Commercial spraying for Zimmerman pine moth and mountain beetle
We have four large Austrian Pine in our yard, and for the last several years have had them sprayed two times a year - usually late March and August. Last year they said we needed them sprayed three times a year because we also had the Mountain Pine Beetle. They want to spray tomorrow (tues, 3/29). The weather forecast calls for "breezy", and Wednesday for snow, rain, and wind. They have sprayed in high winds before, and I wonder how effective that is? Also, are three spraying a year necessary? I have one of CSU's bulletins on the Zimmerman, and it says to spray in early April or in August.
Arapahoe County Colorado trees and shrubs
Trunk sprays made during windy conditions can result in "overspray" where some or much of the spray ends up on non-target plants.
One spray yearly for Zimmerman is sufficient.
As for Mountain Pine Beetle - it is primarily found in native ponderosa pine or lodgepole pine forests. When it is found in urban landscape pines, it is usually in Scotch pine, and usually in urban-forest interface areas. Mountain Pine beetle is currently not as big a problem as it was 5-10 years ago.
So, its doubtful that your Austrian pines have Mountain Pine Beetle - UNLESS someone has brought infested pine firewood from foothills/mountain areas into your neighborhood.
The image suggests this yellowish sap ooze is not the result of Mtn Pine Beetle. And - it would take more than one "hit" for MPB to injure a large Austrian Pine.
It could be due to Zimmerman pine moth, although that is usually higher in the tree, usually at the junction of trunk and side branches. See photo.
It's also possible that some kind of physical injury caused the ooze of sap - perhaps a rock thrown by lawnmower, an errant practice swing with a 8-iron, a hailstone hit or ???.
Suggest you carefully scrape away yellow sap ooze with an old knife or putty knife. Look for any evidence of insect activity under the ooze area. You may see some insects gathered there that were just hanging out in the protected habitat created by the ooze.
Keep the area as dry as possible. Spray with an insecticide as directed in the Zimmerman pine moth fact sheet.
Water the pine's rooting area during dry snowless periods in winter months.