Oriental fruit moth biofix in relation to peach bloom: An historical perspective

Greetings, I hope this finds everyone safe and sane during these troubled and uncertain times. As you know, we have had to suspend our in-person Extension programming until further notice, so will try to provide relevant content via posts like this. We have had pheromone traps for oriental fruit moth (OFM) deployed in our orchards here at the Winchester AREC for 1 week, but no captures yet, despite full bloom of Redhaven peaches on March 23. This got me wondering about how OFM biofix (the onset of sustained flight and captures in the Spring) has related to full bloom in peaches over the years. In general, they tend to occur reasonably close together, but I’m interested in the question, “how close together”? The reason this is relevant is that one strong option for managing first generation OFM in peaches is mating disruption, whether by the sprayable pheromone or hand-placed dispensers (both of which can be applied during peach bloom). I compared the dates of OFM biofix and full bloom of Redhaven peaches at this AREC over 17 years spanning 2001 – 2019, looking at whether biofix occurred before, during, or after full bloom. Turns out that the average difference in days between those two events was zero. On other words, the average OFM biofix date occurred on the recorded date of Redhaven full bloom. Having said that, the range was from -11 days (i.e. biofix before full bloom) to +12 days (i.e. biofix after full bloom). Of the 10 years between 2001 and 2010, there were 4 years when biofix occurred before full bloom, 4 years when biofix and full bloom occurred on the same date, and only 2 years when biofix occurred after full bloom. Interestingly, in the 8 years between 2011 and 2020 (no bloom data for 2017 and 2018), there has been only 1 year when biofix occurred before full bloom, 1 year when they occurred on the same date, and 6 years when biofix occurred after full bloom (including this year). This makes me wonder whether the generally milder winters we have experienced in recent times have had a greater effect on tree development rate than OFM development rate, but of course that is pure speculation. Anyway, the take-home message is that mating disruption for OFM is not yet required here in the northern Virginia region. Of course tree and pest development typically happen more quickly in central and southern Virginia than they do here in Winchester. Pheromone traps provide a very sensitive indication of the beginning of OFM flight (and also of other key pests, like codling moth) and can guide your timing of mating disruption applications. I will keep you posted about our OFM captures, which would not be expected until the weather warms considerably compared with today. We will put our codling moth traps our in March and also keep you posted about captures in those.

Until next time, best wishes.

Leave a Reply

Your email address will not be published. Required fields are marked *