Eastern White Pine

Set white pine in non-compacted sandy or loamy soil with good drainage and a pH between 5.5 and 6.5. Keep it well back from roads, driveways, and drain fields that get winter salt, and off heavy clay or any spot where water stands. Almost every case of white pine decline traces back to the site rather than a pathogen - the tree does not grow well and often dies on clay or where soil pH runs above 7, and its roots are unusually intolerant of salt, compaction, and moisture extremes.

In spring, when orange blisters erupt from swollen bark, scan branches for cankers. Cut any cankered branch at least six inches beyond the visible symptom on the trunk side, taking it back to a branch union, and never remove more than a third of the canopy at once. On young trees of five to seven years, also strip the lowest branches, working up to no more than a third to half the tree's height and repeating every other year until the lower eight or nine feet of trunk are clear. If a canker has already reached the trunk, the tree cannot be saved by pruning. Cronartium ribicola infects needles on the lowest, dampest branches and grows toward the trunk over years, so a branch cut before the fungus arrives at the main stem ends the infection - but a trunk canker eventually girdles and kills the tree. Removing low branches takes away the humid infection court where the spores land.

If you want to hold this pine's size, pinch or cut the soft new candles back while they are still elongating - the moment to do it is when this year's needles are about half the length of last year's. Do not cut branches back behind the current year's growth. Pines set a whorl of buds only at the tip of each shoot and form no lateral buds along old stems, so a cut behind the candle leaves a stub that can never push a new branch. Pinching while the shoot is still growing leaves time for it to set terminal buds for next year.

Start in the first warm days of early spring, as soon as the ground thaws and warms past about 50 degrees F — in most of the range that is late March to mid-April, well before the leader looks like anything is wrong. Examine the top 10 to 12 inches of the topmost leader, right up under the terminal bud cluster, for glistening pin-sized droplets of resin. Check the leader again a week later, because those punctures are the only warning you get. Overwintered adult weevils climb the leader to feed and cut egg sites just below the terminal bud, and a female deposits an average of 100 eggs. The resin beads are the tree bleeding from those punctures - by the time the leader curls in summer, the season's growth is already lost.

If this tree has been weeviled before, spray bifenthrin, permethrin, or cyfluthrin on the terminal leader and upper trunk in early spring, around 25 to 65 growing degree days base 50 - roughly when forsythia blooms nearby, and as soon as resin droplets show. A second application two weeks later maintains coverage. Spray the leader and upper trunk only, never the whole tree. The insecticide is aimed at overwintered adults during the short window when they are climbing the leader to feed and lay eggs. Once eggs hatch, the larvae are under bark where no contact spray reaches them.

When a leader wilts into a curled shepherd's crook and turns yellow-red, cut it off well below the dead tissue and burn or bag it - do not leave it on the ground. Then pick one live lateral shoot in the top whorl to become the new leader, and cut the remaining laterals in that whorl back by at least half. The larvae are still finishing under that dead bark and will chew out as new adults in late summer to overwinter in the duff and attack again. Removing the leader early takes the brood with it, and shortening the competing laterals lets a single shoot take over instead of leaving a forked, multi-stemmed tree.

In early summer, look for older needles yellowing and browning and then shedding, leaving thin tufts of only the current year's growth at the branch tips. If it recurs, thin crowded groves and limb up to move air through the canopy, and remove dead and diseased branches. Fungicides are rarely worthwhile on a landscape white pine because the damage you see was set a year earlier, and the right product differs by which pathogen you have - identify it through your county Extension office before spending on any spray. Brown spot needle blight, Bifusella needle cast, and Dooks needle blight all infect the new needles during wet weather while they are elongating from May to July, but the browning does not appear until roughly a year later - so what you are seeing is last year's wet spring, and the main lever you have is drying the canopy faster.