most of the materials we use in the orchards this time of the year. However, by the time these predators control Rosy apple aphids, the damage can be quite severe.
  • If you’ve had a lot of damage from Rosies in the past, then you might consider applying a light rate of neonicotinoid. The application can be variety-specific and area-specific.
  • An alternative to neonicotinoid: Try applying a low rate of a generic Imidacloprid like Alias.


THE NEXT CALL will be on Tuesday, June 21 at 8am Central Time. Please remember that we have begun using the new call-in number (that is 760-569-7676, access code 272044). If you have any questions for John, send them to John at jgaue@mwt.net (or, if you can’t email, call at 608-604-0234) by Monday.

———————–

On free Skype calling: Remember that with this new service, you can use Skype to call in to the live call for free. It looked like we had one, or at most two, people taking advantage of the free Skype-to-Skype feature today. Please see the previous announcement emails for information about how to set this up.

A couple other people had some problems with the setup, however. They added the FreeConferenceCallHD.7605697676 contact but the contact remained offline or unavailable. If you add the contact and it says it’s offline, just go ahead and try to call it anyway by right clicking on the contact and clicking “Call.”

If you’d like to try setting up Skype before next week’s call, please feel free to test out your setup by dialing the conference call service at any time during the week. Also, if you run into any problems getting it to work or have any questions about Skype, please contact me at armccullough@wisc.edu or 541-207-6535 (my cell) so we can figure it out together.

Call playback: Please note that the playback phone number has changed as of May 24, 2011. As of right now, it is not possible to play back an old recording for free using a Skype-to-Skype connection. To hear the most recent call, please dial the following regular phone number:

  • Dial: (760) 569-7699, then enter this access code: 272044.

Call archives:

  • Dial: 641-715-3800, then enter this access code: 28864 (this number has not changed).

*REMINDER: If you join the live calls, please mute your line by pressing *6 to avoid unwanted feedback. If you want to ask a question or make a comment, you can unmute your line by pressing *6 again. Thanks!