Extension Educator, Horticulture
There is a smorgasbord of things to worry about these days. You could worry about the fattening little things on the dessert table or the overwhelming meat and potatoes things. Or better yet, forget the smorgasbord. Go on a picnic with your sweetie, lay in the grass and watch the clouds drift by.
Luckily there are few occurrences in this world that may first seem alarming but are actually a normal cycle of the landscape.
This time of year it is common for white pines as well as other pines to lose their old interior needles. In autumn the needles go from yellow, straw to brown colored. Since they seem to do it quickly, it can be quite alarming. As long as the new needles on the ends of the branches remain green, there is no cause for alarm. Spruces and firs also lose their older needles but the interior older needles tend to just thin out over several years rather then a one-time fall shedding.
Arborvitaes are common evergreens with scale like needles on flattened branchlets. In fall arborvitae will also lose the older interior branchlets which first turn brown before they drop.
Sometimes people may notice green plantlike things growing on the sides of tree trunks. These are not some sort of parasite sucking the life out of the tree, but the lovely and under appreciated lichens and moss. Lichens are quite fascinating. They are actually a symbiotic union of two organisms, a fungus and a blue or blue-green alga. Only a microscope can distinguish where one ends and the other begins. The alga through photosynthesis provides carbohydrates and vitamins while the fungus obtains the necessary water and minerals. Both survive in a mutually beneficial arrangement.
The tree trunk or rock where the lichen has attached is neither hurt nor helped from the lichen. It's just the landing pad. Lichen can be quite beautiful and varied. Some may be flat or look leafy like kale and maybe red, green or blue green. Moss can also be found on tree trunks but also does no harm to the tree.
Some twigs and leaves especially those of maples, oaks, hackberries and cherries have odd-looking bumps, warts and growths on them. The bumps actually have great names such as maple bladder gall, roly-poly gall on oak, succulent oak gall and hackberry nipple gall. Some of the bumps—like the ones on maples—are bright red and pretty in a weird sort of way.
Galls are growths on leaves, stems and twigs of many different plants. Galls can be created by insects, mites, bacteria, fungi and nematodes. Most common galls are caused by insects and mites.
Galls are actually created by the plants themselves in response to feeding or egg-laying by certain species of insects and mites. As gall-making insects feed or lay eggs, usually in early spring, they create mechanical damage. The damage and/or the insect saliva initiates the production of plant growth hormones. These hormones produce abnormal cell growth that results in the development of the galls.
Oaks can have numerous types of galls. Out of the over 800 species of gall making wasps in North America, 731 of them attack oaks. Oak deformities are of various sizes, shapes, and colors on leaves, twigs, flowers, acorns and buds. Galls are so commonly found on oaks that many people think the galls are typical parts of the plants. Some early botanical drawings actually show galls as part of the normal plant.
The good news about galls is the majority does little or no damage to trees. The trees are just well accessorized. Generally there is enough unaffected foliage for the trees to remain vigorous and there is one less thing to worry about.