IPM Conference Calls 2011: July 12, Summary and Download

 

Download the recording from the Tuesday, July 12 call here.

 

Call Summary

Grower Questions

-   3:18 – How do you apply lime to or paint the trunks of the trees?

• I know a lot of people who use latex paint, but I don’t know anything about using lime.
• Cheap latex paint is usually the material people use to protect their trunks from winter injury.
• If you have more information about lime, please contact John or Alex.

-   4:25 – What do we know about trap placement strategies for insects other than codling moth? (for Red-banded leaf rollers, Oblique-banded leaf rollers)

• In general, RBLR, OBLR, and all other leaf rollers are much easier to sample for because they have a wider host range than CM. As a general rule, then, we don’t have to worry about trap placement as much. We don’t have to worry so much about how high the trap is or where it’s located.
• The most important thing with RBLR and OBLR is how you use the trap counts. Overall, it’s recommended that you use them simply as indicators of when the flight is beginning and when it ends so that you know when to be sampling for larval hatches.
• However, you should interpret the RBLR counts and OBLR counts in different ways.
  • OBLR trap counts are directly indicative of the relative pressure of egg-laying from females. In addition, OBLR tend to concentrate in certain areas.
    • So, use relatively more OBLR traps so that you keep a good watch on the geography, timing, and severity of the hatch.
    • MSU researchers say that, for example, if you only get 10 or 15 OBLRs in a trap, you probably won’t have a serious issue with larval hatch. If you get 40 or 50, however, you’ll likely have a more severe hatch.
    • No matter what, you need to scout for larval hatch before spraying. You shouldn’t be basing a spray on the pheromone trap count alone.
    • RBLR trap counts, on the other hand, are not reflective of the possible hatch that will occur. Even if you do see hotspots with high trap counts, you can’t necessarily infer that the hatch will be that much more severe in those areas. RBLR traps should therefore only be used to tell when to start monitoring for larval hatch and when to stop.
      • I might only put 2 RB traps out in a 100-acre orchard.
• As long as the traps are placed where the wind can get at it, the height of the trap shouldn’t matter much. Use the 5 or 6-foot rule of thumb.

 

-   10:12 – Second biofix for codling moth

• Somebody mentioned to me that they set their 2^nd biofix for codling moth on July 7^th.
• It’s confusing to talk about biofixes for 2^nd generation. You should set your second biofix from your first biofix. The second biofix should follow the first by about 1000 degree days.
• If your trapping shows a jump in CM earlier than 1000 degree days after first biofix, then it is likely due to a “B-hump” in first-generation CM. Most people south of the Twin Cities and Eau Claire who don’t use mating disruption showed a “B-hump” in first-generation CM, and people that live further north will probably experience it soon if they haven’t already. That B-hump should indicate the conclusion of the first-generation flight.
• In New York, they start counting degree days from a preset date.  If you read Scaffolds from last week, they say that CM development as of July 11 shows 2^nd-generation adult emergence at 13% at Marlborough and 1% at Geneva. If you go to the last page of the Scaffolds where it says “Upcoming Pest Events,” they will show you not only the current degree day accumulations and coming events for various pests, but they will give you a range of degree day accumulations. For example, at Geneva they currently have a degree day accumulation of 1204 degree days, base-50. Their second flight of CM historically begins somewhere between 1023 and 1500 degree days. So you have a range of about 500 degree days — that is, the average plus and minus the standard deviation. That shows you how variable that second generation start can be when not set from first biofix.
• If you start your degree days from your first biofix, it’s a lot more straightforward. Your second flight should emerge between 900 and 1100 degree days after your first biofix.

 

-   14:18 – How do you control for Japanese beetle? What should you spray for it (Imidan vs Assail)?

