Pest News Update

Pest Observations for the week ending April 25, 2008
by Jill Sidebottom

• Twig aphids have started to reproduce.

• I haven't seen many predators yet except some dusty wings. The lady beetles are feeding on Cinara aphids though, of course. Haven't seen any feeding on twig aphids yet.
  
• There are small cones emerging, but they are currently still too small to harbor the aphids, so treatments with Di-Syston or other non-dimethoate products should still give good control for several more days.
  
• We've been evaluating fall Talstar treatments in the last couple of weeks.
  Treatments made with a hose application by and large look great with few to no aphids alive. However, growers should still be cautious and check again before bud break so alternative twig aphid controls can be made if trees are nearing harvest.
  Some mistblower treatmens with Talstar are working and others are not.
  Bryan and I were in one field this week where control was great in most of the field, but in the very center where coverage wouldn't be great, there were plenty of live aphids. The grower thought he might go back and treat the middles with Di-Syston.
  
• From observations I've made this spring, it appears that many of the fall Talstar treated twig aphid eggs did not hatch. Many looked plump and alive, but when pricked they were blackened inside. However, in some instances the eggs did hatch, but the aphids appeared to have died. In many samples I found tiny obviously long dead aphids.
  The same was true for the Thionex, but more of the eggs appeared to have hatched than with Talstar. In most cases the fall applied Thionex is not giving adequate control of twig aphids. In fact, Bryan and I have been following one field in Alleghany County. At this site, the grower applied Thionex this spring with a mistblower and got excellent control of balsam woolly adelgid. However, when we did beat samples just this week, there were plenty of live aphids. Apparently the BWA was controlled but not the BTA.
  Where Talstar was applied in the fall, we are seeing few problems with rust mites. Cinara aphids are by and large not present. There may have been control of spider mites as well, but the jury is still out on that one. Of all the fields I've been in, I've only seen one treated in the fall with Talstar that needs rust mite controls this spring.
  
• This week I evaluated where Bryan and I treated trees with either Prev-Am at 0.8% solution or horticultural oil with 2% solution on March 10. This was before the eggs started to hatch. The oil only gave about 75% control of the twig aphids. This was a treatment that people appear to have been sucessful with in Maine, but results are great here. Jeff Vance took me to another field in Yancey County that was treated about the same time with oil and there were live aphids and Cinara aphids both. At the field Bryan sprayed, the Cinara aphids were killed with the oil. A few of the trees appeared to have some burn with the oil where we sprayed.
  In the Prev-Am plot, I didn't find any live aphids this week and the Cinaras were also killed. There was no burn. We plan on treating some adjacent trees on Monday with Prev-Am at the high rate (0.8%), the low rate (0.4%), and lower than labeled rate (0.2%) to see how well twig aphids are controlled. There are certainly a lot of them in that field.
  Jerry is also planning on looking at Orthene at this site.
  
• Jerry Moody had a grower try Mavrik for rosette bud mite control last year. It seems to have worked well, so we plan on trying some ourselves in June.
  
• Bryan and I have also applied pre-budbreak treatments for elongate hemlock scale control. This is not the time of year I recommend, but since people are treating trees now, we thought we would see if it worked. We applied either horticultural oil at 2%, Prev-Am at 0.8%, dimethoate, Asana, or
  dimethoate+Asana. I'll let you know what we find in about a month.