Remember our concern about the mistletoe? (https://wordpress.com/view/tonytomeo.wordpress.com) You might think that everyone would be pleased to see it gone. Yet, there is the concern that whatever killed the mistletoe might kill something else. That is what happened when the SODS killed so many coast live oaks after being ignored for a long time in the tan oaks. We were aware that the tan oaks were dying, but because the trees were so unpopular, we were not too concerned about it.
Now the box elders are dying around Felton. It is hard to say how widespread the problem is because it has not been investigated yet. Like tan oaks and mistletoe, the native box elders are not exactly popular trees. They do not even make good firewood. We only use them as firewood to get rid of them. However, when so many are die, it leaves big holes in the forest canopy. This is not really a problem, since the forest will have no problem filling the holes in, but it certainly gets our attention. Will the disease or insect pathogen that killed the box elders kill something else next?
The trees seemed healthy as they defoliated last autumn. They were bare through winter when the San Lorenzo River came up higher than it had since 1982. A few box elders got taken away by the River, along with all sorts of other riparian trees from the flood zone, but that is to be expected. Then, after the River receded, many box elders that were in the flood zone did not foliate in the spring. A few foliated, only to have their new foliage shrivel and die shortly afterward. Some of the dead trees became infested with boring beetles. All of the dead trees deteriorated rapidly through summer, and some have dropped big limbs or fallen over.
What is happening with the box elders could be completely normal, and caused by an endemic pathogen; but it makes one wonder. There are so many new insects and diseases being brought in with plants arriving from all over the world, without any regulations to limit the spread of such insects and diseases.