Flowering Cnerry Tree Blite - Ask Extension
About 6 years ago we planted three flowering cherry trees is the tiny city garden across from our home in Bolton Hill, center city. This Spring when a...
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Flowering Cnerry Tree Blite #307479
Asked March 16, 2016, 3:52 PM EDT
About 6 years ago we planted three flowering cherry trees is the tiny city garden across from our home in Bolton Hill, center city. This Spring when all the other neighborhood trees started to bloom, we noticed that there were hardly any blossoms on the trees. Upon inspection, we notice that, since last year, all three have developed a nasty blite on the bark and it has consumed them. The trees seems to be blistered, rough, and have unhealthy looking bark. Thank You! Thom
Baltimore City County Maryland
Expert Response
Without a photo we can only guess as to what is affecting your cherry tree. One thing that comes to mind are lichens, which do not hurt trees. https://extension.umd.edu/hgic/lichens-trees-and-shrubs Another is black knot. https://extension.umd.edu/hgic/black-knot-trees If it is neither of these problems, send us photos. vw
Thank you for your response. I've attached 3 photos. You can see from the 1st photo that the foliage is unusually sparse, which got my attention. The 2nd and 3rd photos are close-ups, and they show the ten of thousands of blisters on the bark. The camera doesn't do them justice, but perhaps you can magnify the images on your side. The blisters are definitely new for 2016, and super strange. What do you think? Are they too far gone? Thom
Your trees have a scale infestation, the worst one our entomologist has ever seen. The "blisters" are the females, but in addition to them, much of the bark is covered with the males. The species of scale on your trees is Lecanium scale. This is a native insect and our other native predator insects usually eat enough of them to keep their numbers under control. As your trees get older and stronger, it may cease to be a problem.
Scale insects, when they are in their adult stage, cover themselves with a covering like a turtleshell in order to protect themselves. Insecticide sprays cannot penetrate the covers, but you can spray them with horticultural oils which smother the scale. Also, in their juvenile stage--called crawlers--they do not have a covering and thus are susceptible to insect sprays.
What you need to do now is this: Scrub the bark of the tree with a stiff-bristled brush (not wire) to knock the covers off. Then spray all the scale-infested bark with a horticultural oil. The oil must NOT be diluted for a dormant oil rate, because your tree is not dormant (i.e. it is actively growing leaves now). The oil must be diluted for an actively growing tree. Read the label carefully for instructions on how to dilute it.
In late May-early June, the eggs will hatch and the young crawlers will start crawling around. You can put bands of double-sided sticky tape on the tree to help you see them (they'll get stuck). At that time, spray with horticultural oil again. You can spray more than once if you're not sure about the timing.
Young trees growing on poor sites and newly transplanted trees are the most susceptible to an infestation of this scale. Be sure to water your trees during dry spells, and apply mulch no more than 2-3" deep and keep it a couple of inches away from the trunk. Never pile mulch on trunks.
Here are photos and more info on scale: http://extension.umd.edu/hgic/armored-and-soft-scales-trees-and-shrubs
ECN
Scale insects, when they are in their adult stage, cover themselves with a covering like a turtleshell in order to protect themselves. Insecticide sprays cannot penetrate the covers, but you can spray them with horticultural oils which smother the scale. Also, in their juvenile stage--called crawlers--they do not have a covering and thus are susceptible to insect sprays.
What you need to do now is this: Scrub the bark of the tree with a stiff-bristled brush (not wire) to knock the covers off. Then spray all the scale-infested bark with a horticultural oil. The oil must NOT be diluted for a dormant oil rate, because your tree is not dormant (i.e. it is actively growing leaves now). The oil must be diluted for an actively growing tree. Read the label carefully for instructions on how to dilute it.
In late May-early June, the eggs will hatch and the young crawlers will start crawling around. You can put bands of double-sided sticky tape on the tree to help you see them (they'll get stuck). At that time, spray with horticultural oil again. You can spray more than once if you're not sure about the timing.
Young trees growing on poor sites and newly transplanted trees are the most susceptible to an infestation of this scale. Be sure to water your trees during dry spells, and apply mulch no more than 2-3" deep and keep it a couple of inches away from the trunk. Never pile mulch on trunks.
Here are photos and more info on scale: http://extension.umd.edu/hgic/armored-and-soft-scales-trees-and-shrubs
ECN
