Here you will learn how to survey for the presence of HWA
Biologically, the optimal survey period is from March to May, within an overall survey period running from November to June. Plan to complete this survey in April and May.
Bring a notebook and a GPS if you have one, and a camera or your smart phone..
Examine the maps provided (Maps of Hemlock stands in Kings County) and select a convenient stand.
Cursory Survey If your intent is to conduct a cursory survey, walk throughout the stand, covering as much of the stand as possible and examine branches on trees if you can reach them or pick up broken off branches on the ground and examine the underside for HWA woolly sacks. Record in your notebook how many trees and how many branches you examine and how many have presence of HWA. Take pictures of infected branches. Send the information on your survey plus pictures to email@example.com
Proper Survey This sampling method is best suited for large stands (10 ha), but smaller stands can be examined.
1. Briefly recon the site and roughly ascertain the location of four blocks that encompass the stand (see figure below).
Figure. Example of zig-zagging pattern for use in larger hemlock stands that have been divided into four blocks.
2. Go to a central point of the first block and arbitrarily select the first tree to examine. Trees should have two branches that can be reached from the ground, but a second branch on an adjacent or nearby tree is acceptable or if branches cannot be reached, look at recently broken off branches on the forest floor.
3. closely examine the underside of the terminal foliage for the presence or absence of white woolly masses at the base of hemlock needles of two branches. Record presence/absence of HWA. If present take a picture of the branch with the woolly sacks.
4. go to the next location 25 paces in the direction indicated in the figure above and repeat steps 2 and 3. Repeat until 25 trees have been examined. If you are finding several branches with woolly sacks you do not have to take a picture every time you find one.
5. Go to the next block and repeat procedure.
6. Continue until the four blocks and 100 trees have been examined.
Compute the level of infestation as indicated below: Percent infested trees = (number of infested trees) / (number of trees inspected) × 100
Send your data plus pictures to Ron.Neville@inspection.gc.ca
Visit only one site at a time to minimize the spread of HWA. Ideally wash your clothes after a visit to a site, and/or you can use a lint roller to get rid of any crawlers potentially on your clothes.