Thanks Peter and Burkhard for these updates.

    Based on what I saw in the Kentville area in 2021, and drawing from memory, a key factor may be continuity of soil water supply over time within the rooting zone.

    Reviewing the Kentville observations; I walked up Beech Hill Road, which usually has much water in wheel ruts until late summer and was astonished to find it mostly dry and bone dry as Beech became more common and at the height of land. All Beech at the height of land except saplings less than 6'? high were dead.

    On the other hand, leaves on the numerous small Beech in my North Alton woodlot (faces North) showed little or no discoloration all summer (Morristown sandy loam {grows Wire Birch up to 13" perhaps 16" in diameter}). In addition to high water holding capacity of soil there, the trees also are watered by downhill seepage.

    On another site SE of Palmeter subdivision, on a North facing slope Beech up to est. 14" diameter at stump and est. 100' tall had slight discoloration (perhaps wind damage) and seedlings est. 10-29' tall had no leaf discoration.

    On a third site, north facing seepy slope which feeds a small brook which I have seen off and on since 1960 always with some water Beech from est. 2" to 8" at ground level have continued to look fine.

    On a fourth site, my Pine woods in Cambridge (Cornwallis Sandy Loam) I was surprised to see a young Beech 10 to 15' tall growing well. The tilled land up slope is irrigated so there may be some sub-irrigation.  

    So I am convinced that continuity of soil moisture supply is a key factor which allows Beech to shrug off moderate leaf damage by this insect.

    So I will dust off a suggestion I made last year; there is an excellent soil survey map of NS issued roughly about 1980 which would help with respect to wild Beech. In urban residential areas soil maps may mislead due to crap fill hauled in. 

    The "Geotome" (aka shovel) works also.

    And guidelines; a root can not grow into dry soil, capillary rise can move water upward but only if there is continuity with depth of fine soil, feeder roots typically die over the dormant season and can grow again in spring only if soil moisture is adequate. Unless there are barriers to downward movement water moves straight down and not sideways. Water extraction by a deciduous tree starts near the surface and near the trunk and proceeds outward and downward.

    In closing, one more famous line of advice: "You can see a lot by looking"

Dave