• If you have JB on any variety in your orchard, there are a number of different materials you can apply.
  • One of the Neem products (Aza-Direct, Neem-X)
  • An organophosphate (Imidan)
  • A neonicatinoid (Assail or Calypso)
  • Surround
  • Some people are still using pyrethroids
• You can break these materials down into two camps: ones that kill the beetles, and ones that repels the beetles.
• If you already have JB pressure, you don’t want to use a repellant material alone. The beetles have already begun using an aggregation pheromone to attract others of its kind.
  • If you put Surround or Neem out there, you will most likely not convince them to leave. The beetles are already there, and they are keyed in that this is a good feeding site.
• The rule of thumb is that you have to remove the JB first before you apply a suppressant, repellant, or anti-feedant (like Assail of Calypso).
  • If the JB are already in the trees, you could apply Assail and Calypso at their highest rate and not see a significant reduction in JB numbers. You might kill some beetles, but more will continue coming into the orchard, attracted by the aggregation pheromone. You most likely won’t see a reduction in the damage to your trees.
• How do you clean off the JB? Overall, there aren’t a lot of materials to choose from to clean those off.
  • Pyganic might do it, especially if it’s a hot day. But I don’t know how much mortality it would generate. It might just knock them out for a half-hour and then allow them to come back.
  • Conventional growers can use an organophosphate.
  • Carbaryl. I would hesitate to use Carbaryl at this stage of the game, however, because of its effect on beneficials. If you have to use it, using it in August would be less damaging to beneficial than using it now would.
• However, using any of the repellant, suppressant, or anti-feedant materials BEFORE the JB arrive seems to work fairly well.
• (In a lot of ways, I wish that everyone would use Surround, because it acts as a general repellant for several different insects that bug us at this time of year.)
• Lesson: If you want to use Neem to repel the JB for the season, it’s a whole lot easier to do if you get the JB off the trees first.

 

Diseases

-   21:05 – Scab

• The scab problems this year are worse than in recent years.
• If you have more scab in certain varieties than in others, you have a limited number of tools at your disposal.
• The most important thing is to NOT GET COMPLACENT simply because it’s been hot and dry. A number of growers have told me in the past few days that they thought scab was supposed to shut down in hot and dry conditions.
• That’s true. But scab acts differently on different cultivars, and acts differently depending on the age of the leaves, the age of the fruit, and the age of the lesions. The younger lesions are going to continue to put out conidia for a longer period of time even if the weather is hot and dry.
• Right now is a good time to scout for lesions on different cultivars in your orchard. Try visually comparing the lesions on, for example, a Honeycrisp to a Macintosh. You’ll see a stark difference between the state, health, “success,” or productivity of the lesions on different varieties.
  • If it’s dark grey or almost black, it’s a very productive, dangerous lesion.
  • If the lesion looks brownish, half-dead, with a dead center and a yellow-ish and gray-ish ring around, it will be producing very little conidia. This type of lesion is typical on Honeycrisp.
  • Doing these comparisons might not make any difference on what you do, but it will show you that scab can still be active in some areas despite the hot and dry weather. You’ll see that Macintosh, Cortland, Jonagold, and Gala are nice hosts for Scab and that Scab can continue putting out sporeseven through the heat.
• If you’re using OMRI-approved materials:
  • Using lime-sulfur is a problem in this kind of heat. It is an option, however, in cooler weather.
• If you’re using conventional materials:
  • You’ll have to use Captan for scab and protect for everything else. Avoid tank-mixing any material (like sterile inhibitors or strobilurins) with that Captan for Sooty blotch or Flyspeck because you will push resistance development much more quickly.
  • It’s better to use straight Captan for Scab and use Topsin-M for Sooty blotch and Flyspeck (these can be tank-mixed). Most Scab is already resistant to Topsin-M.
• Lesson: Stay on top of your protection until those lesions age. If you don’t, you might see a lot of spread even from this point out.
  • If you don’t have a protectant on when it cools off later in the season, Pin scab can erupt and cause problems with storage.

 

-   29:52 – Flyspeck and Sooty blotch

• The model says we are supposed to count leaf wetness hours from petal fall, or from 1-2 weeks after our last full Captan spray, especially if it’s combined with Indar or one of the strobilurins.
• Most people start accumulating LWHs at petal fall to keep things simple. A lot of peoples’ leaf wetness hour accumulations are not close to the model. Most people are not at 175 LWHs yet, much less the 250 LWHs when the first Flyspeck of Sooty blotch lesions would supposedly show up.
• We have not had a lot of sustained high relative humidity. We should therefore probably stick close to the model.
• My feeling is that if you’re due for a Captan cover for Scab or an insecticide for some problem and you’re at 125 LWHs or more, you should consider putting something in with that spray for Sooty blotch and Flyspeck.

