April 27, 2005
Christmas Tree Scouting Report -
Welcome to the Christmas Tree Scouting Report for the week ending April 27, 2005. The next report will be available after 5 PM on Wednesday, May 4th. To receive a FAX of this week’s message, please call (814) 865-1636. If you have pest activity to report, or would like to receive this report by e-mail, please leave a message at 717 772-0521 or e-mail email@example.com and your name will be added to the distribution list.
Eggs of the white pine weevil were found in the terminals of white pine in Adams and Perry Counties. The numbers of weevils being caught in emergence traps are decreasing at our monitoring site. Many growers that have been trapping for the weevil have applied two sprays by now and some are considering a third. Once the female weevils begin to lay eggs under the bark of the terminal leader, chemical control of the larvae that hatch from these eggs is not effective. By the time the larvae begin to feed the only method of control is cutting out the infested terminals and removing them from the field to be destroyed. The next generation of weevils will emerge from infested terminals as early as late July. All infested material should be removed and destroyed by this time.
Some growers will be applying their first application of fungicide for Rhabdocline needle cast on Douglas fir this week. In Adams, Berks, Bucks, Dauphin, Cumberland and York counties infected areas on the undersides of needles were swollen and beginning to split open exposing the orange spores. To determine if it is time to begin spraying at your farm, look to see if 10% of the trees in the field have one or more broken buds per tree. Remember smaller trees break earlier and so do the buds on the south side of trees. The active ingredient used to control Rhabdocline, chlorothalonil, is a protectant fungicide, which needs to be on the new growth before it is exposed to infectious spores.
Another needle disease that is becoming more wide spread in Pennsylvania is spruce needle rust. This needle rust was first detected in Luzerne County in 1991 on blue spruce and has since been detected on other spruce species including Serbian and Sitka spruce. This rust has spread throughout the northeastern counties and as of last year was also found in Bucks, Lancaster and Schuylkill Counties. In 2005, Cumberland County was added as an infected county. To check your spruce, look for yellow banding on the top and bottom of needles in late fall. In early spring these yellow bands take on an orange color and swell as the fungus gets closer to the infectious period, which coincides with the period of new growth. This needle rust follows the same control recommendations as Rhabdocline on Douglas fir. The key to controlling this disease is to protect the newly emerging needles.
Douglas fir needle midge adults began to emerge at the end of last week in Bucks and York counties. There were a few midges in the traps but some could be seen flying around the branches. The cool and rainy weather over the weekend set emergence back. Much more activity was seen this week after the temperature rose. When buds were examined this week, eggs were found between the bud scales at both sites. The female midge deposits her eggs soon after emerging so the window of control is narrow and chemicals need to be in place as soon as emergence is detected. One grower is conducting spray trials to test for timing of application and effectiveness of two chemicals labeled for midge control. Results will be shared as they become available.
When infested grand fir branches from Adams County were examined for elongate hemlock scale crawlers, only two crawlers were found. This site will be monitored as the temperature warms for more crawler activity.
Pine spittlebugs are becoming active on Douglas fir in Adams, Cumberland, and York counties. Spittlebug nymphs and adults extract sap from shoots of Christmas trees and cover themselves with a frothy white spittlemasses. Unless abundant they seldom do harm. However, feeding wounds from the spittlebug can create a pathway for Sphaeropsis fungus to invade weakened trees, especially pines, and kill branches or whole trees.
Eggs laid by overwinter pine bark adelgid females are beginning to hatch on white pine in Adams and Berks counties. No hatch was found on white pine in Schuylkill County. Look for tiny pepper-size nymphs on the new candles. Mature trees are seldom harmed but smaller trees may be stunted or killed. This adelgid can be easily controlled when immature and before they cover themselves with a protective white waxy material.
The Cooley spruce gall adelgids on blue spruce and Douglas fir and the eastern spruce gall adelgids on Norway spruce have all started to lay eggs under the white waxy material and as soon as the new buds open eggs will begin to hatch. The spring control period for these adelgids is over and the next time for control will be in the fall.
The next report will be after 5:00 pm on Wednesday May 4th.