Voyle: Trees may be beyond help
Q: I need to know what to do with my evergreens. They have steadily lost needles for several years. They are some kind of a spruce pine, but all I know is they are about 20 feet tall. Over half of the needles are brown or fell off. Can I have the trees injected with a pesticide into the trunk to fix the problem? How do I fix them?
A: You have to know what your problem is to know what to do.
First order of business is finding out what kind of an evergreen you have. There are no spruce pines. That’s like saying you have a dog monkey. There are none.
If the trees are pines, needles grow on twigs in groups, either two needles or five needles in a group. White pines have five-needle clusters or fascicles. Red, Scotch and Austrian pines have two needles to a fascicle. Spruces and firs have needles attached to twigs as individuals. There are no groups.
If you look at a spruce, the needles are spread almost equally around the twig. A fir will have most of its needles on the top of the branch and very few on the lower portion. Once that is determined, it limits the kinds of diseases or insect problems to the kind of evergreen.
But it is important to recognize two things. If the trees have lost half or more of the needles they should have, saving them is going to be almost impossible. They are damaged enough that often treatment has no effect.
Evergreens, in general, are not candidates for trunk injection. Injected materials do not move in the evergreen’s sap like it would move in a deciduous tree. That basically means that the products will not give any results in an evergreen.
If the evergreens turn out to be blue or white spruce, Rhizosphaera needlecast is a huge problem without a good solution.
Find out more before making any decisions.
Q: I have rhubarb plants that have been growing in the same place for 25 years. They are growing maybe 10 feet away from a big Scotch pine. The plants are always spindly with few leaves and then get some flowers and the plants disappear by July. Have the rhubarb plants stolen all the nutrients or has that Scotch pine done it? Should I buy more plants or cut the tree down?
A: You’ve gotten it down to two miserable choices.
Rhubarb needs full sun to perform well. Take a look at how much direct, unbroken sun the rhubarb gets each day. If it is less than eight hours, it’s time for a change.
Digging up rhubarb and moving it makes much more sense that cutting down a tree.
If you are viewing both the pine and rhubarb as nutrient thieves, your thinking is not correct. All plants will take nutrients from the soil for growth. They are not robbing the soil. Nutrients can be added.
You can get a soil test and recommendation at: www.msusoiltest.com for $25. But the rhubarb may not be growing as well as it should because the roots have gotten to old and woody.
Find a full-sun location and mix one-third of the big holes you will dig with compost or composted manure. Wait until there are some small green leaves on the plant. When you dig up the root, you can use an ax or a hatchet to split the root into several chunks with each having a group of leaves.
Replant in the newly improved soil but set the root chunks at the same depth that they were originally but not touching each other. Put 3 inches of straw as mulch around the plants on the soil surface.
When the rhubarb produces flower stalks, cut them off immediately. The plant wants to make seeds and its job is done for the season and it shuts down.
But give the plants a year or two to look better in their new sunny location. Rhubarb can be picked in the spring but by June, the rhubarb party is over.
Gretchen Voyle, horticulture educator for the Michigan State University Extension – Livingston County, can be reached by phone at 517-546-3950.