Insects - Self Diagnosis
- Discoloration, Drooping, Wilting, General lack of vigor in the affected plant.
Insects can cause considerable damage to trees and shrubs. By defoliating trees or sucking out their sap, insects retard their growth, weakening and sometimes killing them. By boring into the trunk and branches, they interfere with sap flow and weaken the tree structure to a point where it may be easily blown over by the wind. Insects may also carry disease by providing an entry way for fungi, bacteria and viruses.
It is important to remember, however, that many insects are beneficial rather than destructive; they help with pollination or act as predators of more harmful species. Therefore, killing all insects without regard to their kind and function can actually be detrimental to tree health.
Insects may be divided into three categories according to their method of feeding: chewing, sucking, and boring. Insects from each group have characteristic patterns of damage which will help you determine the culprit and the proper treatment. Always consult a tree care expert if you have any doubt about the nature of the insect problem or the proper treatment.
Chewing Insects eat plant tissue such as leaves, flowers, buds and twigs. Indications of damage by these insects is often seen by uneven or broken margins on the leaves or other affected plant parts. A few examples from this large insect category are:
Beetles and their larvae (grubs) The Mountain Pine Beetle is a bark beetle that has recently attacked our area
Webworms (Tent Caterpillars are the most common in Billings)
Sucking Insects insert a special beak into the tissues of leaves, twigs, branches, flowers, or fruit and then suck out the plant's juices. Some typical examples of sucking insects are aphids, mealy bugs, thrips and leaf hoppers. Damage caused by these pests is often indicated by:
Boring Insects are characterized by the tunnels they make in the wood of a tree as they eat through it. Because each kind has its own style and tunnel pattern, borers may be identified by their work even after they have left the scene. Eventually most borers eat their way into a tree, making a round opening out of which they eject a characteristic substance called a frass, composed of semi-digested wood.Trees infested with borers typically show a thinness of crown and a gradual or sudden decline in vigor. Conclusive symptoms are circular holes in the trunk or branches with frass and sometimes dripping sap, which forms a dark stain along the bark. Borer holes may be distinguished from other holes (such as those made by birds) because they are deep, irregularly located, and usually made at an angle, indicating tunnels underneath. (Sapsucker holes are very shallow and made in even rows.) When borers eat a tree's heartwood or sapwood only, they cause mostly structural damage which weakens the tree. Their tunnels also provide entry for other insects and wood-rotting fungi. Borers that eat the inner bark and the cambium directly destroy the tree's vital parts and kill it quickly.
The treatment method used for a particular insect problem will depend on the species involved, the extent of the problem, and a variety of other factors specific to the situation and local regulations.
Diseases can be classified into two broad categories:
- Those caused by infectious or living agents (Biotic)
- Those caused by non-infectious, or non-living agents. (Abiotic)
Examples of infectious agents include fungi, viruses, and bacteria. Non-infectious diseases, which account for 70 to 90 percent of all plant problems in urban areas, can be caused by such factors as nutrient deficiencies, temperature extremes, vandalism, pollutants, and fluctuations in moisture. Factors of non-infectious diseases can often produce symptoms similar to those caused by infectious diseases; therefore it is essential to distinguish between the two in order to give proper treatment.
Correct diagnosis of plant disease requires a careful examination of the situation and systematic elimination of possibilities by following a few important steps.
Identify the plant. Because infectious pathogens are mostly plant-specific, this information can quickly limit the number of suspected diseases.
Look for a pattern of abnormality. This can often provide key information regarding the cause of the problem. For example, if the affected plants are restricted to a walkway, road or fence, the disorder could be a result of wood preservatives, de-icing salts, or other harsh chemicals.
Always consult a professional if you have any doubt about the nature of the insect or disease problem as well as the proper treatment.