Chinese elm, Jacqueline Hillier variety tends to do that -- other varieties much less. I think they are called adventudinous buds (did I get it right?) -- potential branches, not insects. You can gently rub them off, if you don't like them but be careful not to damage the bark. The tree will continue to produce them. Looks like a healthy tree to me.

Is it scale? (suction cup type insects that dont appear to be able to move, they are often brown, and if you scrape em off, you can see little white granules come out of em' sometimes? I had those attack my yucca last year. I take a q-tip or a washcloth and pour rubbing alcohol on it and scrub them off, it takes some time, but each time you do it, there are less and less. In fact, the only way I could have access to the scale in the leaf crotches of my yucca was to put the alcohol in a mister and spray the hole tree and even fill up the leaf crotches.

bboy, I've searched and haven't found anything that resembles the problem. What are the long brown scaley structures all along the twigs? You can see them in the picture. They are all over the branches and all over some of our trees too. Up until now I thought they were harmless.

As mentioned earlier, there is already some resistance present in the American elm population. Several resistant trees have been identified (showing various degrees of resistance), and there are surely more growing in the wild that have not been identified. Evolution is defined as the change over time in the genetic variation in a population. If some heritable phenotype (characteristic) becomes more or less prevalent in a population, evolution has occurred. In the case of elm trees, resistance to DED has certainly become more prevalent, since such a large percentage of susceptible trees have died. So, evolution has occurred. In this case, it does not take very long, since the genetic variation for resistance was already present in the population. Several resistant cultivars are available, and they are being planted by homeowners and parks all over the place. Pollen from these trees will surely speed up the distribution of DED resistance into the wild populations. You are correct that susceptible trees reach reproductive age before they succumb to DED. It is possible that new mutations which confer resistance will arise in that segment of the population, but there is no telling how long that will take. Such an estimate would require a lot of information that is just not available. In any case, I suspect this path wil be much slower than the one facilitated by the widespread planting of the various resistant cultivars. WRT to the DED genome project, I suspect that is more likely to lead to treatments for susceptible trees, rather than the development of DED resistant trees. An interesting quote from the link above: "itâÂÂs only a matter of time before most the elm trees are gone". I've got some news for you.....most of the elms are already gone! Alex