Showing posts with label galls. Show all posts
Showing posts with label galls. Show all posts
Large-leaved Linden mite leaf galls
Spruce Pineapple or Pseudocone galls
"Pineapple" or "Pseudocone" galls occur on several species of Spruce trees including; Norway, Sitka, Englemann and Colorado blue. They are a chemically induced growth distortion caused by a small aphid like insect called a "Pineapple gall adelgid" that lays up to one hundred eggs, one of each of up to 100 Spruce needles at the tip of the new growth. When the new aphids hatch they begin to suck on the soft new growth needles which in turn provokes the gall like growth reaction as the needles begin to swell and end up morphing into each other.
At first glance these pineapple shaped galls can be easily mistaken for cones (thus the name "pseudocone"). The image above shows a newly formed gall beside a seed cone on an Englemann Spruce tree.
The inside of the gall is rather fibrous and "woody" with small pockets. Spraying the galls to get rid of the insects is to no avail as the aphids are usually well protected inside the gall structure.
The pineapple galls end up drying out and dying leaving a dark brown carcas behind that does not do any real harm to the tree but can stunt growth to the branchet it has grown on. In some instances the branchlet will keep growing past the gall while in others the gall halts the growth all together for that branchlet.
Olive tree tuberculosis
Olive tree tuberculosis is a disease found on Olive trees in Spain that is caused by the bacteria Pseudomonas syringae. When this bacteria is introduced into a wound on the tree caused by hail, pruning or by the beating of the branches to harvest the Olives it results in the formation of a gall like formation that starts off round and light brown and then grows into an irregular wart shaped canker that ends up with a dark brown color and very hard.
There is no cure for Olive tree tuberculosis other than careful pruning with clean tools. Most often however the condition is not treated as it does limited harm to the tree. An infected tree can often continue producing for a number of years after becoming infected. The best prevention seems to be to use clean tools to avoid spreading the bacteria in the process of pruning and to try to avoid excessive damage to younger branches during harvest.
The dark objects in the tree below are not olives but rather cankers caused by the Pseudomonas syringae bacteria.
Red-Pea Galls on Quercus pyrenaica Oaks
This is a collection of images of Red Pea Galls taken from one Quercus pyrenaica tree (In English this tree is called the Pyrenean Oak although in fact this species is not hardly found at all in the Pyrenees mountains but rather in central and southern Spain. All these images were taken on the same day and depict the galls in their stage of formation. Another name for these is Red Currant Galls. In a previous post I have blogged about the "Apple Galls" associated with the Pyrenean Oak as well.
I found these pea sized galls on a tree in the Spanish region of Extremadura in the province of Cacares near the small town of Logrosan. I was a bit puzzled at first because the galls did not look anything like the apple galls or the marble galls that I am familiar with. I knew that some galls formed on the reverse side of some Oak leaves but on these trees there were numerous galls on the tree flower. The image below is of a cluster of these galls that formed on a flower and continued to form even after the flower had released most of its polen.
Suspecting that they were galls I cut one of the larger ones open and found the larvae of what I believe is the Cynips divisa wasp inside. See image below. I also collected a few and placed them in a jar to see if I can get a look at what the wasp looks like when it emerges from the gall.
The images below are of these same galls when they form on the undersides of the leaves.
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