I receive many calls during the year about tree health, so I tend to write about trees more than any other subject. Right now, many of the trees in the county are looking a little stressed. There are several different issues that your tree may be trying to handle right now, so to help your tree; finding out what is wrong is the first step to helping it stay healthy.
One of the major issues we do come across in the County is Iron Chlorosis. That does not mean that the iron is not present in the soil, but the pH levels are high. This ties up iron in the soil, not allowing the trees to access it. Since many of the trees in the area have compromised root systems because of the drought, it makes it even more difficult for the trees to pull iron out of the soil, causing some trees, such as Maples and Pin Oaks to have a yellowish cast to their leaves first, then branch dieback, and possibly death if it is not treated. There are many ways to help treat iron Chlorosis. You can use a chelated iron source containing EDDHA such as Sequestar 6%, drenching it into the soil, or you can inject iron directly into the cambium of the tree, or spray an iron solution directly onto the leaves. You can also treat your soil with Sulfur. The idea is to acidify a small quantity of soil so the tree can absorb the iron it needs from these areas. This will only work on non calcareous soils. A mixture of equal parts of iron sulfate and elemental sulfur are mixed together, and the mixture is placed in holes made under the drip-line of the tree. K-State Research and Extension has a publication that will help you decide which treatment is the best for you if your tree is suffering from Iron Chlorosis.
Other reasons for trees to look stressed at this time of year are insects. Identification of the pest is essential to knowing if and when to treat for the insect. Some insect damage will kill your tree, and some is just an esthetic nuisance. Borers, a secondary pest caused from drought stress can girdle the tree under the bark, cutting off its ability to bring essentials up or down the tree. Elm Leaf Beetles, on the other hand, give Elms a burned look from consuming the liquids out of the leaves, causing them to look scorched. For each insect, the treatment may be different, so it is better to ask someone for identification. Then if you need to treat your tree, you will know what to use so that the treatment is the most effective one you can use for your situation.
The most important resource for keeping your tree healthy in the first place is water. Adequate water will keep the roots healthy, and allow the tree to bring up nutrients from the soil allowing the tree to get what it needs in the form of water, oxygen, and minerals. The best practice for watering an established tree is to water 8-12 inches deep from the trunk to the drip-line of the tree. Most roots are located in the top 6 to 24 inches of the soil to better access the oxygen and minerals that are more abundant in that region. Giving your tree a deep soak every two to three weeks will keep the balance of air and water and helps the tree stay healthy. Remember to take into account if there have been any significant rains. If we have had a lot of rain, you may not need to water right away. A good way to check is to use a long screwdriver or something similar and slide it into the ground around your tree. Once you hit dry soil, you will not be able to push it any farther using just your own power. If it will go in twelve inches, then you may not need to water right away.
Alicia Boor is the Agriculture and Natural Resources agent for Barton County K-State Research and Extension. You can contact her by e-mail at aboor@ksu.edu or calling 620-793-1910