Arthropod Management Update

Lorsban (chlorpyrifos) Agreement between Dow AgroSciences and EPA

The following information is from a June 8, 2000 press release by Dow AgroSceinces regarding changes to the use of chlorpyrifos.   Note that the specific  impact on apples is that, as of December 31, 2000,  the use of Lorsban-4E and Lorsban 50W  will be restricted to pre-bloom application only.  The EPA also intends to reduce the tolerance of chlorpyrifos residues in apples.

"Dow AgroSciences has reached agreement with the U.S. Environmental Protection Agency (EPA) on changes in the use of insecticides containing chlorpyrifos, in alignment with the Clinton  Administration's stated goal of reducing the potential exposure of children  to all pesticides. The agreement relates most directly to residential applications of the insecticides, and will have minimal impact on most  agricultural uses of chlorpyrifos (the active ingredient in Lorsban* insecticides).....As a result of the agreement with the EPA, Lorsban-4E insecticide (and Lorsban 50W insecticide packaged in containers smaller than 25 pounds) will become Restricted Use Pesticides, effective Feb. 1, 2001. These products will now be subject to the applicator licensing, application and handling requirements associated with Restricted Use Pesticides. Restricted Entry Intervals (REI) following treatments of Lorsban insecticides on some nut, fruit and vegetable crops will also be extended, but are not likely to affect current worker practices in most crops. The agreement has essentially no impact on uses of Lorsban 15G granular insecticide, and Lorsban 15G remains a non-Restricted Use Pesticide. In addition, effective Dec. 31, 2000, the agreement restricts use of Lorsban-4E and Lorsban 50W in apples to pre-bloom applications only. The EPA also intends to reduce the tolerance for chlorpyrifos residues in apples."

Plum Curculio

Where are the PC this season?   In most orchards it appears that pressure has been light.  As you can see from the following table which gives the estimated  degree day accumulation for  six sites around Vermont  from 95% Petal Fall,  we are supposedly NOT out of the potential PC activity period.  Based on a Cornell model, insecticide residue should be maintained until 340 DD have accumulated.   A recent report from Massachusetts indicated that in some blocks that have 'run out' of residual insecticide activity,  increase in damage by late invading PC has been observed.   The bottom line is to be make sure to keep checking traditional 'hot spots' for fresh PC damage.

Update of General DD Accumulation

The following tables have the estimated DD accumulation, base 50F, from Jan. 1 and the arthropod events that are associated with different DD accumulation.   Note the difference in DD from this same date last year !! 

In addition, we have been tracking DD accumulation (base 50F) from the first  CM trap capture at the UVM Hort.Res.Center  (May 15) and in Shoreham (May 23) and have reached an estimated 298 DD at the UVM HRC and 293 DD at Shoreham as of June 19.  It is estimated that 3% egg hatch occurs around 250 DD.   Please see the June 6th IPM Alert for information on timing of sprays for CM. 

European Red Mite Thresholds Through the End of July

At least the cool, wet weather is not favorable for mite build-up.  Over the last two weeks,  very few mites have been observed in orchards that we have visited.  However, a few orchards had populations of  ERM eggs on leaves that warranted close watching.   The following are the thresholds for motile (moving adults and nymphs) ERM through the end of July:

In the Spotlight ...  Apple Maggot

In this section of the Vermont Apple Newsletter,  a different arthropod or disease is featured.  This information is part of  "Key Arthropods, Diseases, and Vertebrates affecting Apples:  A Synopsis"  by Jessica Reardon and Lorraine Berkett and which appeared in the Back to Basics Resource Notebook, March 22, 2000.

Apple Maggot Fly (AMF)
Rhagoletis pomonella (Walsh)

• Description: Adult fly is slightly smaller than a common housefly. It has a white dot on its thorax and black banding in the shape of an M on its wings. The larvae resemble typical housefly maggots.
  

• Lifecycle: AMF overwinters in the pupal stage in the soil. Adults emerge in mid to late June, and mate. The females begin laying eggs under the skin of the apple 10 to 14 days later. The larvae then tunnel through the apple flesh, causing the apples to drop prematurely. After the fruit drops, the larvae leave the fruit and enter the soil to pupate. Most New England orchards have only one generation of AMF per year.
  

• Damage: Internal decay and fruit abortion caused by larval tunneling. Surface "stings" caused by oviposition are difficult to detect.
  

• Monitoring
  

• Key times for monitoring: Late June - August.
  

• Monitoring method: Hang a standard sticky red sphere at head height in the fruiting zone on the south side of the tree, away from leaves, near block periphery. Clean spheres as necessary. Place 1 red sphere/2-4 acres, minimum of 5 traps/block. Several variations on the sticky red sphere, including lightweight disposable spheres, are available from IPM supply catalogs. A bait made from synthetic apple volatile may be added to the sphere. The baited spheres have been shown to be 2-4 times more effective in capturing AMF than unbaited spheres. Hang traps in late June in blocks where early ripening cultivars are grown, and in early July for non-early ripening cultivars.
  

• Action threshold: The action threshold is a cumulative average of  2 AMF per trap on non-baited spheres, and 5 AMF per trap on baited spheres.
  

• Cultural: Trapping out the AMF has been tried in some orchards, and may be an effective management tool for some growers.
  

• Chemical: See New England Apple Pest Management Guide