Tree Disease and Insect Control

How Do You Save Your Tree From Infestations and Disease?

Most Common Tree Diseases in New Jersey

•  BLACK KNOT DISEASE - Determining if a tree has a black knot is fortunately very easy to detect. The eye is drawn to the swelling knot known as a gall. As these grow, they spread infection as they the release spores. Branches with black knot must be removed. This will prevent the spread of the disease. It is important to be cautious with the removal of infected branches as well as with the tool used for removing them. The disease can spread from both tool and branch. Branches must be disposed of and removal tools must be thoroughly cleaned.

• DUTCH ELM DISEASE - Dutch elm disease is a vascular wilt disease, it attacks the plant tissues which conduct water, sap and nutrients. Yellowing of wilting leaves in a section of a tree is an early sign of the disease. The leaves then turn brown as the branch dies. While only the crown may be infected at this stage, the disease can spread quite quickly through the rest of the tree. Often fallen leaves are strewn over the lawn in spring or summer, but symptoms often appear first in late spring or early summer. They can also occur any time during the growing season. The rate the disease spreads depends on the susceptibility of the tree. Trees that are infected can die in the season in which they become infected or over a period of serval years. If bark is removed, brown streaks can be seen along the sapwood of wilted branches. The earlier you start to treat the disease; the better as untreated trees will die rapidly.

• NEEDLE CAST - Needle cast diseases cause spruce trees to shed or "cast off" their older needles. Spruce trees then keep only the younger needles at the tip of the branches. This is a treatable disease even though it causes the tree to look as if it dying. It is treated with fungicide.

• SEIRIDIUM CANKER - Seiridium canker disease is another disease that can be treated with fungicide. It mostly affects Leyland and Italian cypress trees. It affects them during long, hot dry periods in the summer. The fungal disease affects all ages and sizes of trees. Cankers form on the stems, branches and in the branch axils (the upper angel between a leaf stalk or branch and the stem or trunk from which it is growing.) causing twig, branch or stem die-back.

• ARMILLARIA ROOT ROT - Armillaria root rot is a root rot disease. It starts in the stumps in rotting oak and maple trees and can spread to other trees through the root system. Infection can be presented by stunted leave growth, yellowing of needles and twig and branch die-back. White rotting fungus, including light or bleached wood can be a displayed symptom of all host trees. A licensed tree expert can manage this disease by removing the infected host trees.

• APPLE SCAB - Apple scab attacks leaves and fruit of apple and ornamental crabapple trees. This fungal disease is presented by yellowed spots on the top of the leaves and dark sports on the bottom. These leaves may twist, and wrinkle then drop in the early summer. On the fruit of these trees, scab-like marks will form on the fruit. Steps can be taken to treat the Apple scab tree and to prevent the spread of fungal spores to nearby trees.

Not all insects are harmful to trees. Some may even be helpful. Before making rash decisions on removing a tree, consult a licensed tree expert. Following is a brief list of harm insects that can harm your trees, but there are many more than these common few. Always check with an expert when noticing an unusual insect activity in your trees.



• SCALE - Scale insects latch onto branches and feed on the sap of the tree. They can be difficult to spot at first for they latch like a leech and stay there. You may not notice the scale insects, without a thorough inspection, until you have a large infestation. A good first sign, however, is yellowing on tree leaves. Another sign is parasitic wasps or lady bugs on your trees for they eat these “scale bugs." Infestations are important to address to maintain the health of your trees and the spread of the infestation.

• GYPSY MOTH - Gypsy moths were spread to North America by a French scientist who was attempting to breed a hybrid silk spinning caterpillar that was less susceptible to disease. It is considered one of the most destructive insects in the eastern United States. An infestation can cause partial defoliation, or complete defoliation of its host trees. They can starve a tree of essential sugar and carbohydrates leaving a tree weak and susceptible to disease, or just kill it entirely. This leaves tree to quickly become a tree hazard when infected with Gypsy Moths.

• ASIAN LONG-HORNED BEETLE - Asian long-horned beetle migrated to North America. It has infested and killed hundreds of trees throughout New Jersey. It likes hardwood tree, but prefers the common northeast maples, elms, willows, and birches. Their identified by a shiny black body with white spots, long antennae and are about one to one-in-a-half inches long. There are detected by leaving a dime sized holes in trees. Trees that have been breeding grounds for these beetles must be removed before more beetles can be produced.
  

THE EMERALD ASH BORER

The emerald ash borer (Agrilus planipennis or EAB), originally is from Asia, it is believed to have migrated to North America by wooden shipping pallets shipped here. The insect is identified by a small, shiny and green beetle. It can destroy large ash trees. An adult beetle usually emerges in mid to late May or depending on the warm weather, sometimes earlier. As the larvae feed under the bark of the ash tree, it disrupts the trees ability to transport water and nutrients. An infestation is easily spotted by bark splitting and die-back. With the presents of these beetles, our entire ash tree population is threatened and could result in the complete extinction of ash trees. Please report all sighting of this dangerous beetle to the NJDEP.

**POTENTIAL DISEASE ALERT**

OaK Wilt in Neighboring States May Travel to New Jersey

As a highly aggressive tree disease, oak wilt affects all types of oak trees. The most susceptible in NJ is their state tree, the red oak. A fungal disease, oak wilt has been attacking trees in neighboring states. If it does spread to NJ, the disease can cause significant harm to our tree population.

Please Alert the NJDEP immediately if you see any signs of oak wilt. Also consult a licensed tree expert to your location as quickly as possible to prevent the spread. Common symptoms consist of discoloration of leaves, wilt, defoliation, and the death of the tree.

The disease is spread by insects spreading fungus from infected tree to healthy tree. Do not attempt to replace the tree in the infected location for the disease is also spread via root connections. Breaking root connections with trenchers, hoes and rock saws can often manage the disease. The best way to treat is fungicide.