IPM Conference Calls 2011: August 2, Summary and Download

Recording

Download the recording of the August 2, 2011 call here.

Important notes

Announcements

-          QUESTIONS: Please send John your response to these questions before next week’s call!

  • 1) Are the sugars and flavors developing normally in the early apples that you’re harvesting? Have you picked any ripe fruit that doesn’t have the flavor that you expected it would have?
  • 2) What have you been using or doing to protect from sun scald (Surround, etc)? Has anybody used one of the sun screen products? If so, what has been your experience with it? I’d like to share that information with other growers.

-          Next week’s call will (most likely) be our last for the season!

  • If we see a flare-up of something in the weeks following the last call, we will post information about it straight to the blog.
  • This is your last chance: If you have any questions for next week, send them to either John (jgaue@mwt.net) or Alex (armccullough@wisc.edu) by Monday, 8/9.

Call Summary

Reminder for ALL conference calls (2:28)

-          If you come up with a question during a conference call, speak up and interrupt John. He loves it!

Weather

Sugar development (2:50)

-          QUESTION FOR GROWERS: Are the sugars and flavors developing normally in the early apples that you’re harvesting? Have you picked any ripe fruit that doesn’t have the flavor that you expected it would have?

  • I would expect that the sugars might not be developing as rapidly as normal because of the high humidity and high heat that we’ve been experiencing.
  • Even though our temperature degree-day totals are catching up to normal (at least in the southern half of Wisconsin), the sugars might not have caught up at the same rate.
  • Send your comments and feedback about this question to John (jgaue@mwt.net).

Sun scald (4:20)

-           QUESTION FOR GROWERS: What have you been using or doing to protect from sun scald (Surround, etc)?

-          Sun scald appears to cause of more fruit damage than just about everything else in the orchard.

-          It’s always discouraging as a consultant to see sunburn make up for all the damage we prevented from insects through our season’s IPM work.

-          Sun burn appears more often on smaller rootstocks with more open canopies and can cause significant economic damage, especially on high-value varieties.

More on sun scald (32:06)

-          Everybody has sun scald on some varieties.

-          Keep an eye on the varieties that are getting sun-scalded. As Dave Rosenberger told us, those damaged apples can be likely spots for fruit rots to invade. Look for fruit rot lesions on the sun-scalded fruits.

Sun screen products (33:35)

-          QUESTION FOR GROWERS: Has anybody used one of the sun screen products? If so, what has been your experience with it? I’d like to share that information with other growers.

-          One grower that I’m working with has been applying 5 to 25 pounds/acre of Surround every two weeks since about June 1.

  • They used 25 lbs/acre on some areas. On most of the orchard, they used 5 lbs/acre through July 1 and then increased it to 10 lbs/acre. (They did applications every two weeks regardless of the application rate).
  • They mentioned that it gets washed off fairly easily.
  • They also said they are seeing some sun scald in certain cultivars like Zestar, Harrelson, and Honeycrisp. However, they don’t have a “control” row to compare to, so it’s hard to say how effective Surround has been at reducing sun scald at those quantities.

-          We need to exchange information with one another about these products and their use in our region. When people don’t have a lot of experience using a product like Surround for sun scald, it’s hard to know how to use it most effectively.

  • Growers tend to be reluctant to apply the full recommended rate of Surround because of how difficult it is to keep suspended in the sprayer, because it’s hard to wash off the fruit if applied too late in the season, etc.

-          There are some other sun screen products available that don’t leave a residue.

  • I’d guess that these clear products do not have insecticidal properties like Surround does.
  • They therefore might be useful for late-season, close-to-harvest sun scald protection.

-          Please write or call John to tell him about your experiences with sun screen products like Surround (jgaue@mwt.net).

 

Heat and pest mortality (22:13)

-          Heat probably has the biggest influence on pests that lay eggs on leaves or fruit (like Codling moth). We can presume that the heat can kill some of the eggs sitting exposed on leaves or fruit.

-          However, judging by what we see out the field, it looks like most of these pests are surviving the heat pretty well.

 

Insects

European corn borer (7:34)

-          Krista mentioned in the DATCP pest bulletin last week that European corn borer flights are just starting in much of the southern half of Wisconsin.

-          Cornell’s Scaffolds journal mentioned that European corn borer can be a problem in fruits as well, even though we usually don’t think of it as one. We tend to catch it as an accidental in some of our pheromone traps, but we don’t put traps up to target it.

-          It is the European corn borer worm that can damage fruit.

