Arthropod Management Update

Update of General DD Accumulation

The following table shows very clearly the accumulated temperature difference between last year and this year.   The second table list the "coming events"  based on further degree day accumulation.   Not listed in the chart is the codling moth (CM) guideline for managing second generation larvae.   Based on a CM model, an insecticide should be applied in orchards with high pressure when 1260 DD (base 50) have accumulated from the date of first flight (i.e., as determined by pheromone traps earlier in the season).   As of August 15,   1282 DD have accumulated at the UVM Hort. Research Center from first adult moth pheromone capture  (May 15)  and   1271 DD have accumulated in Shoreham (from May 23).

Leafminers --  I sincerely hope that you are not seeing the high numbers of 2nd generation mines that we are seeing at the UVM Hort. Research Center !!  Most are in the tissue feeding stage which is too late to treat.   Unfortunately, there will be another generation before the end of the season.   Please note that research indicates that treating the 3rd generation mines is not highly effective. 


Apple Maggot --  Reports from different regions of the Northeast indicate that pressure from AMF has generally  been "light" to date.  The following graph shows the steady increase in weekly trap captures on baited, sticky red spheres at the UVM Hort. Res. Center.   It is this type of season when insecticide applications can be saved through monitoring for AMF presence. 

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