Monthly Archives: May 2016

Plum curculio movement into orchards

Greetings, For the last couple of years we have experienced the kind of weather patterns during the apple bloom and post-bloom periods that are conducive to protracted movement of plum curculio into orchards from their overwintering habitat in adjacent woodlands. While many plum curculio may move into orchards more synchronously in years when conditions are warm and dry during the bloom, therefore resulting in good control when effective products are applied at petal fall, in a year like 2016, this pest may need to be targeted with additional sprays after petal fall, especially in orchards where pressure has been high in recent years. The warming pattern forecasted for next week may well result in increased curculio movement. In the northern regions of Virginia, next week will also bring the critical 250DD post-biofix timing for codling moth and in the central and southern regions, codling moth degree days will approach the 550 mark, at which the second half of first brood codling moth is targeted. Consequently, if both species require management at this time, the insecticides that are considered effective against both include, in alphabetical order, Assail, Calypso, Imidan and Imidan + Lannate.  In our Spray Bulletin for Commercial Tree Fruit Growers, we rate Avaunt quite strongly against plum curculio but somewhat less so for codling moth. Other products, such as many of the pyrethroids, are also rated well against both, as are some of the combination products that contain a pyrethroid and another active ingredient, such as Voliam Xpress or Endigo, although as always, we caution against using these broad-spectrum materials too early and/or too often in the post-bloom period, since secondary pest issues may result.

White peach scale seasonal biology and management

Greetings,  Research in the early 1970’s by Virginia Tech entomologist, Marvin Bobb, showed that white peach scale populations in the Charlottesville area produced first generation crawlers that were present during May. Second generation crawlers were found through July and those of the third generation were present from late August through September. The cool and wet conditions that have prevailed for much of April have likely slowed the rate of white peach scale egg hatch and nymphal development this year, so stone fruit orchards with a history of this pest can be treated for first generation crawlers now. Recommended materials for managing this pest include, in alphabetical order, Centaur, Diazinon, Esteem, Lannate, and Movento.

Historical biofix dates for oriental fruit moth, codling moth, and tufted apple budmoth at the Winchester AREC

“Biofix” is the calendar date on which the first sustained capture of insects emerging from the overwintering generation occurs. At the Winchester research center, we establish biofix for three key moth pests of peaches and/or apples:

  1. oriental fruit moth.
  2. codling moth.
  3. tufted apple budmoth.

Prior to the onset of moth emergence and flight each spring, traps baited with the pheromone lure for each species are deployed in research center orchards and captures are recorded daily. When one or more moths are captured in each of at least two of three traps over at least three consecutive evenings, biofix is set as the first day on which these sustained captures occurred.

Starting on the biofix date, daily heat until accumulations (“degree-days” or “DD”) are calculated based on known developmental threshold temperatures for each species. Accumulated degree-days are used with models that predict the rate of development of eggs and the hatch of larvae for each species. Critical points in the development of each generation of each species are predicted by the model, so that tree fruit growers can time their control measures optimally.

In combination, determining the biofix date and initiating degree-day models based on biofix each year enable best management practices regardless of the potentially large annual variations in the environmental conditions that affect pest emergence and developmental rate. The accompanying table illustrates the annual variations in biofix dates for oriental fruit moth, codling moth, and tufted apple budmoth at the Winchester research center since 2000.

Year Oriental Fruit Moth Codling Moth Tufted Apple Budmoth
2000 April 1 April 29 April 29
2001 April 7 April 30 May 4
2002 March 30 April 27 May 5
2003 April 14 May 3 May 12
2004 April 16 April 30 May 6
2005 April 11 May 8 May 8
2006 April 7 April 23 May 1
2007 April 20 April 30 May 10
2008 April 10 April 25 May 6
2009 April 17 May 2 May 20
2010 April 5 April 29 May 13
2011 April 18 April 26 May 9
2012 March 20 April 14 April 29
2013 April 11 May 2 May 16
2014 April 12 May 8 May 12
2015 April 18 May 4 May 16
2016 April 11 April 25 May 2