 

-          32:15 – Blossom-end rot

• Not very common this year.
• Recognize it by the calyx end of the apple having a dead area around it that looks hollowed-out or sunken.
• There’s nothing we can do about this syndrome. Some varieties are more susceptible to it (Cortland).
• It’s caused by two or three different fungi that enter that calyx end shortly after fruit set. For whatever reason, that calyx didn’t close quickly enough or completely enough, and one of these opportunistic pathogens entered.
• Two things to note:
  • It’s usually variety-specific.
  • It doesn’t spread after the time of first cover. It won’t get worse as the season goes on. The infected apples will probably turn red three weeks sooner than healthy apples, so pick them out before harvest.

 

-   34:05 – Fruit rot

• I haven’t seen any fruit rot this year.
• I’ve looked at some orchards that have received hail in the last 4-5 weeks that has broken fruit skin. Even where the fruit was gouged, I haven’t seen any fruit rot form.
• The theory is that if hail breaks the skin open at the end of July or the first of August, the fruit rot will be able to colonize that broken skin much more easily. On the other hand, if the fruit is in its second or fruit week after petal fall and the skin is broken open, chances are that the skin will heal over and the fruit will avoid infection.
• There’s not much you can do against fruit rot except to have some protectant on before the hail storm.

 

-   36:00 – Powdery mildew

• Powdery mildew is usually not a disease that we worry too much about, because we don’t see much of it this far north.
• It colonizes new, growing tissue. Once the terminal is set, the growth of powdery mildew will stop.
• For any material that you apply for powdery mildew, you should only apply it if your trees haven’t set their terminals.
• It’s mainly a concern for young trees that are growing longer into the summer.

 

-   37:08 – Fire blight

• There is a lot of shoot blight showing up in peoples’ orchards. Most of it is not blossom blight.
• Shoot blight is an indication that the bacteria (Erwina amylovora) is in the tree, whether it’s been quiescent in the tree for a couple of years or longer, and has been stirred up by environmental circumstances.
• I’d like to see someone try spraying a phosphorous acid fungicide (like Aliette, Agri-Fos, etc) to see if it slows down the progression of Shoot blight.
  • If you do try it in a variety, though, please try to leave a “control” area in that same variety so that we can see if there is any difference.
  • The group of phosphorous acid fungicides that I talked about two or three weeks ago (Aliette, Agri-Fos, etc) are systemic fungicides that have short-term life in the tree. They are registered for control of Fire blight as well as root rots (Phytopthera).
  • I’ve never known anyone who sprayed it on a variety showing shoot blight to slow the progress of the blight.
  • It seems to me that the fungicide breaks down quickly within the tree.

Insects

-   39:52 – Codling moth

• Most people should be done with the first generation of CM in the last few days.
• Reminder: If you’re using mating disruption, you should have a Lesser apple worm or Oriential fruit moth trap out.
  • You can’t ignore these internal fruit feeders at the expense of CM.
  • There is too much evidence that if you stop spraying any kind of material targeted toward Lepidoptera, you will have a good chance of having an outbreak of LAW or OFM in the next few years.
• Another reminder: Although the B-hump flight has wound down now, it’s not too late to look for damage.
  • One of the things I’m most concerned about is control later in the summer on the next generation.
  • If you have a lot of clustered apples, the CM second generation will get a whole lot worse. Insecticides do not stick very will to the backside of apple clusters or apples that are covered by vegetation. It’s nearly impossible to control well for CM, OFW, and LAW if you can’t put any insecticide on the backsides of those fruit.

 

-   43:14 – Apple maggot

• A lot of people have picked up AM in the past couple weeks, even in  orchards with very dry soils.
• Keep an eye on your AM traps even if you haven’t gotten any rain.

 

-   43:38 – Oblique-banded and Red-banded

• OBLR flight is extended this year. In some orchards we’re still seeing large OBLR numbers (20+ per week), even as recently as late last week.
• Now the OBLR and RBLR flights are overlapping in a lot of orchards.
• Ordinarily, I don’t worry about the summer generation of either of these insects.
• The biggest problem I normally have with these is with OBLR, because it has one more generation that will hatch at the end of August or early September.
  • When they hatch at that point in the season, they are required to enter apples in order to survive.
  • Therefore, if you disregard this summer generation, you may very well have a lot more fruit damage in September than you might want.
• Recognizing larvae:
  • RBLR larvae are all green.
  • OBLR larvae have the caramel or black head capsule.
• If all the larvae you see in your orchard are green (RBLR), I wouldn’t worry too much about it.

