Apple Pest Report: Friday, July 21, 2006
Vol. 14, No. 14

Scab
   
        The recent hot dry weather has been ideal for inactivating scab lesions.  If you are still finding fresh lesions then there is probably something wrong in the spraying system – either dosage or coverage issues.

Flyspeck and Sooty blotch

The relatively dry conditions over previous couple of weeks have also slowed down flyspeck development.  Heavy rain forecast for Saturday and Sunday July 22-23 will accelerate depletion of previously applied fungicide protection.  The flyspeck respray guidelines at

 http://pronewengland.org/AllModels/MEmodel/RADARME-MonmouthLate.htm#FLYSPECK
can help identify when reapplication is needed.

With the exception of early harvest cultivars, fungicide protection should be reapplied soon after the previous coverage is depleted.  This is because flyspeck infections that start in the last week of July or first week of August are likely to accumulate enough wetting hours to become visible before mid-September harvest dates.

Summer pruning is very effective for reducing flyspeck risk.

Insects and Mites

        As of Tuesday July 18, apple maggot trap captures continued to be very low at Highmoor Farm.  A total of only 3 AM have been caught on 12 traps, for a cumulative average of 0.25 per trap.  The recommended treatment threshold is when cumulative average captures reach 1-2 per trap.

        One central Maine orchard did report high trap captures this week, while low captures were reported for other Maine locations.  Each orchard, and even blocks within an orchard, can have different apple maggot pressure.  The only way to know is to have traps at representative locations around the orchard.

        European red mite 4th generation nymphs are reaching the adult stage.  This is typically the peak ERM population of the year.  As summer progress and day length begins to shorten, an increasing portion of ERM eggs deposited will not hatch until next spring.  Keep an eye out for twospotted spider mites.  They can increase rapidly in hot dry weather, especially where unmowed ground cover dries.

        The recommended mite treatment threshold for July 16 to August 1 is 5 mites per leaf or 77% of leaves with living hatched mites present. 

        If ERM are over threshold, be sure to check the preharvest interval (PHI) required and compare it to expected harvest dates.  Two of the most effective control options are Acramite (PHI 7) and Nexter (PHI 25). 

Kanemite (PHI 14) and Fujimite (PHI 14) are also rated excellent against ERM, but the only efficacy ratings I have for those are from the VA-WV-MD guide (other ratings are closer to home from the NY and PA guides). 

If Apollo (PHI 45), Savey (PHI 28), or Zeal (PHI 28) were not used earlier in the season, and the PHI is not a problem, they are rated effective against ERM, but they are only effective against eggs and nymphs, not adults.  Thus, they are not the best choice for rapid control of an adult population, and may require a week or more to show effect. 

Vendex (PHI 14) might work with a single application, but a high population might require two applications to get equivalent control as the options listed above.

It is too late in the season to use Agri-Mek effectively. 

Danitol (PHI 14) which provides early season mite control may not be effective as a late season miticide.  Moreover, the detriment to beneficial predators by Danitol (a pyrethroid) is at its worst with late season application.

Kelthane (which is being discontinued) (PHI 7) has the same efficacy rating as Vendex.

If twospotted spider mites are over threshold, the most effective options are Acramite, Vendex, Kanemite, and Fujimite.  Zeal is rated highly effective against TSM, but the comment above about lack of efficacy against ERM adults also applies for TSM.

Weeds and groundcover

Weeds have to be actively growing for herbicides to be effective, so time any herbicide applications to follow a rain event.  Avoid applying herbicides during dry, hot conditions when the weeds are not actively growing.

If applying glyphosate (Roundup), be sure to remove suckers ahead of time to allow at least one dry day to prevent suckers, or open wounds where suckers were recently removed, to absorb the herbicide and potentially translocate it back into the tree.

Remember that having some groundcover provides insulation against winter cold, so do not treat so late that there is no time for some regrowth before winter.

Maturity forecast

The preliminary forecast for McIntosh maturity at Highmoor Farm is for starch index 4.0 (adequate maturity to begin picking for long-term storage) to occur around September 15-18, and starch index 6.0 (advanced maturity and end of picking for long-term storage) around September 24.  These are just guesses based on bloom date and temperatures in the first 30 days after full bloom.  They in no way replace the need for starch index testing to see how maturity is actually advancing.

Imidan and Guthion registration changes

Guthion (azinphosmethyl)

The U.S. Environmental Protection Agency (EPA) has announced a preliminary decision to phase out the azinphosmethyl apple use in 2010, because of ecological and farm worker risk concerns.  According to its azinphosmethyl decision document, the following mitigation measures have been proposed for the period of use before the proposed phase out in 2010:

Growers must observe a 100 foot buffer zone around permanent bodies of water.  The current label requires a 25 foot buffer.

The total yearly maximum per acre application rate is reduced from 8 lbs. to 6 lbs. of formulated product.

Growers will be required to observe a buffer zone around houses and occupied buildings.  However, EPA has not determined the buffer zone distance.

EPA will require manufacturers to conduct medical monitoring of post-application workers to provide information to better assess the full nature of the risk to farm workers and to help determine the need for any regulatory action during the phase out period.

Imidan (phosmet)

More importantly for New England, in my opinion at least, is a proposal to ban all use of Imidan in pick your own orchards.  According to the 2004 New England apple grower survey, pick your own sales account for 13% of the New England apple crop.  Imidan was used by 66% of growers on 56% of the acreage for plum curculio, and 76% of growers on 67% of the acreage for apple maggot.  (You can see the survey and results at http://pronewengland.org/INFO/PROInfoSurvey.htm

To see the proposed Imidan and Guthion label changes, the Federal Register notice is available on EPA's Web site at http://www.epa.gov/fedrgstr/EPA-PEST/2006/June/Day-09/p8929.htm

For additional information on AZM, please visit www.epa.gov/pesticides/op/azm.htm

More information on phosmet is available at www.epa.gov/pesticides/op/phosmet.htm

The deadline for submitting comments to EPA on its proposed decision is Aug. 8.  Please contact Jim Cranney at USApple by telephone at (800) 781-4443 or via e-mail at jcranney@usapple.org if you have questions or need additional information.  Comments may be submitted directly to EPA electronically at http://www.regulations.gov in docket number EPA-HQ-OPP-2005-0061 for AZM and docket number EPA-HQ-OPP-2002-0354 for phosmet. 

Heat stroke and PPE

     Waterproof coveralls and other Personal Protective Equipment are necessary tools for safe use of pesticides.  But in hot weather they create their own hazards from heat stroke and dehydration.  The following advice was sent to the apple-crop email list by a Washington fruit grower a couple of years ago:

    “After a 'near-death' experience from heat stroke and dehydration, I did two or three things.

   1. I found a facemask that allowed me to wear glasses without fogging to the point of near blindness.

   2. I limit my time on the spray rig to an hour before taking a short break.

   3. I spoke to a professional pesticide removal expert who wears gear for hours on end.  His advice -- TANK UP ON WATER BEFORE donning your gear.  Dehydration can sneak up on you and you stop thinking clearly before you realize it!

   4. Newer technology has provided many softer chemicals that do not require dangerous protective gear."

Sincerely,                                            
Glen