-          REMEMBER: If you’re seeing fruit damage in August, European corn borer might be one of the culprits.

-          If you want more information about European corn borer, check out the DATCP Pest Survey Bulletin from last week (http://datcpservices.wisconsin.gov/pb/pdf/07-28-11.pdf)  and the August 1, 2011 Scaffolds issue (http://www.scaffolds.entomology.cornell.edu/2011/SCAFFOLDS%208-1-11.pdf).

Spotted-wing drosophila (9:22)

-          Michigan State recently found Spotted-wing drosophila (otherwise known as Cherry vinegar fly) maggots in black raspberries.

  • In 2010 it arrived late and still was trapped in the majority of the counties in southern Michigan.
  • This year’s sighting is TWO MONTHS EARLIER than when they found it last year.
  • That means that if you’re growing any soft fruit (especially cane berries), you need to be trapping for SWD.
  • Also, if you have apples that are starting to ripen, it would be useful to keep trapping for SWD using the vinegar-loaded deli containers.

Apple rust mites (11:46)

-          Question: Should Apple rust mites be controlled, or should you count on predators to keep their numbers down?

  • Apple rust mites are one of the non-pests that we talk about every year as being problems in certain orchards.
  • This time of year, the damage from these mites becomes evident on terminals.
  • If beneficial haven’t established control of the rust mites by now, they probably will not get complete control.
    • However, once the terminals set on your fruit trees, the populations will stabilize and then crash soon afterwards. After the shoots stop growing, the populations will stop growing as well.
  • Difficulties in scouting for and controlling Apple rust mites:
    • They are small and hard to see.
    • Their damage can be confused with a lot of other things.
  • In general, the hot weather we’ve been having recently encourages rapid growth in Apple rust mites as well as Spider mites, Two-spotted mites, and European red mites.
  • In general, I’m not seeing many issues with Apple rust mites. They were more of a concern a month ago. At this point, growers in the southern half or two-thirds of Wisconsin should probably not attempt a miticide or summer oil control against Apple rust mites.

Apple maggot (14:50)

-           Last week, John Wise from Michigan State published a sheet in the MSU FruitCat newsletter on chemical control of Apple maggot. The article gives a list of the chemical classes that are effective against Apple maggot.

-          The table is useful because it gives the mite-flaring potential, residual activity, and optimal application timing for each chemical.

-          As a rule, he doesn’t list generic materials. If you’re using generic forms of some of these insecticides, you won’t see it listed here. You need to know the original brand name of the active ingredient.

-          To read the article and print the table, see: (http://news.msue.msu.edu/news/article/managing_apple_maggots_with_insecticides)

-          Visit the MSU Fruit News site by clicking on the link on the right side of the AppleTalk front page, or click here (http://news.msue.msu.edu/news/category/fruit).

Codling moth (17:07)

-          Most people in the southern 2/3 ofWisconsin and adjoining areas of Minnesota and Illinois are into 2nd-generation CM.

-          One question that comes up during this time: Is it possible to spot-treat for 2nd-generation CM?

  • As a general rule, with 1st-generation, people don’t spot treat because of the other potential insect pests that need to be controlled.
  • In 2nd-generation, however, when fruit is reaching or has reached harvest, spot spraying is a reasonable approach as long as your trapping scheme is sufficient.
  • If trap numbers for 2nd-generation are high in one block and low in another, it’s a fairly common practice to apply larvacides selectively and avoid putting on an entire cover for CM.

-          Virus (20:20)–

  • This is a good time to be using virus to control 2nd-generation CM.
  • There are two or three commonly-used virus materials on the market.
  • These materials are useful in the late season when you have pre-harvest interval concerns.
    • Most of the insecticides that we apply for CM management have pre-harvest intervals of 7-14 days.
    • The virus, on the other hand, has a 0 or 1-day pre-harvest interval.

-          Scouting for 1st-generation damage (23:07)

  • It is NOT too late to scan fruit for 1st-generation CM damage.
  • I’ve been in a couple of orchards in the past week that didn’t control 1st-generation CM well and didn’t know they hadn’t controlled it until they recently went out and scouted for damaged fruit.
  • By scouting for fruit damage, you will get a better idea of how much 1st-generation success or pressure you had, and thus how much 2nd-generation pressure you will have (and need to prepare for).
    • The more 1st-generation damage you have, the harder it will be to control for 2nd-generation.