 

-   45:45 – Potato leaf hopper and White apple leaf hopper

• Right now, we are between generations on White apple leaf hopper.
  • If you had WALH first generation, you’d see the white stippling on the first leaves that come out of the cluster (on the inside of the canopy on bigger trees).
    • If you see significant amounts of damage, you should be on the lookout for the second generation. The second generation can grow fast and cause a lot of damage to the development of fruit and to the tree.
• PLR:
  • We worry about PLR nymphs, not the adults.
    • They will be on terminals and will especially be problems on young trees that need to grow.
    • I won’t go into the control of it, because there are a number of different materials that you can use.
    • I will just say that the only other reason to control them would be for the honeydew that they emit from their feeding.
      • If you start seeing leaves and fruit that are speckled with little shiny dots that appear when you turn them into and out of the sunlight, it’s either aphid honeydew or leaf hopper honeydew.
      • Those spots are only surface problems, cosmetic issues. They will, however, begin to look like Flyspeck as the dots of sugar darken when they get colonized by fungi.

 

-   48:51 – Stink bugs

• We’re seeing lots of stink bug egg masses.
  • They are little clusters of barrel-shaped eggs. Most of the ones you see will be empty.
• It’s difficult to tell nymphs apart. If you see the bugs right after they’ve hatched out and clustered around the egg mass, don’t worry yet about whether they are Brown marmorated or Green or Brown stink bugs.
  • Chances are, though, that they are Green or Brown stink bugs, because we haven’t had significant Brown marmorated reported in the state, yet.
• You’ll start seeing adults and fruit damage by around mid-August.
• I’ll talk about control next week.

 

-    50:23 – Tarnished plant bugs

• I’m still seeing fruit damage from TPB as well as adult TPBs in orchards.
• This is not an easy insect to tolerate.
• It might be beneficial to have some flowering plants in the understory.

-   50:42 – Two-spotted spider mites

• Two-spotted spider mites are showing up.
• They are hard to count and hard to see, especially when the colony is just getting started. They are pale green and whitish-green. The two spots don’t show up until the adult stage. I haven’t seen many adults, yet.
• They can grow dramatically when it’s hot and dry.
• If you’re worried about it, pay attention to the bottoms of the leaves. These mites will cause distinct marked white areas along the mid rib on the underside of a leaf. The rest of the underside will be green. If you look along the mid rib with a hand lens, you’ll probably see the white-green nymphs.

 

A note on resistance and resistance management

-   52:20 – We talked for a long time to CM resistance to OPs. But there is a whole range of other insects that also become resistant.

• I’m afraid that as generic forms of new reduced-risk materials are released and their prices continue to drop, people will tend to overuse them or use them without consideration for the other insects you’re spraying them on.
• I’m specifically referring to the generic imidacloprid (Provado).
  • With the new branding of Alias, the material has dropped in price. It costs as little as $2.50/acre to $7/acre to apply and is cheaper than almost any other material.
  • It’s effective on Apple maggot, San Jose scale, leaf miners, leaf hoppers, Japanese beetle, Wooly apple aphids and other aphids.
  • Because of its low cost, I’ve tended to recommended that people throw it out there against any of these insects.
• BUT if apply Assail or Calypso for CM and then apply imidacloprid for a secondary pest, you will have applied the same family of materials multiple times to at least one multi-generation pest.
  • All of the insects I mentioned above except for leaf hoppers are multigenerational.
• I’m afraid that we will very quickly encourage resistance on one of these secondary pests that currently is hardly on the radar screen.
• The negative effects of this resistance development might not show up for a couple years, but even now I’m seeing some things that lead me to believe that we’ve already started pushing some of these pests toward resistance.
• Lesson: If you’re spraying a neonicatinoid, think about the other multi-generational insects that you might be spraying.

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THE NEXT CALL will be on Tuesday, July 19 at 8am Central Time. SEND IN YOUR QUESTIONS! 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 (or, if you can’t email, call at 608-604-0234) by Monday.

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