Susan / Peter , I use a GV spray as well . Mine is called Virosoft . It comes frozen , I get it into useable amounts right away and refreeze . ( 1 oz )
In BC , we have an authority (SIR ) that is bound and determined that they will wipe out CM . To my knowledge mankind has only erased that which it has not tried to , and there is often some heat in our discussions .
I would like to share an e-mail from last year , and my experience .
" Throughout the season SIR Field Staff collect and record data which is reviewed to determine if there is a potential for CM damage. I am unable to comment on past observations however I have been a Field Supervisor since mid season 2012 and have collected and reviewed the data on this property. There has been a history of large number of captures (SIR threshold is 5 per trap). There is one trap in the orchard which has hit threshold at least 4 times in 2012, and 2 times in 2013. As we are not yet done reading traps the current count 13 puts the trap at threshold reached 2 times so far in the 2014 growing season. In 2013 SIR banded 64 trees and found 30 larva in the bands in the fall. The bands catch only 30% of the larva so when you take the number and times it by three there was a considerable amount of overwintering in the trees to emerge this season. SIR also did a harvest sample in 2011 with a result of 1.20% and another one in 2013 showed 0.60%. Captures and damaged has decreased since then however continuing to catch the amount of moths gives reason not to back off sprays.
" You have provided information about using Virosoft. In looking at the dates you applied the first 2 sprays in June was to early. Virosoft targets larva only. Virosoft is usually applied around 400 degree days or based on moth captures. Based on your captures your first application should have been around June 26 which would have placed you closer to the 400 degree mark. At 400 degree days roughly 66% of the eggs have hatched. Virosoft is also a product that needs to be applied every seven days once started throughout the season. You have a 2 day gap between your first sprays and then roughly 3 weeks till you applied 2 mores sprays with a 2 day gap as well. The 2 day gap is not as much of a concern as the 3 week gap between first set and second set of sprays. Virosoft is a virus which needs to be built up in an orchard. Larva must ingest Virosoft unlike other product where only contact is needed.
We will flag any trees with SIR flagging in which we find CM damage. This year SIR will sample 1000 fruit. I will inform you if there is any damage once the sample is done. If no damage is found, the captures this season are still high. CM is always a season behind. IE: what you catch and damage found this season is based on what management was done in the 2013 growing season. If any sprays were missed or timing was off this could explain why the property has a CM population. Both larva and damage were found in the 2013 growing season....again based on management of the orchard in 2012...ect . "
I got two holistic sprays on to start the year ( 2014 ) . My first virosoft went on about 250 degree days with a second 5 days later . I put a second set on around 700 degree days , 7 days apart .
I had 13 moths in my trap for the season and zero damage in their 1000 fruit audit . There was one holistic spray at the end of the season .
I got two holistic sprays on to start 2015 . We are sitting at 14 weeks with out a capture . There are some stings mostly in the north east corner . I have also found two damage ( I am hand thinning ). On one the frass goes along the skin for about an inch before going inside . It goes in about half way then it looks like something melted , it's just brown watery goo . The second the frass is through the skin and that is all . Taking a chance ? I have not used the GV at all this year .
Don't know if this matters but I have a huge population of yellow jackets ( bees ) and again a huge population of Lady Bugs of which I will quite often find in the clumps of apples when thinning , I will usually find stings there as well. but so far only the two entries , both abnormal . We are also sitting on a stage 2 drought .