So what are all these people doing? Evaluating balsam woolly adelgid (BWA) control of course!
On June 28 of last year, I reported treating some Frasers at the seed orchard near Mount Rogers with Safari using either a soil or trunk application. See post.
Safari (which is still not clearly labeled for Christmas tree application by the way), can be applied with many methods. It can be sprayed on the foliage. It can be applied to the soil. It can be sprayed on the trunk.
We've seen Safari work very well for BWA control spraying the foliage, but these last two methods have been looked at more thoroughly for hemlock woolly adelgid control, though there has been some work conducted in Connecticut by Dr. Richard Cowles looking at elongate hemlock scale control in Fraser fir. To my knowledge, Cowles hasn't looked at BWA control with Safari.
Safari is a really good systemic. But for it to control BWA when it is applied to the soil it would mean that it was taken up by the roots and moved from the vascular system into the tree bark where the adelgids are feeding. With a trunk application, it has to make one more move -- from the bark into the vascular system and back out to the bark throughout the tree.
Two years ago when Jeff Vance and I tried soil applications of Safari, it seemed to work. But there was also a lot of rainfall at the time.
Last summer it was really dry. When we went back to Virigina in the early fall we didn't see any control with the soil or trunk applications. But I was hoping that control would come later, and last Friday, June 17, I went back to make more observations. Brad Edwards and Teresa Herman came with me and helped me collect samples.
The following pictures are of Teresa climbing up above where the Safari trunk applications were made to get a section of bark, and me looking at the bark samples. (I poke the adelgids with the tip of a pocket knife while looking at it with a magnifying lens).
This time we did see some control with the Safari, but only at the highest rates. We also only saw really good control with a soil drench using the highest rate of Safari, and not with the trunk application (which is of course far easier).
There were a couple of problems with this little study. The first was the lack of rain. There wasn't much after the applications were made, so I would like to repeat the study to see if we can get better results. Also, we might not have used enough water with the trunk applications.
But, even if these work, the rates are rather high. The high rate for the Safari trunk spray is 24 ounces in 1 gallon of water. If you use the recommendations which Valent has for HWA control, you would use only 12 ounces in a gallon, but then apply 1 quart of this spray for a tree that has a 10 inch trunk diameter. That gives a rate of 3 ounces Safari per 10 inch trunk diameter. The rate on the soil drench is 1 to 4.2 ounces per 10 inch trunk diameter. And remember that you can't exceed 2.7 pounds Safari per acre per year -- but then at $115 a pound, who could afford it? With these seed orchard trees, you would quickly exceed the rate.
The foliar sprays are 4 to 8 ounces per 100 gallons -- much more affordable and probably just as easy to do. Perhaps we can get by with a bit less coverage and still get control.
In any case, keep looking at this blog for more updates on how Safari is working with different application methods and timing.
|We had a visit from some Mount Rogers ponies on Friday!|