With the relatively cool spring weather we have been having, the first large peak of San Jose scale crawler activity is delayed this year compared to last year. Crawlers have already been observed this season and with the consistently warmer weather we have been having, the SJS development will speed up, so I anticipate the first peak of activity to occur within approximately 10-14 days from now in Fort Valley, GA, so about 14-20 days for the Ridge.
Following the degree day (DD) timing starting at February 1st using a base of 51oF and a max of 90oF, at this point last year we had accumulated 673 DD and this year we are at 496 DD (UGA Weather). I anticipate the first main peak of crawler activity to occur at approximately 700 DD since Feb. 1, which will be in a couple of weeks in Fort Valley. For the Ridge, I’d expect the peak about a week after Fort Valley and then the upstate a week or so after that.
As a reminder, scale crawler activity can be monitored relatively easy (although a bit tedious). Visually inspect limbs for live scale and/or wrap a branch with a strip of electrical tape plus a strip of double sided tape around that (see image below). Focus particularly on trees in blocks with a known history of scale issues.
Management of San Jose crawlers is not necessary for all blocks peaches if all blocks received two dormant oil applications this season. If a dormant spray was missed or you have a block with chronic scale issues, then I would suggest considering crawler management.
Once crawler activity begins to increase, consider management insect grower regulators, such as Esteem (6 oz/acre) or Centaur (34.5 oz/acre). Alternatively, when targeting the scale crawlers, Venerate XC (2 qt/acre applied twice over 7 day period; 4 qt total) or diatomaceous earth (i.e. Celite 610 @ 10 lb/acre) have both showed efficacy at suppressing San Jose scale.
If management occurs later, once the crawlers have already settled and/or you cannot find active crawlers in a block with a history of scale, it may be best to treat with Movento (check label rate). Note that Movento should be applied once the trees have substantial leaf area, flushing new growth, and should be tank mixed with an adjuvant that has spreading and penetrating properties. Anecdotally, I have applied Movento late April and have had really good success.
One concern to note is that white peach scale (pictured above) has been showing up more frequently in middle GA and along the Ridge. I generally don’t talk much about white peach scale because I rarely see infestations at damaging levels, but this scale insect can be just as devastating at San Jose scale, so we all need to keep an eye on this one. Thankfully, our management practices for SJS should keep the white peach scale suppressed as well.
As always, please check out the management guide for more detailed recommendations. And don’t hesitate to let me know if you have any questions.
I’m looking forward to a great season!!!
Take care, everyone!