Wooly apple aphid (47:38)

-          Question from Peter Werts: For many growers, WAA is not a problem because of parasitism. However, should we be concerned about WAA if we’re not seeing biological control, even if the populations remain low? Should we be concerned about the aphids moving down into the roots even in small numbers?

  • John: Yes, it is a concern. My feeling is that you want to avoid large populations in September that will migrate down to the roots. But if you have relatively small colonies that are stagnant in size, something is having an effect on them, whether it’s a pathogen, predator, or parasite. If the colonies are small and stable, you should probably not spray an insecticide against them.
  • One thing I will note is that there are LOTS of species syrphid flies out there right now. I expect that we will see a lot of aphid-eating syrphid maggots come out in the next couple weeks.

 

Diseases

On some important differences between diseases and arthropod pests (24:40)

-          A basic difference between diseases and tree fruit arthropod pests:

  • With insects, we’re looking for either damage from the insect or for the insect itself.
  • With diseases, we don’t want to wait until we see the disease, because at that point, the disease is already fully mature and sporulating. By the time we have visual proof that a disease is out there, we have a problem, and at that point, we don’t have many good methods for controlling it.

-          Disease control is about prevention, whether you’re using conventional or OMRI-approved materials.

-          When you’re scouting your fruit, look for subtle things that appear to be aberrations in the skin, whether it is an infected lenticel or a spot on a sun-scaleded area of the fruit.

  • We don’t want to wait until fruit lesions are big, obvious, and sporulating.

-          Remember that this weather (hot and muggy) is conducive to a lot of fruit rots and that you should be keeping an especially close eye on things.

-          Also, remember Dave Rosenberger’s point about using a different fungicide material for your final cover.

  • He suggested that you use one that has longer activity against a resurging Apple scab population in September, is effective against fruit rots, and does not leave a lot of residue like Captan does.

Summer diseases (30:47)

-          You should be watching for them and tracking your leaf wetness hours. These summer disease pathogens should be doing really well (on alternate hosts as well as on apple trees) in this hot and humid weather.

-          Remember that high relative humidity can have the same effect as normal leaf wetting events on encouraging summer disease pathogens. Having above 93% relative humidity is the equivalent of having the leaves wet from dew or rainfall.

 

Spraying technique and resistance management

On methods for testing spray coverage (39:55)

-          Peter Werts: I attended the Effictive Spraying of Orchards workshop with Andrew Landers. Yesterday I tried one of the spray coverage tests he recommended: that is, using ink jet paper and generic food dye. We got the spray loaded with 100 gallons of red-dyed water and put out the ink jet paper sheets. When we finally sprayed the orchard, we didn’t see a single red spot on the ink jet paper. We need to figure out how much food dye is necessary to make this procedure work.

-          John: Can you tell us about your methods?

-          Peter: We were looking to replicate how the grower would spray the orchard. We selected four trees and had the grower make a pass down each side, keeping their nozzles open on both sides. We cut the ink jet paper into strips about 11” long by 2-3” wide, folded them over shoots and branches, and stapled them. We put in about six per tree (over the four trees) and distributed them through the canopy: some on the edges, on the bottom, at the top, in the middle, close to the trunk, in dense fruit clusters, etc. Then we put a few other cards on trees in neighboring rows to see what kind of drift we would get.

-          John: So you know everything got wet, but nothing changed color?

-          Peter: Exactly. We used 7 oz of food dye to 100 gallons of water. I found the cheapest food dye at Woodman’s for $0.89/oz. Most other grocery stores were selling it for $2.50 to $3.50 per ounce. Even though we were spraying only four trees, we needed to put in 100 gallons of water in order to make sure we had real-life pressure levels. If we need to use a lot more food dye to have any color show up, this technique could get pretty expensive.

-          John: Andrew did say that you could use food dye from the grocery store, but maybe he was using something more concentrated in his work. I look forward to hearing his response to your questions about this.

On testing for spray coverage, water volume and IPM (45:50)

-          Testing for spray coverage is very important to effective IPM and long-term success.

-          One of the things that scares me about IPM is that many growers might be using less water than they should.

-          The danger is not complete failure. When you spray a low rate of water, you will rarely see the spray fail completely and be able to automatically know that you got inadequate coverage on the insides of the trees and need to re-spray.

-          Rather, the danger of applying inadequate coverage is underexposing insects or diseases to materials and eventually causing resistance development.

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THE NEXT CALL will be on Tuesday, August 9 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 jgaue@mwt.net (or, if you can’t email, call at 608-604-0234) by Monday.

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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!