Every year we all hear about the need for a Fall (or for that matter Spring) fertilization. Your garden center mentions it, the garden channel has a blurb about it, in fact your landscaper probably has already fed the lawn. But do you really need to fertilize your trees?
According to Best Management Practices for Tree and Shrub Fertilization the most accurate way to determine if your trees need missing nutrients is to have three analysis done.
1. A foliar nutrient analysis to see what the levels are in the leaves. This would be a current determination or levels at the time the sample was taken.
2. A soil nutrient analysis to check the levels of nutrients and salts in the soil. Urban soils can be a bit salty and not that good depending on where you live.
3. A pH analysis to determine the acidity and alkalinity of the soil. A high or low pH can make it difficult for trees to absorb certain elements and may cause others to reach toxic levels.
This approach to fertilization is called prescription fertilization. The essential premise is to make sure your trees actually need to be fertilized. With a proper analysis you can find out what nutrients may be missing. This will help to set plant health goals and what fertilizer to use, if any. It's much like going to your doctor. Your doctor is not going to give you antibiotics without an evaluation or analysis of your health. The same goes for the tree doctor. We aren't supposed to give a tree something it doesn't require.
Also, the prescription fertilization approach is more environmentally aware. Why use a product that may be unnecessary and possibly harmful? It is well known that fertilizer run off causes problems to water ways, mucking up streams and river basins. (Look at the dead zone of the Mississippi Delta.) In addition, unneeded fertilization can make trees grow more quickly and then make them more susceptible to insect problems. And let's not forget the purse. Why waste money on something that may be unnecessary?
So before you consider your next fertilization treatment let's take a few soil samples, send them off to the lab and make an informed decision. If you are having your trees fertilized take a brake and reevaluate the approach to your tree care needs. Yes, your trees are valuable and proper care is important, but proper care is based on accurate information. As the tree owner you wouldn't you like to have your trees cared for properly, with reason and evidence, especially if it actually saves you money?
Feel free to call us with any questions. In the meantime, enjoy the rain. It seems we have turned the corner and the Earth has tilted toward Winter.
